JPH03124648A - Duplicate carrier control method for recording paper - Google Patents

Abstract

PURPOSE:To make it possible to pull easily a piece of detail paper out of the side of a feeder in order to be removed by changing the set value of detection time for judgement on duplicate carrying by the side of a form, and thereby suspending carrying operations at a position where the rear end of the leading piece of recording paper which is fed in over-lapped relation, remains on the feeder side in a fixing device. CONSTITUTION:When a piece of detail paper is fed from a feeder, both of the period T1 from the time when a regist sensor 5 is turned on to the time when paired regist rollers 7 are turned on and of the period T2 from the time when the paired regist rollers 7 are turned on to the time when duplicate carrying is detected, are estimated in response to the size of the piece of detail paper. In the second place, when the discrete value since the regist sensor 5 has been turned down, becomes the set value T1, the paired regist rollers 7 start carrying operations, and judgement on duplicate carrying is thereby made when the condition of the regist sensor 5 turned on is still continued beyond the set time T2, the carrying operations by the paired regist rollers 7 are thereby suspended so that a part of the rear end of a leading piece of recording paper is left on the feeder side in a fixing device.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a multi-feed conveyance control system for recording paper in an image forming apparatus such as a laser printer or a copying machine.

(Prior art) As a double feed conveyance control system for recording paper, if a registration sensor does not turn off and remains on even after a certain period of time has elapsed since the recording paper started being conveyed from a pair of registration rollers, It was determined that double feeding occurred because the recording paper could not be removed from the pair of registration rollers.

(Problem to be Solved by the Invention) Since the setting time for determining the double feed in the above method is constant regardless of the size of the recording paper, when the conveyance is stopped due to the determination of double feed, depending on the paper size, the setting time shown in FIG. As illustrated, there are cases where the trailing edge 2a of the leading edge recording paper 2A, which has stopped at the position of the fixing device 1, does not remain long enough to be pulled out on the paper feed side (A). For this reason, when removing the remaining paper in the machine, the long recording paper protrudes from the paper discharge side (B) and is pulled out from there.

As a result, there was a problem in that the unfixed toner 3b adhered to the fixing roller IR, staining the recording paper when the next print was made after processing the remaining paper.

The figure shows a state during double feeding, where the leading edge 2b of the next recording paper 2B overlaps with the lower side of the first recording paper 2A and is sandwiched between the fixing roller IR and the pressure roller IP of the fixing device 1. ing. A portion of the leading recording paper 2A is fixed by a fixing device, and is shown as toner 3a after fixing.

(Objective of the Invention) The present invention solves the above problems by changing the time T2 (setting value) until double feeding is determined for each paper size of the recording paper used.
An object of the present invention is to provide a multi-feed conveyance control system for recording paper in which a part of the trailing edge of the multi-feed recording paper remains on the paper feed side of a fixing device.

(Structure and operation) In order to achieve the above object, the present invention, when feeding recording paper from the paper feeding section, adjusts the time T□ from the registration sensor ON to the registration roller pair ON and the paper size of the recording paper. A time T2 from when the registration roller pair is turned on until double feeding is detected is set in advance, and when the count value from the registration sensor on reaches the set time T□, conveyance is started from the registration roller pair, and the registration sensor is turned on. When the set time T is exceeded, it is determined that double feeding has occurred and the conveyance is stopped.

A feature is that a part of the rear end of the leading recording paper remains on the paper feeding side of the fixing device.

The present invention has a time T2 until double feeding is determined for each paper size of recording paper.
Since the paper is stopped during double feed by changing the number of pages, a part of the trailing edge of the recording paper (jammed paper) during double feed remains on the paper feed side of the fixing device, and the remaining paper can be removed from this paper feed side. Because you can
This can be done without staining the fixing roller with unfixed toner.

(Embodiment) FIG. 5 shows a schematic diagram of the configuration of a laser printer as an example in which the present invention is implemented. As shown in the figure, a registration sensor 15 is provided just before the pair of registration rollers 7. To briefly explain this operation, a paper feed cassette 5 is removably loaded into the printer main body 4. The recording paper 2 fed from the paper feeding device 6 in the direction of arrow A is timed by a pair of registration rollers 7 and is conveyed to a latent image carrier consisting of a photoreceptor 8 on a drum.

The photoreceptor 8 is rotated one clockwise direction, and at this time, the surface is charged by the charging charger 9, and the laser optical system l
A laser beam is irradiated from O to form an electrostatic latent image on the photoreceptor. This latent image is visualized by toner when passing through the developing bag N11.

This visible image is transferred by the transfer separation charger 12.

The image is transferred to the recording paper 2 conveyed to the photoreceptor 8, and the recording paper 2 that is in close contact with the photoreceptor 8 is electrostatically separated.

Thereafter, the recording paper 2 is conveyed to the fixing device 1, the visible image on the recording paper 2 is fixed, and the recording paper 2 is discharged to the paper discharge section 13 in the direction of arrow B.

On the other hand, residual toner is removed from the photoreceptor 8 after the visible image has been transferred by a cleaning device 414 having a cleaning blade. The toner removed from the photoreceptor is collected by a cleaning device.

FIG. 1 shows a functional block diagram of an embodiment for implementing the method of the present invention. In the figure, reference numeral 16 denotes a microcomputer (CPU) constituting the control section of the printer main body 4 shown in FIG. Program R
OM, RAM for working.

Ilo etc. are omitted. Here, the counter 16-1 starts the registration roller pair 7 after the registration sensor 15 is turned on.
The time T until the register roller pair 7 is turned on, and the time T2' after the registration roller pair 7 is turned on are counted.

The memory 16-2 stores the time T2 set for each paper size from when the pair of registration rollers is turned on to when double feeding is detected. Comparator 16-3 compares the count value of counter 16-1 (time T2' after the registration roller pair is turned on) and time T2 set in memory 16-2. Note that each part 16-1 to 16-3 of the CPU 16H can also be processed by software.

Further, 17 is a motor driver for the registration roller pair 7.
Controls the rotational drive and stop of the fixing roller IR, etc.

Next, the operation will be described using the flowchart shown in FIG.

First, before the paper feed device 6 starts feeding the recording paper 2 in the paper feed cassette 5, a registration sensor 1 is set for each paper size.
Time T1 from turning on of 5 to turning on of registration roller pair 7
(setting value) and the time T from turning on the pair of registration rollers 7 to detecting double feeding (setting value) (Sl). Thereafter, the paper feeding device 6 starts feeding the recording paper 2 (S2), and when the registration sensor 15 is turned on (Yes in S), the counter 16-1 starts counting (S4). The comparator 16-3 cannot judge that the count value of the counter has reached time T□.
(Yes), conveyance of the recording paper from the pair of registration rollers 7 is started under the control of the motor driver 17 (SG).

This is for timing the writing from the laser optical system 10 and the conveyance of the recording paper 2.

As described above, the recording paper starts to be conveyed from the pair of registration rollers 7, and the counter 16-1 starts counting anew (
S7). After this, the comparator 16-3 determines whether the counted value (time T2') reaches time 'r2 (5Il) and time T2'.
If the registration sensor 15 turns off before reaching 2 (S
Yes), normal transport control is performed (Sg).

However, when the registration sensor 15 remains on (No in SIl) and exceeds time T2 (Yes in S1o), the motor driver 17 determines that double feeding is occurring and stops the rotation (conveyance) of the fixing roller IR (S1t). - The operation of the double feed detection by the comparator 16-3 described above will be described with reference to the flowchart shown in FIG. Here, resist sensor 1
Since the time T (set value) from turning on the paper size 5 to the registration roller pair 7 can be kept at a constant value, the explanation will be omitted. Set time T2 and time T□ until detection (S
l). Then, the time '1'1 is inputted from the counter 16-1 (S2).

Next, the comparator 16-3 compares the paper size Q of the recording paper to start feeding with the reference size L (S,)
.

If the paper size α is larger than the cocoon weight size L (Ye of S,
s).

T, = La/V -...11) However, La is the maximum paper passing size ■ is the linear velocity of the recording paper (S4).

Also, when one paper size A < L (No in Sa), double feed detection is accelerated by (standard size L) - (paper size Q) (
S.).

FIG. 4 is a diagram showing the conveyance stop position of the recording paper when double feeding is detected in the present invention (1) and the prior art (2).

If the maximum feeding size is normally A size recording paper (length in the feeding direction LaIIWll), for example, if the registration sensor does not turn off after A size transport, conventionally it has been determined that there is a double feed.

Therefore, when double feeding, A size and B size recording paper
As shown in (1), recording paper 2 (jammed paper) can be removed from the paper feed side (A), but C size recording paper is (2)
), it was not possible to remove the recording paper from the paper feed side (A) because the trailing edge 2a of the recording paper was short.

As described above, in the present invention, the time T2 from when the pair of registration rollers 7 starts transporting the recording paper 2 to when double feeding is determined is set for each paper size. The trailing edge 2a (C size) of the recording paper is on the paper feed side of the fixing device 1 (
In A), the length is sufficient for pulling out.

In other words, since the double feed detection (time T2) is accelerated by the amount (reference size L - paper size Q) shown in equation (2) above (length ρ), the C The size recording paper can be easily pulled out from the paper feed side (A).

(Effects of the Invention) As explained above, the present invention changes the set value of the double-feed judgment detection time for each paper size, so that the trailing edge of the first recording paper that is double-fed remains on the paper feed side of the fixing device. Transport is now stopped at the position. As a result, when the recording paper is removed, it can be easily pulled out from the paper feeding side, so that the fixing roller is not contaminated. Therefore, even in printing after double feeding, the recording paper passing through the fixing device can be ejected without staining it.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of an embodiment for implementing the method of the present invention, FIGS. 2 and 3 are flowcharts for explaining the operation of FIG. 1, and FIG. 4 is a functional block diagram of an embodiment of the present invention. FIG. 5 is a schematic diagram of the configuration of a laser printer as an example of the present invention, and FIG. 6 illustrates the direction in which the recording paper is pulled out in the fixing device. This is a diagram. 5... Registration sensor, 7... Registration roller pair, 16... Microcomputer (CP
U), 16-1... Counter, 16-2... Memory, 16-3... Comparator, 17... Motor driver, IR... Fixing roller.

Claims (1)

[Claims] When feeding recording paper from the paper feed unit, the time T_1 from the registration sensor on to the registration roller pair on, and the time T_2 from the registration roller pair on to double feed detection depending on the paper size of the recording paper are set in advance. Then, when the count value from the registration sensor ON reaches the set time T_1, transport is started from the pair of registration rollers, and when the registration sensor ON state exceeds the set time T_1, it is determined that double feeding has occurred and transport is stopped. A multi-feed conveyance control system for recording paper, characterized in that a part of the trailing edge of the first recording paper remains on the paper feed side of a fixing device.