JP2002370413A - Sheet carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent erroneous detection of jam when carriage of sheets is resumed after temporary interruption. SOLUTION: When a plurality of sheets are carried, at a predetermined sheet interval, along a carrying passage and carriage of the plurality of sheets is resumed after temporary interruption, the sheet interval is corrected longer than a time required for a flag 170 to be reset to a position of solid line after the rear end of the sheet passed through the flag 170.

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 sheet fed in a state in which a registration roller provided immediately before a photosensitive drum is stopped abuts a nip portion of the registration roller to skew the sheet. It is configured to correct. In a copying machine where the distance of the conveyance path from the paper feeding unit to the photosensitive drum is long, to increase the productivity of the copying machine,
The subsequent sheets are sequentially fed without waiting for the preceding sheet to form an image on the photosensitive drum. Therefore, a plurality of sheets exist in the transport path from the sheet feeding unit to the photosensitive drum.

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

[0004] A flag-type sensor is provided on the transport path of the conventional copying apparatus. This detects the presence of a sheet by detecting that the movable member (flag) has been moved down. This sensor detects that the leading edge of the sheet has reached the sensor position,
A stagnant jam is detected by not detecting the trailing edge of the sheet within a predetermined time during sheet conveyance.

[0005]

It is desired to further improve the productivity of such a conventional copying apparatus, and it is necessary to further reduce the sheet interval. However, if the sheet interval is made shorter than in the past, a shift in the sheet stop position, which has not been affected conventionally, becomes a problem. The roller for feeding the sheet is driven by a DC motor via a clutch. When the sheet is temporarily stopped, the clutch is released. When the clutch is released, the roller stops due to friction of the bearing of the roller. 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 pressed against the registration roller. I approach the seat. In this state, the feeding of all the sheets temporarily stopped in the transport path is simultaneously resumed, and in some cases, the distance between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet may be extremely short. There is. In such a case,
After the trailing end of the preceding sheet has passed through the flag type sensor provided on the conveyance path, before the movable member (flag) of the flag type sensor returns to the position without the sheet, the leading end of the succeeding sheet is moved to the movable member (flag). May be defeated, and may be erroneously detected as staying jam even though it is not actually staying jam.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a transporting means for transporting a plurality of sheets along a transporting path at a predetermined sheet interval, When the movable member set at the position is tilted down by the sheet to the second position, the presence of the sheet is detected, and when the movable member returns to the first position after passing the sheet, the absence of the sheet is detected. After temporarily stopping conveyance of a plurality of sheets by the detection means and the conveyance means, a control means for resuming conveyance of the plurality of sheets by the conveyance means, and a sheet interval at the time of resumption of sheet conveyance by the conveyance means, Correcting means for correcting an interval corresponding to a time longer than a time required for the movable member to return to the first position after the rear end of the sheet has passed through the movable member. There is provided a sheet conveying apparatus according to claim and.

[0007]

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 310, document feeder 320, sheet folding machine 33
0, and the finisher 340. Printer 100
Forms an original image read by the scanner 310 by an electrophotographic method or an image received via a network on a sheet. The document feeder 320 automatically feeds a document to a reading position of the scanner 310. The optional sheet feeding deck D200 has a large-capacity sheet stacking unit, and is mounted on the printer 100 as required by the user. The operation unit 300 inputs settings of the image forming apparatus and displays the state of the image forming apparatus. The sheet folding machine 330 Z-folds an A3-size sheet. When folding is not set in the operation unit 300, the sheet is fed to the downstream finisher 340 without folding the sheet. The finisher 340 is a sheet discharging unit having a plurality of sheet discharging 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 a discharge tray.

In the printer 100, the laser light emitting section 1
Reference numeral 50 emits a laser beam corresponding to an image from the scanner 310 or an image received via a network. This laser beam 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 a fixing roller 154. Fixing roller 15
The sheet that has passed through No. 4 is sent to a sheet folding machine 330 on the downstream side via a discharge path 158, or is turned upside down via a double-sided path 156 and sent to the photosensitive drum 152 again.

The printer 100 includes a paper cassette D108,
Sheets can be fed from D109, sheet feeding decks D110 and D111, and manual sheet feeding section 160, and sheets can also be fed from optional sheet feeding deck D200.

FIG. 2 shows a configuration of sheet conveyance in the printer 100. The sheets stacked in the sheet cassette D108 are picked up by the rollers R108, and are separated from the sheets other than the uppermost sheet and sent out. This sheet has rollers R100, R101, R102, R103, R1
14, and is transported to the photosensitive drum 152 by R115.
Similarly, the sheet sent from the sheet feeding cassette D109 by the roller R109 is a roller R101, R102, R1.
03, R114, and R115 are conveyed to the photosensitive drum 152. In addition, the rollers R11
The sheets sent out by the rollers 0 are rollers R103 and R11.
4, transported to the photosensitive drum 152 by R115. Further, the sheets sent out from the sheet feeding deck D111 by the rollers R111 are rollers R105, R106, R10.
7, and are conveyed to the photosensitive drum 152 by R114 and R115. Further, the roller R112
Are fed by rollers R113, R115
To the photosensitive drum 152. The sheet sent from the optional sheet feeding deck D200 by the roller R202 is conveyed to the photosensitive drum 152 by the rollers R201, R114, and R115.

Sheets fed from sheet feeding units such as sheet feeding cassettes D108 and D109, sheet feeding decks D110 and D111, manual sheet feeding unit 160, optional sheet feeding deck D200, and duplex path 156 may be skewed. Therefore, the skew of the sheet is corrected by abutting the sheet against the registration roller R115 with the registration roller R115 stopped. In order to increase the productivity of the image forming apparatus, the preceding sheet is
The subsequent sheets are sequentially fed without waiting for an image to be formed by 52. For this reason, there are a plurality of sheets in the transport path from the sheet feeding unit to the photosensitive drum 152. Since the sheet abutted against the registration resist roller R115 is in a substantially stopped state, the subsequent sheet is also temporarily stopped so as not to catch up with this sheet so that the subsequent sheet cannot catch up.

Rollers R100 to R103, R105 to R
115, R201, and R202 are each a clutch C10
0 to C103, C105 to C115, C201, C20
2 through a motor 120. Motor 12
0 is a DC motor. Motor 1 by connecting clutch
The driving force of the motor 120 is transmitted to the rollers, and the driving force of the motor 120 is not transmitted to the rollers by releasing the clutch.

The rollers R114 and R115 are provided with electromagnetic brakes B114 and B115, respectively.
Clutches C114 and C1 corresponding to each roller
By turning on the electromagnetic brakes B114 and B115 together with the release of the roller 15, the rollers R114 and R115 can be stopped instantaneously.

Rollers R100 to R103, R105 to R
No electromagnetic brake is provided for 113, R201, and R202, and the stop of the roller is performed only by releasing the clutch. Since no electromagnetic brake is provided for each of these rollers, the cost of the image forming apparatus can be reduced. When the clutch is released, the rotation of the roller stops due to the friction of the roller bearing and the friction of the contact portion of the roller pair. The friction at the contact portion of the roller pair differs depending on the material of the roller. The amount of rotation of the roller from the release of the clutch to the stop of the roller, that is, the amount of sheet advance from the stop of the sheet, depends 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 the sheet is pinched by a plurality of types of rollers, they affect each other, and the amount of sheet advance from clutch release to sheet stop differs.

Table 1 shows the type of bearing of each roller, the material of the roller, the mechanical structure of the roller drive, and the presence or absence of an electromagnetic brake. Rollers R100, R101, R105, R106,
R113 and R201 are rubber rollers held by sintered bearings, and are not provided with an electromagnetic brake. Roller R
Reference numerals 102 and R103 denote rubber rollers held by bearings, and are not provided with an electromagnetic brake. The roller R107 is a sponge roller held by a bearing, and is not provided with an electromagnetic brake. The roller R107 conveys the sheet and performs decurling. Rollers R108, R109, R110, R111,
R112 and R202 are separation rollers formed of rubber rollers, and have a mechanical structure in which one of the pair of rollers 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.
115 are provided. Registration registration roller R1
Reference numeral 15 denotes that after the preceding sheet has been fed, the subsequent sheet fed at small sheet intervals must be stationary when it arrives, so that the rotation of the roller can be stopped instantaneously after the trailing edge of the sheet has passed through the roller. An electromagnetic brake is provided. Further, since the roller R114 must be stopped accurately when a predetermined amount of sheet has been fed after the sheet abuts against the registration roller R115, an electromagnetic brake is provided to stop the roller instantly after driving the roller for a predetermined time. I have.

[0017]

[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, the roller which takes time from the release of the clutch to the stop of the rotation of the roller is a rubber roller held by a bearing bearing. A sponge roller held by a bearing, a rubber roller held by a sintered bearing, and a separation roller having a separation mechanism stop in the shortest time.

Rollers R100 to R103, R105 to R
Sensors S100 to S115, S201, and S202 are provided near 115, R201, and R202, respectively. Further, a sensor S11 is provided upstream of the photosensitive drum 152.
5 and S114 are provided. The sensor S115 is for timing to stop when the sheet is conveyed by a predetermined amount after the leading end of the sheet abuts the nip portion of the registration roller R115. The sensor S114 is for setting the timing at which the laser light emitting unit 150 forms a latent image on the photosensitive drum 152.

Sensors S102, S106, S107, S
104, S114, S115, S112, S113
As shown in FIG. 8, this is a flag type sensor including a movable flag 170 and a light emitting unit and a light receiving unit 172 provided in the movable range of the flag. (Movable member). When the flag 170 blocks the light path between the light emitting unit and the light receiving unit 172, that is, when the flag 170 is not tilted down 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 path between the light emitting unit and the light receiving unit 172, that is, when the flag 170 is not tilted on the sheet (when the flag 170 is at the second position), it is determined that there is a sheet. As described above, the flag 170 indicates that the light emitting unit and the light receiving unit 17
By detecting whether or not the optical path between the two is blocked, the leading end of the sheet and the presence or absence of the sheet are detected. The flag 170 is biased by a spring so as to be in a solid line state. When the trailing edge of the sheet comes off, the flag 170 returns to block the light path of the light emitting unit and the light receiving unit 172.
70 does not return instantaneously, and a return causes a time lag, so that it is difficult to accurately detect the rear end of the sheet. As described above, since the flag type sensor is not suitable for accurately detecting the trailing edge of the sheet, the rollers R108 and R1 which detect the trailing edge of the preceding sheet at the time of feeding and create an accurate sheet interval.
09, R110, and sensors S108 and S1 near R111
00, S109, S101, S110, S102, S1
11, an optical sensor is used for S105.

Sensors S108, S100, S109, S
101, S110, S102, S111, S105
As shown in FIG. 9, an optical sensor including a light emitting unit 174 and a light receiving unit 176, and whether or not the sheet blocks an optical path between the light emitting unit 174 and the light receiving unit 176 when the conveyed sheet passes through the sensor. By detecting the presence or absence of the sheet, the leading and trailing ends of the sheet and the presence or absence of the sheet are detected.

The photosensitive drum 152 is driven by a motor 128
The fixing roller 154 is driven by the motor 130. The sheet sent to the double-sided path 156 is conveyed by rollers 138, 136, 134, and 132.
The roller 138 is driven by the motor 126 by the rollers 136, 1
34 is a motor 124 and rollers 132 are a motor 12
2 driven. The motors 126, 124, 122 are stepping motors. In the two-sided pass, the motor needs to rotate forward and reverse to switch back the sheet, and when receiving the sheet from the upstream side in the two-sided pass, it rotates at the speed matching the fixing roller, and then closes the sheet interval. It is necessary to rotate at a high speed and stop the rotation when the sheet reaches a predetermined position. Therefore, a stepping motor that can easily and accurately control the speed is employed.

FIG. 3 is a block diagram related to clutch control. Outputs from the sensors S100 to S115, S201, and S202 are input to the CPU 180. The CPU 180 controls the driving of the motor 120 via the amplifier 186. FIG.
Although not shown, the CPU 180 includes a motor 128,
It also controls the driving of 130, 122, 124, and 126. Further, the CPU 180 includes clutches C100 to C10.
3. Control connection and release of C105 to C115, C201, and C202. The setting input on the operation unit 300 is C
Input to the PU 180, the CPU 180 causes the operation unit 300 to perform a predetermined operation screen display. The control program to be executed by the CPU 180 is an RO readable by the CPU 180.
M182. The control program described later is also stored in the ROM 182. CPU18
0 writes data necessary for the control to the RAM 184 backed up by a battery. The RAM 184 also stores data measured for correction control described later.
Is written to. EEPROM instead of RAM 184
A non-volatile memory such as

Next, with reference to FIGS. 4 and 5, the characteristics of the roller when the clutch is disengaged and the clutch is connected in the configuration in which the roller is driven via the clutch will be described. FIG. 4 shows an example of a configuration for driving a roller via a clutch. FIGS. 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. The roller RA is driven by a motor M via a clutch CA. A roller RB is provided downstream of the roller RA. Sensors SA and SB are provided upstream of the rollers RA and RB, respectively. Roller R
A does not have an electromagnetic brake.

FIG. 5 shows that the sheet SH is temporarily stopped by releasing the clutch CA while the sheet SH is being conveyed by the roller RA, and then the clutch CA is connected to connect the sheet SH.
Movement of the sheet SH when the sheet H is conveyed again (the roller RA
Characteristic). The vertical axis indicates the distance of the sheet SH, and the horizontal axis indicates time. SH0 instantaneously stops the sheet SH at time t4, shows the movement of the virtual sheet SH that is instantaneously conveyed at the predetermined speed V1 at time t5, and SH0 'shows the actual movement of the sheet SH.

At time t4 when the sheet SH is temporarily stopped while the sheet SH conveyed from the upstream side is being conveyed by the roller RA, 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 engaging the clutch CA. Clutch C
In order to stop the roller RA only by releasing A, FIG.
As shown in SH0 'of FIG.
The sheet SH stops at a position advanced by one. As described above, the advance amount x1 depends on the type of roller bearing, the material of the roller,
It depends on the mechanical structure of the roller drive and the individual differences of the rollers. In addition, since it takes time until the clutch CA is completely connected, a delay occurs in the rising of the conveyance of the sheet SH.
The advance amount of the sheet SH with respect to the position SH0 of the virtual sheet SH decreases to x2.

In general, the amount of sheet advance from clutch release to roller stop is greater than the amount of sheet delay when the clutch is engaged. Therefore, if the clutch CA is engaged after the clutch CA is released, a virtual The sheet position is advanced by x2 from the sheet position. As described later, the clutch connection timing is advanced by the amount x2, that is, the time ΔT
By delaying by A, the correction is made so as to be a virtual sheet position.

The time ΔTA is from time t1 when the leading end of the sheet SH passes through the sensor SA to time t2 when passing through the sensor SB.
The actual time TA ′ until the clutch CA is released is assumed to be zero, and the sheet delay is assumed to be zero when the clutch CA is engaged. Time from time t1 when passing through sensor SA to time t3 when passing through sensor SB) to time T
It can be obtained by subtracting A '. When the sheet SH is conveyed at a speed V1 over a distance X1 from the sensor SA to the sensor SB, the virtual time TA is equal to the sensor SA-S
It is equal to the sum of the movement time X1 / V1 of the sheet SH between B and the suspension time TB. Therefore, ΔTA can be obtained by the following equation. The calculation of ΔTA is performed by the CPU 180, and the CPU 180 stores the ΔTA in the battery-backed RAM 184.

ΔTA = TA−TA ′ = (X1 / V1 + TB) −TA ′ = X1 / V1− (TA′−TB)

FIG. 6 is a diagram showing the movement of the leading end of the sheet when the above-described correction of ΔTA is not performed when the sheet is continuously fed from the sheet feeding cassette D108. With the registration rollers R115 stopped, the sheets SH1, S
H2 and SH3 are replaced by rollers R100, R101, R102,
The paper is fed by R103 and R114. Sensors S108 and S100 determine that the distance between the leading edge of each preceding sheet and the leading edge of the succeeding sheet is d1, that is, the distance between the trailing edge of the preceding sheet and the succeeding sheet is d3 as shown in FIG. 7A. The clutch C108 is engaged according to the detection of the rear end of the preceding sheet. At timing t11 when the leading end of the sheet SH1 is fed to the roller 115, the roller R11
4. Stop R103, R102, R101, R100. The roller R114 is stopped by the release of the clutch C114 and the electromagnetic brake B114.
R102, R101, and R100 each have a clutch C1.
03, C102, C101, and C100 are stopped only by release. Since the sheet SH2 advances when the roller R102 stops, the sheet SH2 is moved from the leading end of the sheet SH1.
The distance to the tip of H2 is d2 shorter than d1. Next, at a predetermined timing t12 when image formation is performed, the sheet S
H1 is fed by registration rollers R115 and R114, and simultaneously SH2 and SH3 are also fed by rollers R114 and R10.
3, transported by R102, R101, R100. Therefore, the sheet SH2 is conveyed with the distance between the leading end of the sheet SH1 and the leading end of the sheet SH2 being d2.

FIG. 7 shows the state of the sheet SH1 from the leading end of the sheet SH1.
2 and the distance from the rear end of the sheet SH1 to the sheet S
It is a figure which shows the relationship of the distance to the front-end | tip of H2. FIG.
As shown in (1), the sheet S starts from the leading end of the sheet SH1.
When the distance to the leading end of H2 is d1, the distance from the trailing end of sheet SH1 to the leading end of sheet SH2 is d3. The distance d3 is determined by the flag position of the sheet present state (second position) between the time when the flag 170 of the flag type sensor such as the sensor S104 passes after the rear end of the sheet SH1 passes and the front end of the sheet SH2 reaches. Is the interval corresponding to the time during which it is possible to return from the sheet position) to the flag position (first position) in the sheet absence state. As shown in FIG. 7 (2), the sheet S
When the distance from the leading end of H1 to the leading end of sheet SH2 is d2, the distance from the trailing end of sheet SH1 to the leading end of sheet SH2 is d4, which is shorter than d3.

The distance from the rear end of the sheet SH1 to the front end of the sheet SH2 is the sensor S104.
If the flag 170 is not a sufficient distance to return to the flag position of the no-sheet state between the time when the front end of the sheet SH2 reaches the sensor S104 after passing through the sensor S104, the detection result of the sensor S104 is after the sheet SH1. Since the presence of the sheet is continuously indicated from the end passing to the arrival at the leading end of the sheet SH2, it is erroneously detected that the jam is not the jam but the jam.

Further, the sheet SH1 is moved from the rear end of the sheet SH1.
The distance to the leading edge of the registration roller R115 is determined after the rear end of the sheet SH1 passes through the registration roller R115.
If the distance is such that the leading end of the sheet SH2 reaches the registration roller R115 before the sheet SH2 is completely stopped, not only the skew of the sheet SH2 cannot be corrected, but also
Because the leading end position of the sheet SH2 during standby is shifted,
There is a disadvantage that an image formed on the sheet is displaced.

FIG. 10 is a diagram showing the movement of the leading end of the sheet when the above-described correction of ΔTA is performed when the sheet is continuously fed from the sheet feeding cassette D108. The operation up to timing t12 is the same as in FIG. Paper cassette D108
The sheet is separated and fed such that the distance between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet is d1. The distance d1 is a distance at which the erroneous detection of the stagnant jam and the positional displacement of the image do not occur, and is a distance reduced to an extent that productivity can be increased as compared with the related art.

The sheet SH1 is fed by the registration rollers R115 and R114 at a predetermined timing t12 when an image is formed. SH2 after ΔTA from timing t12
Is transported by rollers R114, R103, R102, and R101. When the advance amount of the sheet SH3 is the same as that of the sheet SH2, conveyance of the sheet SH3 is started simultaneously with the sheet SH2. The sheet SH2 is conveyed while the distance between the leading end of the sheet SH1 and the leading end of the sheet SH2 is d1 ′.
The distance between the leading end of the sheet SH1 and the leading end of the sheet SH2 is Δ
Since it has been corrected by TA, it becomes d1 '. d1 'is d1
Although the distance is shorter by the connection delay of the clutch C115, the distance of the connection delay of this clutch is smaller than the sheet advance amount when the upstream clutch is released. The distance d1 'is a distance at which the erroneous detection of the stay jam and the positional displacement of the image do not occur at least.

Accordingly, the rear end of the sheet SH1 and the sheet SH1
The distance of the tip of No. 2 is corrected so that the sensor S104 does not erroneously detect a stagnant jam, and erroneous detection of a stagnant jam can be prevented.

That is, a conveying means for conveying a plurality of sheets along a conveying path at a predetermined sheet interval, and a movable member set at a first position on the conveying path is tilted down by the sheets to a second position. After detecting the presence of a sheet, and detecting the absence of a sheet by detecting that the movable member has returned to the first position after the passage of the sheet, the conveyance of a plurality of sheets by the conveyance unit is temporarily stopped. Control means for restarting conveyance of a plurality of sheets by the conveyance means,
The sheet interval at the time of resuming the sheet conveyance by the conveying unit is corrected to an interval corresponding to a time longer than a time required for the movable member to return to the first position after at least the trailing end of the sheet has passed through the movable member. With the correction means, when the conveyance of the sheet is temporarily stopped and then restarted, it is possible to prevent erroneous detection of a stay jam.

These controls are performed by the CPU 180, and the CPU 180 controls the battery-backed RA.
ΔTA is read from M184 to perform the above-described correction control. Although it has been described that ΔTA measured and calculated is stored in the RAM 184 and is read and subjected to correction control,
Not limited to this, ΔTA previously obtained at the design stage is
The same effect can be obtained by storing the data in the OM 182 and reading out the data from the ROM 182 to perform the correction control.

FIG. 11 and Table 2 show a combination of rollers for holding 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. ΔT in Table 2
Information other than A (i) is stored in the ROM 182.
X1 (i) is the distance between the sensor SA (i) and the sensor SB (i). Regarding ΔTA (i), the RAM 1 is associated with a measurement area number in a clutch measurement mode described later.
84.

[0040]

[Table 2]

FIGS. 12 to 15 are flowcharts of the clutch measurement mode. A program for executing this flowchart is stored in the ROM 182,
0 is read and executed. The service mode clutch adjustment value measurement screen (FIG. 22) is displayed on the operation unit 300, and the clutch measurement mode is executed in response to the start key being touched. In starting the execution of the clutch measurement mode, the CPU 180 controls the motor 120,
Turn on 128, 130 and other motors.

First, based on the detection result of the sheet presence / absence sensor provided in the sheet feeding cassette D108, the sheet feeding cassette D
It is determined whether there is a sheet in S (S400). If there is no sheet, a warning is displayed on the operation unit 300 to set an A4 or letter-size sheet in the sheet feeding cassette D (S402). If there is a sheet in the sheet cassette D108, it is determined whether the sheet is A4 or letter size based on the detection result of the sheet size sensor (S
404). If it is neither A4 nor letter size, the process proceeds to step S402.

If it is determined in step S404 that the size is A4 or letter size, 0 is set in the variable i (S40).
6). Then, the clutches C114 and C115 are connected (S408), and one sheet is fed from the sheet feeding cassette D108 (S410). The pickup roller of the roller R108 is driven by a solenoid. When the solenoid is off, the pickup roller is driven by the sheet feeding cassette D10.
8 has landed on the sheet. Paper cassette D1
08 to feed the sheet, by connecting the clutch C108, the pick-up roller and the roller R1 are connected.
08 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 cassette D108.

Next, when the sensor S100 is turned on (S
418), a clutch measurement process described later is executed (S4).
20). This clutch measurement process is repeated until the sensor S104 is turned on (S422). That is, a plurality of areas are measured on one sheet. That is, the conveyance of the sheet is stopped between the first sensor and the second sensor, and the conveyance of the sheet is restarted after the lapse of a predetermined time. From the time when the first sensor detects the end of the sheet, Second
The sensor measures the time until the sensor detects the end of the sheet, and stops the sheet temporarily stopped between the first sensor and the second sensor between the second sensor and the third sensor. ,
The conveyance of the sheet is restarted after a predetermined time has elapsed, and the third sensor is moved from the time when the second sensor detects the end of the sheet.
The sensor measures the time until the sensor detects the end of the sheet.

Next, based on the detection result of the sheet presence / absence sensor provided on the sheet feeding deck D111, the sheet feeding deck D11
1 (S424), and if there is no sheet, an A4 or letter size sheet is fed to the sheet feeding deck D.
A warning is displayed on the operation unit 300 to set the setting to 111 (S426). If there is a sheet on the sheet feeding deck D111, it is determined whether the sheet is A4 or letter size based on the detection result of the sheet size sensor (S42).
8). If it is neither A4 nor letter size, the process proceeds to step S426.

If it is determined in step S428 that the size is A4 or letter size, one sheet is fed from the sheet feeding deck D111 (S430). The pickup roller of the roller R111 is driven by a solenoid. When the solenoid is off, the pickup roller is driven by the sheet feeding deck D1.
11 is in a state of landing on the sheet. Paper feed deck D1
In order to feed a sheet from the pickup 11, the pickup roller and the roller R 1 are connected by connecting the clutch C 111.
11 is driven. 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 sheet feeding deck D111.

Next, when the sensor S105 is turned on (S
436), a clutch measurement process is executed (S438).
This clutch measurement process is repeated until the sensor S107 is turned on (S440).

The image forming apparatus of this embodiment includes a roller R10
Since no sensor is provided between R6 and R107, the measurement of area 6 and area 7 must be performed by both sensors S106 and S107, so the sheet used for the measurement of area 6 is discharged and another The sheet is newly fed and the area 7 is measured by the sensors S106 and S10.
7 must be performed.

Therefore, the paper feed deck D111 returns to A4
Or, feed a letter-size sheet. Paper feed deck D
It is determined whether there is a sheet in the sheet feeding deck D111 based on the detection result of the sheet presence sensor provided in the sheet 111 (S4).
42) If there is no sheet, the operation unit 3 sets an A4 or letter size sheet on the sheet feeding deck D111.
A warning is displayed at 00 (S444). Paper feed deck D111
If there is a sheet, it is determined whether the sheet is A4 or letter size based on the detection result of the sheet size sensor (S446). If it is neither A4 nor letter size, the process proceeds to step S444.

If it is determined in step S446 that the size is A4 or letter size, the sheet feeding deck D1
Then, one sheet is fed from 11 (S448).

Next, when the sensor S106 is turned on (S
454), a clutch measurement process is executed (S456).
Thus, in the clutch measurement mode, the sheet feeding deck D111
After that, a total of two sheets are fed for measurement.

Next, based on the detection result of the sheet presence / absence sensor provided on the sheet feeding deck D200, the sheet feeding deck D20
(S458), and if there is no sheet, an A4 or letter size sheet is fed to the sheet feeding deck D.
A warning is displayed on the operation unit 300 so as to be set to 200 (S460). If there is a sheet in the sheet feeding deck D200, it is determined whether the sheet is A4 or letter size based on the detection result of the sheet size sensor (S46).
2). If it is neither A4 nor letter size, the process proceeds to step S460.

If it is determined in step S462 that the size is A4 or letter size, one sheet is fed from the sheet feeding deck D201 (S464). The pickup roller of the roller R201 is driven by a solenoid. When the solenoid is off, the pickup roller is driven by the sheet feeding deck D2.
01 has landed on the sheet. Paper feed deck D2
01 to feed the sheet, the clutch C201 is connected, and the pickup roller and the roller R2 are connected.
01 is driven. 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 sheet feeding deck D201.

Next, when the sensor S201 is turned on (S
470), and a clutch measurement process is executed (S472).
After the clutch measurement process, when it is detected that all the sheets have been discharged by the sensor provided in the paper discharge unit, the process ends (S4).
74).

FIG. 16 is a flowchart of the clutch measurement process called in the above-described clutch measurement mode. A program for executing this flowchart is stored in the ROM 182, 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 counted up during the execution of the program. The CPU 180 can manage the current time using this counter.

First, 1 is added to the variable i (S500), and R
With reference to the rollers in the area i shown in Table 2 stored in the OM 182, the corresponding clutches are engaged (S501), and the current time is set to t1 (i) (S501).
502). Then, T in Table 2 stored in the ROM 182
Referring to C (i), wait for TC (i) time (S50).
4) The clutches of the rollers in the area i and the area (i-1) are released (S506). When the variable i is 1, area 0 does not exist, so the clutch of the roller in area 1 is released. Then, after waiting for TB time (S508), the clutches of the rollers in the area i are engaged (S510).
Referring to SB (i) in Table 2, the output of sensor SB (i) is monitored, and when sensor SB (i) is turned on (S512), the current time is set to t2 (i) (S512).
514). Then, t2 (i) -t1 (i) is obtained, and T2 (i) -t1 (i) is obtained.
A '(i) is set (S516), and X1 (i) in Table 2 is set.
With reference to X1 (i) / V1- (TA '(i) -TB)
Is stored in the RAM 184 in association with the area number i as ΔTA (i) (S518), and the process returns to the clutch measurement mode shown in FIGS.

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

Further, as shown in FIG. 22, the operation section 300 displays whether the measurement is being performed or the measurement is completed. Further, ΔTA (i) may be displayed on the operation unit 300 as shown in FIG.

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

First, in order to correct the skew of the sheet by the registration roller R115, the clutch C115 is released and the brake B115 is turned on to stop the registration roller R115 (S600). And the operation unit 3
The sheet is continuously fed from the sheet feeding deck or the sheet feeding cassette designated by 00 so that the distance between the trailing edge of the preceding sheet and the leading edge of the succeeding sheet is d3 (S60).
2). In the sheet feeding control of step S602, the conveyance amount of each sheet is managed based on the detection result of the sensor and the sheet conveyance time, and the front end position information (the registration roller R115 to the front end position information) always indicates the latest front end position of each sheet. ) Along with the size information of each sheet.
To memorize. It is determined whether the sensor S115 has been turned on, that is, whether the leading edge of the preceding sheet has reached the sensor S115 (S604), and if not turned on, the step S602 is continued. If it is turned on in step S604, the process waits for a TL time (S606), and performs a sheet feeding temporary stop process described later (S608). In the sheet feeding suspension 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 indicates that the registration roller R is moved after the leading edge of the sheet has passed the sensor S115.
This is the time during which the sheet is conveyed by a predetermined amount after the nip 115 is reached.

When the timing at which the image formed on the photosensitive drum 152 coincides with the sheet is reached (S610), a sheet feeding restart process described later is performed (S610).
612). It is determined whether this sheet is the last sheet on which an image is to be formed (S614), and if not, the process returns to step S602. If it is the last sheet, the process ends when the last sheet is discharged by the discharge roller (S61).
6).

FIG. 18 is a flowchart of the sheet feeding temporary stop processing called in the above-mentioned sheet feeding control.
The program for executing this flowchart is RO
It is stored in M182 and read and executed by the CPU 180. The sheet feeding suspension 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 one near the registration roller R115, that is, from the downstream side to the upstream side. First, the clutch C114 is released (S70).
0), the brake B114 is turned on (S702). Then, 1 is set to the variable i (S704), and the ROM 182 is set.
Is released (S706).

[0063]

[Table 3]

Then, the current time is set to t (i) (S708), and 1 is added to the variable i (S710). It is determined whether or not the variable i has become 14, and if not, the process returns to step S706. When the variable i becomes 14, the process returns to the sheet feeding control of FIG.

FIG. 19 is a flowchart of the sheet feeding resumption processing called in the above-described sheet feeding control. The program for executing this flowchart is ROM1
82, and are read and executed by the CPU 180. In the sheet feeding restart process, first, the brake B11
5 and B114 are turned off (S800, S802), and the clutches C115, C114 are connected (S804, S80).
6). Next, 1 is set to the variable i (S808), and 0 is set to the variable TWT of the total waiting time (S81).
0). Then, the leading edge position information (distance from the registration roller R115) of each sheet in the conveyance path stored in the RAM 184 and the position information of the roller R (i) corresponding to the clutch C (i) stored in the ROM 182 ( Distance from the registration roller R115), the clutch C
It is determined whether the roller R (i) corresponding to (i) is holding the sheet (S812). If it is determined that the roller R (i) is holding the sheet, the information on the leading edge position of each sheet in the conveyance path stored in the RAM 184 and the ROM
Referring to the position information of the other rollers stored in 182, it is determined whether the sheet held by the roller R (i) is held by the downstream roller (the roller on the photosensitive drum 152 side) (S814). . If the sheet held by the roller R (i) is not held by the downstream roller, a clutch connection process described later is performed (S816).
One is added to the variable i (S818). If it is determined in step S812 that the roller R (i) is not holding the sheet, or if it is determined that the sheet held by the roller R (i) is held by the downstream roller, the process proceeds to step S818. . After step S818, the variable i is 1
It is determined whether the number has reached 4 (S820). If the number has not reached 14, the process returns to step S812. When the variable i becomes 14, the process returns to the sheet feeding control of FIG.

FIGS. 20 and 21 are flowcharts of the clutch connection process called in the sheet feeding restart process described above. A program for executing this flowchart is stored in the ROM 182, and is read and executed by the CPU 180. In the clutch engagement process, first, the current time -t (i) is obtained and set to a variable DT (S9).
00). Then, it is determined whether the sheet is being fed from one of the paper feed cassettes D108 and D109 and the paper feed deck D110 (S902), and the paper feed cassettes D108 and D1 are determined.
09, if the sheet is fed from one of the sheet feeding decks D110, the leading edge position information of each sheet in the conveyance path stored in the RAM 184, the roller position information and the roller type stored in the ROM 182. Refer to the information,
It is determined whether the sheet held between the rollers R (i) is held between the separation rollers (S904). Roller R
When the sheet held in (i) is held by the separation roller, even if the sheet is held by another roller, the sheet is affected by the separation roller having a short stop time. Is set to ΔTA (1) (S906).

If it is determined in step S904 that the sheet held by the roller R (i) is not held by the separation roller, the ROM 182 and the RAM 1
Referring to 84, it is determined whether the sheet held by the roller R (i) is held by the bearing rubber roller (S908). If it is determined that the sheet held by the roller R (i) is not held by the bearing rubber roller, the sheet is held by only the sintered bearing rubber roller. (S910). If it is determined that the sheet held by the roller R (i) is held by the bearing rubber roller, the ROM 182 and the RAM
Referring to 184, it is determined whether the sheet held by the roller R (i) is held by the sintered bearing rubber roller (S912). If it is determined that the sheet held between the rollers R (i) is held between the sintered bearing rubber rollers, the sheet is held between the sintered bearing rubber roller and the bearing rubber roller.
TA (3) is set (S914). Roller R (i)
If it is determined that the sheet sandwiched by the bearings is not sandwiched by the sintered bearing rubber rollers, since the sheet is sandwiched only by the bearing bearing rubber rollers, the variable WT is set to ΔTA (4).
Is set (S916).

In step S902, the sheet cassette D10
8, D109, when sheet feeding is being performed from a sheet feeding unit other than the sheet feeding deck D110, it is determined whether sheet feeding is being performed 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 held by the roller R (i) is held by the separation roller by referring to the ROM 182 and the RAM 184 as described above (S920). . When it is determined that the sheet nipped by the roller R (i) is nipped by the separation roller, even if the sheet is nipped by another roller, the sheet is affected by the separation roller having a short stop time. Set ΔTA (5) to WT (S92)
2). When it is determined that the sheet nipped by the roller R (i) is not nipped by the separation roller, the roller R (i) is referred to the ROM 182 and the RAM 184 as described above.
It is determined whether or not the sheet held in (i) is held by the bearing sponge roller (S924). When the sheet held between the rollers R (i) is not held between the bearing bearing sponge rollers, the sheet is held between only the sintered bearing rubber rollers.
ΔTA (6) is set to T (S926). Roller R
When the sheet held in (i) is held between the bearing bearing sponge rollers, the sheet is held between the sintered bearing rubber roller and the bearing bearing sponge roller, so that the variable WT is set to ΔTA (7). (S928). In step S918, the sheet feeding deck D111
, The variable WT is set to ΔTA
(8) is set (S930).

In the image forming apparatus of this embodiment, measured data is used when feeding a sheet of the same size as that used in the clutch measurement mode in the sheet feeding control. When a sheet having a larger size is pinched by three or more rollers, and there is a combination of rollers not measured in the clutch measurement mode, among a plurality of areas to which the roller pinching the sheet belongs, Select the data with the shortest time from clutch release to stop.

Steps S906, S910, S914,
After performing a data set on the variable WT in S916, S922, S926, S928, and S930, the variable WT
It is determined whether it is larger than WT (S932). If the variable WT is larger than the variable TWT, WT−TWT is obtained and set to the variable WT (S934), and the variable WT is set to the variable TWT.
In the following cases, the variable WT is set to 0 (S936).
Here, the drive timing of the clutch corresponding to the roller holding the succeeding sheet is adjusted in accordance with the delay in driving the clutch corresponding to the roller holding the preceding sheet.

After setting the data in 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, the variable WT is set to DT (S94).
0). If the temporary release time of the clutch C (i) is shorter than the clutch connection delay time, that is, the time required until the roller stops (sheet stops), the amount of advance of the sheet during the temporary release of the clutch C (i) is reduced by the roller R ( i) Since the sheet advance amount until the stop is not reached, the clutch C
This is because the delay may be delayed by the temporary release time of (i). Then, it is determined whether the variable WT is larger than 0 (S9).
42). If the variable WT is equal to or smaller than DT in step S938, the process proceeds to step S942. If the variable WT is greater than 0 in step S942, the process waits for the WT time (S94
4) The clutch corresponding to the roller holding the sheet held between the clutch C (i) and the roller R (i) is connected (S946). At this time, the variable T
A value obtained by adding WT to WT is set in a variable TWT (S9).
45). If the variable WT is 0 in step S942, the flow advances to step S946 to immediately engage the clutch corresponding to the clutch holding the sheet held by the clutch C (i) and the roller R (i). And FIG.
The process returns to the sheet feeding restarting process.

[0072]

As described above, according to the present invention,
A conveying unit that conveys a plurality of sheets along a conveyance path at a predetermined sheet interval, and a movable member set at a first position in the conveyance path being tilted down by the sheets to a second position. Detecting means for detecting the presence of a sheet, detecting that there is no sheet by returning the movable member to the first position after passing the sheet, temporarily stopping conveyance of a plurality of sheets by the conveyance means, and Control means for restarting conveyance of a plurality of sheets by means, and a sheet interval when sheet conveyance by the conveyance means is restarted, wherein the movable member is moved to the first position after at least a trailing end of the sheet has passed through the movable member. Correction means for correcting the interval to a time corresponding to a time longer than the time required to return to the original state. It is possible to prevent erroneous detection of the catcher arm.

[Brief description of the drawings]

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

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

FIG. 3 is a block diagram related to clutch control.

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

FIG. 5 is a diagram illustrating characteristics of a roller when the clutch is connected after the clutch is released.

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

FIG. 7 is a diagram illustrating a distance from a rear end of the sheet SH1 to a 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 illustrating the movement of the leading end of a sheet when 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 suspension process.

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

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

FIG. 21 is a flowchart of a clutch connection 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.

[Explanation of symbols]

100 image forming apparatus R100 to R103, R105 to 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 deck

Continuation of the front page (72) Inventor Manabu Yamauchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tomoyasu Yoshikawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroto Nishihara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Ikuo Takeuchi 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo In Canon Inc. (72) Invention Person Kenji Fukushi Inside Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Shinsuke Ubayashi Inside Canon Inc. 3- 30-2 Shimomaruko 3-chome, Ota-ku, Tokyo (72) Takashi Nakanishi 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 2C058 AB16 AC08 AD04 AE02 AE09 AF04 AF20 AF23 GA14 GB05 GB14 GB31 GB32 GB47 2H072 AA03 AA09 AA13 AA16 AA17 AA29 AA32 AB07 BA03 BA09 CA02 JA02

Claims (1)

[Claims] A transport unit configured to transport a plurality of sheets along a transport path at a predetermined sheet interval; and a second position in which a movable member set at a first position on the transport path is tilted down by the sheets. Detecting means for detecting the presence of a sheet, and detecting the absence of a sheet by returning the movable member to the first position after the passage of the sheet, temporarily stopping the conveyance of a plurality of sheets by the conveyance means. Control means for restarting the conveyance of a plurality of sheets by the conveyance means, and a sheet interval at the time of resumption of sheet conveyance by the conveyance means, wherein at least the rear end of the sheet passes through the movable member, and A correction unit configured to correct an interval corresponding to a time longer than a time required to return to the first position.