JP2003321149A - Sheet conveyer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an unnecessary sheet from being consumed, by conducting print on a sheet used for measurement, and to store the sheet printed with a data to make a service person check a condition of a clutch component in a sheet conveyer. <P>SOLUTION: This conveyer is provided with an image forming means for forming an image on the sheet, a first, second and third rollers for conveying the sheet, a driving means for driving the first, second and third rollers, a first, second and third clutches for transmitting driving force of the driving means to the first, second and third rollers, a control means for controlling connection and release for the first, second and third clutches, a first data as to the stopping characteristic when the first and second clutches are released when the first and second rollers grasp the sheet, and a second data as to the stopping characteristic when the second and third clutches are released when the second and third rollers grasp the sheet. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device for conveying a sheet.

[0002]

2. Description of the Related Art In a conventional electrophotographic copying apparatus, a skewed sheet is fed by abutting a sheet fed with a registration roller provided immediately in front of a photosensitive drum being stopped against a nip portion of the registration roller. It is configured to correct. In a copying machine with a long distance between the paper feed section and the photosensitive drum, in order to improve the productivity of the copying machine,
Subsequent sheets are sequentially fed without waiting for the preceding sheet to be imaged by the photosensitive drum. Therefore, a plurality of sheets are present in the transport path from the paper feed unit to the photosensitive drum.

At the timing of correcting skew of the sheet,
The sheet is in a substantially stopped state at the position of the registration roller, so that the succeeding sheet cannot catch up with this sheet.
Subsequent sheets are also suspended depending on this. Then, the roller immediately before the photosensitive drum and the roller from the paper feeding unit to the photosensitive drum are simultaneously driven in synchronization with the rotation timing of the image on the photosensitive drum, and the feeding of a plurality of sheets in the conveying path is restarted.

[0004]

It is desired to further improve the productivity of such a conventional copying apparatus, and for that purpose, it is necessary to further reduce the sheet interval. However, if the sheet interval is made shorter than in the conventional case, the shift of the sheet stop position, which has not affected the conventional case, becomes a problem. The roller for feeding the sheet is driven by a DC motor through a clutch, and the clutch is released when the sheet is temporarily stopped. When the clutch is released, the roller stops due to friction of the roller bearing. Since the roller is stopped by the friction of the bearing, the roller slightly rotates from the release of the clutch to the stop of the roller, and the subsequent sheet sandwiched by such a roller is abutted against the registration roller. It approaches the seat. In this state, since the feeding of all the sheets temporarily stopped in the conveyance path is restarted at the same time, the trailing edge of the preceding sheet and the leading edge of the succeeding sheet are fed in a state where the distance between them is extremely close, Abnormality may occur in sheet conveyance control.

[0005]

In order to solve the above problems, the present invention provides an image forming means for forming an image on a sheet, first, second and third rollers for conveying the sheet, and the first and second rollers. Drive means for driving the first, second and third rollers, first, second and third clutches for transmitting the drive force of the drive means to the first, second and third rollers, and First, second
And control means for controlling engagement and disengagement of the third clutch, and stopping of the sheet when releasing the first and second clutches while the sheet is nipped by the first and second rollers. First data on characteristics and the second and third
When the rollers are holding the sheet, the second and third
Storage means for storing second data relating to the stop characteristics of the seat when the clutch is released, the first,
When the sheet is conveyed by the second and third rollers, the first image stored in the storage unit is recorded by the image forming unit.
The present invention provides a sheet conveying device characterized by printing 1 and second data on a conveyed sheet.

Further, the first memory stored in the memory means.
The second and third data are data corresponding to the amount of advance of the sheet conveyed by the first and second rollers when the first and second clutches are released, and the second and third clutches. Is data corresponding to the amount of advance of the sheet conveyed by the second and third rollers when is released.

Further, in the control means, the sheet is
One of the first data and the second data is selected according to which one of the first, second, and third rollers is nipped.

Further, in the control means, the sheet is the first
When the sheet is nipped by the second roller and is not nipped by the third roller, the first data is selected, and the sheet is nipped by the second and third rollers and nipped by the first roller. The second data is selected when there is no such data.

Further, when the first data has a stop characteristic in which the sheet stops in a shorter time than the second data, the control means determines that the sheet is the first, second and third sheets. It is characterized in that the first data is selected when it is nipped by the third roller.

Further, when the second data has a stop characteristic in which the sheet stops in a shorter time than the first data, the control means determines that the sheet is the first, second and third sheets. The second data is selected when it is nipped by the third roller.

[0011]

FIG. 1 shows an image forming apparatus according to an embodiment of the present invention. The image forming apparatus of this embodiment includes a printer 10
0, optional paper feed deck D200, operation unit 300, scanner 31
0, a document feeder 320, a sheet folding machine 330, and a finisher 340. The printer 100 forms an original image read by the scanner 310 or an image received via a network by electrophotography on a sheet. The document feeder 320 automatically feeds the document to the reading position of the scanner 310. The optional paper feed deck D200 has a large-capacity sheet stacking unit, and is attached to the printer 100 as required by the user. The operation unit 300 inputs the settings of the image forming apparatus and displays the state of the image forming apparatus. Sheet folding machine 330 is A3
Z-fold a size sheet. When folding is not set in the operation unit 300, the sheet is sent to the finisher 340 on the downstream side without folding the sheet. The finisher 340 is a sheet discharge unit having a plurality of sheet discharge trays, and is also a sheet finishing unit that performs sheet binding processing and the like. The finisher 340 discharges the sheet conveyed from the upstream side to the sheet discharge tray.

In the printer 100, the laser emitting section 150 emits laser light according to the image from the scanner 310 or the image received via the network. This laser light is applied to the photosensitive drum 152, and a latent image is formed on the photosensitive drum 152. The photosensitive drum 152 is developed with toner, and the toner image is transferred to the fed sheet. The toner transferred to the sheet is fixed on the sheet by the fixing roller 154. The sheet that has passed the fixing roller 154 is sent to the sheet folding machine 330 on the downstream side via the discharge path 158, or the sheet is turned upside down via the double-sided path 156 and sent again to the photosensitive drum 152.

The printer 100 includes paper feed cassettes D108, D109,
Sheets can be fed from the paper feed decks D110 and D111 and the manual paper feed section 160, and further, sheets can be fed from the optional paper feed deck D200.

FIG. 2 shows the structure of sheet conveyance in the printer 100. The sheets stacked in the sheet feeding cassette D108 are picked up by the roller R108, separated from the sheets other than the uppermost sheet, and sent out. This sheet is roller R100,
It is conveyed to the photosensitive drum 152 by R101, R102, R103, R114, and R115. Similarly, the sheets sent by the roller R109 from the paper feeding cassette D109 are the rollers R101, R102, R103, R1.
14, the sheet is conveyed to the photosensitive drum 152 by R115. The sheet sent from the paper feed deck D110 by the roller R110 is conveyed to the photosensitive drum 152 by the rollers R103, R114, and R115. Further, the sheets sent by the roller R111 from the paper feed deck D111 are the rollers R105, R106, R107, R114, R1.
It is conveyed to the photosensitive drum 152 by 15. Further, the sheet sent from the manual paper feeding unit 160 by the roller R112 is conveyed to the photosensitive drum 152 by the rollers R113 and R115. Further, the sheet sent from the optional paper feed deck D200 by the roller R202 is conveyed to the photosensitive drum 152 by the rollers R201, R114, and R115.

Paper feed cassettes D108, D109, paper feed deck D11
0, D111, manual paper feed section 160, optional paper feed deck D20
0, and sheets fed from the paper feed unit such as the double-sided path 156 may skew, so the registration resist roller
The skew of the sheet is corrected by abutting the sheet against the resist registration roller R115 with R115 stopped. Further, in order to improve the productivity of the image forming apparatus, the subsequent sheets are sequentially fed without waiting for the preceding sheet to form an image on the photosensitive drum 152. Therefore, there are a plurality of sheets in the transport path from the paper feed unit to the photosensitive drum 152. Since the sheet abutted on the resist registration roller R115 is in a substantially stopped state, the succeeding sheet is also subordinately stopped so that the succeeding sheet cannot catch up with this sheet.

Rollers R100-R103, R105-R115, R201, R2
02 is clutch C100-C103, C105-C115, C201,
It is driven by the motor 120 via C202. Motor 120
It is a DC motor. The driving force of the motor 120 is transmitted to the rollers by connecting the clutch, and the motor is released by releasing the clutch.
The driving force of 120 is not transmitted to the rollers.

The rollers R114 and R115 are provided with electromagnetic brakes B114 and B115, respectively. By releasing the clutches C114 and C115 corresponding to the respective rollers and turning on the electromagnetic brakes B114 and B115, the rollers R114 and B115 are turned on.
And R115 can be stopped instantly.

Rollers R100 to R103, R105 to R113, R201, R2
The 02 does not have an electromagnetic brake, so the roller is stopped only by releasing the clutch. Since no electromagnetic brake is provided on each of these rollers, the cost of the image forming apparatus can be reduced. When the clutch is released, the roller rotation is stopped due to the friction of the roller bearing and the friction of the contact portion of the roller pair. The friction of the contact portion of the roller pair differs depending on the material of the rollers. The amount of roller rotation from clutch release to roller stop, that is, the amount of sheet advance from sheet stop, varies depending on various factors such as the frictional force of the roller bearing, the mechanical structure of the roller, the material of the roller, and the individual difference of the roller. When these sheets are sandwiched by a plurality of types of rollers, they affect each other, and the sheet advance amount from the clutch release to the sheet stop varies.

Table 1 shows the type of bearing of each roller, the material of the roller, the mechanical structure for driving the roller, and the presence or absence of an electromagnetic brake. The rollers R100, R101, R105, R106, R113, R201 are rubber rollers held by sintered bearings, and no electromagnetic brake is provided. The rollers R102 and R103 are rubber rollers held by bearing bearings, and no electromagnetic brake is provided. The roller R107 is a sponge roller held by a bearing bearing and is not provided with an electromagnetic brake. The roller R107 not only carries the sheet but also removes the curl. Rollers R108, R109, R110, R111, R112, R2
Reference numeral 02 denotes a separation roller composed of a rubber roller, and has a mechanical structure in which one of the roller pair rotates in the feeding direction and the other rotates in the direction opposite to the feeding direction for sheet separation.

The rollers R114 and R115 are rubber rollers held by sintered bearings and provided with electromagnetic brakes B114 and B115. RegistrationRegistration roller R115 must be stationary after the preceding sheet is fed, and when the succeeding sheets fed at small sheet intervals arrive, the trailing edge of the sheet exits the roller and then the roller rotates instantly. An electromagnetic brake that can be stopped is provided. Also roller
Since the R114 has to stop accurately when a predetermined amount of the sheet has been fed after the sheet hits the registration roller R115, an electromagnetic brake is provided to stop the roller after driving for a predetermined time.

[0021]

[Table 1]

With respect to the roller not provided with the electromagnetic brake, the rotation of the roller is stopped by releasing the clutch. However, it takes a long time from the clutch release to the stop of the roller rotation because of the rubber roller held by the bearing. In addition, a sponge roller held by a bearing bearing, a rubber roller held by a sintered bearing, and a separation roller having a separation mechanism that stops in the shortest time.

Rollers R100 to R103, R105 to R115, R201, R2
Sensors S100 to S115, S201, and S202 are provided near 02, respectively. Further, sensors S115 and S114 are provided on the upstream side of the photosensitive drum 152. The sensor S115 is for timing to stop the sheet when the front end of the sheet hits the nip portion of the registration roller R115 and is conveyed by a predetermined amount. The sensor S114 is a laser emission unit
This is for the timing of forming a latent image on the photosensitive drum 152 by the 150.

Sensors S102, S106, S107, S104, S114, S1
15, S112 and S113 are movable flags 170 as shown in FIG.
And a flag type sensor composed of a light emitting portion and a light receiving portion 172 provided in the movable range of the flag, and is configured such that the sheet falls down the flag 170 (movable member) when the conveyed sheet passes through the sensor. When the flag 170 blocks the optical paths of the light emitting unit and the light receiving unit 172, that is, when the flag 170 is not tilted by the sheet (when the flag 170 is at the first position), it is determined that there is no sheet. When the flag 170 does not block the optical paths of the light emitting unit and the light receiving unit 172, that is, when the flag 170 is not tilted to the sheet (the flag 170 is the second
Sheet), it is determined that there is a seat. In this way, by detecting whether or not the flag 170 blocks the optical path between the light emitting unit and the light receiving unit 172, the leading edge of the sheet and the presence or absence of the sheet are detected. The flag 170 is urged by a spring to be in the state of a solid line, and when the rear end of the sheet comes out, the flag 170 returns so as to block the optical paths of the light emitting portion and the light receiving portion 172, but the flag 170 returns instantly. Otherwise, there is a time lag in returning, so it is difficult to accurately detect the trailing edge of the seat. In this way, the flag type sensor is not suitable for accurate detection of the trailing edge of the sheet, so that the rollers near the rollers R108, R109, R110, and R111 that detect the trailing edge of the preceding sheet at the time of feeding to create an accurate sheet interval. Sensor S108, S10
Optical sensors are used for 0, S109, S101, S110, S102, S111, and S105.

Sensors S108, S100, S109, S101, S110, S1
02, S111, and S105 are a light emitting unit 174 and a light receiving unit as shown in FIG.
176 is an optical sensor, which detects whether or not the sheet interrupts the optical path between the light emitting unit 174 and the light receiving unit 176 when the conveyed sheet passes through the sensor. Detects the presence of edges and sheets.

The photosensitive drum 152 is driven by a motor 128, and the fixing roller 154 is driven by a motor 130. In addition, the sheet sent to the double-sided path 156 has rollers 138, 136, 134,
It is carried by 132. The roller 138 is driven by the motor 126.
The rollers 136 and 134 are driven by the motor 124, and the roller 132 is driven by the motor.
Driven by 122. The motors 126, 124, 122 are stepping motors. In the double-sided pass, the motor must be rotated in the forward and reverse directions to switch back the sheet, and when the sheet is received from the upstream side in the double-sided pass, it rotates at the speed matched with the fixing roller, and then the sheet interval is reduced. Since it is necessary to rotate at a high speed and stop the rotation when the sheet comes to a predetermined position, a stepping motor that can easily and accurately control the speed is adopted.

FIG. 3 is a block diagram of clutch control. The outputs of the sensors S100 to S115, S201, S202 are input to the CPU 180. The CPU 180 controls driving of the motor 120 via the amplifier 186. Although not shown in FIG. 3, the CPU 180 also controls driving of the motors 128, 130, 122, 124, and 126. Further, the CPU 180 has clutches C100 to C103, C105 to C115, C201,
Controls the connection and release of C202. The settings input through the operation unit 300 are input into the CPU 180, and the CPU 180 causes the operation unit 300 to display a predetermined operation screen. The control program to be executed by the CPU 180 is stored in the ROM 182 readable by the CPU 180. The control program to be described later is also stored in the ROM 182. The data necessary for the CPU 180 to control is written in the battery-backed RAM 184.
RA is also applied to the data measured for correction control described later.
Written to M184. A nonvolatile memory such as an EEPROM may be used instead of the RAM184.

Next, the characteristics of the roller when the roller is driven via the clutch and the clutch is connected after the clutch is released will be described with reference to FIGS. 4 and 5. FIG. 4 shows an example of a configuration for driving the roller via a clutch. 4 (1) to 4 (3) show how the sheet SH is conveyed, and FIGS. 4 (4) to 4 (6) are timing charts of the sensor SA, the clutch CA, and the sensor SB, respectively. roller
RA is driven by a motor M via a clutch CA. A roller RB is provided on the downstream side of the roller RA. roller
Sensors SA and SB are provided on the upstream sides of RA and RB, respectively. The roller RA is not equipped with an electromagnetic brake.

FIG. 5 shows the sheet SH when the clutch CA is released and the sheet SH is temporarily stopped while the sheet SH is being conveyed by the roller RA, and then the clutch CA is connected to convey the sheet SH again. It shows the movement (characteristics of the roller RA).
The vertical axis represents the distance of the sheet SH and the horizontal axis represents time. SH0 instantaneously stops the sheet SH at time t4, and at time t5, the sheet SH instantaneously indicates the movement of the virtual sheet SH conveyed at a predetermined speed V1, and SH0 ′ indicates the movement of the actual sheet SH.

While the roller RA is transporting the sheet SH transported from the upstream side, at time t4 when the sheet SH is temporarily stopped, the roller RA is stopped by releasing the clutch CA. Next, at time t5 when the conveyance of the sheet SH is restarted, the roller RA is driven by connecting the clutch CA. Since the roller RA is stopped only by releasing the clutch CA, the sheet SH stops at the position advanced by the advance amount X1 from the virtual stop position as shown in SH0 ′ of FIG. As described above, the amount of advance X1 varies depending on the type of roller bearing, the material of the roller, the mechanical structure of the roller drive, and the individual difference of the roller. Further, since it takes time to completely connect the clutch CA, the rising of the conveyance of the sheet SH is delayed, so that the sheet S with respect to the position SH0 of the virtual sheet SH is delayed.
The amount of progress of H is reduced to X2.

Generally, the sheet advance amount from the clutch release to the roller stop is larger than the sheet delay amount at the time of clutch engagement. Therefore, when the clutch CA is released and then the clutch CA is engaged, a virtual The seat position is advanced by X2 from the seat position. As will be described later, the clutch engagement timing is delayed by the advance amount X2, that is, the time ΔTA, so that the virtual seat position is corrected.

The time ΔTA is the actual time TA ′ from the time t1 when the leading edge of the sheet SH passes the sensor SA to the time t2 when the leading edge of the sheet SH passes the sensor SB, and the sheet advance amount when the clutch CA is released is From the virtual time TA (time from the time t1 when the seat SH passes the sensor SA to the time t3 when the sensor SH passes the sensor SA) from zero to the time TA 'when zero and the seat delay amount when the clutch CA is engaged are set to zero. It can be obtained by subtracting. When the sheet SH is conveyed at the speed V1 at the distance X1 from the sensor SA to the sensor SB, the virtual time TA is the sensor SA.
It is equal to the movement time X1 / V1 of the sheet SH between −SB and the suspension time TB. Therefore, ΔTA can be calculated by the following equation. CPU180 calculates ΔTA, and CPU180 calculates ΔTA
The TA is stored in the battery-backed RAM 184.

.DELTA.TA = TA-TA '= (X1 / V1 + TB) -TA' = X1 / V1- (TA'-TB) FIG. 6 shows the above-mentioned .DELTA.TA when continuously feeding sheets from the paper feed cassette D108. It is a figure which shows the movement of the front-end | tip of a sheet | seat, when minute correction is not performed. While the registration roller R115 is stopped, the sheets SH1, SH2 and SH3 are set to the rollers R100 and R10.
Feed by 1, R102, R103, R114. Sensors S108 and S100 are used so that the distance between the leading edge of each preceding sheet and the trailing sheet becomes D1, that is, the distance between the trailing edge of the preceding sheet and the succeeding sheet becomes D3 as shown in FIG. 7 (1). The clutch C108 is connected according to the detection of the trailing edge of the preceding sheet. The rollers R114, R103, R102, R101, and R100 are stopped at the timing t11 when the leading edge of the sheet SH1 is fed to the roller 115. The roller R114 is stopped by the release of the clutch C114 and the electromagnetic brake B114, and the rollers R103, R102, R10
1, R100 is stopped only by releasing the clutches C103, C102, C101, C100, respectively. Sheet SH2 is roller R102
Since the vehicle advances when the sheet is stopped, the distance from the leading edge of the sheet SH1 to the leading edge of the sheet SH2 is D2, which is shorter than D1. Next, the sheet SH1 is fed by the registration rollers R115 and R114 at a predetermined timing t12 for image formation, and at the same time SH
2. SH3 is also conveyed by rollers R114, R103, R102, R101, R100. Therefore, the sheet SH2 is conveyed with the distance between the leading edge of the sheet SH1 and the leading edge of the sheet SH2 being D2.

FIG. 7 is a diagram showing the relationship between the distance from the leading edge of the sheet SH1 to the leading edge of the sheet SH2 and the distance from the rear edge of the sheet SH1 to the leading edge of the sheet SH2. As shown in Fig. 7 (1), the distance from the tip of sheet SH1 to the tip of sheet SH2 is
At D1, the distance from the rear end of the sheet SH1 to the front end of the sheet SH2 is D3. This distance D3 is determined by the flag position of the flag sensor (such as the sensor S104) between when the trailing edge of the sheet SH1 passes and when the leading edge of the sheet SH2 reaches the flag position in the sheet state (second This is an interval corresponding to the time it takes to return from the flag position (1) to the flag position (first position) in the no-seat state. Sheet as shown in Figure 7 (2)
When the distance from the tip of SH1 to the tip of sheet SH2 is D2,
The distance from the rear end of the sheet SH1 to the front end of the sheet SH2 is D4, which is shorter than D3.

The distance from the trailing edge of the sheet SH1 to the leading edge of the sheet SH2 is such that the flag 170 indicates that there is no sheet between the trailing edge of the sheet SH1 passing the sensor S104 and the leading edge of the sheet SH2 reaching the sensor S104. If the distance is not sufficient to return to the flag position of the state, the detection result of the sensor S104 indicates that the sheet is continuously present from the passage of the trailing edge of the sheet SH1 to the arrival of the leading edge of the sheet SH2. Instead, it will be falsely detected as a jam.

Further, the distance from the trailing edge of the sheet SH1 to the leading edge of the sheet SH2 is such that the trailing edge of the sheet SH1 is the registration roller R11.
If the distance that the leading edge of the sheet SH2 reaches the registration roller R115 between the time of passing 5 and the registration roller R115 is completely stopped, not only skew feeding of the sheet SH2 cannot be corrected but also the sheet Since the leading edge position of the SH2 is shifted during standby, there occurs a problem that the image formed on the sheet is displaced.

FIG. 10 is a diagram showing the movement of the leading edge of the sheet when the above-described correction of ΔTA is performed when the sheet is continuously fed from the sheet feeding cassette D108. Up to the timing t12, it is the same as in FIG. Regarding the sheet feeding interval from the sheet feeding cassette D108, sheet separation and sheet feeding are performed so that the distance from the trailing edge of the preceding sheet to the leading edge of the succeeding sheet is D1. The distance D1 is a distance that does not cause at least the above-described erroneous detection of the jammed jam and the position shift of the image, and is a distance that is shortened to the extent that the productivity can be improved as compared with the conventional one.

The sheet SH1 is fed by the registration rollers R115 and R114 at a predetermined timing t12 when image formation is performed. After ΔTA from timing t12, set SH2 to rollers R114, R10
Transported by 3, R102, R101. If the amount of advance of sheet SH3 is the same as that of sheet SH2, sheet SH2 and sheet SH
Start the transportation of 3. The sheet SH2 is conveyed with the distance between the leading edge of the sheet SH1 and the leading edge of the sheet SH2 being D1 ′. Since the distance between the leading edge of the sheet SH1 and the leading edge of the sheet SH2 is corrected by ΔTA, it becomes D1 ′. D1 'is clutch C115 than D1
Although the distance is shortened by the connection delay amount of, the distance of the connection delay of the clutch is smaller than the seat advance amount when the upstream side clutch is released. This distance D1 'is at least a distance at which the above-mentioned erroneous detection of the jammed jam and displacement of the image do not occur. Therefore, the distance between the rear end of the sheet SH1 and the front end of the sheet SH2 is corrected by the sensor S104 to the extent that it is not erroneously detected as a stay jam, and erroneous detection of a stay jam can be prevented. Further, the distance between the rear end of the sheet SH1 and the front end of the sheet SH2 is corrected to the distance that the front end of the sheet SH2 reaches the registration roller R115 after the rear end of the sheet SH1 exits the registration roller R115 and then the registration roller R115 stops. As a result, it is possible to prevent the displacement of the image.

These controls are performed by the CPU 180, and the CPU 1
80 reads out ΔTA from the battery-backed RAM 184 and performs the above-mentioned correction control. Although ΔTA measured and calculated is stored in RAM184, and it is explained that it is read out and subjected to correction control, but this is not the only option, and ΔTA previously obtained at the design stage is stored in ROM182 and read out from ROM182. The same effect can be obtained even if the correction control is performed by the above.

FIG. 11 and Table 2 show combinations of rollers that sandwich an A4 size sheet or a letter size sheet when the sheet feeding is temporarily stopped in the clutch measurement mode, that is, a measurement area in the clutch measurement mode. ΔTA in Table 2
Information excluding (i) is stored in the ROM 182. X1 (i)
Is the distance between the sensor SA (i) and the sensor SB (i). ΔTA
Regarding (i), it is stored in the RAM 184 in association with the measurement area number in the clutch measurement mode described later.

[0041]

[Table 2]

12 to 15 are flowcharts of the clutch measurement mode. A program for executing this flowchart is stored in the ROM 182, read by the CPU 180 and executed. The clutch adjustment value measurement screen (FIG. 22) in the service mode is displayed on the operation unit 300, and the clutch measurement mode is executed in response to the touch of the start key. At the start of execution of this clutch measurement mode, the CPU 180 turns on the motors 120, 128, 130 and other motors.

First, it is determined whether or not there is a sheet in the sheet feeding cassette D108 based on the detection result of the sheet presence / absence sensor provided in the sheet feeding cassette D108 (S400).
A warning is displayed on the operation unit 300 to set an A4 or letter size sheet in the paper feed cassette D108 (S402). If there is a sheet in the paper feed cassette D108, it is determined whether the sheet is A4 size or letter size based on the detection result of the sheet size sensor (S404). If neither A4 nor letter size, proceed to step S402.

If it is determined in step S404 that the size is A4 or letter size, 0 is set to the variable i (S406). Then, the clutches C114 and C115 are connected (S408), and one sheet is fed from the paper feed cassette D108 (S410). roller
The pickup roller of R108 is driven by a solenoid, and when this solenoid is off, the pickup roller is in a state of landing on the sheet in the paper feed cassette D108. To feed a sheet from paper cassette D108, use clutch C108
By connecting the pickup roller and roller
R108 is driven. When the sensor S108 is turned on, the solenoid of the pickup roller is turned on to separate the pickup roller from the sheet in the sheet feeding cassette D108.

Next, when the sensor S100 is turned on (S41
8) Then, the clutch measurement process described later is executed (S420).
At this time, the data measured by the clutch measurement process
Store in ROM184. This clutch measurement process is performed by the sensor S104
Repeat until is turned on (S422).

Further, when the sensor S114 is turned on (S423),
The data stored in the printer 100 is printed on a sheet by each process job (S424).

That is, one sheet measures a plurality of areas. That is, the conveyance of the sheet is stopped between the first sensor and the second sensor, the conveyance of the sheet is restarted after a predetermined time has elapsed, and from the time when the first sensor detects the edge of the sheet. The time until the second sensor detects the edge of the sheet is measured, and the sheet temporarily stopped between the first sensor and the second sensor is placed between the second sensor and the third sensor. Stop, restart sheet conveyance after a predetermined time has elapsed, and measure the time from when the second sensor detects the edge of the sheet to when the third sensor detects the edge of the sheet To do. Then, the measured data is printed on the sheet used for the measurement.

Next, it is determined whether there is a sheet in the sheet feeding deck D111 based on the detection result of the sheet presence / absence sensor provided in the sheet feeding deck D111 (S425), and if there is no sheet, A4 or letter size sheet A warning is displayed on the operation unit 300 to set the paper feed deck D111 (S426). Paper feed deck D11
If there is a sheet in 1, it is determined whether the sheet is A4 or letter size based on the detection result of the sheet size sensor (S428). If neither A4 nor letter size, proceed to step S426.

When it is determined in step S428 that the size is A4 or letter size, one sheet is fed from the paper feed deck D111 (S430). The pickup roller of the roller R111 is driven by a solenoid, and when the solenoid is off, the pickup roller is in a state of landing on the sheet in the paper feed deck D111. To feed a sheet from the paper feed deck D111, the clutch C111 is connected to drive the pickup roller and the roller R111. When the sensor S111 is turned on, the solenoid of the pickup roller is turned on to separate the pickup roller from the sheet in the paper feed deck D111. Next, when the sensor S105 is turned on (S43
6), clutch measurement processing is executed (S438). This clutch measurement process is repeated until the sensor S107 is turned on (S440).

Next, when the sensor S114 is turned on (S44
1) The data stored in the printer 100 is printed on a sheet by each process job (S442).

In the image forming apparatus of this embodiment, the roller R106 and
Since no sensor is provided between R107, both the measurement of area 6 and area 7 must be performed by sensors S106 and S107, so the sheet used for measurement of area 6 is ejected and another sheet is replaced. Newly delivered area
Seven measurements must be made by sensors S106 and S107.

Therefore, the A4 or letter size sheet is fed again from the paper feed deck D111. It is determined whether there is a sheet in the sheet feeding deck D111 based on the detection result of the sheet presence / absence sensor provided in the sheet feeding deck D111 (S443). If there is no sheet, an A4 or letter size sheet is fed into the sheet feeding deck D1.
A warning is displayed on the operation unit 300 to set it to 11 (S44
Four). If there is a sheet in the paper feed deck D111, it is determined whether the sheet is A4 or letter size based on the detection result of the sheet size sensor (S446). If neither A4 nor letter size, proceed to step S444.

When it is determined in step S446 that the size is A4 or letter size, one sheet is fed from the paper feed deck D111 similarly to step S430 (S448).

Next, when the sensor S106 is turned on (S45
4), clutch measurement processing is executed (S456).

Next, when the sensor S114 is turned on (S45
7) The data stored in the printer 100 is printed on the sheet by each process job (S458).

As described above, in the clutch measurement mode, a total of two sheets are fed from the paper feed deck D111 to perform measurement.

Next, it is determined whether there is a sheet in the sheet feeding deck D200 based on the detection result of the sheet presence / absence sensor provided in the sheet feeding deck D200 (S459), and if there is no sheet, an A4 or letter size sheet A warning is displayed on the operation unit 300 to set the to the paper feed deck D200 (S460). Paper feed deck D20
If there is a sheet at 0, it is determined whether the sheet is A4 size or letter size based on the detection result of the sheet size sensor (S462). If neither A4 nor letter size, proceed to step S460.

When it is determined in step S462 that the size is A4 or letter size, one sheet is fed from the paper feed deck D201 (S464). The pickup roller of the roller R201 is driven by a solenoid, and when the solenoid is off, the pickup roller is in a state of landing on the sheet in the paper feed deck D201. To feed a sheet from the paper feed deck D201, the pickup roller and the roller R201 are driven by connecting the clutch C201. When the sensor S201 is turned on, the solenoid of the pickup roller is turned on to separate the pickup roller from the sheet in the paper feed deck D201. Next, when the sensor S201 is turned on (S47
0), clutch measurement processing is executed (S472).

Next, when the sensor S114 is turned on (S47
4) The data stored in the printer 100 is printed on the sheet by each process job (S476).

After the clutch measurement processing, when the sensor provided in the paper discharge section detects that all the sheets have been discharged, the processing ends (S478).

In the above description, the data of each clutch measurement is printed on the sheet used in each clutch measurement process, but the data of all clutches may be printed on the final sheet.

FIG. 16 is a flowchart of the clutch measuring process called in the above-mentioned clutch measuring mode.
The program for executing this flowchart is ROM1
It is stored in 82 and is read and executed by the CPU 180.
The CPU 180 has a built-in free-run counter for managing the current time, which is automatically incremented during program execution, and the CPU 180 can manage the current time by this counter.

First, 1 is added to the variable i (S500), and ROM182
Referring to the rollers in the area i shown in Table 2 stored in Table 2, the clutches corresponding to these are connected (S501),
The current time is set in t1 (i) (S502). And RO
Referring to TC (i) in Table 2 stored in M182, TC (i)
After waiting time (S504), the clutches of the rollers in area i and area (i1) are released (S506). Since the area 0 does not exist when the variable i is 1, the roller clutch in the area 1 is released. After waiting TB time (S508), the clutch of the roller in the area i is connected (S510). Table 2
SB (i) of the sensor, the output of the sensor SB (i) is monitored, and when the sensor SB (i) is turned on (S512),
The current time is set in t2 (i) (S514). And t2
(I) -t1 (i) is found and set in TA '(i) (S51
6), referring to X1 (i) in Table 2, X1 (i) / V1- (TA '
(I) -TB) is calculated and stored as ΔTA (i) in the RAM 184 in association with the area number i (S518), and the process returns to the clutch measurement mode of FIGS. 12 to 15.

The measurement of each area is performed as described above. Note that TC1 has a time sufficient for the leading edge of the sheet to pass through the first roller located downstream of the sensor SA (i) and the second roller located downstream of the sensor SA (i) and the sensor SB ( i) is the time when the leading edge of the sheet does not reach, and TC2 is a time sufficient for the leading edge of the sheet to pass through the roller located second downstream of the sensor SA (i) and the sheet is detected by the sensor SB (i). It is the time when the tip of does not reach.

Further, as shown in FIG. 22, the operation unit 300 displays whether or not the measurement is being performed or the measurement is completed. Further, as shown in FIG. 23, ΔTA (i) may be displayed on the operation unit 300.

FIG. 17 shows the paper feed decks D110, D111, D200, the paper feed cassette D108, and the paper feed cassette D108 when the image forming apparatus forms an image.
9 is a flowchart of sheet feeding control for feeding a sheet from any of D109 to the photosensitive drum 152. A program for executing this flowchart is stored in the ROM 182, read by the CPU 180 and executed.

First, in order to correct the skew feeding of the sheet by the registration roller R115, the clutch C115 is released and the brake B115 is turned on in order to stop the registration roller R115 (S600). Then, the sheet is continuously fed from the paper feed deck or the paper feed cassette designated by the operation unit 300, and the distance between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet is D3 (S602). . In the sheet feeding control in step S602, the transport amount of each sheet is managed based on the detection result of the sensor and the transport time of the sheet, and the leading edge position information indicating the latest leading edge position of each sheet (from the registration roller R115 Distance) with size information for each sheet
Store in RAM184. It is determined whether the sensor S115 is turned on, that is, the leading edge of the most preceding sheet reaches the sensor S115 (S604).
Continue with S602. If turned on in step S604, TL
After waiting time (S606), a sheet feeding temporary stop process described later is performed (S608). In the sheet feeding temporary stop process, the most preceding sheet is temporarily stopped, and all the succeeding sheets are temporarily stopped so that the succeeding sheet does not collide with the preceding sheet. TL shows that after the leading edge of the sheet has passed the sensor S115 and hits the nip part of the registration roller R115,
It is a time for carrying out a predetermined amount of sheet conveyance.

Then, at a timing when the image formed on the photosensitive drum 152 and the sheet coincide with each other (S6
10), the sheet feeding restart process described later is performed (S612). It is determined whether or not this sheet is the final sheet to be image-formed (S614), and if it is not the final sheet, the process returns to step S602.
If it is the final sheet, the process ends when the final sheet is ejected by the ejection roller (S616).

FIG. 18 is a flowchart of the sheet feeding temporary stop process called by the above-described sheet feeding control. The program to execute this flowchart is ROM182
Stored in the memory, and is read and executed by the CPU 180. The sheet feeding temporary stop process is performed according to the clutch control order shown in Table 3 stored in the ROM 182. The clutch control order is from the order closer to the registration roller R115, that is, from the downstream side to the upstream side. First, clutch C1
Release 14 (S700) and turn on brake B114 (S70
2). Then, the variable i is set to 1 (S704), and the clutch C (i) shown in Table 3 stored in the ROM 182 is released (S706).

[0070]

[Table 3]

Then, the current time is set in t (i) (S
708), and 1 is added to the variable i (S710). It is determined whether the variable i has become 14, and if it has not become 14, the process returns to step S706. When the variable i becomes 14, the process returns to the sheet feeding control shown in FIG.

FIG. 19 is a flow chart of the sheet feeding restart processing called by the above-described sheet feeding control. A program for executing this flowchart is stored in the ROM 182, read by the CPU 180 and executed. In the sheet feeding restart process, first, the brakes B115 and B114 are turned off (S800, S802), and the clutches C115, C114 are connected (S80).
4, S806). Next, the variable i is set to 1 (S808), and the total waiting time variable TWT is set to 0 (S810). Then, the leading edge position information (distance from the registration roller R115) of each sheet in the conveyance path stored in the RAM184 and the ROM182
Roller R corresponding to clutch C (i) stored in
By referring to the position information (distance from the registration roller R115) in (i), it is determined whether or not the roller R (i) corresponding to the clutch C (i) holds the sheet (S812). Laura R
If (i) determines that the sheet is sandwiched, RAM1
The sheet nipped by the roller R (i) refers to the leading end position information of each sheet in the conveyance path stored in 84 and the position information of the other rollers stored in the ROM 182, and the downstream side roller ( It is determined whether or not it is nipped by the roller on the photosensitive drum 152 side (S814). If the sheet nipped by the roller R (i) is not nipped by the downstream roller, clutch connection processing described later is performed (S816), and the variable i
Is incremented by 1 (S818). When it is determined in step S812 that the roller R (i) does not hold the sheet, or the roller R (i)
If it is determined by (i) that the sandwiched sheet is sandwiched by the downstream roller, the process proceeds to step S818. After step S818, it is determined whether the variable i has become 14 (S82
If it is not 0) or 14, it returns to step S812. When the variable i becomes 14, the process returns to the sheet feeding control of FIG.

20 and 21 are flowcharts of the clutch connecting process called in the above-described sheet feeding resuming process. The program to execute this flowchart is
It is stored in the ROM 182 and is read and executed by the CPU 180. In the clutch connection process, first, the current time −t (i)
And set it in the variable DT (S900). Then, it is determined whether the sheet is being fed from the sheet feeding cassettes D108, D109, or the sheet feeding deck D110 (S902), and the sheet feeding cassette D1 is set.
If the sheet is being fed from 08, D109, or the paper feed deck D110, the leading edge position information of each sheet in the conveyance path stored in the RAM 184, the roller position information stored in the ROM 182, and the roller position information stored in the ROM 182. Refer to the type information of Rola R
It is determined whether the sheet nipped in (i) is nipped by the separation roller (S904). When the sheet nipped by the roller R (i) is nipped by the separation roller, even if the sheet is nipped by another roller, it is affected by the separation roller having a short stop time, and therefore the waiting time is reduced. ΔTA (1) is set to the variable WT (S906).

When it is determined in step S904 that the sheet nipped by the roller R (i) is not nipped by the separation roller, the ROM 182 and the RAM 184 are referred to in the same manner as described above.
It is determined whether or not the sheet sandwiched by the roller R (i) is sandwiched by the bearing bearing rubber roller (S908). When it is determined that the sheet sandwiched by the roller R (i) is not sandwiched by the bearing bearing rubber roller, the sheet is sandwiched only by the sintered bearing rubber roller, so ΔTA (2) is set in the variable WT. Yes (S910). Laura R
If it is determined that the sheet sandwiched in (i) is sandwiched between the bearing bearing rubber rollers, the same as above.
By referring to the ROM 182 and the RAM 184, it is determined whether the sheet sandwiched by the roller R (i) is sandwiched by the sintered bearing rubber roller (S912). When it is determined that the sheet sandwiched by the roller R (i) is sandwiched by the sintered bearing rubber roller, the sheet is sandwiched by the sintered bearing rubber roller and the bearing bearing rubber roller, so the variable WT
Set ΔTA (3) to (S914). If it is determined that the sheet sandwiched by the roller R (i) is not sandwiched by the sintered bearing rubber roller, the variable bearing WT is set to ΔTA (4) because it is sandwiched only by the bearing bearing rubber roller (S916). ).

In step S902, the paper feed cassettes D108, D109,
When sheets are being fed from a sheet feeding unit other than the sheet feeding deck D110, it is determined whether sheets are being fed from the sheet feeding deck D111 (S918). When the sheet is being fed from the sheet feeding deck D111, it is determined whether the sheet nipped by the roller R (i) is nipped by the separation roller by referring to the ROM 182 and the RAM 184 similarly to the above (S920). . Laura R
When it is determined that the sheet sandwiched in (i) is sandwiched by the separation rollers, even if the sheet is sandwiched by another roller, it is affected by the separation roller having a short stop time. Set ΔTA (5) (S92
2). If it is determined that the sheet nipped by the roller R (i) is not nipped by the separation roller, RO is the same as above.
With reference to M182 and RAM184, it is determined whether the sheet held by the roller R (i) is held by the bearing bearing sponge roller (S924). If the sheet sandwiched by the roller R (i) is not sandwiched by the bearing-bearing sponge roller, the sheet is sandwiched only by the sintered bearing rubber roller, so ΔTA (6) is set to the variable WT (S926). ). When the sheet sandwiched between the rollers R (i) is sandwiched between the bearing-bearing sponge rollers, the sheet is sandwiched between the sintered bearing rubber roller and the bearing-bearing sponge roller.
Set (7) (S928). If sheets are being fed from the paper feed deck D111 in step S918, the variable WT is set to ΔTA.
Set (8) (S930).

In the image forming apparatus of the present embodiment, the measured data is used when the sheet of the same size as the sheet used in the clutch measurement mode is fed in the sheet feeding control, but the sheet used in the clutch measurement mode is used. When sandwiching a sheet of a larger size with three or more rollers, and there is a combination of rollers not measured in the clutch measurement mode, among the multiple areas to which the rollers sandwiching the sheet belong, Select the data with the shortest time from clutch release to stop.

Steps S906, S910, S914, S916, S922,
After performing data set on variable WT in S926, S928, S930,
It is determined whether the variable WT is larger than the variable TWT (S932). When the variable WT is larger than the variable TWT, the WT-TWT is calculated and the variable
Set to WT (S934), and if the variable WT is less than or equal to the variable TWT,
The variable WT is set to 0 (S936). Here, the drive timing of the clutch corresponding to the roller nipping the succeeding sheet is adjusted in accordance with the delay in driving the clutch corresponding to the roller nipping the preceding sheet.

After data is set to the variable WT in steps S934 and S936, it is determined whether the variable WT is larger than the variable DT (S938). If the variable WT is larger than the variable DT,
Set to DT (S940). When the temporary release time of the clutch C (i) is shorter than the delay time of clutch engagement, that is, the time required to stop the roller (sheet stop), the amount of advance of the sheet during the temporary release of the clutch C (i) is the roller R.
(I) Since there is no sheet advance until the stop,
This is because it is sufficient to delay the clutch C (i) by the temporary disengagement time. Then, it is determined whether the variable WT is larger than 0 (S942). When the variable WT is less than or equal to DT in step S938, the process proceeds to step S942. Variable WT in step S942
If is greater than 0, wait WT time (S944), and connect the clutch corresponding to the roller holding the sheet held by the clutch C (i) and the roller R (i) (S946). At this time, a value obtained by adding WT to the variable TWT is set in the variable TWT (S945). Variable WT in step S942
If is 0, the process proceeds to step S946 and the clutch C is immediately
(I) and the roller R (i) connects the clutch corresponding to the roller holding the sheet held by the roller. Then, the process returns to the sheet feeding restart process of FIG.

FIG. 24 shows an example of a layout in which the measured data is image-formed on the sheet used in the clutch measurement process in the clutch measurement process. The measured value for each clutch is displayed.

[0080]

As described above, according to the invention described in claim 1, the first, second and third rollers for conveying the sheet and the first, second and third rollers are driven. Of the driving means, the first, second and third clutches for transmitting the driving force of the driving means to the first, second and third rollers, and the first, second and third clutches. Control means for controlling connection and disengagement, and first data relating to a stop characteristic of the sheet when the first and second rollers release the first and second clutches while sandwiching the sheet. And the second
And the second roller when the third roller is sandwiching the sheet.
And a storage means for storing second data relating to the stop characteristic of the sheet when the third clutch is released, and when the sheet is conveyed by the first, second and third rollers. By the image forming apparatus, the first and second data stored in the storage unit are printed on the sheet used for measurement, whereby unnecessary consumption of the sheet can be prevented. Further, the service person can check the state of the clutch parts of the sheet conveying device by storing the sheet on which the data is printed.

According to a second aspect of the present invention, the first and second data stored in the storage means are the first and second data when the first and second clutches are released. It corresponds to the data corresponding to the amount of advance of the sheet conveyed by the second roller and the amount of advance of the sheet conveyed by the second and third rollers when the second and third clutches are released. Since it is data, it is possible to easily correct the advanced sheet position due to the stop characteristics of the first, second, and third rollers.

According to a third aspect of the invention, the control means sets the first and second rollers according to which of the first, second and third rollers the sheet is nipped. Select any of the data, so the first, second and third
It is possible to control the sheet position which changes depending on the combination of the stop characteristics of the rollers.

Further, according to the invention described in claim 4, when the sheet is sandwiched by the first and second rollers but not by the third roller, the control means outputs the first data. When the sheet is pinched by the second and third rollers but not pinched by the first roller, the second data is selected, so the first, second, and third rollers are stopped. It is possible to accurately control the seat position that changes depending on the combination of characteristics.

Further, according to the invention described in claim 5, when the control means exhibits a stop characteristic that the sheet stops in a shorter time than the second data, When the sheet is nipped by the first, second and third rollers, the first data is selected, so when the sheet is nipped by the first, second and third rollers Even when there is no data regarding the stop characteristics of the sheet, it is possible to control the sheet position that changes depending on the combination of the stop characteristics of the first, second and third rollers.

Further, according to the invention of claim 6, the control means, when the second data shows a stop characteristic that the sheet stops in a shorter time than the first data, When the sheet is nipped by the first, second and third rollers, the second data is selected, so when the sheet is nipped by the first, second and third rollers Even when there is no data regarding the stop characteristics of the sheet, it is possible to control the sheet position that changes depending on the combination of the stop characteristics of the first, second and third rollers.

[Brief description of drawings]

FIG. 1 is a diagram showing an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of sheet conveyance in the printer 100.

FIG. 3 is a block diagram of clutch control.

FIG. 4 is a diagram showing a configuration for measuring characteristics of a roller when the clutch is engaged after the clutch is released.

FIG. 5 is a diagram showing characteristics of the roller when the clutch is engaged after the clutch is released.

FIG. 6 is a diagram showing the movement of the leading edge of the sheet when the correction for ΔTA is not performed.

FIG. 7 is a diagram showing a distance from the rear end of the sheet SH1 to the front end of the sheet SH2.

FIG. 8 is a diagram showing a configuration of a flag type sensor.

FIG. 9 is a diagram showing a configuration of an optical sensor.

FIG. 10 is a diagram showing the movement of the leading edge of the sheet when the correction for ΔTA is performed.

FIG. 11 is a diagram showing a measurement area in a clutch measurement mode.

FIG. 12 is a flowchart of a clutch measurement mode.

FIG. 13 is a flowchart of a clutch measurement mode.

FIG. 14 is a flowchart of a clutch measurement mode.

FIG. 15 is a flowchart of a clutch measurement mode.

FIG. 16 is a flowchart of a clutch measurement process.

FIG. 17 is a flowchart of sheet feeding control.

FIG. 18 is a flowchart of a sheet feeding temporary stop process.

FIG. 19 is a flowchart of a sheet feeding restart process.

FIG. 20 is a flowchart of a clutch connecting process.

FIG. 21 is a flowchart of a clutch connecting process.

FIG. 22 is a diagram showing a clutch adjustment value measurement screen in a service mode.

FIG. 23 is a diagram showing a clutch adjustment value measurement screen in a service mode.

FIG. 24 is a diagram showing an example of a layout in which measured data is image-formed on a sheet.

[Explanation of symbols]

100 image forming equipment R100-R103, R105-R114, R201, R202 roller R115 Registration roller C100-C103, C105-C115, C201, C202 clutch S100 to S115, S201, S202 sensor 120 motor 152 Photosensitive drum D108, D109 paper cassette D110, D111, D200 paper feed deck

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Manabu Yamauchi             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation (72) Inventor Ichiro Sasaki             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation (72) Inventor ▲ Yoshi ▼ Tomoyasu Kawa             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation F-term (reference) 3F102 AA01 AB01 BA02 BA07 BB02                       CA02 CA03 CB01 CB07 DA08                       EA03 EC07 FA08 FA09

Claims (6)

[Claims] 1. An image forming means for forming an image on a sheet, first, second and third rollers for conveying the sheet, and drive means for driving the first, second and third rollers, Controls connection and release of the first, second and third clutches for transmitting the driving force of the driving means to the first, second and third rollers, and the first, second and third clutches Control means for, the first and second rollers and first data regarding the stop characteristics of the sheet when the first and second clutch is released while sandwiching the sheet, and the second and The third relating to the stop characteristics of the sheet when the second and third clutches are released while the third roller is sandwiching the sheet.
Storage means for storing the data of 2, the first and second stored in the storage means by the image forming means when the sheet is conveyed by the first, second and third rollers. 2. A sheet conveying device, which prints the data of 2 on the conveyed sheet. 2. The first and second data stored in the storage means are data of sheets conveyed by the first and second rollers when the first and second clutches are released. The data corresponding to the amount of advance and the data corresponding to the amount of advance of the sheet conveyed by the second and third rollers when the second and third clutches are released. The sheet conveying device described in 1. 3. The control unit is configured such that the sheets are the first and second sheets.
2. The sheet conveying device according to claim 1, wherein either one of the first data and the second data is selected depending on which one of the first and second rollers holds the sheet. 4. The control means selects the first data when the sheet is nipped by the first and second rollers and is not nipped by the third roller, and the sheet is the second data.
4. The sheet conveying device according to claim 3, wherein the second data is selected when the sheet is sandwiched by the third roller and not sandwiched by the first roller. 5. The control means, when the first data has a stop characteristic in which the sheet stops in a shorter time than the second data, causes the sheet to have the first, second, and
5. The sheet conveying apparatus according to claim 4, wherein the first data is selected when the sheet is nipped by the three rollers. 6. The control means, when the second data has a stop characteristic in which the sheet stops in a shorter time than the first data, the sheet causes the first, second and
5. The sheet conveying apparatus according to claim 4, wherein the second data is selected when the sheet is nipped by the third roller.