JP2780203B2 - Image forming device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus having a recording paper conveying means constituted by a plurality of mutually independent driving systems.

2. Description of the Related Art A copying machine is an example of an image forming apparatus, and a recent copying machine tends to be provided with a paper feeding cabinet equipped with a plurality of paper feeding cassettes each storing copying paper of different sizes. . That is, by providing such a paper feed cabinet, it is possible to reduce the frequency of cumbersome replenishment of copy sheets, thereby improving the usability of the copier.

Incidentally, in a copying machine provided with a paper feeding cabinet as described above, a driving system including an image forming system including a photosensitive drum and each transport roller in the copying machine main body, and a copy paper from a paper feeding cassette in the paper feeding cabinet. And a drive system for feeding the paper to the copying machine main body.

Of these, the former drive system uses a main motor for driving the photosensitive drum as a drive source, and synchronizes the rotation of the photosensitive drum with the timing at which copy paper is conveyed to a transfer charger disposed around the photosensitive drum. It is constituted by a pair of intermediate rollers for conveying a copy sheet to a pair of rollers and a pair of timing rollers. The roller pair and the main motor are connected by an on / off clutch, and drive control of the roller pair is performed by controlling the on / off state of the on / off clutch.

On the other hand, the latter drive system uses a paper feed cabinet drive motor provided in the paper feed cabinet as a drive source, a paper feed roller for taking out copy paper from the paper feed cassette, and a plurality of copy paper fed by the paper feed roller. And a pair of transport rollers for transporting the separated copy paper to the position of the intermediate roller pair. The transport roller pair
It is connected to a paper feed cabinet drive motor via a gear mechanism.

Problems to be Solved by the Invention Meanwhile, in the case of the above-described drive system, since the former drive system takes a form of driving the timing roller pair and the intermediate roller pair via the on / off clutch, when each roller is stopped or restarted. While the inertia at the time of driving is relatively small, the inertia of the transport roller pair in the latter drive system is large because the pair is driven directly via a gear mechanism. For this reason, the leading and trailing ends of the copy paper are both driven by the two driving systems, more specifically, when the copy paper is stopped while straddling the intermediate roller pair and the transport roller pair, and when the copy paper is straddled. When the transport roller pair and the intermediate roller pair are driven again, the following disadvantages occur.

That is, as shown in FIG. 8A, if the intermediate roller pair and the transport roller pair are to be stopped at the same time, the intermediate roller pair is stopped first due to a difference in inertia, and then the transport roller pair is stopped. You. Therefore, the conveying roller pair conveys the copy paper in the stopped state at the leading end forward by an amount indicated by diagonal lines in the drawing, so that an unnecessarily large loop is formed at an intermediate portion of the copy paper, and in some cases, the copy is performed. The paper breaks,
The disadvantage is that the quality of the copy paper is impaired and jamming is induced.

On the other hand, as shown in FIG. 8 (b), if the intermediate roller pair and the transport roller pair, which are stopped with the leading and trailing ends of the copy paper being sandwiched, are simultaneously driven, the inertia difference As a result, the intermediate roller pair rises first (starts driving), and the copy paper is conveyed at a stretch from the state of 0 speed, so that the leading end of the copy paper is rapidly pulled forward,
There is a drawback that a great deal of stress is generated on the copy paper and the quality thereof is impaired.

The drawback is that the length of the copy paper in the transport direction is the distance X between the timing roller pair and the transport roller pair (the distance A between the timing roller pair 22 and the intermediate roller pair 23 shown in FIG.
Sum of the distance B between the intermediate roller pair 23 and the transport roller pair 205)
Occurs when larger than That is, when the length of the copy sheet in the transport direction is greater than the distance X, the transport of the copy sheet is stopped when the leading edge of the copy sheet reaches the position of the timing roller pair 22, and the intermediate portion and the rear of the copy sheet are stopped. This is because a state occurs where the end straddles the intermediate roller pair 23 and the transport roller pair 205.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an image forming apparatus capable of reliably performing the operation of conveying a recording sheet and eliminating the above-described disadvantages of the related art.

Means for Solving the Problems The present invention relates to an image forming apparatus having a recording paper transporting unit constituted by a plurality of independent drive systems, wherein the recording paper transported by the recording paper transporting unit is transferred to a plurality of drive systems. When the vehicle is stopped in a straddling state, the drive system having a large inertia is stopped first.

Further, the present invention is characterized in that when re-driving a plurality of drive systems on which the recording paper is straddling, the drive systems having a large inertia are driven first.

Operation According to the above configuration, by providing an appropriate time difference between the time when the plurality of drive systems are stopped or the time when the plurality of drive systems are stopped, a state in which the plurality of drive systems are stopped and re-driven when straddling the plurality of drive systems. No large tensile force or compressive force acts on the recording paper.

Embodiment An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing the entire configuration of a copying machine to which the present invention is applied. The copying machine includes a copying machine main body 100 and a paper feed cabinet 200 that is disposed below the copying machine main body and supplies copying paper to the copying machine main body 100.

(Configuration of Copying Machine Main Body 100) A photosensitive drum 1 that rotates in a counterclockwise direction indicated by an arrow a is provided in the center of the inside of the copying machine main body 100. Rotation of the photosensitive drum 1 is effected by the main motor M ₁ provided inside the copying machine main body 100. Around the photosensitive drum 1,
In the rotation direction, the charger 2, the image end / inter-image eraser 3, the developing devices 4a, 4b, 4c, the transfer charger 5, the separation charger 6, the cleaning device 7, and the eraser lamp 8
Is provided.

The photoreceptor drum 1 is provided with a photoreceptor layer on its surface, and is uniformly charged by passing through a charging charger 2.
An image is exposed from the scanning optical system 10, and an electrostatic latent image is formed on the surface. Then, the developing devices 4a, 4b, 4c
Supplies a toner image to form a toner image. The image end / inter-image eraser 3 has a plurality of light emitting diodes arranged in the image width direction, and removes unnecessary charges on the surface of the photosensitive drum 1 during image formation.

The scanning optical system 10 is provided so that the original image can be scanned below the platen glass 11, and includes an exposure lamp 12 and a movable mirror.
13, 14, 15, 16, 17, a mirror 18, and a lens 19. The exposure lamp 12 and the movable mirror 13 move in the direction of arrow b at a speed of (v / m) (where m is the copy magnification) with respect to the peripheral speed v of the photosensitive drum 1 (constant irrespective of the same magnification or variable magnification). Is driven by a scan motor (not shown) so as to move integrally. The scan motor also moves the movable mirrors 14 and 15 integrally in the direction of arrow b at a speed of (v / 2m).

When changing the copy magnification, the lens 19 is moved on the optical axis, and the mirror 18 is moved and rocked. Such movement and swing of the lens 19 and the mirror 18 are performed by a stepping motor (not shown).

The copy paper is fed into the copier main body 100 from the manual paper feed mechanism 20 or the paper feed cabinet 200 set at the lower left portion of the copier main body 100. The manual paper feed mechanism 20 includes a separation roller pair 24 that separates and transports the copy sheets set on the paper feed tray 21 one by one, and a detection that is provided downstream of the separation roller pair 24 and detects a transport state of the copy paper. the sensor S _1, provided upstream of the separating roller pair 24, and a sensor S _X for detecting the set state of the copying paper. When the detection sensor S _X detects the copy paper, and feeds the copy paper separation roller pair 24 is fielded one by one by rotating the timing roller pair 22, sensor S ₁
However, when the fed copy paper is detected, a microcomputer (CPU) described later issues a scan start signal to the scanning optical system 10.

The copying paper fed into the copying machine main body 100 is temporarily stopped by the timing roller pair 22 and then supplied to the position of the transfer charger 5 in synchronization with the toner image formed on the surface of the photosensitive drum 1. Then, the toner image is transferred by the transfer charger 5.

The copy paper on which the toner image has been transferred is separated from the surface of the photosensitive drum 1 by the separation charger 6, and the transfer belt 11
0 is supplied to the fixing device 111. Then, the fixing device 11
A fixing process of the toner image is performed by 1, and thereafter, the toner image is discharged onto a discharge tray 113 by a discharge roller pair 112. on the other hand,
Although residual toner and residual charges are present on the surface of the photosensitive drum 1 after the transfer, the cleaning device 7 removes the residual toner, and the eraser lamp 8 removes the residual charge. Thereafter, the next copy process is prepared.

(Configuration of Paper Feeding Cabinet 200) In the paper feeding cabinet 200, four paper feeding cassettes 201, 202, 203, and 204 that store copy papers of different sizes are vertically arranged. These paper cassettes 201, 202, 203, 2
04 is provided with an automatic paper feeding mechanism for a paper feed cabinet drive motor M ₂ and the same drive source, configuration is substantially the same, it will be described below uppermost sheet feeding cassette 201 as an example. In each of the paper feed cassettes 201, 202, 203, and 204, there is provided paper size detecting means 251, 252, 253, 2 for detecting the size of the copy paper.
54 are provided respectively.

Paper Feed Cabinet driving motor M _2, when turned on the print key outside figure is started. Also, the ON operation of the print key, is driven main motor M _1, thereby driving the image forming system including a photosensitive drum 1 is started.

Paper Feed Cabinet driving motor M ₂ includes a sheet feeding cassette 201
The copy paper stored in the inside is taken out, and is conveyed to an intermediate roller pair 23 disposed at a portion near the lower portion of the copying machine main body 100 and corresponding to the entry side of the timing roller pair 22. This transport operation is performed by a paper feed roller 210 for feeding the copy paper in the paper feed cassette 201, and a separation roller pair 211 for separating the uppermost copy paper from a plurality of copy papers fed by the paper feed roller 210. The transfer is performed via a pair of transport rollers 205 provided at the upper left end of the paper feed cabinet 200.

Driving of the paper feed roller 210 and the separation roller pair 211 is performed through a non-illustrated input switching clutch which is set to the state entered when the driving paper feed cabinet drive motor M _2. The drive of the conveying roller pair 205 is performed by a feed cabinet drive motor M ₂ via a gear mechanism (or a belt pulley mechanism).

The copy paper separated by the separation roller pair 211 one by one is
Turns on the sheet feed sensor S ₂ provided at the outlet side of the separation roller pair 211 and is then supplied to the conveying roller pair 205. Copy paper leaving the pair of conveying rollers 205, a pair of intermediate rollers before sensor S ₃ is turned on, is supplied to the intermediate roller pair 23. Intermediate roller pair 23
Supplies the copy paper supplied thereto to the timing roller pair 22. A pair of timing rollers before sensor S ₄ for detecting that the leading end of the copy sheet to the position reaches is provided on the upstream side of the pair of timing rollers 22.

Intermediate rollers before sensor S ₃ after a predetermined time has elapsed from the time it is turned on, issues a scan start signal to the scanning optical system 10. Thereby, the driving of the image forming system, that is, the image forming operation is started thereafter. Further, when the pair of timing rollers before sensor S ₄ detects the copy paper, the CPU30, which has received the detection signal is off intermediate clutch 31 to be cooperative to the intermediate roller pair 23 stops driving the pair of intermediate rollers 23, the sheet the driving of the paper cabinet drive motor M ₂ is stopped to stop the conveying roller pair 205 (see FIG. 2).

Regarding the configuration of the sheet cassettes 202, 203, and 204, the portions corresponding to the sheet cassette 201 and components around the sheet cassette 201 are denoted by the related numbers (220, 230, 240, etc.), and description thereof is omitted. . Also, each separating roller pair 221, 23
Paper feed sensor S ₂ provided at the outlet side of the 1,241 are assigned the same number S _2.

(Motor drive circuit details) Next, details of the motor drive circuit for driving and controlling the main motor M ₁ and the sheet feeding cabinet drive motor M ₂ in accordance with Figure 2, illustrating a sheet feeding cabinet drive motor M ₂ as an example.

The CPU 30 is a control center of the copying machine,
Controlling the driving of the paper feed cabinet drive motor M ₂ with the imaging process. Paper Feed Cabinet driving motor M ₂ is configured as a DC motor of a three-phase, are driven and controlled through the drive being IC33 connected between the CPU 30.

That is, when the remote signal (drive start command signal) 35 is provided to drive IC33 from CPU 30, the drive phases of the feeding cabinet drive motor M ₂ as shown, is connected IC33
Are set to 24V, ground, and high impedance, respectively, and each terminal changes in the order of 24V → ground → high impedance → 24V → ground → due to the switching operation of the transistor in the drive IC33. Accordingly, the driving of the paper feed cabinet drive motor M ₂ is performed.

The rotation speed control of the paper feed cabinet drive motor M ₂ is performed by controlling the switching timing of the phase of the driving voltage of the 24V is applied, specifically, CPU 30
The drive IC 33 is provided with a clock pattern from the clock IC 32 that generates a predetermined clock pattern in response to a command signal from the IC.

On the other hand, of stopping the sheet feeding cabinet drive motor M ₂ is, CPU 3
This is performed by the brake signal 36 given from 0. The brake signal 36 is applied to the switching transistors 34a, 34b,
Given to each phase of the sheet feeding cabinet drive motor M ₂ through 34c, the potential between each phase becomes identical at that time, the paper feed cabinet drive motor M ₂ is stopped by this.

In order to prevent the switching transistors 34a, 34b and 34c from being destroyed, a brake signal 36 is given after the remote signal 35 is turned off, and vice versa.
After the switch 36 is turned off, a remote signal 35 is provided.

Also, the CPU 30 has an intermediate roller pair front sensor S as shown in the figure.
_3, a pair of timing rollers before sensor S ₄ and paper size detection means 2
Various sensors are connected as such 51,252,253,254, driving of the paper feed cabinet drive motor M ₂ is controlled according to the detection results. In the drawing, 31 is an intermediate clutch which interlocking the main motor M ₁ and the intermediate rollers 23, driving of the intermediate roller pair 23, is being stopped by this the input cut.

(Overall control contents of CPU 30) Next, according to the flowcharts shown in FIGS.
Specific control contents of the CPU 30 will be described. However, FIG. 3 is a flowchart showing a main flow, and FIG. 4 is a flowchart showing a subroutine relating to motor control contents.

In the main flow, when the power is turned on or reset and the program starts, the CPU 30 clears the contents of the RAM (not shown) and performs initial settings for setting timer values of various timers described later (S1). Next, in step S2, the time required to execute the main flow once is set in an internal timer.

Next, for example, input processing is performed to capture information from various sensors shown in FIGS. 1 and 2 and communication information from another CPU (sub-control unit) (not shown) (S3). When the input processing is completed, Output processing for controlling on / off specified in each subroutine shown in step S5 and step S6 is performed (S4).

When the output processing is completed, a subroutine related to the paper feed control shown in step S5 is executed. In this subroutine, processing such as setting of a jamming detection timer for checking a conveyance interval and a conveyance timing of each copy paper when the copy paper in the paper feed cabinet 200 is conveyed to the copier main body 100 or a conveyance error at that time is performed. , But the details are omitted.

When the subroutine shown in step S5 is executed, the subroutine related to the control of the motor shown in step S6 is executed. When the subroutine is completed, a copy operation process is performed (S7). Next, other processing such as communication processing with another CPU is performed (S8), and the processing per one time of the main flow is completed with the end of the timer time limit set in the internal timer, and thereafter, the power is turned on. While the processing is being performed, the processing from step S2 is repeated.

(Motor Control Contents) Next, details of the subroutine shown in step S6 will be described with reference to FIG. In this subroutine,
First, the count value of the state counter is checked in step S601. The state counter can have 13 types of state values from “0” to “12”, and the values are rewritten when the program steps through each of the routines from “0” to “12”. Each routine from “0” to “12” refers to a group of steps on each multi-branch line that has been multi-branched from step S601.

Each of the routines “0” to “12” includes steps S605 and S605.
601, S611, S615, S617, S621, S624, S629, S634, S63
7, the method includes steps of changing the state value of the state counter, such as S642, S647, S651, S655, S657, S662, and S663.

When the power is turned on and the CPU 30 starts up, the state value of the state counter is “0”, so the program steps through the “0” routine and returns to the main flow. When the process advances to step S601 again, the state value of the state counter is checked, and the routine jumps to the routine specified by the state value. When this routine has been completed, the process returns to the main flow again to advance the main flow. Then, when the process reaches step S601, the process jumps to the routine specified by the state value of the state counter, and advances the routine. Thereafter, this operation is repeated.

Next, the routines “0” to “12” will be described in order. In the routine of "0", in step S602, the copy key on, the OFF state, to determine whether a copy operation is started, when confirming that it has started, the speed of the paper feed cabinet drive motor M ₂ ' Set to H "speed (S603) and drive as described above
The remote signal 35 is output to the IC 33 (S604). Thus,
Speed of the feeding cabinet drive motor M ₂ is set to "H" speed. When the motor speed is set to “H” speed, the state value of the state counter is rewritten to “1” (S605), and the process returns to the main flow.

On the other hand, in step S602, if the copying operation has not been started, and turns off the remote signal 35 for the paper feed cabinet drive motor M ₂ (S606), the process returns to the main flow.

The "H" speed refers to a speed higher than the system (image forming process) speed of the copying machine main body 100, and the transport speed and the system speed until the leading edge of the copy paper is transported to the position of the intermediate roller pair 23. Since the speed is irrelevant to the speed, the copy paper is transported at the "H" speed to the position of the intermediate roller pair 23 to increase the paper feed time, and an efficient copy operation is ultimately performed. This speed control is performed by changing the clock pattern. In a case where the copy paper is transported to the position of the intermediate roller pair 23 at such an "H" speed, the lowermost paper feed cabinet 20 in FIG.
From 4 becomes especially useful when conveying copy paper.

Paper Feed Cabinet driving motor M ₂ is adapted to the above-mentioned "H""L" speed corresponding to system speed to another speed is set, both speed if necessary adapted to be switched appropriately ing. As for the “L” speed, the system speed of the copying machine main body 100 differs depending on the model. You.

Next, the “1” routine will be described. In the routine of the "1", performs control for switching to the "L" speed the speed of the paper feed cabinet drive motor M ₂ from "H" speed. That is, first in step S607, the determining whether the copying operation is started, when confirming that has started, then the intermediate roller pair before the sensor S ₃ determines whether the ON (S608). Confirms that the ON, in step S609, switching to the "L" speed the speed of the paper feed cabinet drive motor M _2, the state value of the state counter is rewritten to "2" (S61
0), and return to the main flow.

On the other hand, if the copy operation has not started in step S607, the state value is rewritten to “0” (S6).
11) Return to the main flow. Step S6
In 08, when the intermediate roller pair before the sensor S ₃ is not turned on, yet since copy paper in this position is not come is conveyed, without speed change of the paper feed cabinet drive motor M _2, namely "H "Return to main flow with speed set.

In the routine of "2", a timer for starting the brake which differs depending on the size of the copy sheet, that is, the length of the copy sheet in the transport direction is set. That is, first in step S612, it is determined whether the timing roller pair before the sensor S ₄ is on, confirms that the on, the detection signal from the paper size detection unit 251, etc., the size of the copy paper It is determined whether or not it is equal to or more than the above X (S61)
3).

If it is X or more, for the reasons mentioned at the above prior art, the paper feed cabinet drive motor M ₂ and the main motor
Assuming that emit simultaneously OFF command to M _1, different stop time of the conveying roller pair 205 and the intermediate roller pair 23 due to differences in inertia, the inconvenience bending in the copy sheet at portion A shown in FIG. 7 since occur, in order to prevent this, in this embodiment first sets the brake delay timer to determine whether to stop at any time the feed cabinet drive motor M ₂ at step S614 to the timer (S614).
Next, the state value is rewritten to “3”, and the process returns to the main flow.

On the other hand, in step S612, when the timing roller pair before the sensor S ₄ is not turned on, the process directly returns to the main flow. If the size of the copy paper is smaller than X in step S613, there is no possibility that the above-described inconvenience will occur. In this case, in step S616, the amount of deviation in the width direction of the copy paper transport path is eliminated. Set the loop timer to set the amount of loop needed to do this. Next, the state value is rewritten to "6" (S615), and the process returns to the main flow.

Figure 5 (a), (b) shows a detail of the brake delay timer and loop timer, brake delay timer, CPU 30 at the time-feed cabinet drive motor M ₂ to the timing roller pair before the sensor S ₄ is turned on refers to the time until the brake signal 36 is emitted from the other hand, the loop timer time timing roller pair before the sensor S ₄ is turned on -
It means the time until the CPU 30 issues a clutch release signal to the intermediate clutch 31. Incidentally, the difference between the loop timer and brake delay timer, the paper feed cabinet drive motor M ₂
The time difference between the time when the brake signal 36 is issued and the time when the clutch disengagement signal is issued to the intermediate clutch 31 is hereinafter referred to as an intermediate clutch off delay timer.

The CPU 30 sets the brake delay timer and the intermediate clutch off delay timer to separate timers respectively, counts the timer value, recognizes that the brake delay timer and the intermediate clutch off delay timer have expired at the time of counting up, and At this point, a brake signal 36 and a clutch release signal are issued. By setting such a delay timer, the transport roller pair 205 and the intermediate roller pair 23 can be stopped simultaneously, as shown in FIG.

Next, the routine “3” will be described. In this routine, performs off process of the remote signal 35 for the paper feed cabinet drive motor M _2. That is, first, step S618
In, the count of the brake delay timer set in step S614 is started, and in step S619, it is determined whether or not the count is up.

When counting up, the remote signal issued earlier
35 is turned off (S620), and then the state value is rewritten to "4" (S621), and the process returns to the main flow. On the other hand, if the count has not been counted up, the process returns to the main flow.

In the routine of "4", first, in step S622, issues a brake signal 36 with respect to the paper feed cabinet drive motor M _2. Here, it was decided to issue a brake signal 36, since the paper feed cabinet drive motor M ₂ does not stop immediately, braked, with gain time until reaching the stop, the paper feed cabinet drive motor M _{This is} to ensure that ₂ is stopped. Further, the remote signal 35 is turned off in step S620 before the brake signal 36 is issued, as described above, because the switching transistors 34a, 34b,
This is to protect the motor drive circuit including the 34c.

When the processing of step S622 is completed, the intermediate clutch off delay timer is set to the next applicable timer (S62
3). Then, the state value is rewritten to “5” (S62
4), return to the main flow.

In the routine of "5", first, in step S625, counting of the intermediate clutch off delay timer set in step S623 is started, and it is determined whether or not the count is up (S626). If the count is up, the intermediate clutch 31 is disengaged at that time (S627). Then, step S6
The brake signal 36 for the paper feed cabinet drive motor M ₂ is turned off at 28, the state value is rewritten to "9" (S62
9) Return to the main flow. On the other hand, step S62
In step 6, if the counter does not count up, the process returns to the main flow. Here, the reason why the brake signal 36 is turned off in step S628 is to protect the motor drive circuit for the above-described reason.

Next, the routine “6” will be described. “6”
The routine from "8" to "8" is performed when it is determined as No in step S613. In the routine of “6”, first, the count of the loop timer set in the step S616 is started (S630), and it is determined whether or not the count is up (S631).
The cut (S632), turns off the remote signal 35 for the paper feed cabinet drive motor M ₂ (S633), the state value "7"
(S634), and returns to the main flow.
On the other hand, if it is determined in step S631 that the count has not been increased, the process directly returns to the main flow.

In the routine “7”, the paper feed cabinet drive motor M ₂
Then, the brake signal 36 is turned on (S635), the brake timer is set (S636), the state value is rewritten to "8" (S637), and the process returns to the main flow.

Next, the routine “8” will be described. In this routine, as the copying process progresses,
Since 200 has a good time even by supplying a copy sheet to the transfer charger 5 supplied from, performs processing for turning off the feeding cabinet drive motor M ₂ in this routine.

Specifically, first, in step S638, the on state of the signal for driving the timing roller pair 22 is checked, and if not, the brake timer set in step S636 is counted in step S639, It is determined whether the count has been increased (S640). If counted up, since the paper feed cabinet drive motor M ₂ is stopped at that time, turns off the brake signal 36 (S641). Then, the state value is rewritten to “9” (S642), and the process returns to the main flow.

On the other hand, if it is determined Yes in step S638, the processes in steps S641 to S642 are performed, and the process returns to the main flow. If it is determined in step S640 that the count has not been increased, the process returns to the main flow.

In the “9” routine, first, in step S643,
Check the signals on state to drive the timing roller pair 22, when determining that the ON state, in step S644, the timing roller pair is set to the state to enter the clutch for interlocking the main motor M ₁ and the timing roller pair 22 22 is turned on and then emit remote signal 35 with respect to the paper feed cabinet drive motor M ₂ (S645). Then, in step S646, the engaged state of the intermediate clutch 31, that is, the intermediate clutch on-delay timer for delaying the driving of the intermediate roller pair 23 is set, and the state value is rewritten to "10" (S647). To return. on the other hand,
If it is determined as No in step S643, the process returns to the main flow.

Here, the driving of the intermediate roller pair 23 delayed than the driving of the paper feed cabinet drive motor M ₂ is due to a difference in inertia of both for the rise of the conveying roller pair 205 is slower than the intermediate roller pair 23, the copy sheet The tip of the paper is pulled, causing a great deal of stress on the copy paper, causing damage to the copy paper,
This is to prevent the copy paper from being transported in a skewed state.

In the routine “10”, the intermediate clutch on-delay timer set in step S646 starts counting (S6
48), it is determined whether or not the count is up in step S649. If it is determined that the count has been increased, the intermediate clutch 31 is set to the engaged state in step S650, the state value is rewritten to "11", and the process returns to the main flow. On the other hand, if it is determined in step S649 that the count has not been counted up, the process returns to the main flow.

In the routine of "11", whether the intermediate rollers before sensor S ₃ is turned off in step S652, i.e., that the trailing edge of the copy sheet, it is determined whether or passes through the intermediate roller pair before the sensor S _3, missing After confirmation, it is determined whether the copy operation is ongoing (S653). If it is determined that the copying is in progress, the next copy paper is conveyed from the paper feed cabinet 200. to switch the speed of the cabinet drive motor M ₂ to "H" speed, sets the speed change-over timer of the paper feed cabinet drive motor M ₂ (S654), then the state value is rewritten to "12" (S
655), and returns to the main flow.

On the other hand, in step S653, if it is determined that the copying operation is completed, and turns off the remote signal 35 for the paper feed cabinet drive motor M ₂ (S656), and then rewritten to the state value "0" (S657), the main flow To return. Further, in step S652, the intermediate rollers before sensor S ₃ is when it is determined to be turned on, the process directly returns to the main flow.

In the routine of "12", in step S658, first, the intermediate rollers before sensor S ₃ it is determined whether the ON confirms that on, the state value to perform the copy operation "2 "(S663), and returns to the main flow.

On the other hand, when the intermediate roller pair before the sensor S ₃ is not turned on, counts the timer value of the timer set in step S654 (S659), it determines whether the timer value is counted up (S660) . If counted up, the paper feed cabinet drive motor so as to quickly transport the following order of copy paper to the position of the intermediate roller pair before the sensor S ₃
Switching the speed of M ₂ to the "H" speed (S661), and then rewritten to state value "1" (S662), the process returns to the main flow.

According to the above control contents, as shown in FIGS. 6 (a) and 6 (b), when the leading and trailing ends of the copy paper straddle the transport roller pair 205 and the intermediate roller pair 23, the illustrated time
By setting t ₁ , t ₂ , and t ₃ , the transport roller pair 205 and the intermediate roller pair 23 can be stopped at the same time, and both can be driven again at a convenient time. However, FIG. 6 (a)
Is a graph showing a decrease in the speed of the conveying roller pair 205 and the intermediate roller pair 23 with time taken along the horizontal axis. FIG. 6B is a graph showing the rise of the speed of the transport roller pair 205 and the intermediate roller pair 23 on the vertical axis and time on the horizontal axis.

Note that the time t ₁ corresponds to the intermediate clutch off delay timer specifically described in the step S623 and shown in FIG. 5 (a). However, the value of t _1, is not limited to the value of the illustrated example, according to the structure or the like of the transport path of the copying paper, the desired deflection is generated in the copying paper in the A portion of the example Figure 7 Such a value may be taken.

The time t ₃ corresponds to the intermediate clutch-on delay timer described in step 648, the time t ₂ is the time issued a remote signal 35 with respect to the paper feed cabinet drive motor M ₂ ~
This corresponds to a dead time until driving is started.

Accordingly, t ₃ −t ₂ corresponds to the time difference between the _two when re-driven, and in the illustrated example, the speeds of the two are set to be the same at an intermediate point in time from the rising of the rotation of the transport roller pair 205 to reaching the constant speed. did. Note that the time difference t ₃ −t ₂ may be set at the time when the transport roller pair 205 and the intermediate roller pair 23 rise simultaneously at the time of re-driving. In this case, the one-way rotation axis of the transport roller pair 205 may be used. By providing the clutch, the stress due to the tension of the copy paper can be reduced, but FIG. 8 (b)
As shown in ( _2), by setting t ₃ −t ₂ , the value can be suppressed to a small value based on the amount of deflection of the copy paper and the stress due to tension.

In the above illustrated example, a paper feed cabinet equipped with four paper feed cassettes is attached to the copying machine main body. However, the number of paper feed cassettes provided in the paper feed cabinet is not limited to four. . In the above embodiment, the case where the present invention is applied to a copying machine having two drive systems has been described. However, the present invention can be similarly applied to a copier having three or more different drive systems. Further, in the above embodiment, the case where the present invention is applied to a copying machine has been described.
Of course, the present invention can be similarly applied to other image forming apparatuses such as a facsimile apparatus having a similar image forming unit and a paper feed cabinet.

According to the image forming apparatus of the first aspect, since a plurality of drive systems can be stopped at the same time, a compressive force does not act on a recording sheet that is stopped while straddling these drive systems. .
Therefore, no center fold occurs in the middle portion of the recording paper, and the quality of the recording paper is not deteriorated. Also, no jamming occurs.

According to the image forming apparatus of the present invention, since a plurality of drive systems in which the recording paper is straddled are simultaneously re-driven, a great amount of tensile force or stress acts on the recording paper. And the quality of the recording paper is not impaired.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the entire configuration of a copying machine to which the present invention is applied, FIG. 2 is a circuit diagram showing details of a motor drive circuit, FIG. 3 is a flowchart showing a main flow, and FIG. 5 (a) and 5 (b) are graphs showing details of a brake delay timer and a loop timer, and FIG. 6 (a) is a vertical axis of a conveying roller pair and an intermediate roller pair. It is a graph which shows reduction of these speeds, taking time on a horizontal axis as speed. FIG. 6B is a graph showing the rise of these speeds with the vertical axis representing the speed of the conveying roller pair and the intermediate roller pair and the horizontal axis representing the time, and FIG. 7 is a graph showing the conveying roller pair and the intermediate roller pair. FIGS. 8 (a) and (b) show the positional relationship of FIGS. 6 (a) and 6 (b) showing a conventional example.
It is a similar graph. 1 ... Photoconductor drum, 22 ... Timing roller pair, 23 ...
… Intermediate roller pair, 30… CPU, 100 …… Copier body, 200
…… Paper feed cabinet, 201 …… Paper feed cassette, S ₂ ……
Feed sensor, S ₃ …… Intermediate roller vs. front sensor, S ₄ …… Timing roller vs. front sensor, M ₁ …… Main motor, M ₂ ……
Paper feed cabinet drive motor.

Claims (2)

(57) [Claims] An image forming apparatus having a recording paper transporting means constituted by a plurality of independent driving systems, wherein the recording paper transported by said recording paper transporting means extends over a plurality of driving systems. An image forming apparatus characterized in that when stopping, a drive system having a large inertia is stopped first. 2. The drive system according to claim 1, wherein when re-driving the plurality of drive systems on which the recording paper is straddling, the drive systems having large inertia are driven first. Image forming device.