JPS6138092B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to detecting a copy paper jam in a copying machine.

Conventionally, to detect a copy paper jam in a copying machine, a front detection switch 4 and a rear detection switch are installed at the front and rear of the fixing section 8 in the copying machine main body 1 during the copy paper transport path, for example, as shown in FIG. 5 is set. In this detection method, the leading edge of the copy paper 3 fed and conveyed from the paper feed section 2 is detected by the front detection switch 4, and after the leading edge of the copy paper 3 has passed the regular time, When the rear detection switch 5 does not detect the paper jam, it is determined that a paper jam has occurred in the conveyance path leading to the rear detection switch 5. In this case, the power is turned off and power supply to the heat source of the fixing unit 8 is stopped.

Further, after the leading edge of the copy paper 3 turns off the rear detection switch 5 at a predetermined time, the switch 5 is turned OFF when the rear edge of the copy paper 3 leaves the rear detection switch 5. If the rear detection switch 5 does not turn off even after the specified time has elapsed after the rear detection switch 5 has been turned on, it is assumed that a paper jam has occurred and the power is turned off again.
It's off.

In the former case, the time from when the leading edge of the copy paper 3 turns on the front detection switch 4 to when the rear detection switch 5 is turned on depends on the distance between the two switches and the copy paper 3.
It depends only on the conveying speed of the copy paper 3, and is unrelated to the length of the copy paper 3. In this case, after the rear detection switch 5 detects the leading edge of the copy paper 3, the paper jam of the copy paper 3 is not detected. The latter solves this problem. However, in the latter case, the time from when the leading edge of the copy paper 3 turns on the rear detection switch 5 to when the rear edge of the copy paper 3 leaves the rear detection switch 5 and turns it off depends on the transport speed (constant) and the copy paper It varies depending on the length of 3. However, in the conventional method, the regular time required for the latter case is set based on the longest copy paper used in the copying machine, and this time is applied uniformly to any other short copy paper. . This is because, if a short copy paper is used as a reference, there is a risk that a long copy paper will always be detected as a paper jam. According to this, the longest copy paper with max length 6
Using a copy paper 7 having an extremely short length compared to
For example, when a paper jam occurs in the fixing unit 8 t seconds after the rear detection switch 5 detects the leading edge of the copy paper, at least (
max/V-t) seconds, the power will not be turned off due to paper jam detection. However, V is the copy paper conveyance speed.

On the other hand, after turning on the backward detection switch 5, the passage time of the copy paper 7 of the same length through the rear detection switch 5 is determined.
Assuming the time required to turn off the power, the detection time if a paper jam occurs after t seconds is (/V-
t). The difference between the two is (max/V-t)-(/
V-t)=max-/V. Therefore, according to the conventional method, the length of copy paper 7 is uniformly set based on the longest copy paper 6 as described above, and the time required for paper jam detection is set as a standard. There is a high risk of ignition.

The above method mainly detects a paper jam in the fixing unit 8 and turns off the heat source, but even if a paper jam occurs in another conveyance path, the paper other than the copy paper will be turned off until the paper jam is detected. parts and equipment are working. Therefore, problems such as scratches and damage may occur due to contact between the copy paper and the operating device. for example,
If one end of the copy paper gets caught in the transfer section or a paper jam occurs, the copy paper transport device will continue to transport the copy paper unless this is detected promptly and the function is not stopped. Therefore, the copy paper is stuffed into the transfer section in a dumpling shape. The result is that the copy paper scratches the photoreceptor located directly above the transfer device or scatters toner that is electrostatically adhered onto the photoreceptor as it continues to rotate. Furthermore, when taking out the dumpling-shaped copy paper, the discharge wire in the charger of the transfer section is often cut.

The present invention has been made in view of the above drawbacks,
The purpose is to quickly determine a paper jam by setting the time required for determining a paper jam according to the length of copy paper. This is intended to prevent the copy paper from burning out, smoking, catching fire, etc. in the fixing device, or from damaging or disrupting the functions of various copying machine devices due to jammed copy paper.

Hereinafter, the present invention will be explained according to examples.

FIG. 2 is provided to explain the paper jam detection method according to the present invention. 1 is a configuration diagram of a copying machine mainly showing a copy paper conveyance path 10. FIG. In the figure, 11 is the main body of the copying machine, 12 is a paper feed section for the copy paper 13, 14 is a paper entry detection switch that detects the fed copy paper 13, 1
5 is a detection switch provided in the front near the transfer area in the copy paper conveyance path; 16 is a fixing device provided oppositely in the conveyance path; and 17 is a paper output detection switch provided at the rear of the fixing device. It is.

Further, reference numeral 18 indicates a photosensitive drum 19 in the transfer area.
20 is a charger that uniformly charges the photoreceptor, 21 is a developing section that develops the electrostatic latent image formed on the surface of the photoreceptor, and 22 is a static eliminator for the photoreceptor. , 23 is a cleaning device for removing toner remaining on the photoreceptor.

In the above configuration, the present invention provides the detection switch 1
If a paper jam of the copy paper 13 between 4 and 15 is detected, for example, the photosensitive drum 19 and the devices disposed opposite thereto are stopped, and the conveyance of the copy paper is stopped. Further, if a paper jam is detected between the detection switches 15 and 17, the heat source of the fixing device 16 is also turned off.

Next, paper jam detection according to the present invention will be described in detail.
Now, when the copy paper 13 is fed and conveyed from the paper feed section 12 of the copying machine main body 11, the leading edge of the copy paper 13 is detected by the detection switch 1.
4 is turned ON, the trailing edge of the copy paper 13 leaves the detection switch 14, and the time taken for the copy paper 13 to pass is counted and temporarily stored until the switch is turned OFF. After this, the copy paper 13 reaches the detection switch 15. Therefore, if the paper does not arrive even after a predetermined period of time has elapsed, it is determined that there is a paper jam. When the actual time is reached, the temporarily stored time is subtracted from that point. Then, when the trailing edge of the copy paper 13 has passed through the detection switch 15 and the detection switch 15 is turned off, the subtraction is stopped.

Here, the copy paper 13 turns on the detection switch 15.
After that, the detection switch 15 is turned on before a borrow signal is generated in the subtraction from the temporary storage section.
If it is not turned off, it is determined that there is a paper jam and, for example, the photosensitive drum 19 and the copy paper 13 conveyance system are stopped as described above.

This copying machine 11 is capable of copying, for example, up to A3 size copy paper, and we will now exemplify the case where A6 size copy paper is used. Also, a case will be described in which a paper jam occurs in the transfer charger 18 after passing through the detection switch 15. A3
The length of the size copy paper is 420 mm, the length of A6 size copy paper is 148 mm, and if the distance between the detection switch 15 and the transfer charger 18 is 100 mm, and the copy paper conveyance speed is 160 mm/sec, the length of the copy paper is 148 mm. According to the paper jam detection of the invention, a paper jam is detected after 148-100/160 mm-sec/mm = 0.3 seconds have elapsed after the paper jam, and the paper jam indicator lamp is turned on and at least the photoconductor 19 and the copying machine are activated. It is possible to stop the paper transport mechanism and protect various devices. However, in the conventional paper jam detection method, the paper jam detection time is uniformly set even when the maximum copy paper A3 passes through the detection switch 15. A paper jam cannot be detected until mm-sec/mm=2.0 seconds have elapsed.

On the other hand, the detection of a paper jam between the detection switch 15 and the detection switch 17 is similar to that described above. Copy paper 1 detected by detection switch 14
The passage time of No. 3 is the same as the passage time detected by the detection switch 15 as long as the conveyance speed is constant.

Therefore, the passing time counted by the detection switch 14 may be used as is, and this time may be subtracted from the time when the detection switch 17 detects the leading edge of the copy paper 13.

Furthermore, in the embodiment described above, the time taken for the copy paper 13 to pass through the detection switch 14 is memorized, and this time is subtracted when the copy paper passes through the detection switch 15, and if a borrow signal is output, it is determined that there is a paper jam. . However, in reality, various mechanical errors are considered. Therefore, if the front detection switch 14 is
When counting up the time taken by 3 to pass in the storage section, it is desirable to add the error time as an initial value (preset) in advance.

FIG. 3 shows a circuit configuration showing a specific example for implementing the present invention. 30 in the figure is an up-down counter that counts the passing time detected by the detection switch according to the present invention and temporarily stores the time. The up-down counter 30 has input terminals T _U for inputting a signal for counting up (time pulse TB), T _D for inputting a signal for counting down (time pulse TB), and input terminals D _A and D for presetting. It has input terminals for _B , D _C , D _D and presetting.
The up-down counter 30 also has a borrow signal output terminal (BRO). The up/down counter 30 includes flip-flops A ₁ , B ₁ , C ₁ , D _{1 , . .} . and counts up and down signals. That is, A ₁ has a weight of 2 ⁰ , B ₁ has a weight of 2 ¹ , C ₁ has a weight of 2 ² and D ₁ has a weight of 2 ³ . Input terminals D _A , D _B , D of up-down counter 30
_C and D _D are for setting flip-flops A ₁ , B ₁ , C ₁ and D ₁ and are set when a signal (“L”) is input to the input terminal. In other words, the input power terminals D _A , D _B , D _C , and D _D are connected to the error setting circuit 31 that preliminarily counts the value of the mechanical error described above. The error setting circuit 31 has switches ab and cd having respective weights, and by turning on the switches, a flip-flop of each weight of the up-down counter 30 is set.

In the circuit diagram, 32 is a clock circuit that generates a time pulse TB every 50 msec, for example. The time pulse TB from the clock circuit 32 is input to the NAND gate 33 together with the signal from the output of the borrow signal.

The detection switch 14 or 15 is turned ON when the copy paper 13 is detected, and sends the "H" signal to the NAND gate 34.
At the same time, it is input to the NAND gate 35 or the NAND gate 36. Said nand gate 35
Or at the other input terminal of 36, the NAND gate 3
A signal from 4 and a signal from NAND gate 33 are input. In other words, the detection switch 14
When turned ON, the NAND gate 35 is enabled, and the time signal (time pulse) from the NAND gate 33 is activated.
TB) is input to T _U of the up-down counter 30 and counted up. Conversely, detection switch 1
5 turns on, the time signal from the NAND gate 33 is input to T _D of the up-down counter 30 via the NAND gate 36, and is counted down.
Furthermore, if both detection switches 14 and 15 are turned ON, both NAND gates 35 and 3 are activated by the output of NAND gate 34.
6 is restricted, and no time signal is input to T _U and T _D .

Further, the borrow signal from the up-down counter 30 is inputted to the base of a switching transistor 38 via an inverter 37, and controls energization of a jam relay 39 connected to the transistor 38. This jam relay 39 is a keep relay and can only be released manually.
Further, when the relay 39 is set (energized), it stops at least the photosensitive drum 19 and the copy paper 13 conveyance mechanism. Here, although the circuit shown in FIG. 3 detects a paper jam in the transport path 10 between the detection switches 14 and 15, a similar circuit configuration may be used between the detection switches 15 and 17. In this case, the power supply to the fixing device 16 as well as the photosensitive drum 19 and the transport mechanism is stopped.

The operation of the circuit configuration shown in FIG. 3 will be explained below with reference to the time chart shown in FIG. 4. Before the sheet feeding operation starts in the sheet feeding section 12, a signal for presetting the up-down counter 30 is input to the terminal. As a result, the time corresponding to the error is inputted from the error setting circuit 31. According to this embodiment, "3" is preset. That is, flip-flops A ₁ and B ₁ are set and count "3".

Thereafter, according to the operation of the paper feed section 12, the copy paper 13
When the copy paper is fed and conveyed, the paper entry detection switch 14 detects the leading edge of the copy paper. At this time, the switch 14 is turned on and the NAND gate 35 is opened. Therefore, the time pulse TB output from the clock circuit 32 every 50 msec passes through the NAND gate 33 and is input to the T _U terminal of the up-down counter 30 via the NAND gate 35. As a result, the up-down counter 30 adds and counts the time pulses TB output every 50 msec. This counting state is A ₁ of the time chart,
The operating states of the flip-flops B ₁ , C ₁ , D ₁ . . . are as shown below.

After that, when the detection switch 15 is turned on while the copy paper 13 is passing through the detection switch 14, the output of the NAND gate 34 becomes "L", and the NAND gate 3
The output of No. 5 is always "H". Therefore, the up-down counter 30 stops counting. Similarly, the NAND gate 36 continues,
It is “H” and the up/down counter is 30.
never starts the countdown. This is equivalent to canceling the count up and count down.

Next, when the copy paper 13 leaves the detection switch 14 and is turned OFF, and is passing through the detection switch 15, the output of the NAND gate 35 remains "H", and the NAND gate 36 outputs the output of the time base 32.
Outputs pulse PB every 50msec. Therefore, the up-down counter 30 starts counting down. In the time chart of the embodiment, the count when the copy paper 13 is normally conveyed, indicated by a solid line, starts from "3" and ends at "3".

However, the copy paper 13 turns on the detection switch 15.
If the paper jams and the machine stops, the countdown continues as shown in the dashed line.
A borrow signal is output by the TB signal after counting "0". The signal (“L”) from this causes the transistor 38 to be activated via the inverter 37.
Turn on. Therefore, the jam relay 39 is energized. Therefore, at least the photosensitive drum 19 and the copy paper transport mechanism are stopped. Further, the paper jam detection according to the present invention using the detection switch 17 can be performed in a similar manner in terms of the circuit.

Furthermore, in the explanation of the operation of the circuit shown in FIG. 3, the case where the copy paper 13 is detected by the detection switch 15 while the copy paper 13 is being detected by the detection switch 14 is illustrated. However, the same applies to a device in which the copy paper 13 is detected by the detection switch 15 after the copy paper 13 leaves the detection switch 14. In this case, the process until the leading edge of the copy paper is detected by the detection switch 15 is the same as in the conventional case (the former).
Detecting paper jam. The present invention is characterized in that a paper jam is detected after the leading edge is detected by the detection switch 15, and this detection is quickly performed.

As explained above, in the conventional paper jam detection method, the presence or absence of a paper jam is determined by uniformly assuming that copy paper, which has different lengths depending on the type, is the longest copy paper. However, in the present invention, in order to detect a paper jam by determining the length of each of different types of copy paper,
Compared to conventional methods, paper jams can be detected sooner. In particular, according to the present invention, paper jam detection can be performed based on the count content of the counting means, so there is no need for the troublesome work of setting a value in advance in order to detect paper jam as in the conventional method. Moreover, there is no need to provide means for comparing the set value and the count value, and the circuit configuration can be significantly simplified. In addition, the detection means placed before and after the conveyance path that conveys the copy paper can temporarily stop the counting operation of the counting means that counts the length of the copy paper, so that the length of the copy paper can be completely adjusted. Paper jams can be detected reliably and quickly regardless of the situation. This makes it possible to detect paper jams, which is very effective in preventing wave damage to various devices of the copying machine, burnout of copy paper in the fixing device, smoke generation, ignition, etc. due to paper jams.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a copy paper transport path in a copying machine to explain a conventional paper jam detection method, and FIG. 2 is a schematic block diagram of a copy machine to explain paper jam detection in the present invention. , FIG. 3 is a circuit configuration diagram showing a specific example of paper jam detection according to the present invention, and FIG. 4 is a time chart for explaining the operation of FIG. 3. 11: Copying machine body, 13: Copy paper, 14: Paper entry detection switch, 15: Intermediate detection switch, 16:
Fixing device, 17: paper output detection switch, 18: transfer charger, 19: photosensitive drum.

Claims (1)

[Claims] 1. First and second detection means arranged before and after the copy paper transport path in the copying machine to detect the copy paper being transported, a pulse output means that outputs a constant pulse train signal, and a signal from the pulse output means. a counting means having respective input terminals for counting up or counting down, and actuated by a copy paper detection signal from the first detection means, and supplying a signal from the pulse output means to the count-up terminal of the counting means. a first gate means for supplying a signal from the pulse output means to a countdown terminal of the counting means, which is activated by a copy paper detection signal from the second detection means;
regulating means for regulating the operation of the first and second gate means when both the first and second detecting means detect copy paper; and a regulating means for generating a paper jam signal when the counting means counts down to a predetermined count. A paper jam detection device for a copying machine, comprising a means for outputting.