JPH09244322A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To classify and discharge reusable recording sheets residing on a carrying passage in emergency stop. SOLUTION: A recording sheet management table 5 manages the condition of recording sheets on a carrying passage in accordance with instructions from a host device 6 and signal output a recording sheet sensor 7. To discharge recording sheets residing on the carrying passage in emergency stop, an instruction is given from a restarting switch 8 and, when the sensor 7 at the entrance of a discharge tray shows ON, data are read out of the recording sheet management table 5 about the condition of the recording sheets resulting in the sensor 7 showing ON. A residing recording sheet judgement part 9 determines which tray the recording sheets are discharged to and which way a gate changed to, in accordance with the data. A change control part 13 outputs an instruction to change the gate 14 in accordance with the determination of the residing recording sheet judgement part 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus suitable for efficiently processing a recording sheet remaining in the image forming apparatus when an abnormality occurs.

[0002]

2. Description of the Related Art Conventionally, when an abnormality such as a recording paper jam (hereinafter referred to as a "jam") occurs in an image forming apparatus and the operation is stopped urgently, the recording paper is conveyed on a recording paper conveying path in the image forming apparatus. May remain. In particular, in a large-sized image forming apparatus, the conveying path is long, and images may be continuously formed on a large number of recording sheets, so that a large number of recording sheets may remain on the conveying path.

Usually, when the abnormality of the image forming apparatus is a jam, the operator manually removes the recording paper (hereinafter, referred to as “jam paper”) that causes the jam, and then, when the printing is resumed, the paper is fed to the conveyance path. All remaining recording paper is automatically discharged to the purge tray. The recording paper discharged to the purge tray is regularly discarded, but some of these recording papers have no image printed on them, or some have images printed on only one side. Those that have can be reused.

However, in the purge tray, various types of recording paper are mixed, such as a blank paper on both sides, a blank paper on only one side, and a paper on which both sides have been co-transferred but have not undergone a fixing process. Therefore, it takes a lot of time to select reusable ones from the above and set at least one side of which is blank in the paper feed tray or the recording paper cassette, and therefore these recording papers are actually reused. Without
Often thrown away.

In recent years, from the viewpoint of securing resources, there is an increasing need to reuse these recording papers, and various proposals have been made for that purpose. For example, Japanese Patent Laid-Open No. 1-1228
In the copying machine described in JP-A-55-55 or JP-A-1-122856, the recording paper remaining in the transport path upstream of the transfer section is once taken out to the stock section, and the recording paper taken out to this stock section is taken out. It is provided with a re-passing (conveying) means for returning to the conveying path upstream of the transfer section.

[0006]

The copying machine described in the above publication still has the following problems. That is, in these copying machines, the recording paper returned to the conveyance path by the reconveying means is only double-sided blank paper,
There is a problem that the recording paper used on one side is not reused.

In an apparatus using a fixing device that fuses and fixes toner by using a heating type fixing roller, when unfixed recording paper remains at a position sandwiched by the fixing rollers during an emergency stop, The unfixed toner may stain the fixing roller.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide an image forming apparatus capable of effectively reusing recording paper remaining in the apparatus when the operation is restarted after an emergency stop. To do.

[0009]

SUMMARY OF THE INVENTION To solve the above problems and to achieve the object, the present invention provides a plurality of sensor means arranged on a conveying path for detecting passage of a recording sheet, and outputs of the sensor means. Means for creating a recording paper management table including the current position of the recording paper on the transport path and the print progress status of the recording paper based on the signal, and at the time of restarting after an abnormal stop,
A residual recording paper discriminating means for discriminating a reusable recording paper on the basis of the judgment result by judging the print progress status of the recording paper on the conveyance path with reference to the recording paper management table, and The first feature is that the recording sheet that can be reused and the recording sheet that cannot be reused are sorted and stored according to the progress of printing.

Further, according to the present invention, the sorting and collecting means separately stores the double-sided unprinted recording paper, the single-sided unprinted recording paper, and the double-sided printed recording paper, and the residual recording paper discriminating means. A second feature is that it includes a switching unit that forms a transport path for discharging the recording paper to each of the discharge trays based on the result.

Further, according to the present invention, the sorting / collecting means includes an intermediate tray for accommodating a recording sheet having a blank surface.
A third feature is that a recording paper return path for taking out from the intermediate tray and conveying it to the image transfer device is provided.

According to the first to third features, it is possible to separately collect reusable recording paper remaining in the conveying path and recording paper that is not reused. Especially according to the second feature,
The reusable recording paper can be further classified into two types and discharged according to the usage state of each side of the recording paper. Further, according to the third feature, reusable recording paper can be fed to the image transfer device via the intermediate tray.

Further, according to the present invention, there is provided a means for inputting a cleaning instruction for wiping the toner adhering to the image fixing means for cleaning, and a recording sheet is fed from the intermediate tray to the conveying path according to the cleaning instruction. And a cleaning operation means for passing through the fixing means.
There is a feature. According to the fourth feature, the recording paper discharged to the intermediate tray can be used for removing stains on the fixing unit.

Further, according to the present invention, the sorting prohibition instruction means for inputting an instruction to prohibit the separate collection of the recording paper on the conveying path and the instruction to prohibit the separate collecting are provided, and all the sheets on the conveying path are restarted after the abnormal stop. The fifth characteristic is that the recording sheet of No. 2 is conveyed to a discharge tray for accommodating the recording sheet on which the both sides have been printed. According to the fifth feature, for example, when it is necessary to print using a new recording paper, or when the operator actually wants to perform sorting while manually checking, it is automatically sorted and discharged. Can be banned.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. 2 and 3 are cross-sectional views showing the configuration of the image forming apparatus. In particular, FIG. 2 shows a sheet feeding section, and FIG. 3 shows an image forming section and an ejecting section of the image forming apparatus. Although the paper feed unit and the image forming unit are arranged integrally or adjacently, they are shown in two drawings for convenience of illustration.
In FIG. 2, the paper feed unit 1 includes paper feed trays 10, 11, and 1.
2 is provided, and the recording papers stored in the respective paper feed trays 10 to 12 are sequentially drawn out from the uppermost one to the transport path. Each of the paper feed trays 10 to 12 has pull-out rollers 10a, 11a,
12a and pull-out belts 10b, 11b, 12b are provided, and rollers 1a, 1b, 1c are provided on the conveying path. Further, a recording paper detection sensor (hereinafter, simply referred to as “sensor”) s1 is provided between the pull-out rollers 10a, 11a, 12a and the pull-out belts 10b, 11b, 12b.
s2 and s3 are arranged. The arrow A indicates the conveyance direction of the recording paper.

Further, in FIG. 3, the image forming unit 2 is provided with an image transfer device 20 and a fixing device 21, which transfers the image onto the recording paper fed from the paper feed trays 10 to 12, and then the next stage. The recording paper is discharged to the discharge unit 3 of. The image transfer device 20 is composed of a photoconductor, a transfer roller, and the like, but the configuration is well known, and therefore the diagram is simplified. Fixing device 21
Is configured so that the toner is fused and fixed on the recording paper by a pair of heating rollers. The rollers 2a, 2b, 2c, 2d, 2e, 2f, 2g, and
2h, 2i, 2j, a guide roller set 2k, and sensors s4 to s12 are provided. Inversion gates 22 and 23 are provided between the sensor s7 and the sensor s12,
When printing images on both sides of the recording paper, the reversing gates 22 and 23 are operated to guide the recording paper conveyed from the direction of the fixing device 21 to the roller 2f side, that is, the direction of arrow C.

The discharge section 3 includes discharge trays 30, 31, 3
2, 33, 34 are provided. Among these, the discharge trays 30 and 31 are for receiving the recording paper on which printing is normally performed (hereinafter, referred to as “normal tray”). The discharge tray 32 is a tray that receives recording paper that remains on the conveyance path at the time of an emergency stop and has no images printed on both sides (hereinafter referred to as “double-sided blank paper tray”). The reference numeral 33 is for receiving a recording sheet printed on only one side (hereinafter, referred to as “single side blank sheet tray”). Further, in the discharge tray 34, the recording paper that has been used on both sides and the recording paper that has remained in the conveyance path at the time of an emergency stop in the case where the recording paper that has been used for both sides is not in the mode in which the recording paper is separately discharged depending on whether or not the recording paper has been printed It accepts all of the above (hereinafter referred to as "purge tray").

Rollers 3a and 3b, a conveyor belt 35, and belt wheels 36 and 37 around which the belt 35 is wound are provided on the conveyor path of the discharge section 3. Further, sensors s13 to s19 for detecting the recording paper are provided in the conveyance path, and the sensor s2 is provided at the entrance of the normal trays 30 and 31.
0 and s21 are sensors s at the entrance of the double-sided blank paper tray 32.
22 has a sensor s23 at the entrance of the single-sided blank paper tray 33.
However, sensors s19 are arranged at the inlets of the purge trays 34, respectively.

Further, at the entrances of the normal trays 30 and 31, the double-sided blank sheet tray 32, and the single-sided blank sheet tray 33, there are provided gates that open when receiving the recording sheets in these trays, and these gates have a well-known configuration. However, the illustration is omitted to avoid complication of the drawing.

With the above structure, the recording paper pulled out from any of the paper feed trays 10 to 12 is conveyed to the image forming section 2 in the direction of arrow B, and is conveyed in the following route. First, in the case of single-sided printing, the recording paper is the rollers 2a to 2d.
Is guided to reach the image transfer device 20, and the image is transferred. After the image is transferred, the recording sheet has the image fixed by the fixing device 21, is guided by the rollers 2e, 2j, 3a, 3b and the conveyor belt 35, and is ejected to one of the normal trays 30 and 31. In this case, the recording paper is discharged with the so-called face-down with the printing surface facing downward, but when discharging with the so-called face-up with the printing surface facing upward, the reversing gates 22 and 23 are used. After reversing the recording paper, the recording paper is guided to the conveyance path for discharge. The reversal of the recording paper is performed by first guiding the recording paper to the upper detour C1 in the figure by the reversing gate 22 and then returning it to the original transport path via the detour C2.

In the case of double-sided printing, the recording paper on the surface of which the image has been printed passes through the fixing device 21, is then inverted by the inversion gates 22 and 23, and is guided in the direction of arrow C.
That is, the recording sheet is once guided in the direction of the roller 2j by the reversing gates 22 and 23, and then pulled back again to be guided in the direction C, and the roller 2f, the guide roller set 2k, and the rollers 2g to 2g.
The sheet is fed to the image transfer device 20 via the rollers i, 2c and 2d. After the image is printed on the back side by the image transfer device 20,
As in the case of single-sided printing, the sheet is discharged to either of the normal trays 30 and 31.

The structure of the control unit of the image forming apparatus will be described with reference to the block diagram of FIG. In the figure, bus 4
PIO (parallel interface) 41, CPU4
2, ROM43, RAM44 are connected, the PIO4
An image forming control circuit 45, a conveyance control circuit 46, and a recording paper detection control circuit 47 are connected to the apparatus 1.

In the RAM 44, a recording paper management table for managing the state of the recording paper on the conveyance path is set. FIG.
FIG. 6 is a diagram showing an example of a recording paper management table. The number of lines corresponding to the maximum number of recording sheets is set in the recording sheet management table so that the state of the maximum number of recording sheets that can exist on the conveyance path can be managed. A “recording paper number” is assigned to the recording paper pulled out from the paper supply unit 1. The "recording paper number" is sequentially assigned to the recording papers supplied in a series of print jobs. For example, when an image is printed on 20 sheets of recording paper, the “recording paper number” is “1” to “20”.

In this way, the recording paper existing on the transport path is specified by the recording paper number. “Recording paper position” is information indicating where on the conveyance path the recording paper is located,
The recording paper of the recording paper number is displayed corresponding to the sensor that has passed the latest. That is, when the recording sheet has passed the sensor s1 but has not yet reached the sensor s4, the recording sheet position is "1".

"Size" describes the size of the recording paper recognized by the selected paper feed tray because the size of the recording paper stored in the paper feed trays 10 to 12 is known in advance. The “mode” represents the distinction between the print modes of double-sided printing and single-sided printing. This mode can be determined by an instruction included in the print information supplied from the host device connected to the image forming apparatus. The “surface usage state” is determined by whether or not an image is transferred by the image transfer device 20. Whether or not the image has been transferred is determined by the passage of the sensor s6, and when the sensor s6 passes, the value of the "use state of the surface" is updated. That is, the initial value of the "use state of the surface" is "0", and when the sensor s6 is passed, the initial value "0" is updated with the value "1", and the value "1" indicates that "one side has been used". It is shown that there is. The value of the "face usage state" is updated only when the sensor s6 is passed in the printing state, and is not updated when the recording paper is ejected at the time of restart after the emergency stop.

Next, the recording paper discharge control of the image forming apparatus having the above structure will be described with reference to a flow chart.
In addition, the update of "Recording paper position" of the recording paper management table is
This is performed for all the recording papers on the transport path, but here, for the recording papers that have passed the sensors s16 and s17, which are directly necessary for determining to which discharge tray the recording papers should be ejected when restarting after an emergency stop. Only the separate emission control will be described. The following flowchart is executed at a fixed interrupt timing. The same applies to the flowcharts described below.

The determination of the "on" or "off" state of the sensor is made by observing the change of the "on" or "off" of the sensor.
That is, the “on” or “off” state of each sensor is stored in the memory, and this memory is referred to at the interrupt timing. If the state changes from “off” to “on”, the sensor “on” is detected. To judge.

In FIG. 4, in step S1, it is determined whether or not the sensor s16 is "on". If the sensor s16 is "on", the process proceeds to step S3 to update the recording paper position in the recording paper management table. Specifically, a recording paper number having "15" corresponding to the sensor located immediately upstream of the sensor s16 in the recording paper management table, that is, the sensor s15 as the "recording paper position" is detected, and the recording paper number "recording" is detected. The “paper position” information is updated with “16”. When applied to the example of FIG. 8, the “recording paper position” information of the recording paper number “3” is set to “16”.
Update with.

When there are two or more recording sheet management tables having the same "recording sheet position" information, the recording sheet located on the downstream side, that is, the recording sheet having a large recording sheet number is the object of updating here. To process. That is, there may be two “recording sheet positions” having the same value, one immediately after the recording sheet position is updated and one immediately before the recording sheet position is updated. For example, as a result of executing step S3, in the example of FIG. 8, the recording paper positions of the recording paper numbers “2” and “3” are both “16”.

In step S4, it is determined whether or not the sorting / transporting prohibition mode is set. This is determined according to the instruction previously input by the operator. If the mode is not the separate conveyance prohibition mode, the process advances to step S5 to refer to the recording sheet management table, and the "side usage state" of the recording sheet whose recording sheet position is updated is "0", that is, whether both sides are unused. To judge. If both sides are not used, the process proceeds to step S6 and the gate at the entrance of the both sides blank sheet tray 32 is opened to guide the recording sheet to the both sides blank sheet tray 32. In the example of FIG. 8, since the “face usage state” is “2”, that is, both sides have been used, the determination in step S5 is negative, and step S6 is skipped to proceed to step S2. If the sensor s16 is not "on", the determination in step S1 is negative and the process proceeds to step S2. If the separated conveyance prohibition mode is designated, the process proceeds from step S4 to step S2.

In step S2, it is determined whether or not the sensor s17 is "on". If the sensor s17 is "on", the process proceeds to step S7, and the sensor s17 immediately upstream of the sensor s17 is detected.
The recording paper number having "16" as the "recording paper position" corresponding to 16 is detected, and the "recording paper position" information of the recording paper number is updated with "17". Here, the "recording paper position" is "1.
Since there are two recording paper numbers "6", the recording paper position is updated for the larger recording paper number, as described above.

In step S8, it is determined whether or not the sorting / transportation prohibition mode is set. If the mode is not the separate conveyance prohibition mode, the process proceeds to step S9, and it is determined from the recording sheet management table whether the "use state of one side" of the recording sheet is "1", that is, whether one side has been used. If one side has been used, the process proceeds to step S10 to open the gate at the entrance of the one side blank paper tray 33 to guide the recording paper to the one side blank paper tray 33. If the "face usage state" is not "1", the process of this flowchart is terminated. The same is true when the sensor s18 is not "ON" or when the separated conveyance prohibition mode is designated.

Regarding the recording paper used on both sides,
The determinations in steps S5 and S9 are negative, and the sheet is not guided to either the double-sided blank sheet tray 32 or the single-sided blank sheet tray 33, and consequently is discharged to the purge tray 34.

Next, a second embodiment of the present invention will be described. 5 and 6 are cross-sectional views showing the configuration of the image forming apparatus according to the second embodiment. In particular, FIG. 5 shows a sheet feeding section, and FIG. 6 shows an image forming section and an ejecting section of the image forming apparatus. Indicates. The same reference numerals as those in FIGS. 2 and 3 indicate the same or equivalent portions. Although the paper feed unit and the image forming unit are arranged integrally or adjacently, they are shown in two drawings for convenience of illustration. In FIG. 5, the paper feed unit 1 is provided with a paper feed tray 10, the paper feed tray 10 is provided with a drawing roller 10a and a drawing belt 10b, and rollers 1a, 1 are provided on the conveying path.
b and 1c are provided. Further, a sensor s1 is arranged between the pull-out roller 10a and the pull-out belt 10b. The arrow A indicates the conveyance direction of the recording paper.

Further, in FIG. 6, the image forming section 2 is provided with an image transfer device 20 and a fixing device 21. Rollers 2a, 2b, 2c, 2d, 2e, 2 are provided in the recording paper conveyance path.
f, 2g, 2h, 2i, 2j, 2m, 2p, 2q, 2r
And guide roller set 2k, and sensors s3 to s17
Is provided. An inversion gate 24 is provided between the sensor s6 and the sensor s10, and the inversion gate 24 is provided between the sensor s15 and the sensor s10.
Inversion gates 25 and 26 are provided between the gates 16 and 16. By switching the reversing gate 24, the recording paper conveyed from the direction of the fixing device 21 is once guided to the detour C2 and then in the direction of arrow C.

An intermediate tray 330 is provided next to the roller 2q, and recording paper whose one or both sides are unused is discharged to the intermediate tray 330. The reusable recording paper accumulated in the intermediate tray 330 is pulled out by the belt device 2n and conveyed to the image transfer device 20. Further, at the time of double-sided printing, the reversing gate 26 is switched so as to guide the recording paper passing through the guide roller set 2k to the roller 2h side. The recording paper guided to the roller 2h side by the switching of the reversing gate 26 is conveyed to the image transfer device 20 and printed on the back surface.

The reversing gate 25 guides the recording sheet guided by the roller 2p to the detour C3 and then to the roller 2m side via the detour C4. The reversing gate 26 is also used to guide the recording paper conveyed through the roller 2m to the intermediate tray 330.

The discharge section 3 is provided with discharge trays 30 and 34. Among these, the discharge tray 30 is a normal tray that receives a recording sheet on which printing is normally performed. The discharge tray 34 remains in the transport path at the time of an emergency stop when it is not in the mode of discharging the recording paper left on the transport path at the time of the emergency stop by using both-sided used recording paper and whether the recording paper is printed or not. It is a purge tray that accepts all the recording paper that was used.

Rollers 3a, 3b,
3c and 3d, a conveyor belt 35, and belt wheels 36 and 37 around which the belt 35 is wound are provided. Further, sensors s11 to s14 for detecting the recording paper are provided in the transport path, and the sensor s1 is provided at the entrance of the normal tray 30.
8 is provided with a sensor s19 at the inlet of the purge tray 34.

Further, the normal tray 30 and the purge tray 34 are provided at the entrances thereof with gates that open when receiving recording paper in these trays, but these gates have a well-known structure and are shown in order to avoid complication of the drawing. Is omitted.

With the above structure, the recording paper pulled out from the paper feed tray 10 is conveyed in the direction of arrow B and is conveyed in the following route. First, in the case of single-sided printing, the recording paper is guided by the rollers 2a to 2d to reach the image transfer device 20, and the image is transferred. The image on the recording sheet after the image is transferred is fixed by the fixing device 21, and the rollers 2e, 2j,
The sheet is guided by the conveying belts 3a and 3b and is conveyed to the normal tray 30.

In the case of double-sided printing, the recording paper having the image printed on the front surface passes through the fixing device 21, is inverted by the inversion gate 24 and is once guided to the detour C2, and then in the direction of arrow C. Will be guided to. After that, the recording paper is roller 2
f, guide roller set 2k, rollers 2h, 2r, 2c, 2d
After that, the image is transferred to the image transfer device 20. Image transfer device 2
After the image is printed on the back side with 0, it is discharged onto the normal tray 30 as in the case of single-sided printing.

Further, at the time of restarting after an emergency stop, the recording paper used on both sides is discharged to the purge tray, but the recording paper whose one side or both sides are unused is collected on the intermediate tray 330. Also in the second embodiment, the state of the recording paper on the transport path is managed by the recording paper management table.

Next, recording paper discharge control of the image forming apparatus according to the second embodiment will be described. When restarting after an emergency stop, the recording paper is not on the conveyance path after the sensor s13. This is because the recording paper is discharged to the normal tray 30 in the normal printing operation. Further, the recording paper immediately after passing the sensor s7 or s8 has been printed on only one side in the double-sided printing mode, and even if the recording paper is not inverted as it is, the intermediate tray 33 is in a face-up state.
It can be discharged to 0. Therefore, when restarting after an emergency stop, first, the reversing gate 26 is switched to discharge the recording paper at the recording paper position “7” or “8” to the intermediate tray 330.

When the recording paper other than the recording paper position "7" or "8" is conveyed, the reversing gate 24 is switched to the default state, that is, to guide the recording paper in the D direction. Then, the conveying path is selected so that the recording paper passes through the sensors s14 and s15 and the reversing gate 25, is guided by the reversing gate 26 in the direction of the roller 2g, and is discharged to the intermediate tray 330. However, the used recording paper on both sides is discharged to the purge tray 34, and the used recording paper on one side in the one-sided printing mode is reversed by the reversing gate 25 via the detours C3 and C4 and then discharged to the intermediate tray 330. Let Further, since the recording paper on which one side is printed and the recording paper which is not used on both sides in the double-sided printing mode can be guided to the intermediate tray 330 in a face-up state without being reversed, the reversing gate 25 for passing the detours C3 and C4 is provided. Do not switch.

Recording paper conveyance control after an emergency stop will be described with reference to a flowchart. First, a case will be described with reference to FIG. 9 in which the operation of whether or not to discharge the recording paper to the purge tray 34 is controlled by the state of the sensor s13. In the figure, in step S20, the sensor s13 is "on".
If the sensor s13 is "on", the process proceeds to step S21, and the sensor s13 of the recording paper management table is determined.
The recording paper number having "12" as the "recording paper position" corresponding to the sensor s12 located upstream of is detected, and the "recording paper position" information of the recording paper number is updated to "13". The process when there are two or more records having the same value in the “recording paper position” information in the recording paper management table is the same as in the first embodiment.

In step S22, it is determined whether or not the sorting / transportation prohibition mode is set. If the mode is not the separate conveyance prohibition mode, the process proceeds to step S23, and it is determined from the recording sheet management table whether the "use state of side" of the recording sheet is "2", that is, whether both sides have been used. If both sides have been used, the process proceeds to step S24 and the gate at the inlet of the purge tray 34 is opened.

Further, in the case of the separated conveyance prohibition mode, all the recording paper remaining in the conveyance path at the time of the emergency stop is discharged to the purge tray 34 regardless of the "state of use of the surface". Therefore, the processing proceeds to step S24. 34 Open the gate at the entrance. If both sides of the recording paper have not been printed, the determination in step S23 is negative, and in this case, the recording paper is conveyed to the intermediate tray 330, so the purge tray 34
This flow chart is exited without opening the entrance gate.

Next, the processing for the operation of the inverting gate 25 will be described with reference to the flowchart. Inversion gate 25
Then, when guiding the recording paper conveyed from the discharge unit 3 to the intermediate tray 330 for reuse, the reversing operation is performed so that the recording paper is discharged face-up to the intermediate tray 330.

In FIG. 10, in step S30, it is determined whether or not the sensor s15 is "on". If the sensor s15 is "on", the process proceeds to step S31. The step S3
In No. 1, the recording paper number having "14" corresponding to the sensor s14 located upstream of the sensor s15 in the recording paper management table as the "recording paper position" is detected, and the "recording paper position" information of the recording paper number is detected. Update with "15".

In step S32, it is determined whether the "side usage state" of the recording sheet whose "recording sheet position" is "15" has been used on one side. If not used on one side,
Since it is determined that the recording paper is not used on both sides, the reversing gate 25 ends the processing of this flowchart without switching.

If it is determined that the one side has been used from the "side usage state", the process proceeds to step S33, and it is determined whether the two-sided printing mode is set. In the double-sided printing mode, the recording paper is stored in the sensors s16, s17,
Since the sheet remains on the conveyance path in which s3, s4, s5, and s6 are arranged, and it is not necessary to reverse the sheet for face-up discharge, the reversing gate 25 is similar to the recording sheet that is not used on both sides. The process of this flowchart is completed without switching.

On the other hand, when it is determined in step S33 that the mode is not the double-sided printing mode, the recording sheet remains on the conveyance path where the sensors s5, s6, s10, s11, and s12 are arranged at the time of emergency stop. Since it is necessary to reverse the sheet for face-up discharge, step S
In step 34, the reversing gate 25 is switched, and the recording paper is passed through the detours C3 and C4.

As described above, in the second embodiment, at the time of emergency stop, among the recording papers remaining on the conveyance path, at least one unused recording paper is ejected to the intermediate tray 330 for reuse. It was done. The recording paper accumulated in the intermediate tray 330 can be pulled out by the roller 2n and used when printing in the single-sided printing mode is instructed.

The recording paper accumulated in the intermediate tray 330 can be used not only for printing but also effectively as follows. For example, the fixing roller 21 may be contaminated with unfixed toner as described above. The dirt on the fixing roller 21 can be cleaned by passing the recording paper without energizing the image transfer device 20. Therefore, as the recording paper used for this cleaning, the intermediate tray 33 is used.
The recording paper accumulated in 0 can be used.

Specifically, an input unit for instructing cleaning of the fixing roller 21 is provided, and when an instruction is input from this input unit, the image transfer device 20 is not energized and the intermediate tray 330 is operated. Pull out the recording paper. Then, the recording paper is passed between the fixing rollers 21 to clean the fixing rollers 21.

If the recording paper remains sandwiched by the fixing roller 21 at the time of an emergency stop, the fixing roller 21 may be soiled by the unfixed recording paper at the time of restart, but otherwise. Then, the fixing roller 21 is not soiled. Therefore, depending on the position of the recording paper during an emergency stop,
It may be possible to automatically determine whether or not to clean the fixing roller 21, and to feed the recording paper from the intermediate tray 330 depending on the result.

Next, the main function of the control device for performing the above operation will be described. In the block diagram of FIG.
Registration contents are set and updated in the recording paper management table 5 based on an instruction from a higher-level device 6 such as a host computer and output signals of a plurality of sensors 7 that detect passage of recording paper. The restart switch 8 is a switch for discharging the recording paper remaining on the conveyance path after the emergency stop. A command is given from the restart switch 8, and
The sensor that is arranged corresponding to the discharge tray for separate collection and the sensor 7 that is provided immediately before the gate are “ON”.
Then, data is read from the recording paper management table 5 regarding the state of the recording paper with the sensor 7 turned “on”. Based on this data, the residual recording paper discriminating unit 9 determines to which tray the recording paper is to be discharged, and how to switch the gate for that purpose. The algorithm for switching the gate is as described with reference to the flow charts in FIGS.

When the switching of the gate is determined, the switching control unit 13 outputs a switching command to the gate 14. The gate 14 is a gate provided at the entrance of the discharge trays 32 and 33 and the purge tray 34 for separating and collecting the recording paper, or a reversal provided at a midway of the conveying path for guiding the recording paper to the intermediate tray 330. It is a gate. When an instruction is input from the sorting / conveyance prohibition instructing section 15, the switching control section 13 causes all of the recording paper to be removed from the purge tray 34.
The gate 14 is switched so that it is discharged to.

[0060]

As is apparent from the above description, according to the inventions of claims 1 to 5, it is possible to separate and collect reusable recording paper remaining in the conveyance path and recording paper that is not reused. it can. Particularly, according to the second aspect of the present invention, the reusable recording paper can be further classified into two types and discharged according to the usage state of each side of the recording paper. further,
According to the third aspect of the invention, the reusable recording paper can be fed to the image transfer device through the intermediate tray, so that the reusable recording paper can be easily reused.

Further, according to the invention of claim 4, the recording paper discharged to the intermediate tray can be used for removing stains on the fixing means, so that it is possible to prevent wasteful use of new recording paper.

According to the invention of claim 5, for example,
It is possible to prevent the chart paper from being automatically sorted when it is necessary to print using a new chart paper, or when the operator actually wants to perform sorting while checking manually, making it possible to perform various printing tasks. Is also easy to handle.

[Brief description of drawings]

FIG. 1 is a block diagram showing functions of a control device of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a paper feeding unit of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a configuration of an image forming unit and a discharge unit of the image forming apparatus according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a discharge tray selection process according to the first embodiment.

FIG. 5 is a cross-sectional view showing a configuration of a paper feeding unit of an image forming apparatus according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a configuration of an image forming unit and a discharging unit of an image forming apparatus according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a hardware configuration of a control device.

FIG. 8 is a diagram showing an example of a recording paper management table.

FIG. 9 is a flowchart showing a discharge tray selection process according to the second embodiment.

FIG. 10 is a flowchart showing an intermediate tray selection process according to the second embodiment.

[Explanation of symbols]

1 ... Paper feeding unit, 2 ... Image forming unit, 3 ... Ejecting unit, 6 ...
Host device, 7 ... Sensor, 8 ... Restart switch, 9
... remaining recording paper discriminating unit, 13 ... switching control unit, 14 ... gate, 15 ... sorting conveyance prohibition instruction unit

Claims (5)

[Claims] 1. An image transfer device provided in the middle of the conveyance path for printing an image on the recording paper, which has a conveyance path for guiding the recording paper pulled out from a paper feeding device to a device for ejecting the recording paper. In the image forming apparatus, a plurality of sensor means arranged on the conveyance path for detecting passage of the recording paper, and a current position of the recording paper on the conveyance path and a print progress of the recording paper based on an output signal of the sensor means. A means for creating a recording paper management table including the status, and upon restarting after an abnormal stop, refer to the recording paper management table to determine the print progress status of the recording paper on the conveyance path,
Remaining recording paper discriminating means for discriminating reusable recording papers based on the judgment result, and sorting for storing reusable recording papers and non-reusable recording papers separately according to the print progress status of both sides of the recording papers An image forming apparatus comprising: a collecting unit. 2. The separation collection means, based on the judgment result of the residual recording paper discriminating means, a discharge tray for separately storing the double-sided unprinted recording paper, the single-sided unprinted recording paper, and the double-sided printed recording paper, respectively. The image forming apparatus according to claim 1, further comprising a switching unit that forms a conveyance path for discharging the recording paper to each of the discharge trays. 3. The separating / collecting means includes an intermediate tray for accommodating recording paper having a blank surface left, and a recording paper returning path for taking out from the intermediate tray and conveying it to the image transfer device. The image forming apparatus according to claim 1. 4. A means for inputting a cleaning instruction to wipe and clean the toner adhering to the image fixing means, and a recording sheet is fed from the intermediate tray to a conveyance path according to the cleaning instruction to fix the recording sheet. The image forming apparatus according to claim 3, further comprising a cleaning operation unit that allows the image forming unit to pass through the unit. 5. A separation prohibition instruction means for inputting an instruction to prohibit the separate collection of the recording paper on the conveyance path, and all recording papers on the conveyance path at the time of restart after an abnormal stop according to the instruction to prohibit the separate collection. 3. The image forming apparatus according to claim 2, further comprising: a unit configured to convey the sheet to a discharge tray that stores the double-sided printed recording sheet.