JPH0228667A - Jam detecting device on sheet supply route for image forming device - Google Patents

Abstract

PURPOSE:To feed sheets in a stabilized way and to prepare copies at maximum capacity by equipping the title device with a sheet feeding system and a jam detecting means. CONSTITUTION:When a sheet is moved on a paper supply route 60, the reference time of a jam signal for that sheet can be set by the AND of two signals of the signal that are a signal passing a registration gate 21 and the signal of a solenoid off-sensor 81. Even when there is a delay in the moving timing of a previous sheet due to change in magnification and reduction, a timer is started to operate from a point when the previous sheet passes the registration gate 21. Therefore, even when the sheet is fed closely to the previous sheet on the paper supply route 60 ranging from a sheet housing means 71 to the registration gate 21, time is not counted by the timer while the sheet is stopped within the paper supply route 60. As a result, the number of copies made per unit time can be increased.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is an image forming apparatus such as a copying machine, in which paper sent from a paper storage means such as a paper tray is transferred to an image carrier such as a photoreceptor drum. Regarding a device for detecting a paper jam in a paper conveyance path when conveying toward an image transfer unit, in particular, when there is a preceding paper in the paper conveyance path, the device detects a jam for a subsequent sheet. The present invention relates to a device that enables accurate operation.

(Prior Art) In image forming devices such as copying machines, facsimile machines, printers, etc. that transfer images onto paper according to image information, there is a , feeding the paper from the paper feed section through the paper conveyance path, positioning the paper according to the image information in the image transfer section, and transferring the image according to the set image mode. is made possible.

In an image forming apparatus configured such that a plurality of types of paper of different sizes can be stored in the paper feed section of the image forming apparatus, and the paper can be selected according to image information, for example, as shown in FIG. A paper feeding device as shown may be used. In the conventional paper feeding device shown in FIG. 5, paper storage means 71a such as a plurality of paper trays,
, 71b... are provided, and a paper feeding means 7 such as a paper feed roller provided for these paper storage means.
3a, 73b .

Further, in order to position the leading edge of the paper with respect to the photosensitive drum 10 as an image carrier for transferring an image to the paper, a portion of the paper feed path 60 in front of the photosensitive drum is provided. A registration gate 21 is provided in order to position the leading edge of the paper and align the image formed on the image carrier, and a registration roller device @ 20 i'ii is provided following the gate 21. ! It is location.

In the conventional apparatus described above, when four paper storage means are installed, the paper sent out from the upper two paper storage means is the result of the previous paper passing through the registration sensor 82e. , performs the feeding operation for the next sheet.

Therefore, the jam detection operation in the paper feed path is performed by the registration sensor 82e detecting the jam within a predetermined time after the paper feed roller starts driving, and thereby confirming that the paper is being transported in a normal state. It becomes possible to detect the presence of

Furthermore, when feeding paper from the lower two paper storage means, especially when feeding paper from the bottom paper storage means 71d, the paper feed path 60 is longer than the paper length, so The time required for the paper to pass through the paper feed path 60 is relatively long. Therefore, when using the above-mentioned control method, the interval between sheets is set to be large, so the number of copies made per unit time is smaller than when using the upper sheet storage means.

Therefore, in the paper feed path 60 as described above, a sensor 81e is disposed at the paper ejection portion from the third and fourth tier paper storage means in the paper feed path. When the trailing edge of the paper is detected by 81e, a feed signal for the next paper is output.

Therefore, when paper is fed from the paper storage means of the third and fourth stages, the number of copies per unit time in continuous copying is the same as that of the first and second stages.

In the above-mentioned conventional apparatus, the solenoid off sensor 81e and the sensor 82e provided in the vicinity of the registration gate 21 are used, and the paper being carried out from the paper storage means is detected by both sensors. By detecting whether or not the paper is being transported normally in the paper path, it is possible to control the operation of each device in the main body of the copying machine and the feeding of the paper in the paper feed path.

Furthermore, in the conventional apparatus shown in FIG. 5, the paper is conveyed in a state as shown in the timing chart of FIG. That is, the paper is sent out from the paper storage means, conveyed through the paper feed path 60, and temporarily stopped at the registration gate 21. At this time, the paper is fed a little excessively to form a loop at the leading end.

When the gate 21 is opened, the nip by the registration roller 20 can be performed satisfactorily by the loop at the leading edge of the paper, and the paper reaches the tacking position with respect to the image carrier 10 (the image carrier 10). Even when the image is transferred from σ, it becomes σ.

Furthermore, in the operation of feeding out the second and subsequent sheets of paper, the first sheet of paper is sent out from the upper two tiers of paper storage means, and the trailing edge of the paper is moved to the registration sensor 8.
2e, and for the paper storage means in the lower 1llllJ 2nd stage, after being detected by the feed solenoid off sensor 81e, the paper is carried out from the respective paper storage means and fed at the same speed as the previous sheet. Paper path 6
0, and is similarly transported toward the image transfer section by the image carrier.

(Problems to be Solved by the Invention) In the conventional image forming apparatus as described above, when feeding paper from the upper paper accommodating means among the plurality of paper accommodating means provided in the paper feeding section, , the paper can be transported at a speed corresponding to the maximum paper transport speed of the device.

However, when paper is fed from a paper storage means that is close to the image transfer unit, the paper transport distance is relatively short, so the number of copies that can be made depends on the maximum performance of the image forming device. It will be what you get. However, when feeding paper from a paper storage device located far away from the image transfer unit, the paper transport speed within the paper transport path is constant, so the time required to transport the paper is In response to the detection signal from the sensor installed on the conveyance path, even if the next paper is sent out, the conveyance distance will be longer.
A problem arises in that the number of copies is reduced.

That is, in an image forming apparatus such as a conventional copying machine as described above, when paper is fed from a paper feed tray close to a photoreceptor drum, the maximum capacity of the copying machine is, for example, 35 sheets per sheet. Even if the number of sheets is approximately 32, if the paper is fed from the lowest paper feed tray, the number of sheets will drop to about 32, and the problem is that the maximum capacity of the device cannot be fully utilized. Occur.

When using the image forming apparatus as described above, in order to increase the number of copies per unit time, it is conceivable to increase the process speed and the speeds of the paper conveyance device and the optical system.

However, in devices such as conventional copying machines, increasing the paper conveyance speed and the speed of the optical system requires, for example, not only the drive system such as the conveyance roller device, but also the entire mechanism of the paper conveyance device. In addition to requiring significant changes,
Many problems arise, such as increasing the speed of toner image formation, transfer, and other processes, which cannot be addressed simply by changing the speed of the paper transport device.

In addition, in an apparatus having a reduction/enlargement function, there is a problem in that the scanning speed of the optical system changes depending on the reduction/enlargement ratio. Then, the scanning speed of the optical system changes in accordance with the reduction/enlargement ratio as described above, and when the paper passes the sensor 81e and outputs an activation signal to the optical system, the optical system moves. The time from the start of the process to the time when the registration gate is opened is detected by the optical sensor and changes depending on the magnification ratio.

For example, when performing enlarged copying, the moving speed of the optical system is set to be slow, so the time it takes for the optical system to pass through the optical sensor and open the registration gate is 100% of the normal copying time. The time required for the corresponding paper to pass through the registration gate is delayed.

However, even when copying is performed under the conditions described above,
Since the next sheet is transported at the same speed as the speed at which it is carried out from the sheet storage means, the subsequent sheet may be very close to the previous sheet.

Furthermore, when transporting paper in the paper feed path, detecting the paper at the feeding section and setting the time until the paper is detected by the registration sensor as the reference time for the jam signal. , if the previous paper passes through the registration gate with a delay, the time for the subsequent paper to reach the registration gate will be delayed.
This causes problems such as a jam signal being output and the operation of the device being stopped.

(Objective of the Invention) The present invention solves the drawbacks of conventionally used devices as described above. By using the signal from the registration sensor that is linked to the It is an object of the present invention to provide an apparatus that can increase the number of copies per unit time by allowing the sheets to be conveyed in close proximity to each other.

(Means and effects for solving the problem) A jam detection device in a paper feed path of an image forming apparatus according to the present invention uses a paper feeding means from a paper storage means toward an image transfer section for an image carrier or the like. The paper is configured to be able to send the paper through a paper transport path, temporarily stop the paper at a portion of the paper transport path in front of the image transfer unit, and send out the paper in accordance with the information of the image to be transferred. It is related to the device.

In the apparatus of the present invention, the paper transport path includes a detection means for detecting the discharge of paper from each paper storage means, and a feed solenoid off sensor as a detection means for detecting the paper in the paper transport path. and a registration sensor in front of the image transfer section. Then, the paper detection signals from each of the detection means are input to the control device of the image forming apparatus, and when paper is continuously fed from the same paper storage means, the control device detects the previous paper. A signal that has passed through the registration sensor and is sent to the image transfer unit,
2. The following paper has been detected by the lower feed solenoid off sensor, which is the detection means for detecting the following paper.
A timer for detecting a jam in the paper conveyance path is started using two signals.

In the jam detection device in the paper feed path of the image forming apparatus of the present invention configured as described above, when the paper is moved in the paper feed path, the reference time of the jam signal for the paper is registered. It can be set by ANDing two signals: the signal passed through the gate and the solenoid off sensor. Even if the timing of movement of the previous paper is delayed due to a change in the reduction/enlargement ratio, the movement of the previous paper is delayed from the time the previous paper passes through the registration gate.
A timer will be activated.

Therefore, even if sheets of paper are conveyed closely together in the paper feed path from the paper storage means to the registration gate, the timer does not count the time that the paper is stopped in the paper feed path. Therefore, even if the paper stops in the paper feed path in accordance with the transport status of the preceding paper, it will not be affected by the stop time, etc., and a jam signal will be output if the paper is being transported normally. It becomes something that never happens. Therefore, when performing continuous copying, compared to the conventional method in which the trailing edge of the paper passes the registration sensor and then the next paper is sent out, the apparatus of the present invention requires less time. , after the trailing edge of the paper is detected by a sensor that detects the paper being taken out from the paper storage means,
By adopting the method of sending out the next sheet, it is possible to increase the number of sheets per unit time.

(Example) The configuration of a jam detection device in a paper feed path of an image forming apparatus of the present invention will be described according to an illustrated example.

The embodiment shown in FIG. 1 is applied to a copying machine as an image forming apparatus, and a plurality of paper storage means are provided for the paper feeding device of the copying machine, and a paper tray as the paper storage means is provided. From there, the paper is conveyed through the paper feed path 60 toward the image transfer section of the photoreceptor drum 10.
The toner image formed on the paper is transferred to the paper.

The paper feed path 60 of the copying machine described above is provided with guide plates for regulating both sides of the paper and transport roller devices 65b to 65d, in the same way as the paper transport path in a normal copying machine, and furthermore, the paper feed path 60 of the copying machine is Four paper feed trays 71a for the paper feed tray 60
An ejection path is connected between each of the sections 71d and 71d.

Further, a registration storage fan gate 21 and a registration roller 20 are provided at the upper part of the paper feed path 60, and the paper once stopped by the registration gate 21 is moved so that the leading edge of the paper is connected to the photoreceptor drum 10. The toner image formed on the surface of the photoreceptor drum is transferred by the image transfer portion of the photoreceptor drum.

As will be described later, the paper feed path 60 in the apparatus of the present invention is connected to a transport path 55 from an intermediate tray for double-sided copying and multiple copying.
The single-sided copied paper from the conveyance path 55 is introduced into a paper feed path 60, and the image can be transferred from the photoreceptor drum through the paper feed path.

Paper feed trays 71a to 71d provided in the paper feed section of the present invention
In the present invention, a paper feeding means and a paper handling mechanism are provided at each paper feeding portion, and in the case of the present invention, a paper feeding roller 7
3a to 73d, and retard pads 74a to 74d arranged corresponding to the paper feed rollers.

Then, the paper stored in the paper feed tray is taken out by the roughening roller, and the paper is sorted by the retard pad, and the paper is separated one by one and sent to the paper feed path 6o via the connection path. transport it.

Furthermore, in the paper feed section 70 of the present invention, the upper two paper feed rollers 73a and 73b among the paper feed rollers corresponding to the four paper feed trays and the transport roller device 65b are driven by one motor. The other two paper feed rollers 73C1°73d and the two conveyance roller devices 65c and 65d are set as a group 90 to be driven by separate motors.

Each paper feed row is provided with a driving solenoid, and when the solenoid is energized, it drives the paper feed roller and feeds paper from a predetermined paper feed tray. It is configured as follows.

In the paper feed section 70 of the present invention configured as described above,
Feedout sensors 80a to 80d are provided for each of the delivery paths from the paper feed trays, feed solenoid off sensors 81b to 81d are provided between the paper feed paths and the delivery paths for each paper feed tray, and a registration gate is provided. Registration sensor 82 in part 21
are arranged, and the paper is detected by each of these sensors.

Among the sensors mentioned above, feedout sensor 8
0 indicates that the paper is being fed normally if the paper is detected within a certain period of time after the drive command is output to the paper feed roller when the paper is carried out from the paper feed tray by the paper feed roller. This is to make it possible to detect that an action is being performed.

In addition, a feed solenoid off sensor 8 is provided in the middle of the paper feed path 60 corresponding to each output path.
1, when the sensor detects that the paper is sent from the paper feed tray to the paper feed path, it outputs an OFF signal to the solenoid of the corresponding paper feed roller and stops the drive of the paper feed roller. Then, the paper is set to be transported by the transport roller device in the paper feed path.

Further, the detection signal from the feedout sensor 80 is also used as a drive start signal for the optical system of the main body of the copying machine. That is, in the paper feed section 70 of the present invention, each stage of paper feed trays 71a to
When the paper fed out from the paper 71d is subjected to continuous copying operations, the trailing edge of the previous paper is detected by the feedout sensor 80, and a feedout signal for the next paper is outputted via the control device. also serves as a drive signal for the optical system. In the case of the first tray, the driving of the optical system is started by this signal, whereas in the case of the second to fourth trays, the signal is processed via a timer. is performed, so the paper is controlled so that it is always waiting at the registration gate.

Next, the paper feeding mode of the present invention will be explained based on the timing chart of the operation of each device shown in FIG. 2 and the timing chart showing the state of paper movement shown in FIG. 3.

As shown in the timing chart of FIG. 2, when a copying signal is input to the copying machine, each drive motor in groups 90 and 91 of the conveying device is rotated to drive the conveying rollers 81b to 81d. At the same time, each paper feed roller can be driven.

When information to start copying is input using a button on the control panel, the solenoid for the paper feed roller of the corresponding paper feed tray is turned on, and the drive of that paper feed roller is started. In this example, a case will be described in which, for example, the lowest paper feed tray 71d is used as the paper feed tray that feeds paper.

When feeding paper from the paper feed tray 71d, the solenoid of the paper feed roller 73d of the paper feed tray is turned on, the paper feed roller 73d starts rotating, and the paper in the paper feed tray is separated. Send out one sheet in the same state.

Then, the paper is transferred to the feedout sensor 8 on the output path.
When detected by 0d, it is confirmed that the paper is being fed normally, and the paper is further conveyed toward the paper feed path.

The detection signal from this feedout sensor 80d is
It is output as a control signal for the optical system, and when that signal is input to the control device, a timer for driving the optical device is activated.
After time T1 has elapsed, driving of the optical system is started.

Next, when the leading edge of the paper guided to the paper feed path 60 is detected by the feed solenoid off sensor 81d, the solenoid of the paper feed roller 73d is turned off, the drive of the paper feed row 73d is stopped, and the paper is removed. It will be in a state where it will be transported by the transport roller device.

When the paper conveyed through the paper feed path by the conveyance roller device is detected by the registration sensor 82 provided at the registration gate 21, the sheet is then detected by the drive motor after a slight time delay (TO). to stop.

As described above, when the activation signal for the optical system is input to the control device and the start signal for the optical system is output after time T1 has elapsed, the optical system device starts moving and is detected by the optical sensor 83. When the optical system reaches the registration position, it starts scanning the image of the original, irradiates the photoreceptor drum with light reflected from the original, and forms an electrostatic latent image on the photoreceptor drum; Start forming a toner image.

Then, after a predetermined time (T2) has elapsed after the registration position of the optical system has been detected, the registration gate 21 is opened, the drive motors of the drive system groups 90 and 91 are turned on again, and the paper is conveyed toward the image transfer section of the photoreceptor drum, and the toner image on the photoreceptor drum is transferred to the paper.

The above timing chart in Figure 2 explains the operation of each device and the detection operation of each sensor when feeding the first sheet of paper, but the above explanation is given in relation to the second sheet of paper. The movement of the paper is as shown in the timing chart of FIG.

In the timing chart shown in FIG. 3, when the first sheet of paper is transported as described above, the paper jam detection signal is detected by the feed solenoid off sensor at the leading edge of the paper. The timer starts counting based on the information received, and if the registration sensor does not detect paper within a predetermined time Ta, it will assume that the paper has jammed in the paper feed path and output a jam signal. .

On the other hand, in the case of the second sheet of paper, the trailing edge of the first sheet of paper is detected by the feedout sensor 80d, and when that signal is input to the control device, the paper feed roller 73d is immediately activated. The solenoid is turned on and paper feeding operation begins.

Then, the second sheet of paper is detected by the feedout sensor 8.
0d and is detected by the feed solenoid off sensor 81d, and the paper is further conveyed in the paper feed path 60. During the conveyance, when the first sheet is stopped by the registration gate 21, Since the motor of the drive system is stopped, the second sheet of paper is also stopped at the same time.

Thereafter, when the first sheet of paper is moved toward the image transfer section, the second sheet of paper also starts moving at the same time.

In the apparatus of the present invention, as described above, the information that the second sheet of paper has been detected by the feed solenoid off sensor 81d is first input to the control device;
When the registration gate opens and the first sheet of paper is fed out, that signal is input to the control device, and the two signals are ANDed and a jam detection timer is set for the second sheet of paper. starts operating. Even if the time Ta set in the jam timer has elapsed,
If the second sheet of paper is not detected by the registration sensor, it is assumed that the second sheet of paper has jammed in the paper feed path, and a jam signal is output to the control panel of the copier, etc. Stop operation.

Also, in the explanation of paper conveyance mentioned above, the copying magnification is 10.
This was done for the case of 0%, but when the moving speed of the optical system is slow, such as when the copying magnification is 200%, from the time the optical system starts moving until it is detected by the optical sensor. The time will be delayed compared to the case of 100%.

In such a case, as shown by the dotted line in Figure 3,
Since the timing at which the registration gate is opened is delayed, the time when the registration gate is opened can be set as the reference time for the jam signal for the second sheet of paper.

In the control device of the present invention, when transporting paper in the paper feed path, two signals are sent: one is that the paper is detected by the feed solenoid off sensor, and the other is that the previous paper has passed through the registration gate. Using,
A reference time for a jam signal is set, and a predetermined time Ta is counted as a jam detection time.

Therefore, even if the copying machine is set to a reduction/enlargement ratio, there will be no problem in setting the jam detection time for that paper, and the jam detection timer activation start time for each paper will be set accurately. This can be set as detection information for paper.

Furthermore, when transferring images from the photoreceptor drum as described above, in addition to information on the reduction/enlargement ratio set on the copying machine, information such as the binding margin set on the copy may cause a shift in the timing of paper feeding. This may occur.

However, according to the paper feed timing setting method of the present invention, by providing a binding margin at the leading edge of the copy, even if the paper feed timing is off, the paper can still pass through the registration gate. Based on this information, the timer for jam detection for the next paper will be set, so the binding margin setting will not affect paper jam detection, just like the scaling ratio. .

FIG. 4 shows the configuration of a copying machine to which the jam detection device in the paper feed path of the image forming apparatus of the present invention can be applied. The copy shown in this Figure 4! ! ! 1, an automatic document feeder 5 is provided above the platen 2 so as to automatically feed the document. Then, the original set in the original tray 6 is carried in by the paper feed D-rough,
It is configured to be set at a predetermined position on the platen 2 by means of a conveyor belt 8 and to be compatible with scanning by an image forming apparatus disposed below the platen.

Further, an optical system 3 as an image reading device is movably provided on the upper part of the copying machine main body, and the optical system 3 is connected to a lamp 3a, a lamp 3a, as in a general image fs reading device.
It is composed of a plurality of mirrors 3C... and a lens 3b.

The reflected light from the original obtained by the optical system 3 is
The exposure unit 12 irradiates the photoreceptor drum 10 with light to form an electrostatic latent image on the photoreceptor drum.

Around the photosensitive drum 10 described above, a charging corotron 11 and a developing device 13.1 are installed as in the case of normal copying.
3a, and transfer corotron 14, peeling corotron 1
5, a peeling means 16, a cleaning device 17, etc. are arranged.

After the image of the document is irradiated by the exposure unit 12 to form an electrostatic latent image on the photoreceptor drum, toner is supplied from the developing device to the electrostatic latent image to form a toner image. ,
The toner image is transferred onto the paper by discharge from the transfer rollers 1 to 14. After the toner image is transferred to the paper, the toner remaining on the surface of the photoreceptor drum is cleaned by a cleaning device 17 to make it compatible with the next copying operation.

Further, the paper is sent out from the paper feed section 70 and is passed through the paper feed path 60.
The leading edge of the paper passes through the registration roller 20 in front of the photoreceptor drum, and reaches the image transfer area with the conveyance timing of the leading edge of the paper matching the toner image, where the toner image from the photoreceptor drum is transferred. After the image is transferred, the image is introduced into the fixing device 23 by the conveying device 22, where it is heated and pressurized to form a copy.

In the copying machine 1 of the present invention, a branch claw 31 is provided in the middle of the output path from the copy output portion of the fixing device 23 toward the output tray, etc. In the case of double-sided copying or multiple copying, the branch claw 31 is swung to close the ejection path, and the copy formed as a single-sided copy is introduced into the return path 30, and a reversing device provided in the return path 40 and an intermediate paper feeding section 50 that handles single-sided copied paper.

In the return path 30, conveyance roller devices 32 are provided at predetermined intervals.
is arranged, and is configured to be transported by the transport roller device 32 and to supply the single-sided copied paper to the intermediate tray 51 of the intermediate paper feed section 50 via the discharge section 33.

At the same time, a branch claw 41 is provided in the middle of the return path 30.
A reversing device 40 is connected via the branch portion. This reversing device 40 is composed of upper and lower guide plates and a reversing row 542, and a tray 43 is disposed at the tip of the paper guide portion by the guide plates, so that it can support long sheets. .

The intermediate paper feed section 50 has a mechanism that performs the same function as a conventionally used intermediate tray. Once stored in the tray 51, the single-sided copied sheets are aligned, and then the single-sided copied sheets are fed one by one through a feed roller 53, a paper feeding means 52 composed of a paper handling mechanism, etc. configured to send out.

Then, the single-sided copied paper sent out from the intermediate paper feed section 50 is conveyed toward the paper feed path 60 via the conveyance path 55, and according to the conveyance mode shown in FIG.
The photoreceptor drum 10 is fed into an image transfer section.

In addition, in the above-mentioned conveyance path 55, the paper is transferred to the paper feed path 6.
It is necessary to perform side registration of the paper before handing it over to the paper.

Therefore, the conveyance roller device 5 provided on the conveyance path 55
Reference numeral 6 includes a guide means for setting a reference position, which is provided with a diagonal feed roller, which not only conveys the paper but also moves the paper in an oblique direction and places the paper on the back side of the conveyance path. The paper can be slid into the paper feed path 60 with the paper positioned.

Copy I of the invention shown in FIG. 4 above! ! In 1,
A pair of guide means 61 and 62 on both sides forming the paper feed path 60
is configured so that it can be swung from the paper feeding position. If a jam occurs inside the paper feed path 60, the guide plates on both sides constituting the paper conveyance path should be swung in a combined state; 62 is configured to be able to be opened to a state where they are spaced apart.

Furthermore, as described above, a nip roller is arranged on the outer guide plate 61 constituting the paper feed path 60, and the nip roller is pressed with a predetermined pressure against the drive roller provided on the main body of the paper feed section. Set the paper to be conveyed as follows.

Therefore, when paper or single-sided copied paper jams in the paper feed path, the guide plate is swung according to the state of the jam. In other words, in the case of a jam in the paper feed path from the paper feed tray, by setting and swinging the paper feed path 60,
It becomes possible to take out the paper that has stopped in the section of the carry-out path. Furthermore, if the paper is stopped inside the paper feed path 60, after swinging the paper feed path 60, the inner guide plate 62 can be opened and the stopped paper can be taken out. It will be possible.

Furthermore, in the copying machine 1 of the present invention, the paper feed section 70 has four
In addition to the two paper feed trays, a manual feed tray 78 is provided, and the paper is configured to be fed from the manual feed tray 78 via a roller device 79.

In the copying machine of the present invention configured as described above, when performing multiple copies, a single-sided copy sheet is created in the normal copying mode for the paper taken out from the paper feed tray, and the single-sided copy is The flow paper is introduced into the return path 30 via the branch claw 31, and further introduced into the reversing device V140 via the branch claw 41 in the return channel 30.

In the reversing device @ 40, when the trailing edge of the single-sided copy paper exceeds the position of the branching claw, the driving direction of the reversing roller device 42 is switched, the paper is moved in the direction of returning, and the paper is moved under the branching claw 42. The single-sided copy sheet is guided through the section to the lower part of the return path 30 and is discharged via the discharge section 33 to the intermediate paper feed section 50 with the image side facing upward.

Then, the single-sided copied paper stored in the tray 51 of the intermediate paper feed section is transferred to the conveyance path 5 through the paper feed means 52 of the tray.
5 and is fed to the photosensitive drum 10 via the paper feed path 60.
The image is conveyed to an image transfer unit by the printer, another image is transferred in a state superimposed on the previously formed image, is fixed through the fixing device 23, and is ejected to an ejection tray.

In addition, when making a double-sided copy, the paper made as a single-sided copied paper is transferred from the branch claw 31 to the return path 30.
The paper is conveyed directly to the discharge section 33 through the paper, and is housed in the tray 51 with the image side facing down.

Then, the paper is sent out by the paper feed roller device of the intermediate paper feed section 50, is conveyed to the image transfer section of the photosensitive drum 10 via the conveyance path 55 and the paper feed path 60, and is placed on the back side of the single-sided copy sheet. By transferring the image and passing it through the fixing device 23, a double-sided copy is completed.

Therefore, in the apparatus of the present invention, by connecting the reversing device ff140 and the intermediate paper feed section 50 to the return path, multiple copies and double-sided copies can be arbitrarily performed. As described above, by setting the conveyance state of paper in the paper feed path, it is possible to increase the speed of making copies and improve the performance of the copying machine.

Although the above-described apparatus of the present invention is applied to copying as an image forming apparatus, the jam detection apparatus in the paper feed path of the image forming apparatus of the present invention can be used not only for copying machines but also for other applications. In addition, the present invention can be applied to printer devices such as laser printers, devices such as facsimile machines, and devices in general that print using cut paper.

(Effects of the Invention) Since the jam detection device in the paper feed path of the image forming apparatus of the present invention has the above-described configuration, the paper jam detection device in the paper feed path provided in front of the photoreceptor drum is By providing a method for transporting paper and a means for detecting jams, paper can be transported stably, and no matter which paper storage means is used to feed paper, the maximum number of copies made by the image forming apparatus can be increased. You can demonstrate your abilities.

In addition, in the apparatus of the present invention, the operation start timing of the jam detection timer in J3 in the paper feed path is set when the previous paper passes the registration gate, so it depends on the copying magnification and other conditions. , even if the subsequent paper is delayed, the jam signal will not be detected as long as the subsequent paper is being conveyed normally.
It is possible to prevent unnecessary alarms from being output.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the relationship between the paper feeding unit and the paper conveyance device and the sensor in the paper feeding path of the present invention, FIG. 2 is a timing chart showing the operation of the device of the present invention, and FIG. 3 is the movement of paper. FIG. 4 is an explanatory diagram of a copying machine to which the jam detection device in the paper feeding path of the image forming apparatus of the present invention is applied, and FIG. 5 is an explanatory diagram of a conventional paper feeding device. FIG. 6 is a timing chart showing the conveyance state of paper in the apparatus shown in FIG. Reference numerals in the figure 1... Copy machine, 2... Platen, 5.
... Automatic document feeder, 10 ... Photosensitive drum, 20 ... Registration roller,
21... Registration gate, 23...
... Fixing device, 30 ... Return path, 31 ...
... Branch claw, 40 ... Reversing device, 42 ...
... Reversing roller, 50 ... Intermediate paper feeding section, 5
3... Paper feed roller, 55... Conveyance path,
60... Paper feed path, 61, 62... Guide plate, 65... Conveyance roller device, 70...
...Paper feeding section, 71...Paper storage means, 73...
... Paper feed roller, 80 ... Feed out sensor 81 ... Feed solenoid off sensor, 82 ... Registration sensor,
83... Optical sensor Fig. 2 Fig. 6

Claims (1)

[Scope of Claims] A paper sheet is sent from a paper storage means to an image transfer section for an image carrier or the like via a paper conveyance path using a paper feed means, and a portion of the paper conveyance path in front of the image transfer section In the apparatus configured to temporarily stop a sheet of paper and send out the sheet of paper in accordance with information of an image to be transferred, a detection means for detecting conveyance of the sheet of paper from each sheet storage means to the sheet transport path. , a detection means for detecting paper in the paper transport path, and a registration sensor in front of the image transfer section,
When paper detection signals from each of the detection means are input to the control device of the image forming apparatus, and when paper is continuously fed from the same paper storage means,
The control device uses two signals: a signal indicating that the previous paper has passed through the registration sensor and is sent toward the image transfer unit, and a signal that the following paper has been detected by the detection means. A jam detection device in a paper feed path of an image forming apparatus, characterized in that a timer for detecting a jam in the paper transport path is started to operate.