JPH0470634B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field] The present invention relates to a copying machine.

[Prior Art] Normally, in a copying machine, if paper gets jammed somewhere along its conveyance path and a jam occurs, there is a risk of damaging various devices. Therefore, a paper detector is provided at an appropriate location on the transport path, such as a registration section for correctly positioning the paper on the photoreceptor, and monitors whether the paper is passing through the transport path at the appropriate timing.
This is how jams are detected.

Conventionally, such jam detection has been performed based on the timing at which the paper feeder begins to feed the paper from the paper cassette, resulting in the following inconveniences.

In other words, for example, if a jam occurs while making multiple copies, even if the operator removes the paper causing the jam, the subsequent paper has just been fed out of the paper cassette and cannot be discovered by the operator. If this is not done, the paper may be left in a state where it has advanced to a position where it is not detected by the paper detector in the middle of the conveyance path.

In this case, when the operator resumes copying after finishing the post-processing of the jam, the paper remaining in the middle of the conveyance path causes the jam to occur again, and the jam processing continues, making the operation cumbersome.

In addition, if the paper remaining in the conveyance path is not detected as a jam, the paper may adhere to the photoconductor, pass through the transfer section or separation section, and enter the cleaning section that removes the residual toner on the photoconductor. There is a risk of damaging the cleaning section.

[Objective] The present invention has been made in order to eliminate the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a copying machine that can reliably remove paper remaining in the conveyance path without detecting it as a jam. purpose.

[Configuration] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a copying machine DM according to an embodiment of the present invention.
It shows an overview.

In the figure, 1 is a photoreceptor drum that is driven to rotate in the direction of the arrow; 2 is a charger that uniformly charges the surface of the photoreceptor drum 1; and 3 is a charger that charges a document (not shown) on the charged photoreceptor drum 1. It is an optical system that exposes an image, and an electrostatic latent image of the exposed image is formed on the surface of the photoreceptor drum 1. This electrostatic latent image is developed with toner by a developing device 4.

5 is a paper feed roller that feeds the paper PP from the paper cassette 6; 7 is a pair of transport rollers that are constantly rotating in the direction of the arrow and conveys the paper PP sent out by the paper feed roller 5; 8 is a guide plate that guides the paper PP. be.

9 is the tip of the toner image on the photosensitive drum 1 and the paper
A pair of registration rollers 10 are used to align the tip of the PP with the toner image on the photoreceptor drum 1.
Transfer chargers 11 and 12 for transferring to PP are separation chargers and separation claws for separating the paper PP from the photosensitive drum 1, and the separation claw 12 is normally retracted to the position shown by the broken line and the photosensitive drum 1 is separated from the photosensitive drum 1. The surface of the body drum 1 is prevented from being damaged.

13 is a vacuum type conveyor belt that adsorbs and conveys the separated paper PP, 14 is a paper PP
A fixing roller pair 15 fixes the toner image by heating and pressing the paper PP, and 15 is an ejection tray from which the paper PP is ejected.

Reference numerals 16 and 17 denote a pre-cleaning static elimination charger and a cleaning section that clean the surface of the photoreceptor drum 1, and 18 a static elimination charger that eliminates static electricity from the surface of the photoreceptor drum 1. Further, 19 is a paper detector for detecting that the paper PP is located at the position of the registration roller pair 9.

Each of the above elements of the copying machine DM is controlled in synchronization so as to properly execute the well-known copying process.

Now, in the present invention, when the paper detector 19 detects paper PP within a certain period of time after the start of copying, this is not detected as a jam, and the separating claw 12 is controlled based on this detection timing. This paper PP is ejected to an ejection tray 15.

A means for realizing such control is shown in FIG.

In the figure, 20 is a main body control section that controls each element of the copying machine DM, and in the illustrated circuit, among the control signals output from this main body control section 20, the clutch (not shown) of the paper feed roller 5 is turned on and off. a registration clutch control signal RC that turns on and off the clutch (not shown) of the registration roller pair 9; Main motor control signal that turns on and off (not shown)
SM is used.

Further, 21 is a print key provided on an operation panel (not shown), and 2 is a jam reset switch that the operator operates after releasing the jam when a jam occurs, and the print start signal PS of the print key 21 and the jam reset switch are The jam reset signal JR of 22 is sent to the main body control section 2.
added to 0.

Now, suppose that the operator turns on the print key 21 to make a copy.The print start signal PS (see FIG. 3a) is output, the flip-flops 30 and 31 are reset, and these output signals S ₁ and S ₂ (See Figure 3 d and g)
The logic level of becomes "L", and the AND circuit 32,
33 is rendered inactive.

At the same time, the main body control section 20 starts copying control, and the main motor control signal SM (see Fig. 3b)
At the same time as starting up, the resist clutch control signal
The RC (see FIG. 3e) is preliminarily operated for a predetermined time _T1 to release the deflection, etc., occurring in the pair of registration rollers 9.

In addition, the main body control section 20 raises the paper feed clutch control signal FC (see FIG. 3c) at a predetermined timing, holds it for a time _T2 , operates the paper feed roller 5, and starts the first sheet of paper. Send out the PP from the paper cassette 6.

The rising edge of the signal FC is detected by the differentiating circuit 34, which sets the flip-flop 30 so that its output signal _S1 attains the logic level "H", thereby enabling the AND circuit 32 to operate.

Here, if the paper PP has already been sent out and stopped at any position on the guide plate 8 before this copying, the paper PP is transported by the transport roller pair 7, and then the registration roller Since the paper is conveyed by the pair 9, it is detected by the paper detector 19, and its detection signal DP (see FIG. 3h) rises.

At the rising edge of this signal DP, _{a signal P 1 (} third
A monomulti 35 generating a signal P 2 (see FIG. 3) and a monomulti 36 generating a signal P ₂ (see FIG. 3l) with a pulse width τ ₂ are triggered.

Here, the pulse width τ ₁ is used to set the jam detection timing in the registration section, and its value is determined from when the leading edge of the paper PP is detected by the paper detector 19 to when the trailing edge of the paper PP is detected by the paper detector 19. The value is set to a value slightly longer than the time required for the paper PP to pass through the paper detector 19, that is, the time required for the paper PP to pass the paper detector 19.

Further, the pulse width τ ₂ is for setting the timing to turn on the separation solenoid 38,
The value is a time shorter than the time required from when the leading edge of the paper PP is detected by the paper detector 19 until the leading edge of the paper PP reaches the separating claw 12, that is,
Paper PP from registration roller pair 9 to separation claw 12
is set to a value slightly shorter than the time required to move. Therefore, in this case, pulse width τ ₁ is set to a larger value than pulse width τ ₂ .

Therefore, the signal P ₂ falls earlier than the signal P ₁ , and the monomulti 37 is triggered at the falling edge of the signal P ₂ , and the signal _{P 3} (third
(see figure m) is output, and the separation claw solenoid 38
added to. Thereby, separation pawl solenoid 3
8 is turned on for a period of pulse width τ ₃ from the rise of this signal P ₃ , and the separating claw 12 is displaced in the manner shown by the solid line in FIG. 1 during that period. Here, the pulse width τ ₃ is the paper
The time required for the leading edge of the paper PP to reliably pass through the separation claw 12 is set to a value that allows the separation claw 12 to separate the leading edge of the paper PP.

As a result, after the separation solenoid 38 is turned on and the separation claw 12 comes into contact with the photosensitive drum 1, the paper
The leading edge of the PP reaches the separation claw 12, and the paper PP is separated from the photoreceptor drum 1 by the separation claw 12.
The separated paper PP is discharged onto the discharge tray 15 by the conveyor belt 13.

Furthermore, the falling edge of the signal P ₁ is detected by the differentiating circuit 39 and the signal S ₃ (see Figure 3 j) is output at this timing, but at this point, the paper has already been
PP is passing through the paper detector 19, and the detection signal DP
is in a state of falling, and as a result,
Since AND circuit 33 is inactive, flip-flop 40 is not set (see FIG. 3k), and as a result, jam indicator 41 is not activated. Similarly, since the state of the output terminal of flip-flop 40 does not change, main body control section 20 continues copy control.

After this, the above-mentioned time _T1 passes, the resist clutch control signal RC falls, and the differentiating circuit 4
When the signal S ₄ (see Fig. 3 f) is output from 2,
Flip-flop 31 is set, thereby making AND circuit 33 operable. Therefore, normal jam detection is executed thereafter.

On the other hand, the paper fed out by the paper feed roller 5
Think about PP. If this paper PP does not jam in the registration roller pair 9, the paper PP has already passed the paper detector 19 when the signal _S3 is output, so the logic level of the signal DP is "L", and the paper is not jammed. Since AND circuit 33 is inactive, flip-flop 40 is not set.

Furthermore, if the paper PP is jammed at the registration roller pair 9, the logic level of the signal DP when the signal _S3 is output is "H" as shown by the broken line in FIG. Then the flip-flop 40 is set. Therefore, a jam is displayed and the occurrence of a jam is detected by the main body control section 20, and the main motor control signal SM is lowered to stop the photosensitive drum 1 and the like.

Thereafter, when the operator removes the jammed paper PP with the registration roller pair 9 and turns on the jam reset switch 22, the AND circuit 43 operates and the flip-flop 40 is reset, thereby disabling the jam indicator 41. At the same time, the main body control unit 20 is notified that the jam has been released.

Therefore, the main body control section 20 puts each element in a normal standby state and enters a state in which it waits for input from the print key 21.

In this way, in this embodiment, the jam detection operation is prohibited from the time the print key 21 is turned on until the paper PP fed from the paper cassette 6 reaches the pair of registration rollers 9. When the paper PP passing through the register roller pair 9 is detected during the period in which this jam operation is prohibited, the separation claw 12 is operated to separate the paper PP from the photosensitive drum 1 and the paper is ejected. .

Therefore, for example, when restarting after a jam, it is possible to prevent the paper PP remaining on the guide plate 8 from causing the jam detection state again or from causing damage to the cleaning section 17. can do.

Note that if a paper collation device is connected to the copying machine DM, the paper PP ejected before the first regular sheet is ejected to the output tray without being sent to the paper collation device, and the paper PP is ejected before the first regular sheet. Only the paper is sent to the paper collating device.

[Effects] As explained above, according to the present invention, when a paper other than the regular first paper is detected in the conveyance path within a predetermined time after the start of copying, it is ejected by the separating means. Also, jam detection is prohibited. Therefore, damage to the cleaning section due to residual paper can be prevented, and a situation in which jam detection occurs continuously can be avoided.

[Brief explanation of the drawing]

Figure 1 is a conceptual diagram showing one embodiment of the present invention, Figure 2 is a conceptual diagram showing an embodiment of the present invention.
The figure is a block diagram showing an example of a control system.
-m are waveform diagrams showing the operation of each part of the control system. 9... Registration roller, 12... Separation claw, 19... Paper detector, 20... Main body control unit, 21... Print key, 22... Jam reset switch, 30, 3
1, 40...flip flop, 32, 33, 43
...AND circuit, 34, 39, 42... Differential circuit, 3
5, 36, 37... Mono multi, 38... Separation claw solenoid, 41... Jam indicator.

Claims (1)

[Claims] 1. In a copying machine that detects as a jam the presence of paper sent out from a paper feeder in a registration section at a time other than a predetermined timing, and separates the paper after transfer from a photoreceptor by a separation means, When paper is detected in the registration section within a predetermined time after the start, the separation means is operated for a predetermined period from the time required from the detection timing until the leading edge of the detected paper moves to the vicinity of the photoreceptor. A copying machine characterized by comprising a control means for ejecting the detected paper.