JP4510273B2 - Paper feeding device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a FAX, and more particularly to jam detection of the paper feeding apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a paper feeding device that feeds and transports paper (cut paper) on which an image is transferred or recorded from a paper cassette to an image forming (transfer or recording) position, the paper feed motor starts to rotate in response to a paper feed request. After waiting for the motor rising time until the speed reaches a certain speed, the paper feed clutch for transmitting the driving force from the paper feed motor to the paper feed roller is turned on. As a result, the paper feed roller rotates and a sheet of paper is picked up from the paper feed cassette.
[0003]
At this time, the start of the delay jam determination timer for determining the paper feed delay jam starts with the feed clutch being turned on. If the transport sensor arranged in the paper transport path does not detect the leading edge of the paper even if the paper feed delay jam determination timer exceeds the delay jam determination time, it is determined that the paper feed is delayed and paper feed is performed again (paper feed retry). Or decide to transition to the jam handling state.
[0004]
Also, the start of the stay jam timer for determining the paper feed stay jam starts from the fact that the transport sensor detects the leading edge of the paper. If the conveyance sensor does not detect the trailing edge of the paper even if the paper feed staying jam determination timer exceeds the set time, it is determined that the paper feed stays, and the jam processing state is entered.
[0005]
[Problems to be solved by the invention]
Conventionally, the first sheet of the copy is in a state where the paper feed motor is stopped, and in order to start paper feed, a sufficient time is required for the motor to start up. It is also a factor that lengthens the copy time of the first sheet. Therefore, in order to shorten the copy time of the first sheet, it is desirable to shorten the motor start-up time. However, the motor start-up time is determined by the characteristics of the motor and the like, and it is not easy to improve this technically and in terms of apparatus cost. On the other hand, if paper feeding is started without waiting for the motor startup time, the motor rotation speed at that time does not reach the desired speed. Therefore, the paper that has started feeding while the paper feed motor is starting reaches the transport sensor, or the time for detecting the trailing edge by the transport sensor is delayed from the scheduled time, and the transport state can be accurately detected. Can not. In the worst case, when the determination time exceeds the set time of the determination timer even though there is no defect in the conveyance state, the processing state shifts to a delayed jam or stay jam.
[0006]
An object of the present invention is to enable the paper feed state that can shorten the copy time (first copy time) of the first copy by enabling the normal detection of the paper conveyance state even during startup of the paper feed motor. It is to provide a feeding device.
[0007]
[Means for Solving the Problems]
The paper feeding method according to the present invention is a paper feeding method for feeding and transporting paper from the paper feeding unit to the image forming unit in the image forming apparatus, and before the target speed is reached after the paper feeding motor starts rotating. The transport delay time compared to when the paper feed motor starts feeding after the paper feed motor reaches the target speed is obtained from the motor start-up characteristics and the paper feed start timing, and the jam determination time is determined by the transport delay time. The value is corrected, and the elapsed time from the paper feed start timing is compared with the corrected jam determination time to perform jam determination.
[0008]
This makes it possible to correct the target time to reach the transport sensor according to the acceleration state no matter when the paper feed motor is started, so that a jam can be erroneously detected regardless of the paper feed start timing. In addition, in the first paper feeding, the motor acceleration waiting time can be reduced.
[0009]
The paper feeding device of the present invention that realizes the above method picks up the paper one by one from the paper feeding unit in the paper feeding device that feeds and conveys the paper from the paper feeding unit to the image forming unit in the image forming apparatus. A pickup roller, a paper feed motor for applying a driving force to the pickup roller via a paper feed clutch, a transport roller for transporting the picked-up paper, and a transported paper that is disposed in the transport path first. , A first timer for measuring the time after the start of rotation of the paper feed motor, a second timer for measuring the time after driving the paper feed clutch, and the values of the second timer Is compared with a predetermined jam determination time to determine a jam, and the value of the first timer at the time of driving the paper feed clutch and the rising characteristic of the paper feed motor And a means for determining whether or not paper feed has started before reaching the target speed of the paper feed motor, and when paper feed has started before reaching the target speed of the paper feed motor, And a means for correcting the value of the jam determination time based on the conveyance delay time compared to the case where paper feeding is started after reaching the target speed.
[0010]
The jam is a paper feed delay jam, and the jam determination time is determined in relation to the time until the leading edge of the paper reaches the transport sensor after the paper feed is started. Alternatively, the jam is a paper feed retention jam, and the jam determination time is determined in relation to the time until the trailing edge of the paper reaches the transport sensor after the paper feed is started.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a sheet feeding device in an image forming apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.
[0012]
FIG. 1 is a diagram illustrating a driving transmission path of the sheet feeding device according to the present embodiment. In this figure, the driving of the sheet feeding motor is transmitted through the gears with black and white stripes. By turning on each of the clutches (CL1, CL2, CL3), it is possible to transmit the drive of the paper feeding motor M2 to the destination. Further, the transmission of driving can be cut off by turning OFF.
[0013]
The main motor M1 and the paper feed motor M2 start rotating due to a print request or the like. Thereafter, when the clutch CL1 is turned on, the drive of the paper feed motor M2 is transmitted to the pickup roller 11 to start picking up and conveying the paper. At the same time, the sheet feeding roller 12 is driven by turning on the clutch CL3. When the paper is carried to the paper feed roller 12, the paper is carried along the transport path by the paper feed roller 12. The sheet that has reached the conveying roller 13 and is further conveyed and sent to the registration roller 14 is temporarily stopped by the registration roller 14 for skew correction. After the loop of the sheet is formed, the registration roller 14 is driven by turning on the clutch CL2. The paper starts to be conveyed again.
[0014]
The sheet conveyed again is sent to the photosensitive drum 15 that has already been rotated by the drive of the main motor M1, and a toner image is formed on the sheet. Further, the toner image is fixed by the fixing roller 16 and is discharged out of the apparatus by the paper discharge roller 17.
[0015]
Further, a conveyance sensor 20 disposed at the exit of the paper feed roller 12 in the sheet conveyance path, a pre-registration sensor 21 disposed in front of the registration roller 14, and a paper discharge sensor disposed at the outlet of the paper discharge roller 17. 22 detects the presence or absence of paper, and measures the timing related to image formation, the arrival time of the paper to each sensor, and the residence time of the paper, and detects the occurrence of various jams based on the measurement results. Can do.
[0016]
The hardware configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG. The control device 60 controls the clutch group 72, the fixing device 73, and the motor group 76 in accordance with operations of the various sensor groups 71 and the operation unit 74, and performs an image forming operation. The control device 60 also controls the high voltage group 77 and the display unit 75 for notifying the user of various information. The high voltage group 77 is a high voltage generating unit used in the electrophotographic process, and usually includes a primary bias, a development AC bias, a development DC bias, a transfer bias, and a static elimination bias.
[0017]
The control device 60 includes a CPU 62, a ROM 61, a RAM 63, a conveyance control unit 64, a paper feed timer 65, a jam timer 66, and other control units 67. The CPU 62 controls the operation of the image forming apparatus according to a control program stored in the ROM 61. The RAM 63 provides a work area and a temporary storage area for the CPU 62. The conveyance control unit 64 controls the motor group 76 to control sheet feeding and conveyance.
[0018]
3 to 5 show the case where the sheet feeding is started without waiting for the motor stabilization time in this embodiment (that is, when the sheet feeding clutch CL1 is turned on before the sheet feeding motor M2 reaches the target speed Vm). FIG. 6 is a control characteristic diagram of a paper feed motor for explaining a paper feed delay jam. 3, 4, and 5 show the ON timing (t2) of the sheet feeding clutch CL1 during acceleration of the sheet feeding motor M2, the predicted ON timing (t3) of the sheet feeding clutch CL1 at the actual speed, and the rising completion timing ( Three cases classified by the relationship with tm) are shown.
[0019]
In FIG. 3, when a print request is input, the paper feed motor M2 starts to accelerate from the stopped state and continues to accelerate until the target speed Vm is reached. At this time, the time from when the paper feed motor M2 is turned on until the target speed Vm is reached is assumed to be tm. This time tm is a known value predicted in advance. Further, the time from when the paper feed motor M2 is turned on to when the paper feed clutch CL1 is turned on is t1. In the present invention, the sheet feeding clutch CL1 is allowed to be turned on even during the rising period of the sheet feeding motor M2, but there are various timings at which the sheet feeding clutch CL1 is turned on. There may be cases. This case is the same as the conventional case.
[0020]
Now, as shown in FIG. 3, a case is considered where the paper feed clutch CL1 is turned on at a relatively early time from the time when the paper feed motor M2 is turned on. Unlike this case, when the paper feed clutch CL1 is turned on at a later time from the time when the paper feed motor M2 is turned on, if the speed of the paper feed motor M2 is the original speed Vm, the time t2 after the elapse of time t0 from the time t1. The leading edge of the sheet should reach the conveyance sensor 20 and be turned on. Since the distance L and the speed Vm from the pickup roller 11 to the conveyance sensor 20 are known, the time t0 is also a known constant value. However, when the paper feeding is started within the rising period of the paper feeding motor M2, the paper traveling distance is insufficient by ΔL in the figure when the time t0 elapses from the time point t1 compared to when the paper is transported at the original speed Vm. . The time during which this ΔL is further advanced is assumed to be Δt. In this example, it is assumed that the speed Vm has not yet been reached at time t3 when time Δt has elapsed from time t2. Since it is assumed that the acceleration at the rising edge of the sheet feeding motor is constant and the time tm is also constant, it can be determined if the time t1 is determined whether the time points t2 and t3 are before or after the time point tm.
[0021]
In the example of FIG. 3, the difference distance ΔL is
ΔL = Vm · (t2−t1) − {((Vx + V) / 2) · (t2−t1)}
here,
Vx = (t2 / tm) Vm
V = (t1 / tm) Vm
[0022]
Therefore,
ΔL = Vm · (t2−t1) − {((t2 / tm) Vm + (t1 / tm) Vm) / 2) (t2−t1)}
= Vm · (t2−t1) − {Vm / (2 · tm)} (t2 + t1) (t2−t1)
It becomes. Here, V is the rotational speed of the paper feed motor M2 when the paper feed clutch CL1 is turned on. Vx is the rotational speed of the paper feed motor M2 at the time when the conveyance sensor is predicted to be turned on.
[0023]
The traveling distance L ′ from the time point t2 to t3, that is, during the time Δt is expressed by the following equation.
L ′ = {Vm / (2 · tm)} (t3 + t2) (t3−t2)
[0024]
To find t3 such that L ′ = ΔL,
Vm · (t2−t1) − {Vm / (2 · tm)} (t2 + t1) (t2−t1)
= {Vm / (2.tm)} (t3 + t2) (t3-t2)
[0025]
Therefore,
t3 = √ {(2 · tm · (t2−t1) + t1 · t1}
Δt = t3−t2
= √ {(2 · tm) · t0 + t1 · t1} −t1−t0 (1)
[0026]
Next, consider the case of t2 <tm ≦ t3 as shown in FIG. In this case, the speed reaches tm between time t2 and time t3. As above,
[0027]
ΔL = Vm · (t2−t1) − {Vm / (2 · tm)} (t2 + t1) (t2−t1)
L ′ = {Vm / (2.tm)} (tm + t2) (tm−t2) + Vm (t3−tm)
[0028]
Therefore, when L3 = ΔL and t3 is obtained,
t3 = t2−t1 + tm− (tm · tm / (2 · tm)) + (t1 · t1 / (2 · tm))
[0029]
Therefore,
Δt = t3−t2
= -T + tm- (tm + t1) (tm-t1) / (2.tm)
= (Tm-t1) (tm-t1) / (2.tm) (2)
[0030]
Next, consider the case of tm ≦ t2, as shown in FIG. In this case, the speed reaches tm before time t2. As above,
[0031]
ΔL = Vm (tm−t1) − {Vm / (2 · tm)} (tm + t1) (tm−t1)
L ′ = Vm / (t3−t2)
[0032]
Therefore, when L3 = ΔL and t3 is obtained,
t3 = (tm / 2) −t1 + t2 + (t1 · t1 / (2 · tm))
[0033]
Therefore,
Δt = t3−t2
= (Tm / 2) -t1 + (t1 · t1 / (2 · tm))
= (Tm-t1) (tm-t1) / (2.tm) (3)
[0034]
FIG. 6 and FIG. 7 are flowcharts of the jam detection process for delayed jam and stagnant jam, respectively, in the present embodiment.
[0035]
In FIG. 6, first, the paper feed timer is started when the paper feed motor M2 is turned on, and the paper feed motor M2 enters an acceleration state (S11). At the same time, the paper feed timer is started. Thereafter, when a pickup command is generated and the sheet feeding clutch CL1 is turned on (S12, Yes), a jam timer is first started for detecting a delayed jam (S13). At the same time, the paper feed timer value at this time is substituted into t1. Next, based on the value of t1, it is determined which of the above three cases applies, and Δt is calculated (S14).
[0036]
Next, it is determined whether tm <t1 (S15). If tm <t1, the acceleration has already been completed as in the conventional case, so the jam timer set time tj is calculated as follows using the following equation (S17).
[0037]
tj = t0 + tk
Here, as described above, t0 is a time until the sheet reaches the conveyance sensor 20 from the clutch ON at the normal speed (after completion of acceleration), and tk is a predetermined margin time with respect to the jam determination margin distance. is there.
[0038]
However, if t1 ≦ tm (S15, No), it is determined that the paper feed clutch is turned on during acceleration. In this case, the paper transport period initially includes an acceleration period slower than the normal speed. As described above, in the paper conveyance in this case, a delay of Δt occurs compared to the case where the clutch is turned on after reaching the normal speed. Therefore, the jam timer set time tj is calculated by the following equation (S16).
[0039]
tj = t0 + Δt + tk
Δt is obtained by the above-described equation. Note that tj may be further corrected in consideration of the response time of the clutch.
[0040]
Next, the process waits until the leading edge of the sheet reaches the conveyance sensor 20 (S18). If the delay jam timer becomes larger than tj before reaching the conveyance sensor 20 (S19, Yes), it is determined that the paper has stopped for some reason and is determined to be a paper feed delay jam (S20). If the conveyance sensor 20 detects the leading edge of the paper before the paper feed delay jam timer reaches tj, it is determined that the paper is normally fed.
[0041]
If it is determined that the sheet feeding is normal, the flow proceeds to the flow of FIG. 7 and the jam timer is started to determine the staying jam, and the sheet feeding timer value (conveyance sensor 20) started when the sheet feeding motor M2 is turned on. (Timer value when the leading edge of the paper is detected) is substituted into t4 (S31). This t4 corresponds to the time from when the paper feed motor is turned on to when the transport sensor is turned on. If tm <t4 (S32, No), it is determined that the acceleration has already ended, and the staying jam timer time tj is calculated by the following equation as usual (S34).
[0042]
tj = ts + tk
Here, ts is the transport time corresponding to the paper length in the transport direction at the normal speed, and tk is the margin time described above.
[0043]
If tm <t4 is not satisfied (S32, No), it is determined that the vehicle is accelerating, and the staying jam timer time tj is calculated by the following equation (S33).
[0044]
tj = ts + Δt + tk
Δt in this equation is calculated by replacing t1 in the case of FIG. 5 with t4. If the jam timer value is larger than tj (S36, Yes) before the trailing edge of the sheet is detected by the transport sensor 20 (S36, Yes), it is considered that the sheet has accumulated for some reason and is set as a retention jam (S37). . If the conveyance sensor 20 detects the trailing edge of the paper before the stay jam timer value becomes larger than tj, it is considered that the paper feeding has been completed normally, and the paper conveyance operation is continued.
[0045]
The preferred embodiment of the present invention has been described above, but various modifications and changes can be made. For example, in the above embodiment, Δt to be added to t0 is calculated, but the time (t0 + Δt) from the feed clutch ON time to the predicted transport sensor ON time is directly calculated from the distance L and the feed motor acceleration. You may make it ask.
[0046]
【The invention's effect】
According to the present invention, the target time to reach the transport sensor can be corrected according to the acceleration state no matter when the paper feed motor is started, so that a jam is erroneously detected regardless of the paper feed start timing. In addition, in the first paper feeding, the motor acceleration waiting time can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a driving transmission path of a sheet feeding device according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a hardware configuration of the image forming apparatus according to the embodiment of the present invention.
FIG. 3 is a control characteristic diagram in the first case of a paper feed motor for explaining paper feed delay jam in the embodiment of the present invention.
FIG. 4 is a control characteristic diagram in the second case of the paper feed motor for explaining paper feed delay jam in the embodiment of the present invention.
FIG. 5 is a control characteristic diagram in the third case of the paper feed motor for explaining paper feed delay jam in the embodiment of the present invention.
FIG. 6 is a flowchart of a jam detection process for a delayed jam according to the embodiment of the present invention.
FIG. 7 is a flowchart of a jam detection process for stagnant jam in the embodiment of the present invention.
[Explanation of symbols]
11 Pickup roller 12 Paper feed roller 13 Transport roller 14 Registration roller 15 Photosensitive drum 16 Fixing roller 17 Paper discharge roller 20 Transport sensor 21 Pre-registration sensor 22 Paper discharge sensor 61 ROM
62 CPU
63 RAM
64 Transport control unit 65 Paper feed timer 66 Jam timer 71 Sensor group 72 Clutch group 73 Fixing device 76 Motor group CL1, CL2, CL3 Clutch M1 Main motor M2 Paper feed motor

Claims (4)

In a paper feeding method for feeding and transporting paper from a paper feeding unit to an image forming unit in an image forming apparatus,
Start feeding before reaching the target speed after the feed motor starts rotating,
The transport delay time compared to when the paper feed motor starts feeding after reaching the target speed is obtained from the motor start-up characteristics and the paper feed start timing.
Correct the jam determination time value by the transport delay time,
A paper feeding method comprising performing jam judgment by comparing an elapsed time from the paper feed start timing with the corrected jam judgment time. In a paper feeding device that feeds and conveys paper from a paper feeding unit to an image forming unit in the image forming apparatus,
A pickup roller for picking up one sheet at a time from the sheet feeding unit;
A paper feed motor that applies driving force to the pickup roller via a paper feed clutch;
A transport roller for transporting the picked up paper;
A transport sensor which is arranged in the transport path and the transported paper first arrives;
A first timer for measuring a time after the start of rotation of the paper feed motor;
A second timer for measuring a time after driving the paper feed clutch;
A jam determination means for performing a jam determination by comparing the value of the second timer with a predetermined jam determination time;
Means for determining whether or not paper feeding is started before reaching a target speed of the paper feeding motor based on a value of the first timer at the time of driving the paper feeding clutch and a rising characteristic of the paper feeding motor;
The value of the jam determination time when the paper feeding is started before reaching the target speed of the paper feeding motor by the transport delay time compared with the case where the paper feeding motor starts the paper feeding after reaching the target speed. Means for correcting
A paper feeding device with 3. The paper feed according to claim 2, wherein the jam is a paper feed delay jam, and the jam determination time is determined in relation to a time until a front end of the paper reaches the transport sensor after the paper feed is started. Feeding device. 3. The paper according to claim 2, wherein the jam is a paper feed retention jam, and the jam determination time is determined in relation to a time until a rear end of the paper reaches the transport sensor after the paper feed is started. Feeding device.

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