JPH05294520A - Paper sheet carrying device - Google Patents

Abstract

PURPOSE:To surely prevent the skew and deviation of the copying paper sheet supplying timing, generation of abnormal noises and excessive tension due to the paper sheet to be drawn, and inconveniencies such as bending or wrinkling of the copying paper sheet. CONSTITUTION:The rotational speed and the rotational quantity of an intermediate roller 22 and a timing roller 23 are detected by means of an intermediate roller rotational sensor 100 and a timing roller rotational sensor 101, and a microcomputer sets the timer T-V of a loop quantity timer based on the starting time of the representative rollers and the difference of the carrying quantity of the copying paper sheet therebetween, and the stopping timing of the intermediate roller 22 is controlled when the loop is formed in the copying paper sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying apparatus for forming a loop on a sheet between a timing roller and an intermediate roller in an image forming apparatus to control registration.

[0002]

2. Description of the Related Art For example, in an electrostatic transfer type image forming apparatus, especially in a copying machine having an exposure optical system, a registration control is performed by forming a loop on a copying paper between a timing roller and an intermediate roller (conveying roller). I'm trying to do. This is to form the loop for the purpose of aligning the leading edge of the exposure image formed on the photosensitive drum with the leading edge of the copy sheet, and for preventing skew of the copy sheet.

The operation of forming the loop will be described in detail. The intermediate roller is stopped after a lapse of a predetermined time after the leading edge of the copy sheet conveyed by the rotation of the intermediate roller passes the registration sensor on the upstream side of the timing roller. By appropriately setting the time until the intermediate roller stops, the copy paper forms a loop by the feeding operation until the intermediate roller stops after first contacting the timing roller in the stopped state. Will be.

The relationship between the size L2 of the loop and the time T-D from the time when the leading edge of the copy paper passes the registration sensor to the time when the driving force transmission to the intermediate roller is stopped is expressed by the following (Equation 1) )become that way. Here, L1 is the distance between the registration sensor and the timing roller, V is the sheet conveyance speed of the intermediate roller, T is the time from when the driving force transmission to the intermediate roller is stopped to when the intermediate roller is actually stopped, ΔT is a total of the above-mentioned device-to-device variation Δt1, copy paper type variation Δt2, and temporal variation Δt3.

[0005]

[Equation 1]

If the loop amount L1 is not appropriate, the following problems will occur. That is, if the loop amount is too small or no loop is formed at all, the leading edge of the copy paper does not sufficiently come into contact with the timing roller, and skew and deviation of the copy paper supply timing cannot be reliably prevented. Also, after the loop is formed,
When the timing roller and the intermediate roller are activated to feed the copy paper toward the photosensitive drum, if the timing roller has a faster rise in rotation, the copy paper is pulled and an abnormal noise is generated or an excessive noise is generated. Tension acts.

On the other hand, when the loop amount is too large, or when the timing roller has a slower rise of rotation,
The copy paper tends to be bent or wrinkled. In order to prevent such a problem, it is necessary to properly set the time T-D. However, the variation Δt1 has a difference (apparatus difference) between apparatuses, especially with the recent increase in speed of copying machines. It tends to be large, and the variation of ΔT cannot be ignored when high-quality copying is desired.

Therefore, conventionally, in order to compensate the variation of ΔT, for example, 2-bit information is input to a microcomputer by a DIP switch and four types of timers (T-
D) is selected. This selection is performed by an operator who visually determines the loop amount and switches the dip switch in an inspection process before the image forming apparatus is shipped from the factory.

[0009]

However, the loop amount adjustment by switching the dip switch described above is a factor that deteriorates productivity, because the adjustment takes a relatively long time and requires skill. Also, the above ΔT
Includes the variation Δt3 with the passage of time, and even if the timer (TD) is selected in the inspection process before shipment, reselection is required due to the change with time. In this case, for example, there is a drawback that a service person or the like has to go to the user's place, visually judge the loop amount, and perform the operation of switching the dip switch again.

In view of the above points, the present invention has drawbacks such as skew, copy paper supply timing deviation, abnormal noise and excessive tension due to the copy paper being pulled, and bending and wrinkling of the copy paper. It is an object of the present invention to provide a sheet conveying apparatus that can reliably prevent the above-mentioned problems and that does not require time and effort for adjustment before shipment and readjustment with respect to variations over time.

[0011]

To achieve the above object, the present invention comprises a timing roller and a carrying roller provided upstream of the timing roller in the paper carrying direction, and the carrying roller is provided with the timing roller stopped. In a sheet conveying device configured to drive a sheet by a predetermined amount to convey a sheet, form a loop on the sheet, and start driving the timing roller and the conveying roller at a predetermined timing to start feeding the sheet. , The detection means for detecting the rotation of the timing roller and / or the conveyance roller, and the detection result of the detection means at the time of starting the paper supply, the conveyance amount of the paper until the timing roller and the conveyance roller reach the steady rotation, respectively. Controls the drive roller stop timing when forming a loop according to the difference It is characterized in that a that the control unit.

Further, instead of the control means, based on the detection result of the detection means at the time of forming the loop, the amount of paper conveyance from the stop of the driving of the conveyance roller to the complete stop of the conveyance roller. Accordingly, it is characterized in that a control means for controlling the drive start timing of the transport roller at the time of starting the supply of the paper is provided.

[0013]

With the above structure, the detecting means detects the rotation of the timing roller and / or the conveying roller. The control means, based on the detection result of the detection means at the time of starting the paper supply, according to the difference in the paper conveyance amount until the timing roller and the conveyance roller reach the steady rotation, respectively.
The drive stop timing of the transport roller when forming a loop is controlled. Alternatively, based on the detection result of the detection unit when forming the loop, when the supply of the sheet is started according to the sheet conveyance amount from the time when the conveyance roller is stopped to the time when the conveyance roller is completely stopped. The drive start timing of the conveyance roller is controlled.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view schematically showing the structure of an optical system moving slit exposure type electrophotographic copying machine 1. The exposure lamp 2 and the reflecting mirror 3 can be integrally moved by scanning to the left in the figure, and the reflecting mirrors 5 and 5'can be moved by scanning in the same direction at half the speed of the exposure lamp 2 and the reflecting mirror 3. By this scanning movement, the original document (not shown) placed on the original table 4 is continuously illuminated by the exposure lamp 2, and the reflected light thereof is reflected by the reflecting mirrors 5 ′, 5 → imaging lens 6 →
It reaches the photoconductor drum 8 via the reflecting mirror 7. Along with the scanning movement of the optical system, the control switch SW1 for starting the timer required for sequence control is turned on, and the intermediate roller 22
The timing switch SW2 for starting the driving of the timing roller 23 is turned on.

The photosensitive drum 8 rotates counterclockwise in the figure. The surface of the photosensitive drum 8 is uniformly charged by the charging charger 9, and then the image is exposed by the optical system to form an original document on the photosensitive drum 8. Electrostatic latent image is formed, and the image is developed by the developing device 10 to form a visible image with toner. On the other hand, the copy paper stored in the paper feed cassette 11 is conveyed by the paper feed roller 12 and the intermediate roller 22 to the timing roller 23 in the stopped state, where it forms a loop on the copy paper and is temporarily stopped. The intermediate roller 22 and the timing roller 23 are provided with an intermediate roller rotation sensor 100 or a timing roller rotation sensor 101, respectively, and the leading edge of the copy paper is located upstream of the timing roller 23 in the copy paper conveyance direction. A registration sensor SW3 for detecting passage has been provided, and the loop amount is controlled as described later.

The temporarily stopped copy paper is sent to the transfer section 13 in synchronism with the toner image formed on the photoconductor drum 8 at the timing when the timing switch SW2 is turned on, and the photoconductor drum is transferred. The toner image on 8 is transferred. The copy sheet onto which the toner image has been transferred is separated by the separation charger 14, and is conveyed by the conveyor belt 15 to a fixing device composed of a heat roller 16 and a pressing roller 17 to fix the toner image. After that, the copy paper is discharged to the tray 19 by the discharge roller 18, and the photosensitive drum 8 is rotationally driven for a predetermined time, and the cleaning device 20 removes the residual toner so that one copy process is completed. It has become.

FIG. 2 shows a control circuit for controlling the copying machine 1. Reference numeral 21 is a microcomputer, which is internally provided with a ROM, a RAM, a shift register, a counter, various timers (each not shown) and the like. , Control is performed according to a predetermined program stored in the ROM. The output port A1, A2, A3 of the microcomputer 21 has a buffer 31 connected to the clutch 12a of the sheet feeding roller 12.
Input terminal of the OR gate OR1 connected to the clutch 22a of the intermediate roller 22, and the OR gate OR connected to the clutch 23a of the timing roller 23.
Two input terminals are connected.

On the other hand, a timing switch SW2 for outputting a timing signal is provided in the buffer 32 at the input port B1.
Connected through. This timing switch SW
2 is also connected to the input terminals of the OR gates OR1 and OR2. Also, input ports B2, B3, B
A registration sensor SW3, an intermediate roller rotation sensor 100, and a timing roller rotation sensor 101 are connected to 4 and 4.

FIG. 3 is a perspective view showing a specific structure of the intermediate roller rotation sensor 100 and the timing roller rotation sensor 101. The intermediate roller rotation sensor 100 and the timing roller rotation sensor 101 include slit disks 100a and 101a and a photo interrupter 100.
b, 101b. The slit disks 100a and 101a are attached to one end of the intermediate roller 22 or the timing roller 23, respectively.
The photo interrupters 100b and 101b output a pulse signal each time the slit disks 100a and 101a rotate by a predetermined angle, and the microcomputer 21 counts this pulse signal, whereby the intermediate roller 22
The rotation speed and the rotation amount of the timing roller 23 are detected. Instead of the sensor that outputs the pulse signal corresponding to the rotation amount as described above, a tacho generator or the like that detects the rotation speed may be used. In this case, the rotation amount can be easily obtained by integrating the detected rotation speed.

A series of operation timings in the main part of the copying machine 1 will be described below with reference to the timing chart shown in FIG. First, when a print command signal generating means (not shown) is operated, an operation signal of the paper feed roller 12 is output until the timer (TA) expires,
The copy paper is sent from the paper feed cassette 11 by the paper feed roller 12 and conveyed to the intermediate roller 22, the exposure lamp 2 is preliminarily turned on at a predetermined constant voltage, and the photosensitive drum 8 starts rotating.

The charging charger 9 is turned on when the timer (TB) started when the timer (TA) times out. Furthermore, a timer (T-
B) a timer (T-
Due to the time increase of C), a predetermined voltage is applied to the exposure lamp 2 by the main lighting circuit including the dimming circuit, the scan clutch for scanning and moving the optical system is turned on, and the driving of the intermediate roller 22 is started. To be done.

When the intermediate roller 22 is driven, the leading edge of the copy sheet reaches the position of the registration sensor SW3 and the registration sensor SW3 is turned on, the loop amount timer (TD).
Is started, and when the time is up, the driving of the intermediate roller 22 is stopped. Here, the timer value of the loop amount timer (TD) is the timing at which a loop of a predetermined size is formed after the copying paper conveyed by the intermediate roller 22 comes into contact with the stopped timing roller 23. It is set so that the time will be up in, but the detailed setting method will be described in detail later.

On the other hand, when the control switch SW1 is turned on by the scanning movement of the optical system, the control switch SW is turned on.
The signal 1 is input to the microcomputer 21 and the timers (TE) and (TG) are started. When the optical system further scans and the timing switch SW2 is turned on before the timer (T-E) times out, the timing signal of the timing switch SW2 is input to the microcomputer 21 and the timer (T-K) is turned on. Is activated. The timing signal is an OR gate OR.
OR gate OR is also input to the input terminals of 1 and OR2.
The outputs from 1 and OR2 are turned on. Therefore, the intermediate roller clutch 22a and the timing roller clutch 23a are turned on, and the intermediate roller 22 and the timing roller 23 are turned on.
Are started at the same timing, and the copy paper is sent to the photosensitive drum 8.

When the timer (TE) times out,
The microcomputer 21 outputs an ON signal to port A
2 and A3, and the outputs of the OR gates OR1 and OR2 are O even after the timing switch SW2 is turned off.
Remains N. Therefore, the intermediate roller 22 and the timing roller 23 are kept in the driven state, and the intermediate roller 22 is stopped after the time T-K from the start of driving, while the timing roller 23 is further after the time T-N.
That is, the copying is stopped at the time when the copying paper is completely fed to the photosensitive drum 8.

When the timer (TG) times out, the charging charger 9 is turned off. Further, when a predetermined time corresponding to the document size has passed since the scanning of the optical system was started, the scanning is stopped and the exposure lamp 2
Is turned off and the heat roller 16 is turned on.
Also, the timer (T-V) is started, and when the time is up, the optical system is returned.

Further, when performing continuous copying, again
The paper feed roller 12 and the intermediate roller 22 are sequentially activated,
The second copy sheet is sent to the position where it reaches the timing roller 23, and the same operation as the first copy sheet is repeated. next,
The control content of the microcomputer 21 for performing the above operation will be described.

First, the main routine will be described with reference to FIG. In this main routine, (S2)-
(S7) is repeated at a predetermined cycle so that each process is apparently executed in parallel. First, copy machine 1
When the power is turned on, the state of each part and the timer value are initialized (S1).

After the initial setting is completed, an internal timer for synchronizing with other CPUs is started (S2),
The loop amount setting routine is executed (S3), and the intermediate roller 2
The target loop amount and the timer value are set according to the rising time of 2 and the like. The detailed processing contents of this loop amount setting routine will be described later. Next, a copy operation routine (S
4) and other routines (S5) such as setting various modes according to the operation of the operator, and further executing another C
Communication processing with the PU is performed (S6).

After that, the time-up of the internal timer started in (S2) is confirmed (S7), and the process returns to (S2). In the loop amount setting routine, the processing shown in FIG. 6 is performed. First, it is determined whether both the intermediate roller 22 and the timing roller 23 are in the driving state (S1
1), if both are in the driving state, both rollers 22, 2 are further
It is determined whether the rotation speed of No. 3 has reached the steady rotation speed (S12).

If YES in (S11) and (S12), it is judged which of the rollers 22 and 23 has a longer rise time (S13). On the other hand, if NO, the rise times cannot be compared. Therefore, the process directly returns to the main routine. Instead of the determination as described above, for example, it may be determined whether or not a predetermined period of time sufficient to reach the steady rotation speed has elapsed since both rollers 22 and 23 were started to be driven. ..

When it is determined in (S13) that the rising time of the intermediate roller 22 is longer, both rollers 22,
The loop amount is reduced by the feed amount (difference of the carry amount) A in the shaded portion in FIG. 7A until 23 reaches the steady rotation speed. That is, the loop amount is the feed amount A
In the above case, the copying paper is not pulled and no abnormal noise is generated or excessive tension is applied, so that the target loop amount L2 'is provided with a margin α of about 2 mm, L2' = A + α ( mm) (S14). However, if this L2 'is smaller than the minimum loop amount β (for example, about 5 mm) that can sufficiently prevent the skew of the copy paper from coming into contact with the timing roller and the deviation of the copy paper supply timing, Set to the minimum loop amount β.

On the other hand, when it is determined that the rise time of the intermediate roller 22 is shorter, the shaded area in FIG. 7B is reached before both rollers 22 and 23 reach the steady rotation speed. The loop amount increases by the feed amount B. Therefore, the target loop amount L2 'is the minimum loop amount β
(S15). L2 '= β (mm) Here, the feed amount B is the loop amount L2 actually formed.
When (= B + β) is large enough to cause a problem such as a paper break on the copy paper, for example, a warning message may be displayed to stop the operation of the copying machine 1.

When the target loop amount L2 'is set as described above, the loop amount timer (T
The timer value T-D of -D) is set as shown in the following (Equation 2) (S16).

[0034]

[Equation 2]

Here, L1 is the distance between the registration sensor SW3 and the timing roller 23, L2 'is the target loop amount,
V is a copy paper conveyance speed by the intermediate roller 22. Further, TR is an extra time corresponding to the amount of loop increase due to inertia when the intermediate roller 22 is stopped, response delay of the clutch 22a, etc., for example, the intermediate roller rotation sensor 100
By detecting the accompanying conveyance amount R from when the stop signal of the intermediate roller 22 is issued to when the intermediate roller 22 is completely stopped, an appropriate value can be obtained regardless of variations between devices or variations with time. It can be automatically requested.

In the above example, the loop amount timer (TD) is set based on the rising time when the intermediate roller 22 and the timing roller 23 are simultaneously driven, but the present invention is not limited to this. Instead, a loop amount timer (T-T) is set so that a predetermined loop amount is obtained based on the accompanying conveyance amount R detected by the intermediate roller rotation sensor 100 and the like.
D) is set, while each of the rollers 22, 23 is set based on the rising time of the intermediate roller 22 and the timing roller 23.
It is also possible to control the drive start timing of (1) to suppress the increase / decrease amount of the loop amount within a predetermined range.

[0037]

As described above, according to the present invention,
It is possible to automatically control the start and stop timings of the transport roller and the timing roller according to the size of the loop during loop formation and the increase or decrease of the loop at the start of paper supply. Defects such as skew and deviation of copy paper supply timing, abnormal noise and excessive tension due to pulling of copy paper, and bending and wrinkles of copy paper without re-adjustment for variations. There is an effect that can be surely prevented.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the configuration of an optical system moving slit exposure type electrophotographic copying machine.

FIG. 2 is a circuit diagram showing a control circuit for controlling a copying machine.

FIG. 3 is a perspective view showing a specific configuration of an intermediate roller rotation sensor and a timing roller rotation sensor.

FIG. 4 is a timing chart showing a series of operation timings in a main part of the copying machine.

FIG. 5 is a flowchart of a main routine of the microcomputer.

FIG. 6 is a flowchart of a loop amount setting routine of the microcomputer.

FIG. 7 is an explanatory diagram showing a relationship between a change in rotation speed and a difference in transport amount at the start of driving of the intermediate roller and the timing roller.

[Explanation of Codes] 1 Optical system moving slit exposure type electrophotographic copying machine 11 Paper feeding cassette 12 Paper feeding roller 12a Paper feeding roller clutch 21 Microcomputer 22 Intermediate roller 22a Intermediate roller clutch 23 Timing roller 23a Timing roller clutch 100 Intermediate roller rotation Sensor 101 Timing roller rotation sensor 100a / 101a Slit disk 100b / 101b Photo interrupter SW1 Control switch SW2 Timing switch SW3 Registration sensor

Claims (2)

[Claims] 1. A paper sheet is provided with a timing roller and a carrying roller provided upstream of the timing roller in the paper carrying direction, and the paper is carried by driving the carrying roller by a predetermined amount while the timing roller is stopped. In a sheet conveying device configured to form a loop and start driving a timing roller and a conveying roller at a predetermined timing to start sheet supply, a detection unit that detects rotation of the timing roller and / or the conveying roller. And, based on the detection result of the detecting means at the time of starting the paper supply, the driving of the conveying roller when forming the loop in accordance with the difference in the amount of paper conveying until the timing roller and the conveying roller reach the steady rotation. A sheet conveying device, comprising: a control unit for controlling a stop timing. . 2. Instead of the control means according to claim 1, the sheet from the time when the driving of the conveying roller is stopped to the time when the conveying roller is completely stopped based on the detection result of the detecting means when forming the loop. A sheet conveying apparatus, comprising: a control unit that controls a drive start timing of a conveying roller when starting to supply a sheet according to a conveying amount.