JP2000272843A - Sheet conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a position of a document by providing the first and second driving sources respectively with the driving amount detecting means, and controlling the conveying of a sheet on the basis of the output of the detecting means of the driving source of the conveying means having the stronger conveying force when the sheet is placed over the first and second conveying paths. SOLUTION: A first driving source (conveying motor) M3 and a second driving source (reversing motor) M2 are respectively provided with a conveying clock sensor 114 and a reverse clock sensor 115 monitoring a document conveying speed and a document position during the conveying. In a case when the document is placed over a document conveying part and a reverse paper feeding-out part, the position of the document is grasped by counting the clock from the conveying clock sensor 114 when the document exists on a position where the conveying force of the document conveying part is larger than that of the reserve paper feeding-out part. Further when the document is advanced, and reaches a position where the relationship of the conveying force between the document conveying part and the reverse paper feeding-out part is reversed, the clock is switched to the clock from the reverse clock sensor 115. Whereby the position of the document can be accurately grasped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus provided in an image forming apparatus such as a copying machine and a laser beam printer, for conveying and placing a sheet material at a predetermined position of an image reading section.

[0002]

2. Description of the Related Art Conventionally, a document feeder such as an ADF (Auto Document Feeder) separates documents set on a document tray one by one and transports the separated documents to a predetermined position of an image forming apparatus. After the image formation, the document discharged from the transport unit is discharged to a discharge tray. To do this,
A plurality of motors in the document feeder are driven to feed the document. Each motor is disposed in each of the transporting units to be driven. It is known that a motor that prevents an original from being jammed (protecting the original) by increasing the speed of an adjacent transporting unit on the downstream side from the upstream side. Have been.

There is also known a motor that uses a DC motor as a motor and controls the conveyance of a document by detecting the feed amount.

[0004]

However, in a document transport apparatus in which adjacent transport sections have different speeds, there are the following drawbacks.

In a document transport apparatus in which adjacent transport sections have a difference in speed so that the speed of a downstream transport section is higher than that of an upstream transport section, the document is moved from the upstream transport section to the downstream transport section. When the document is transferred to the transport unit, the document may be slightly pulled. At that time, slippage has occurred in one of the transport units.

Since the feed amount is detected and controlled when the document is conveyed, if the feed amount on the sliding side is monitored and controlled, the actual movement amount of the document is different. , Can not control correctly. Therefore, not only can the original not be sent correctly, but also the original may be damaged in some cases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a document conveying apparatus in which adjacent conveyance sections are provided with a speed difference so that the speed of a downstream conveyance section is higher than that of an upstream conveyance section. It is therefore an object of the present invention to solve the inconvenience that the position of the document cannot be accurately detected and correct control cannot be performed.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a first transport means for transporting a sheet on a first transport path, and a first transport means for driving the first transport means. A drive source, first detection means for detecting a value proportional to the drive amount of the first drive source, and a second detecting means for transporting the sheet on a second transport path downstream of the first transport path in the transport direction. 2
Transport means, a second drive source for driving the second transport means, a second detection means for detecting a value proportional to a drive amount of the second drive source, and the first detection means Or a control means for controlling the conveyance of the sheet based on the output of the second detection means, wherein the control means controls the sheet to be conveyed by both the first conveyance means and the second conveyance means. When the sheet is conveyed between the first conveyance path and the second conveyance path, the conveyance of the sheet is controlled based on the output of the detection unit corresponding to the driving source of the conveyance unit on the side where the conveyance force is strong. Things.

The present invention also provides a first conveying means for conveying a sheet at a first speed on a first conveying path, and a method for conveying a sheet on a second conveying path adjacent to the first conveying path. A second conveying unit that conveys the sheet at a second conveying speed higher than the first conveying speed; and when the sheet is conveyed across the first conveying path and the second conveying path, Until the sheet is conveyed to the predetermined position of the second conveyance path, conveyance is controlled based on a clock synchronized with the driving of the first conveyance means. After being conveyed to the predetermined position, the second conveyance means is controlled. And control means for controlling the transport based on a clock synchronized with the driving of.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an example of an image forming apparatus main body (copier main body) to which a sheet conveying apparatus according to the present invention can be applied will be described with reference to FIG.

An image forming apparatus main body (copier main body) 801 includes a platen glass 10 as a document placing table, a light source 90
7, lens system 908, paper feeding unit 909, image forming unit 90
2, a sheet transport device (ADF) 802 for feeding the sheet document P to the platen glass 10, a sheet processing device for sorting the sheets on which images are formed and discharged from the copying machine main body 801 are provided.

A paper supply unit 909 stores cassettes S for recording and is detachably mountable to the apparatus main body 801.
1 and the deck 913 arranged on the pedestal 912
have. An image forming unit (image forming unit) 902 includes a cylindrical photosensitive drum 914 and a developing device 91 around the photosensitive drum 914.
5, a transfer charger 916, a separation charger 917, a cleaner 918, a primary charger 919, and the like. On the downstream side of the image forming unit 902, a transport unit 920, a fixing device 904, a discharge roller pair 905, and the like are provided.

The operation of the image forming apparatus main body 801 will be described.

When a paper feed signal is output from a control device (control means) 930 provided on the apparatus main body 801 side, a sheet S is output from a cassette 910, 911 or a deck 913.
Is fed. On the other hand, the light reflected from the light source 907 on the document P placed on the platen glass 10 is
The light is irradiated on the photosensitive drum 914 via the lens system 908. The photosensitive drum 914 has a primary charger 919 in advance.
The electrostatic latent image is formed by irradiation with light, and then the electrostatic latent image is developed by the developing device 915 to form a toner image.

The sheet S fed from the sheet feeding unit 909 is
The skew is corrected by the registration rollers 901, and the skew is sent to the image forming unit 902 at the same timing. In the image forming unit 902, the toner image on the photosensitive drum 914 is transferred to the transferred sheet S by the transfer charger 916, and the sheet S on which the toner image has been transferred is transferred to the transfer charger 916 by the separation charger 917. It is charged to the opposite polarity and separated from the photosensitive drum 914.

Then, the separated sheet S is conveyed to the fixing device 904 by the conveying device 920, and
04, the transfer image is permanently fixed on the sheet S. The sheet S on which the image is fixed is discharged from the apparatus main body 801 by the discharge roller pair 905.

In this way, an image is formed on the sheet S fed from the sheet feeding unit 909, and the sheet S is discharged from the apparatus main body 801.

FIG. 2 is a diagram showing an operation unit of the image copying apparatus 801. In the figure, reference numeral 201 denotes a power switch for controlling power supply to the entire apparatus. A reset key 202 operates as a key for returning to the standard mode during standby. 203 is a copy start key. 20
A clear key 4 is used to clear a numerical value. Reference numeral 205 denotes an ID key, which can prohibit a copying operation unless the operator inputs an ID code. A stop key 206 is used to interrupt or stop copying. 207
Is a guide key, which is used when one wants to know each function. Reference numeral 208 denotes an up cursor key, which is a key for moving a pointer upward on each function setting screen. A down cursor key 209 is a key for moving a pointer downward on each function setting screen. 210
Is a right cursor key for moving the pointer to the right on each function setting screen. A left cursor key 211 is a key for moving the pointer to the left on each function setting screen. Reference numeral 212 denotes an OK key, which is pressed to determine setting conditions on each function setting screen. An execution key 213 is pressed to execute a function output to the lower right of a display screen described later in each function setting screen.

Reference numeral 214 denotes a fixed size reduction key, which is used when a fixed size is reduced and copied to another fixed size. 21
Reference numeral 5 is used to select the same-size copy. A standard enlargement key 216 is used when enlarging and copying a standard size to another standard size. Reference numeral 217 denotes a cassette selection key for selecting a cassette stage to be copied. A copy density adjustment key 218 reduces the density. 219 is AE
This key is used to automatically adjust the copy density to the original density. Reference numeral 220 denotes a copy density adjustment key for increasing the density. Reference numeral 221 denotes a key for specifying sorting, stapling positions, the number of stapling points, and the operation of the sorter such as punching (drilling). Reference numeral 222 denotes a pre-heating key, which is a pre-heating mode O
Used for N / OFF. 223 is an interrupt key,
Use this when you want to interrupt during copying and make a copy. A numeric keypad 224 is used to enter a numerical value.

Reference numerals 225 to 251 and 253 denote keys for setting a mode for leaving the editorial office. 252 is a display screen,
The status of the apparatus, the number of copies, the copy magnification, and the copy paper size are displayed, and the mode to be set is displayed while the copy mode is set.

FIG. 3 is a sectional view showing the structure of the ADF 802. Reference numeral A denotes a document stacking unit for setting a document d on the stacking surface 1a of one document tray.

Reference numeral B denotes a document feeder which separates the uppermost sheet of the document bundle one by one by a friction separation method and conveys the document by a registration roller.

Reference numeral 3 denotes a pickup roller, and reference numeral 6 denotes a middle plate. Each time one document is fed, the pickup roller 3 is lowered above the document bundle, the middle plate 6 is raised and presses the document bundle against the paper feed roller 4 to start a paper feed preparatory operation. Thereafter, the paper feed roller 4 and the pickup roller 3 rotate in the CW direction (clockwise) in the figure by using the separation motor M1 as a drive source, and convey the document. The second and subsequent originals to be fed along with the uppermost sheet are stopped by the friction pieces 5 and stay in the original stacking section A. Thereafter, the document passes between the guide plates 8a and 8b and is guided to the pair of registration rollers 7a and 7b. Registration roller pair 7a,
7b is stopped when the leading edge of the document arrives, and is conveyed to the document conveying section C after forming a loop by conveying by the paper feed roller 4 and correcting skew.

The original conveying section C stretches a conveying belt 11 between a conveying roller 12 and a driven roller 14, and the belt pressing roller 1
The transport belt 11 is pressed against the platen 10 by 3a, 13b, 13c, and 13d. Then, the transport belt 11 is rotated by the drive roller 12 being rotationally driven by the transport motor M3. When a document enters between the transport belt 11 and the platen 10, the document is transported on the platen 10 by the frictional force of the transport belt 11.

When the original that has entered the original transport section C from the original feed section B is transported by the transport belt 11 to a predetermined position on the platen 10, the original is stopped by the stop of the transport motor M3, and the image is read by the original reading section 30. Is read. After the reading is completed, the original is conveyed rightward in the figure by re-driving the conveying motor M3, and is introduced into the reversing sheet discharge section D via the jump table 15.

If there is a subsequent document, the next document is conveyed to a predetermined position in the same manner as the preceding document by the rotation of the conveyance belt 11, and then stops with the stop of the conveyance motor M3 to read the document. An image is read by the unit 30. During the execution of the reading operation, the preceding document is turned upside down by the reverse discharge unit D, and the operation of being transported to the discharge stacking unit E is continuously executed. The reversing sheet discharging operation will be described.

The reversing sheet discharge section D has a reversing roller 19 and a conveying roller 22a as conveying means, and has a reversing motor M2 as a driving source. The reverse motor M2 is a motor that can rotate forward and reverse. The reverse discharge section D is provided with a transport motor M3
, And can operate independently of the document transport section C driven by.

The original is inverted by the transport belt 11 and the sheet is inverted
When entering, the deflecting plate 16, which regulates the paper path near the entrance, takes the position indicated by the solid line in the figure under the control of the solenoid SL2, and guides the document to the path between the deflecting plate 16 and the guide 17. The document is nipped by a reversing roller 19 and a roller 20 rotating in a CCW (counterclockwise) direction, passes through a path between the guides 21a and 21b, is guided by a guide sheet 24 made of a polyester sheet, and has a paper discharging roller 25 and a reversing roller. It is transported at the 19 nip. (This →
The path of →→→→→ is defined as the first transport path. )

When the trailing edge of the document reaches the point where it has passed between the guides 17 and 18, the reversing motor M2 rotates in the reverse direction and starts switchback conveyance of the document. Guide 18
Is arranged on the right side of the nip of the roller 20, so that the original is guided to the left side of the guide 18,
, Is turned over and discharged to the paper discharge stacking unit E.

Here, since the length L of the path of →→→→→ is longer than the maximum length l of the original in the transport direction of the apparatus, originals of all sizes can be used in the apparatus of this embodiment. During the reading operation of the succeeding document as described above (that is, while the conveyance belt 11 is stopped), the reverse discharge operation can be performed.

However, in the case where the size of the apparatus is not desired to be increased, for example, when the length L of the path →→→→→ cannot be set sufficiently long, as an example, it is assumed that the main size (which is frequently used) is considered. Manuscript size)
Is slightly longer than the length in the transport direction. For a document of a size larger than that, by reversely discharging the document by another method, it is possible to realize an apparatus although productivity is reduced. According to this method, in the case of a document whose length in the transport direction is longer than L, the document does not fit within the path of the reverse discharge unit D, and after the reading operation of the document on the platen is completed,
The document is conveyed in the path of →→→→→, and the drive roller 12 is rotated in the CW direction by driving the motor M3 before the leading edge of the document reaches the transport belt 11. Carry left. afterwards,
When the trailing edge of the document has passed, the document is transported in the reverse direction by rotating the reversing motor M2 and the transport motor M3 in the CCW direction. The original is discharged to the discharge stacking section E from.

By adopting the above-described configuration, it is possible to secure productivity with a document of a main size and to prevent the apparatus from being significantly increased in size. Become.

Next, a method for transporting a double-sided document according to the present embodiment will be described.

First, the original fed from the paper feeding section B to the original transport section C is stopped at a predetermined position on the platen 10 in the same manner as in the case of the single-sided original, and the original reading section 30 outputs the image of the first side. A reading is performed. Thereafter, the driving roller 12 and the reversing roller 19 are rotated in the CCW direction by the driving of the transport motor M3 and the reversing motor M2, and the original after the reading on the platen 10 is moved rightward on the platen 10 in the drawing. . Here, the deflection plate 16 is set at the position indicated by the solid line under the control of the solenoid SL2. As a result, the original enters the reverse discharge section D from the jump table 15 and
It is transported along the route of →→→→→. Here, before the leading end of the inverted document reaches, the rotation direction of the transport motor M3 is switched in the reverse direction, and the driving roller 12 is rotated.
Is rotated in the CW direction. When the leading edge of the document reaches, the document is conveyed on the platen 10 by the conveying belt 11 in the left direction in the figure. Then, the transport motor M3 is stopped so that the document stops at a predetermined position on the platen,
The reading of the image on the second side is performed by the original reading and the rib 30. After the reading is completed, the solenoid SL2 is controlled to switch the deflecting plate 16 to the position indicated by the broken line in the drawing, and the transport motor M3 and the reversing motor M2 are driven to drive the drive roller 12 to C.
By rotating the reversing roller 19 in the CW direction in the CW direction, the document is transported on the platen 10 in the right direction in the figure, passes through the jump table 15 and the left transport surface of the deflecting plate 16,
→ The paper is discharged to the paper output stacking section E via. in this way,
By using the reversing discharge path of the original for the reversing operation of the two-sided original, the path is shared, which leads to advantages such as downsizing of the apparatus and down-counting.

Further, in the present invention, as means for independently driving the document transport section and the reverse discharge section, each is driven by using a motor. However, the same effect can be obtained by using only one motor and providing a clutch in a transmission path for this drive.

FIG. 4 is a block diagram showing a circuit configuration of a control device of the sheet conveying device. The control circuit is a one-chip microcomputer (CPU) 100 with a built-in RAM.
And an EEPROM 103 for backing up adjustment values and set values of the sheet conveying device,
A ROM 102 is provided.

The input ports of the CPU 100 receive signals from various sensors. An output voltage from a slide volume for document width detection is input to an analog / digital conversion terminal of the CPU 100, so that the value of the slide volume can be continuously detected in 255 steps. Further, the registration sensor 116,
Document detection sensor 117, pre-cycle end sensor 11
8. The input from the inversion exit sensor 119 is also analog /
It is input to the digital conversion terminal and monitors the state of the sensor. Further, the output port of the CPU 100
Each load is connected via a driver.

The transport clock sensor 114 and the reverse clock sensor 115 detect the rotation amounts of the transport motor M3 and the reverse motor M2, respectively.
By inputting by 100, the transport speed and the position of the document are grasped. The detected rotation amount is also used for detecting an abnormality of each motor.

The ADF exchanges control data with the copier body via the communication IC 101 (FIG. 4). The received data includes a document feed trigger, a document exchange trigger, a document exchange trigger from the copier body. There is a paper discharge trigger and the like, and the transmission data further includes a document feed / replacement / paper discharge operation completion signal, detected document size data, a final document signal indicating the break of the document bundle, and the like.

A control procedure (control program) for controlling the ADF is stored in the ROM 102 in advance, and each input / output is controlled according to the control procedure.

FIG. 5 is a power supply system diagram of the sheet conveying apparatus. Power is supplied from the image forming apparatus main body 801 to the ADF in two systems, a logic system power supply and a power system power supply.
The logic system power supply includes the logic circuit 303 and the sensor 30.
5 and the like, and the power system power is supplied to the motor driver 304.
And used for driving a motor or the like.

Further, the power system power supply control circuit 301
On / off control of the power system power supply can be performed by a command from the PU 100.

(Transport Speed Control) In the present embodiment, FIG.
When the original moves from the original transport section C to the reverse discharge section D or from the reverse discharge section D to the original transport section C, two drives from the transport motor M3 and the reverse motor M2 are applied to one original. There are cases where forces are applied simultaneously. At this time, in order to prevent the document from being jammed and damaged, the speed is controlled so that the speed of the downstream transport unit is always slightly higher than the speed of the upstream transport unit. The motor used in the present embodiment is a DC motor for both the transport motor M3 and the reversing motor M2,
The document conveyance speed and the position during conveyance are monitored by monitoring a conveyance clock sensor and a reverse clock sensor, respectively.

Here, as shown in FIG. 6, when the document P is transported in the direction of the arrow and straddles the document transport section C and the reverse discharge section D, the transport clock sensor and the reverse clock sensor depend on the position of the document. By monitoring the amount of rotation by switching the position, the correct position of the document is grasped. That is, as shown in FIG. 8, the conveyance force of the document conveyance unit C that is moving by the driving force from the conveyance motor M3 is larger than the conveyance force of the reversing sheet discharging unit that is moving by the driving force from the reversing motor M2. While a document is present, the position of the document is grasped in real time by counting the clock from the transport clock sensor. When the document advances to a position where the relationship between the conveyance forces of the document conveyance unit C and the reverse discharge unit D reverses (point (a) in FIG. 8), the conveyance clock sensor detects The clock is switched to and the counting is performed.

FIG. 9 shows a flowchart of the transport operation at this time. First, after a document is fed and conveyed and placed at a reading position on the platen glass 10, a reading operation is performed (S101). Then, when the reading operation is completed (S
102), the transport motor M3 is driven to start transporting the original in the direction of the reverse discharge section D, and counting of the clock from the transport clock sensor is started (S103). Subsequently, the driving of the reversing motor M2 is also started. When the count number of the clock reaches M (S104), the clock to be counted is switched to the clock from the inverted clock sensor (S105). Here, M represents the number of clocks from the reading position, which corresponds to the position where the relationship of the conveying force is reversed when the document is straddled on the document conveying section C and the reverse discharge section D. In this embodiment, the setting is changed for each document size. For a large-size document such as A3 size, the number of clocks is set so that the trailing edge of the document reaches the belt pressing roller 13c and passes through the nip portion. The number of clocks corresponding to reaching the belt pressing roller 13d and passing the nip is set. At this time, the leading ends of the originals have reached predetermined positions in the reversing section.
Then, the transport of the document is controlled based on the switched clock.

As shown in FIG. 7, the original P is transported in the direction of the arrow from the reverse discharge section D to the original transport section C.
In the case where both sides of the document overlap, the document advances in the direction opposite to the arrow in FIG. 8, and the clock to be monitored is changed from the inverted clock sensor to the transport clock sensor as the transport force relationship is reversed at the point (a). Switch.

FIG. 10 shows a flowchart of the transport operation at this time. First, a document is conveyed through the reversing discharge unit D for reversing operation (S201), and the leading edge of the document reaches a reversing exit sensor (not shown, located at 26 in FIG. 3). When the sensor is turned on (S202), counting of the clock from the inverted clock sensor is started (S202).
203). Before the document enters the document transport section C, the transport motor M3 is driven to rotate the transport belt in the reverse direction.
When the clock count reaches m (S20
4) The clock to be counted is switched to the clock from the carrier clock sensor (S205). Here, m is
The number of clocks from when the reversing exit sensor is turned ON, which corresponds to the position where the relationship of the conveying force is reversed when the document spreads over the document conveying unit D and the reversing discharge unit C. In this embodiment, the setting is changed for each document size. For large-size documents such as A3 size, the number of clocks is set so that the trailing edge of the document reaches the transport rollers 22a and 22b and passes through the nip portion. Sets the number of clocks corresponding to passing through the nip between the paper discharge roller 25 and the reversing roller 19. At this time, the leading ends of the originals have reached the treatment positions in the transport unit. Then, the transport of the document is controlled based on the switched clock.

As a result, even if there is a speed difference between the adjacent conveyance sections and the originals are pulled and one of them is slipping, the position of the original can be accurately grasped.

[0049]

As described above, according to the present invention,
In the sheet transport device, if there is a difference in transport speed between adjacent transport units, the feed position on the side where the transport force is dominant is always monitored to grasp the exact position of the document and damage the document. It is possible to perform optimal transport control without the need.

[Brief description of the drawings]

FIG. 1 is a sectional view of an image forming apparatus.

FIG. 2 illustrates an operation unit of the image forming apparatus.

FIG. 3 is a cross-sectional view of the sheet conveying device.

FIG. 4 is a block diagram related to control of a sheet conveying device.

FIG. 5 is a power supply system diagram of the sheet conveying apparatus.

FIG. 6 is a diagram illustrating a sheet conveyance position.

FIG. 7 is a diagram illustrating a sheet conveyance position.

FIG. 8 is a diagram illustrating switching of a monitor clock of the sheet conveying apparatus.

FIG. 9 is a flowchart illustrating a monitor clock switching process when a document is discharged.

FIG. 10 is a flowchart illustrating a monitor clock switching process when a document is inverted.

[Explanation of symbols]

 1 Document Tray 10 Platen Glass 11 Conveyor Belt 12 Driving Roller 16 Deflector 19 Inverting Roller 100 CPU 114 Conveying Clock Sensor 115 Inverting Clock Sensor 304 Motor Driver 305 Sensor 306 Motor 510 Loading Tray 530 Paper Feeding Unit 531 Half Moon Roller 532 Separating and Conveying Roller 536 Full-surface belt 550 Discharge roller 551 Discharge tray 801 Image forming apparatus main body 802 Sheet transport device M1 Separation motor M2 Reverse motor M3 Transport motor A Document loading section B Document feeding section C Document transport section D Reverse discharging section E Paper loading stack Department

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiyuki Nakajima 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Satoshi Choho 3-30-2 Shimomaruko, Ota-ku, Tokyo Kyano 3F049 AA01 BB07 DA12 EA01 EA12 EA23 EA27 LA01 LB02 3F100 AA04 BA11 CA12 DA04 DA05 DA08 EA04

Claims (15)

[Claims] A first transport unit that transports the sheet on a first transport path; a first drive source that drives the first transport unit; and a drive amount that is proportional to a drive amount of the first drive source. The first to detect the changed value
Detecting means, a second conveying means for conveying the sheet on a second conveying path downstream of the first conveying path in the conveying direction, a second driving source for driving the second conveying means, A second detecting means for detecting a value proportional to the driving amount of the second driving source;
Detecting means, and control means for controlling sheet conveyance based on the output of the first detecting means or the second detecting means, wherein the control means controls whether the sheet is the first conveying means. Detecting means corresponding to the driving source of the conveying means having the stronger conveying force when the sheet is conveyed at a position across the first conveying path and the second conveying path by both the first conveying path and the second conveying path. A sheet conveyance device that controls sheet conveyance based on the output of the sheet. 2. The method according to claim 1, wherein the control unit is configured to perform the first detection when performing the transfer control based on an output of the first detection unit in a direction from the first transfer path to the second transfer path. 2. The sheet conveying apparatus according to claim 1, wherein when the means detects a predetermined amount, the control is switched to conveyance control based on an output of the second detecting means. 3. The first transport means and the second transport means are capable of transporting a sheet in a direction opposite to a normal direction, and the control means is configured to control the first transport from the second transport path. If the second detection means detects a predetermined amount while performing the conveyance control based on the output of the second detection means in the direction toward the path, the control is switched to the conveyance control based on the output of the first detection means. The sheet conveying device according to claim 1, wherein: 4. The first detection means has a counter for counting a clock synchronized with the drive of the first drive source, and the second detection means is synchronized with the drive of the second drive source. 2. The sheet conveying apparatus according to claim 1, further comprising a counter for counting clocks. 5. The sheet conveying apparatus according to claim 1, wherein said second conveying means reverses the sheet. 6. The method according to claim 1, wherein the control unit is configured to convey the sheet from the first conveyance path to the second conveyance path.
3. The sheet conveying device according to claim 2, wherein the conveying speed of the second conveying unit is higher than the conveying speed of the first conveying unit. 7. The method according to claim 1, wherein the control unit is configured to convey the sheet from the second conveyance path to the first conveyance path.
4. The sheet conveying apparatus according to claim 3, wherein the conveying speed of the first conveying unit is set to be higher than the conveying speed of the second conveying unit. 8. The sheet conveying apparatus according to claim 2, wherein the predetermined amount varies depending on the size of the sheet. 9. A first conveying means for conveying a sheet on a first conveying path; a first driving source for driving the first conveying means; and a driving amount proportional to the driving amount of the first driving source. The first to detect the changed value
And a second conveying means for conveying the sheet on a second conveying path downstream of the first conveying path in the conveying direction. A control method for a sheet conveying apparatus, comprising: A first counting step of counting a clock synchronized with the driving of the driving source; a second counting step of counting a clock synchronized with the driving of the second driving source; When the sheet is transported by both of the second transport means at a position across the first transport path and the second transport path, the transport force of the first transport means and the second transport means is strong. A control step of controlling sheet conveyance based on a count value of a clock corresponding to a driving source of a side conveyance unit. 10. In the control step, the first transport path is moved in a direction from the first transport path to the second transport path.
When a predetermined number of clocks are counted in the first count step while the transport control based on the count value in the count step is performed, switching to the transport control based on the count value in the second count step is performed. The control method for a sheet conveying device according to claim 9, wherein: 11. The first transporting means and the second transporting means can transport a sheet in a direction opposite to a normal direction,
In the control step, when the transport control based on the count value in the second count step is performed in a direction from the second transport path to the first transport path, a predetermined value is set in the second count step. 10. The control method according to claim 9, wherein when the number of clocks is counted, the control is switched to the conveyance control based on the count value in the first counting step. 12. The control method according to claim 10, wherein the predetermined amount differs according to the size of the sheet. 13. A first transport means for transporting a sheet at a first speed on a first transport path, and a first transport means for transporting a sheet on a second transport path adjacent to the first transport path. A second transport unit configured to transport at a second transport speed higher than the transport speed; and when the sheet is transported across the first transport path and the second transport path, the sheet is transported at the second transport path. The transport is controlled based on a clock synchronized with the drive of the first transport unit until the transport is performed to a predetermined position of the transport path, and is synchronized with the drive of the second transport unit after the transport to the predetermined position. And a control means for controlling conveyance based on the generated clock. 14. The sheet conveying device according to claim 13, wherein the predetermined position is changed according to a size of the sheet. 15. The sheet conveying apparatus according to claim 13, wherein said first conveying means and said second conveying means are driven by different driving sources.