JPS6134676B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper jam detection device for a scanning copying machine.

In general, paper jam detection devices for copying machines have been proposed that employ various methods. One example is a detector that detects the passage of copy paper near the paper feed path transport start section and near the ejection section. There is a system in which a timer is started at the same time as the leading edge of the copy paper activates a detector near the conveyance start part, and if the copy paper does not reach the vicinity of the discharge part within a predetermined time, a paper jam is detected and displayed.

However, paper jam detection devices using this method have the disadvantage that they cannot start feeding the next copy paper until the copy paper has passed the detector near the ejection section, and are not suitable for high-speed copying machines. It's something that doesn't exist. For this reason, it has been proposed to divide the copy paper transport path into approximately equal intervals and install detectors at each location to detect paper jams. It is not suitable for practical use because it requires high cost and requires extremely complicated control. Generally, a paper jam detection device is designed to stop all functions of the copying machine immediately upon detecting a paper jam, so a scanning type that exposes the image of the original by moving a scanning body such as a document table or an optical system is used. In a copying machine, when the scanning body stops during image exposure, the scanning body is moved back to the initial position before starting the next copy, and if the copying machine is a transfer type, the photoreceptor is There are disadvantages such as the need to idle the scanning body in order to erase the electrostatic image formed before the scanning body stops due to detection of a paper jam.

The present invention solves the above-mentioned drawbacks and provides a scanning copying machine that exposes an image by moving a reciprocating scanning body, in which the scanning body can be reliably returned to the initial position even when a paper jam occurs, and the scanning body can be moved back and forth. The scanning movement itself for image exposure has a function as a timer, that is, the continuous action between the first timer means that is started before the start of scanning and the second timer means that is started when the backward movement is started. It is an object of the present invention to provide a paper jam detection device that is capable of detecting paper jams covering the entire copy paper conveyance path by providing a timer function.

The present invention will be described below with reference to the accompanying drawings.

FIG. 1 schematically shows an original platen scanning type copying machine incorporating a paper jam detection device according to the present invention.
Reference numeral 1 denotes a reciprocating document table on which a document to be copied is placed, and by scanning it in the right direction in the figure, the document image is illuminated by an exposure lamp 2 and mirrors 3, 4, 5 and a lens mirror 6. The images are sequentially projected onto the photoreceptor 7, which rotates through the photoreceptor 7. Around the photoreceptor 7, there is a charging charger 8 for uniformly charging the surface of the photoreceptor, a developing device 9 for developing the electrostatic latent image, and a transfer device for transferring the developed image onto copy paper 10. A charger 11, a separation claw 12 for separating the copy paper 10 from the photoreceptor, a first eraser 13 for erasing residual charges, a cleaner brush 14 for removing residual toner, and a brush for erasing the residual charges once again. A second eraser 15 is provided.

On the other hand, copy sheets 10 of different sizes are stored in upper and lower paper feed cassettes 16 and 17, respectively, and either the paper feed roller 18 or 19 becomes ready for paper feeding by operating a copy size selection switch (not shown). Copy paper 10 is fed. The leading edge of the fed copy paper 10 touches the timing roller 20.
When it is gripped by the roller, it is stopped for a moment to synchronize with the image formed on the photoreceptor, and then the conveyance starts again and is sent to the transfer section via the conveyance rollers 21 and 22. The copy paper on which the image has been transferred is discharged onto a discharge tray 26 via a conveyance belt 23, a fixing heat roller 24, and a discharge roller 25.

Here, the paper jam detection device according to the present invention will be explained.
Between the timing roller 20 and the timing roller 20 are first detection switches 27 and 28 for detecting the leading and trailing edges of the copy paper.
In front of the discharge roller 25, there are also a second detection switch 29 for detecting the leading and trailing edges of the copy paper, a first timer means for detecting a paper jam upstream of the first detection switches 27 and 28, and the first detection switch 29. and second timer means for detecting a paper jam downstream of the switches 27, 28. The first detection switch 27 or 28 detects the leading edge of the copy paper to enable scanning movement of the original platen for image exposure, and detects the trailing edge to move the original platen 1 back after a certain period of time has elapsed. It has the ability to move. Further, as can be understood from FIG. 2, the first timer means includes a first timer T1, and the second timer means includes second to fourth timers.
It is equipped with timers T2, T3, and T4.

The first timer T1 starts simultaneously with the start of rotation of the paper feed rollers 18 and 19, which are activated by the energization of the paper feed solenoid 30.
When the copy paper is normally fed and the first detection switch 27 detects its leading edge, the switch 27 is reset. However, if copy paper is jammed in the paper feed section, the first detection switch 27 is not activated and the first timer T1 is activated.
The machine times out without being reset, stops all functions of the copying machine, and displays a paper jam message.

As described above, the document table 1 moves backward after a certain period of time after the first detection switches 27 and 28 detect the passing of the trailing edge of the copy paper. A second timer T2 is provided. Then, based on the time-up of the second timer T2, the scanning movement of the document table 1 for image exposure is stopped, and the document table 1 is stopped.
begins to return immediately. Further, the second timer T2 starts a third timer T3 based on the time up, and the third timer T3 starts a fourth timer T4 based on the time up.
On the other hand, if the leading edge of the copy paper is detected by the first detection switches 27 and 28, but a paper jam occurs and the switches 27 and 28 do not detect the trailing edge of the copy paper, the second timer T2 does not start. Therefore, the document table 1 continues scanning movement.
In the present invention, paying attention to this point, an overbalance switch 31 is provided on the copying machine main body side to detect the scanning movement limit distance of the document table. When the overbalance switch 31 is operated, the third timer T3 is started. In other words, the first detection switch 27
Alternatively, when the trailing edge of the copy paper is not detected by 28, the document table 1 is moved by the maximum distance, that is, the scanning movement limit distance, and the overlap switch 31 is activated to cause the document table 1 to move backward, and the third timer T3 is started. do. Therefore, in this case, the second timer T2 is omitted. Therefore, when the copy paper does not pass through the first detection switches 27 and 28, the document platen 1
The scanning movement itself serves as a continuous action between the first timer T1 and the third timer T3, which enables the fourth timer T4 to be started and to detect a paper jam based on its time-up. A switch provided adjacent to the overlap switch 31 is a fixed position switch 33, which is turned off by an actuation piece (not shown) provided on the document table to stop the document table when the document table moves backward and returns to the starting position.

A second detection switch 29 located in front of the ejection roller 25 detects paper jams after the copy paper passes normally through the first detection switch 27, and detects when the trailing edge of the copy paper passes through the switch 29. As a result, the fourth timer T4 is reset, and if the paper jam is not detected within a predetermined time, the time is up and the paper jam is detected.

Hereinafter, the operation of the paper jam detection device according to the present invention will be explained based on the copying sequence shown in FIGS. 2 and 3. Note that FIG. 2 shows the sequence when the number of copies is set to a plurality and A4 size copy paper 10 is normally conveyed from the upper cassette 16, and FIG.
7 shows a sequence when a paper jam occurs and is not detected by 7.

In FIG. 2, when the print switch is actuated, paper feed solenoid 30 is energized, which causes paper feed roller 18 to rotate and transport of copy paper 10 to begin. Further, the first timer T1 starts simultaneously with the activation of the paper feed solenoid 30. When the copy paper 10 is normally fed and its leading edge is detected by the first detection switch 27, the first timer T1 is reset, while if the leading edge is not detected within a predetermined time due to a paper jam, it is indicated by a dotted line. As if the time had run out, all functions of the copying machine would stop.

Detection of the leading edge of the copy paper by the first detection switch 27 is performed by a scan relay 34 that starts the document table 1.
A timer t is started to operate the timer t. Then, based on the time-up, the scan relay 34 is activated, and the document table 1 starts scanning movement toward the right in FIG. 1 for image exposure. The reason why the document table 1 is started (operation of the scan relay) is not started simultaneously with the detection of the leading edge by the first detection switch 27, but is started after a slight delay via the timer t.
This is because it takes a time corresponding to the timer t until the exposure lamp 2 reaches the maximum amount of irradiation light. Therefore, if the exposure lamp 2 is turned on in advance by another means rather than by the first detection switch, there is no problem in starting the document table at the same time as the leading edge is detected by the first detection switch 27.

Simultaneously with the start of scanning movement of the document platen 1 by the operation of the scan relay 34, the charging charger 8 is also energized, and as the photoreceptor 7 rotates, latent images are successively formed. On the other hand, when the leading edge of the copy paper 10 is gripped by the timing roller 20, the copy paper 10 stops for a moment because the roller 20 is not yet in operation. This stop is for synchronization with the electrostatic image formed on the photoreceptor, and the timing solenoid 35 operates to move the copy paper 10 to the timing roller 20.
is rotated and transported again.

When the copy paper is conveyed and the passage of the trailing edge is detected by the first detection switch 27, the second timer T is activated.
2 starts, and based on the time-up, the document table 1 stops and immediately moves back. This means that the amount of scanning movement of the original platen 1 varies depending on the length of the copy paper, and this allows high-speed copying when the copy paper is small in size. The second timer T2 further turns off the exposure lamp 2 and the charger 8 based on the time-up, and starts the third timer T3. Then, this third timer T3 starts a fourth timer T4 based on the time up. The fourth timer T4 indicates a paper jam when the timer has expired without being reset within a predetermined time. If a paper jam occurs somewhere, the paper jam is detected by the time-up of the fourth timer T4.

When the document table 1 is returned to the initial position, the fixed position switch 33 is turned off and stopped, while the copy paper 10 continues to be fed, passes through the fixing heat roller 24, and reaches the second detection position before the ejection roller 25. switch 2
9 is actuated by its tip. Then, by detecting the rear end, the fourth timer T4 is reset. Resetting the fourth timer T4 even at the trailing edge of the copy paper in this way ensures that the copy paper is completely ejected from the machine. As described above, paper jam detection for the entire conveyance path for one copy paper is performed, but the conveyance of the second copy paper is started when the scanning movement of the document table 1 is completed.
That is, it is performed around the time the third timer T3 starts, and the same sequence is repeated thereafter. In connection with this, the reason why the third timer T3 and the fourth timer T4 in the present invention are not made into a single timer is that, as mentioned above, the second and third sheets of copy paper are printed at as short an interval as possible. This is to ensure that the operating time of the same timer does not overlap for each copy sheet while feeding the paper, thereby making high-speed copying possible.

Next, referring to FIG. 3, a case will be described in which the trailing edge of the copy sheet is not detected by the first detection switch 27 and a paper jam occurs. First detection switch 27
remains activated by the leading edge of the copy paper, and the second timer T2 is also not activated. Therefore, the document table 1 continues scanning movement and moves by the scanning movement limit distance, and the operating piece 32 operates the overbalance switch 31. As a result, the document table 1 stops and immediately moves back. The overbalance switch 31 further starts the third timer T3 by its operation,
A fourth timer T4 is started based on the time up. Since the copy paper 10 is already jammed, it does not reach the second detection switch 29, and the fourth timer T4 times out, indicating a paper jam and stopping all functions of the copying machine. Therefore, the first
When the passage of copy paper is not detected by the detection switch 27, the scanning movement of the original platen 1 itself serves to provide continuity between the resetting of the first timer T1 and the start of the third timer T3. This is made possible by operating the overbalance switch 31. In other words, the scanning movement of the document table 1 itself functions as a timer, maintaining continuity from the first timer T1 to the fourth timer T4, making it possible to detect paper jams covering the entire transport path.

Although the above-described embodiments are directed to a copying machine with a reciprocating document table, it is of course possible to use a copying machine with a reciprocating optical system. Also, the stop of the scanning movement and the start of the backward movement of the document table 1 are not necessarily performed by the second timer T.
2, and depending on the design, it may be performed simultaneously with the rear end detection by the first detection switch 27, thereby starting the third timer.

As is clear from the above description, the paper jam detection device according to the present invention is used in a scanning copying machine that exposes an image using a reciprocating scanning body, and is activated by the time-up of a timer set at a predetermined timing. A detection device for detecting a paper jam in a copy paper conveyance path includes a copy paper detection means provided at a predetermined position in the copy paper conveyance path to detect the leading and trailing edges of the conveyed copy paper, and A first method for detecting a paper jam upstream of a predetermined position.
a timer means, a second timer means for detecting a paper jam downstream of a predetermined position in the copy paper transport path, a movement detection means for detecting that the scanning body has moved by a predetermined distance or more, and the first timer means. is started at the start timing of paper feeding, and when the copy paper detecting means detects the leading edge of the fed copy paper, the first timer means is reset and the scanning body is scanned and moved for image exposure. a first control means for causing the scanning body to move backward and starting the second timer means when the copy paper detection means detects the trailing edge of the fed copy paper; and the copy paper detection means for feeding the copy paper. and second control means for causing the scanning body to move backward and starting the second timer means when the movement detection means detects movement of the scanning body by a predetermined distance or more before detecting the trailing edge of the copy paper. Since this is a paper jam detection device for a scanning type copying machine, the scanning movement of the scanning body itself has a continuous function from the time after the first timer means is reset until the second timer means is started. This makes it possible to detect paper jams throughout the copy paper transport path with an extremely simple configuration. Furthermore, even in the event of a paper jam, the scanning body always moves back to the initial position, which has the advantage of making it easy to start the next copying operation. Further, since the second timer means includes a plurality of timers, the copy sheets can be conveyed one after another even at short intervals, and high-speed continuous copying can be performed. Since the first timer means also detects paper jams in the paper feed section where paper jams are most likely to occur, this system has many effects such as immediate paper jam indication.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a schematic configuration of a scanning copying machine incorporating a paper jam detection device according to the present invention, and Fig. 2 shows a copying sequence when copy paper is normally fed in the copying machine shown in Fig. 1. The figure shown in FIG. 3 is a sequence diagram when a paper jam occurs. 1... Original table, 27, 28... First detection switch, 29... Second detection switch, 31... Overbalance switch.

Claims (1)

[Claims] 1. A detection method used in a scanning copying machine that exposes an image using a reciprocating scanning body, and detects a paper jam in a copy paper conveyance path based on the time-up of a timer set at a predetermined timing. In the apparatus, a copy paper detection means is provided at a predetermined position on the copy paper transport path and detects the leading and trailing edges of the copy paper being transported, and a copy paper detection means is provided for detecting a paper jam upstream of the predetermined position on the copy paper transport path a first timer means for detecting a paper jam downstream of a predetermined position in the copy paper transport path; a movement detection means for detecting that the scanning body has moved by a predetermined distance or more; The first timer means is started at the start timing of paper feeding, and when the copy paper detection means detects the leading edge of the fed copy paper, the first timer means is reset and the scanning body is moved to scan for image exposure. a first control means for moving the scanning body backward and starting the second timer means when the copy paper detection means detects a trailing edge of the fed copy paper; a second control means for moving the scanning body backward and starting the second timer means when the movement detection means detects movement of the scanning body by a predetermined distance or more before detecting the trailing edge of the fed copy paper; A paper jam detection device for a scanning copying machine, comprising: 2. The second timer means is composed of at least two or more timers, and sequentially starts the next timer when the timer in operation expires;
2. A paper jam detection device for a scanning copying machine according to claim 1, wherein a paper jam is detected by the time-up of a final timer. 3. A paper jam detection device in a scanning copying machine according to claim 1 or 2, wherein the copy paper detection means is provided near a paper feed section in a copy paper conveyance path. .