JP2001166638A - Method and device for forming image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evade the collision of transfer paper without adjusting the paper interval and changing one part of transfer paper carrying timing even if a paper supply defect is caused at the time when an image is formed on both surfaces of the transfer paper while retaining the plural sheets of transfer paper in a machine. SOLUTION: This image forming device is constituted so that the image is formed on both surfaces of the transfer paper while retaining the plural sheets of transfer paper supplied from a paper supply part 30 in the machine. Then, it is provided with an image forming means 50 forming image, a carrying means feeding the transfer paper from the paper supply part to the image forming means and carrying the transfer paper having the image formed on both surfaces, a paper supply sensor detecting whether the transfer paper is supplied from the paper supply part or not and a control means executing the feeding and carrying control of the transfer paper and the image forming control. The control means 110 and 120 execute such control that the image is formed without changing the feeding and carrying timing of the other transfer paper and the image forming timing by stopping the feeding of the transfer paper where a feeding defect is caused when it is detected by the paper supply sensor 191 that the feeding defect of the transfer paper is caused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and an image forming apparatus, and more particularly, to an image forming method for forming an image on both sides of a transfer sheet while retaining a plurality of transfer sheets fed from a sheet feeding section in the apparatus. The present invention relates to a method and an image forming apparatus.

[0002]

2. Description of the Related Art An original is read by an optical system, image data obtained by reading the original is transferred to a recording medium by an electrophotographic method to form an image, and the image-formed recording medium is fixed and discharged to the outside of the apparatus. A forming device is present.

In such an image forming apparatus,
There is also an image forming apparatus capable of forming an image on both sides of a transfer sheet while retaining a plurality of transfer sheets fed from a sheet feeding unit in the apparatus.

[0004]

However, in order to improve the productivity of image formation (the number of output sheets per unit time), the interval between transfer papers (paper interval) in the apparatus has been reduced.

[0005] In this state, if the paper feed from the paper feed unit does not go well and the feed becomes no feed, the paper feed retry is executed as a matter of course. If there is a transfer sheet whose paper feed timing is delayed due to the retry, an image is formed on the first side of the transfer sheet with the delay, and an image is formed on the second side of the transfer sheet with no delay before that. There is a possibility that a collision will occur in terms of timing.

FIG. 8 is a time chart schematically showing the image forming timing of an image forming apparatus capable of forming an image on both sides of a transfer sheet while retaining three transfer sheets fed from a sheet feeding section in the apparatus. It is a chart.

Here,,... Mean the first, second, third and fourth transfer sheets, respectively.
Also, (2), (4), (6), (1), (5),
(3) and (8) are the image formation of the second page of the original, the image formation of the fourth page of the original, the image formation of the sixth page of the original, the image formation of the first page of the original, the image formation of the third page of the original, and the original, respectively. This means image formation on the fifth page and image formation on the eighth page of the document. By performing image formation in this order, image formation on both sides in the original order of 1-2, 3-4, and 5-6 on the first transfer sheet is completed. Here, FIG. 8A shows a normal timing.

Here, the first transfer paper (FIG. 8B)
When the second transfer paper (FIG. 8B) is fed from the paper feeding unit after the paper is fed from the paper feeding unit at the normal timing, a paper feeding failure (no feed: NF) occurs. A retry is performed on the second transfer sheet. This allows
A slight timing delay occurs. Due to this delay,
After the second transfer paper (FIG. 8B), the third transfer paper (FIG. 8B) also has a delay in feeding (see FIGS. 8A and 8B). Comparison).

In this case, the first transfer sheet (FIG. 8 (b) (1)), which has been fed and conveyed at normal timing and has already formed an image on one side, is conveyed reversely.
It is conveyed to the image forming unit for image formation on the other surface.

At this time, the image formation of the third transfer sheet which is delayed (FIGS. 8 (b) and (6)) and the image of the opposite side of the first transfer sheet which is reversely conveyed at normal timing. Timing (FIG. 8B, (1)) causes a timing collision.

Note that such a collision does not occur in single-sided image formation, but is a problem that occurs when productivity is emphasized in double-sided image formation. In order to eliminate such a collision, a margin is provided by widening the paper interval in advance, or the transfer paper ((1) in FIG. 8) when a collision is likely to occur is temporarily stopped (conveyance timing). It is conceivable to provide a mechanism for causing a partial change).

However, if the sheet interval is widened, productivity is undesirably reduced. On the other hand, if a mechanism is provided to stop the transfer paper when a collision is likely to occur,
Sensors for detecting the state, a clutch mechanism for interrupting the drive transmission system, a dedicated control program, and the like are required, which is not preferable because the apparatus becomes expensive and operation reliability may be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and when a plurality of transfer papers are stored in a machine and images are formed on both sides of the transfer papers, even if a paper feeding failure occurs, An object of the present invention is to provide an image forming method and an image forming apparatus capable of avoiding collision of transfer paper without requiring adjustment between paper sheets or partial change of transfer paper conveyance timing.

[0014]

That is, the present invention for solving the above-mentioned problems is as follows. (1) The invention according to claim 1 is an image forming method for forming an image on both sides of a transfer paper while retaining a plurality of transfer papers fed from a paper supply unit inside the apparatus, wherein the transfer paper is supplied from the paper supply unit. If a feeding failure occurs during feeding, stop feeding the transfer paper where the feeding failure has occurred, and execute image formation without changing the timing of feeding and transporting other transfer paper. And an image forming method.

According to a sixth aspect of the present invention, there is provided an image forming apparatus for forming an image on both sides of a transfer sheet while retaining a plurality of transfer sheets fed from a sheet feeding section in the apparatus. Forming means, conveying means for feeding the transfer paper from the paper feeding section to the image forming means, and conveying the image formation on both sides, and paper feeding for detecting the presence or absence of the transfer paper from the paper feeding section And a control unit for controlling the feeding and conveyance and controlling the image formation, wherein the control unit detects a feeding failure of the transfer paper by the paper feeding sensor and detects a feeding failure. Stopping the feeding of the transfer sheet in which the feeding failure has occurred, and performing control to execute image formation without changing the timing of feeding and transporting other transfer sheets and image forming.
An image forming apparatus characterized in that:

In these inventions, images are formed on both sides of the transfer paper while the plurality of transfer papers fed from the paper feed unit are retained in the apparatus, and the transfer paper is fed when the transfer paper is fed from the paper feed unit. When a defect occurs, the feeding of the transfer sheet having the feeding defect is stopped, and the image forming is controlled without changing the timing of feeding and conveying the other transfer sheet. .

For this reason, even if a paper feeding failure occurs,
It is possible to avoid the collision of the transfer paper without the necessity of adjusting the paper interval or partially changing the transfer paper transport timing. (2) The invention according to claim 2 is an image forming method for forming an image on both sides of a transfer sheet while n sheets of transfer paper fed from a sheet feeding unit are retained in the apparatus, and If a feeding failure occurs when any one of the transfer papers is fed from the paper feeding unit, the feeding of the transfer paper in which the feeding failure has occurred is stopped, and the feeding and feeding of another transfer paper are stopped. An image forming method is characterized in that image formation is performed without changing the transport timing.

According to a seventh aspect of the present invention, there is provided an image forming apparatus for forming an image on both sides of a transfer sheet while retaining n transfer sheets fed from a sheet feeding section in the apparatus. An image forming means, a transfer means for feeding the transfer paper from the paper feeding unit to the image forming means, and a transfer for carrying out the image formation on both sides; A paper sensor; and control means for controlling the feeding and transport and controlling image formation. The control means feeds any one of the second to n-th transfer papers by the paper feed sensor. When it is detected that a feeding failure has occurred when feeding from the paper section, the feeding of the transfer paper in which the feeding failure has occurred is stopped, and the timing of feeding, transporting, and forming an image of another transfer paper is stopped. Control to execute image formation without changing
An image forming apparatus characterized in that:

According to these inventions, n supplied from the paper supply unit
If an image is formed on both sides of the transfer paper while the transfer paper stays in the machine, and a feeding failure occurs when the second and subsequent transfer papers are fed from the paper feeding unit, the feeding failure is caused. In addition to stopping the feeding of the generated transfer paper, the control is performed so that the image formation is performed without changing the timing of feeding and transporting the other transfer paper.

For this reason, even if a paper feeding failure occurs,
It is possible to avoid the collision of the transfer paper without the necessity of adjusting the paper interval or partially changing the transfer paper transport timing. (3) The invention according to claim 3 is an image forming method for forming an image on both sides of a transfer paper while retaining a plurality of transfer papers fed from a paper supply unit inside the machine, wherein the transfer paper is supplied from the paper supply unit. If a feeding error occurs during feeding, the feeding of the transfer sheet with the feeding error is retried, and the feeding of the next transfer sheet after the retried transfer sheet is stopped. An image forming method, wherein the image forming is performed without changing the timing of feeding and conveying the transfer paper.

According to a further aspect of the present invention, there is provided an image forming apparatus for forming an image on both sides of a transfer sheet while retaining a plurality of transfer sheets fed from a sheet feeding section in the apparatus. Forming means, conveying means for feeding the transfer paper from the paper feeding section to the image forming means, and conveying the image formation on both sides, and paper feeding for detecting the presence or absence of the transfer paper from the paper feeding section And a control unit for controlling the feeding and conveyance and controlling the image formation, wherein the control unit detects a feeding failure of the transfer paper by the paper feeding sensor and detects a feeding failure. Retry feeding the transfer paper in which the feeding failure has occurred, stop feeding the next transfer paper after the retried transfer paper, and change the timing of feeding and transporting another transfer paper and forming an image. Control to execute image formation without using An image forming apparatus.

According to these inventions, images are formed on both sides of the transfer paper while the plurality of transfer papers fed from the paper feeding section are kept inside the machine, and the transfer paper is fed when the transfer paper is fed from the paper feeding section. If a failure occurs, retry feeding of the transfer paper in which the feeding failure occurred, stop feeding the next transfer paper after the retried transfer paper, and stop feeding and transporting other transfer paper. Control is performed so as to execute image formation without changing the timing.

For this reason, even if a paper feeding failure occurs,
It is possible to avoid the collision of the transfer paper without the necessity of adjusting the paper interval or partially changing the transfer paper transport timing. (4) The invention according to claim 4 is an image forming method for forming an image on both sides of a transfer sheet while retaining n sheets of transfer paper fed from a sheet feeding section in the apparatus, wherein the n-th and prior sheets are provided. If a feeding failure occurs when any one of the transfer papers is fed from the paper feeding unit, the transfer of the transfer paper in which the feeding failure occurred is retried and the next transfer of the retried transfer paper is retried. The image forming method is characterized in that the sheet feeding is stopped and the image forming is executed without changing the timing of feeding and conveying another transfer sheet.

According to a ninth aspect of the present invention, there is provided an image forming apparatus for forming an image on both sides of a transfer sheet while retaining n sheets of transfer paper fed from a sheet feeding section in the apparatus. An image forming means, a transfer means for feeding the transfer paper from the paper feeding unit to the image forming means, and a transfer for carrying out the image formation on both sides; A paper sensor; and control means for controlling the feeding and conveyance and controlling image formation, wherein the control means feeds any one of the (n-1) th or earlier transfer paper by the paper feed sensor. If it is detected that a feeding failure has occurred during feeding from the unit, the feeding of the transfer paper with the feeding failure is retried and the feeding of the next transfer paper after the retried transfer paper is stopped. Change the timing of feeding and transporting other transfer paper and image formation. Performing control to execute an image formation,
An image forming apparatus characterized in that:

In these inventions, n supplied from the paper supply unit
When images are formed on both sides of the transfer paper while the transfer papers are stagnated in the machine, and a feeding failure occurs when the transfer paper of the (n-1) th or earlier is fed from the paper feeding unit, the feeding is performed. Retrying the feeding of the defective transfer paper, stopping the feeding of the next transfer paper after the retried transfer paper, and forming an image without changing the timing of feeding and transporting the other transfer paper Is controlled to execute.

For this reason, even if a paper feeding failure occurs,
It is possible to avoid the collision of the transfer paper without the necessity of adjusting the paper interval or partially changing the transfer paper transport timing. (5) The invention according to claim 5, wherein the image forming order is rearranged in accordance with the stoppage of the feeding of the defective transfer paper. It is an image forming method as described above.

According to a tenth aspect of the present invention, the control means reassigns the image forming order in accordance with the stoppage of the feeding of the defective transfer paper.
Alternatively, an image forming apparatus according to claim 5.

In these inventions, the image forming order is reallocated in accordance with the stoppage of the feeding of the defective transfer paper and the change of the conveyance timing of the remaining transfer paper (change processing of the staying arrangement). Therefore, even if a paper feed failure occurs,
It is possible to avoid the collision of the transfer paper without the necessity of adjusting the paper interval or partially changing the transfer paper transport timing.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, an outline of the image forming apparatus will be described with reference to FIGS.

FIG. 1 is a block diagram showing an example of an electrical configuration of an image forming apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 100 denotes an overall control board for controlling the entire apparatus including image processing control.
U110 is provided. Also, the overall control board 100
Denotes a CCD 120 for reading a document, and an index sensor 1 for detecting a reference position of a laser beam for image formation.
30, control of a laser diode 140 for forming a latent image on the photosensitive drum, an operation unit 150 for receiving an operation input from a user, and an image memory 160 for processing and expanding the read image data. It is carried out.

An engine driving board 200 controls the driving of the image forming engine, and includes a CPU 210 as control means. The engine drive board 200 includes a main motor 220 for transporting the photosensitive drum and the transfer paper, a paper feed motor 230 for feeding the transfer paper from the paper supply cassette, and a transfer paper re-feeding unit for double-sided image formation ( A
ADU motor 240 for driving the DU) to reversely transfer the transfer paper, a solenoid clutch 250 for transmitting or interrupting the driving force, various sensors 260 for detecting the state of each part, and a high voltage generation for generating a high voltage for charging. Part 27
0, a polygon motor 280 for scanning a laser beam for image formation, a fan 290 for exhausting heat from the apparatus
Is being controlled.

FIG. 2 is a configuration diagram showing a sectional configuration of the image forming apparatus used in the embodiment of the present invention. 2, the light source 23 irradiates the original surface of the original, and the reflected light forms an image on a light receiving surface of a CCD 28 serving as a photoelectric conversion unit via mirrors 24, 25, and 26 and an imaging optical system 27.
Here, the light source 23, mirrors 24, 25, 26, an optical system having an imaging optical system 27 and a CCD 28, and an optical system driving unit (not shown) constitute an image reading unit 20.

Then, the read image data of the document is sent from the CCD 28 to the overall control board 100. The image data read by the image reading unit 20 in this manner is subjected to predetermined image processing by the overall control board 100 and stored in the image memory 160.

On the other hand, the transfer paper p is sent out from the paper feed cassette 30a or 30b on which the transfer paper is loaded by the paper feed rollers 231a or 231b, and is conveyed to the image forming section 50. The feed sensor 261a or 261b detects whether or not a feed failure has occurred.
This detection result is transmitted to the engine drive board 200.

The transfer paper p conveyed to the image forming unit 50 is
The sheet is conveyed to the surface of the photosensitive drum 51 serving as an image carrier, with the timing synchronized by a registration roller or the like. Image data is input from the overall control board 100 to the image writing unit 40, and the laser diode 140 in the image writing unit 40
Then, a laser beam corresponding to the image data is irradiated onto the photosensitive drum 51 to form an electrostatic latent image. The electrostatic latent image is developed by the developing unit 53 to form a visible toner image on the photosensitive drum 51.

This toner image is transferred to the transfer paper p by the transfer section 54 on the side of the photosensitive drum 51. Then, the transfer paper p in contact with the photosensitive drum 51 is separated by the separation unit 55. Transfer paper p separated from photoconductor drum 51
Enters the fixing section 59, and the toner image is fixed by heat and pressure. Thus, an image is formed on one surface of the transfer paper p.

When it is necessary to re-feed the sheet in reverse when forming a double-sided image, the transfer sheet p on which the toner image is fixed is
The sheet is conveyed rightward via the guide 61 and enters the reversing section 63. Next, the transfer paper p that has entered the reversing unit 63 is reversed and sent out by the reversing conveyance roller 66 via the reversing conveyance path 64, and is sent to the image forming unit 50 again.

As described above, in the image forming section 50 where the image formation on one side of the document has been completed, the toner remaining on the photosensitive drum 51 is removed by the cleaning section 56, and
It is ready for the next image formation.

In this state, the other surface of the transfer paper p (the surface on which no image has been formed) is carried into the image forming section 50 and an image is formed. The transfer paper p separated from the photosensitive drum 51 by the separation unit 55 is again transferred to the fixing unit 5 via the transport mechanism 58.
Enter 9 and be fixed. In this way, the transfer paper p on which the image formation on the back surface and the front surface has been completed, or the transfer paper p on which the image formation on one surface has been completed, is externally driven by the left discharge roller 66 via the guide 61. Is discharged.

FIG. 4 shows a state in which the image formation on one side of the original transfer paper is completed, and an image is formed on one side of the original transfer paper. FIG. 5 shows a state in which image formation on both sides of the transfer paper has been completed, and an image has been formed on the second side of the transfer paper.

[First Embodiment] The specific operation of this embodiment will be described below. In this embodiment, a method and an apparatus for forming images on both sides of a transfer sheet while n sheets of transfer paper fed from a sheet cassette are retained in the apparatus will be described as an example. Note that, here, the description will be made assuming that n = 3 (see FIG. 4), but n is not limited to 3.

FIG. 3 is a timing diagram schematically showing image forming timing of an image forming apparatus capable of forming an image on both sides of a transfer sheet while retaining three transfer sheets fed from a sheet feeding section in the apparatus. It is a chart.

Here,,... Mean the first, second, third, and fourth transfer sheets, respectively.
Also, (2), (4), (6), (1), (5),
(3) and (8) are the image formation of the second page of the original, the image formation of the fourth page of the original, the image formation of the sixth page of the original, the image formation of the first page of the original, the image formation of the third page of the original, and the original, respectively. This means image formation on the fifth page and image formation on the eighth page of the document. By performing image formation in this order, image formation on both sides in original order such as 1-2, 3-4, and 5-6 on transfer paper is completed. In this case, FIG. 3A shows a normal timing.

Here, the first transfer paper (FIG. 3B)
When a second transfer sheet (FIG. 3B) is fed from the paper feed unit after the paper is fed from the paper feed unit at normal timing, a paper feed failure (no feed: NF) occurs. . If this paper feed failure is detected by the paper feed sensor 261a,
The retry is not executed for the transfer sheet, and the sheet feeding at the original timing is stopped. Then, the second transfer paper is normally fed in time with the feeding timing of the third transfer paper (FIG. 3B).

As a result, the feeding of the original second transfer sheet is stopped, but no change has occurred in other feeding timings (phases) thereafter. Then, the first transfer sheet (FIG. 3 (b) (1)), which has been fed and conveyed at a normal timing and has already formed an image on one side, is conveyed reversely, and the image on the other side is conveyed. It is conveyed to the image forming unit 50 for formation.

At this time, an image is formed at a timing (phase) that should be the third transfer paper (FIGS. 3A and 6).
3 (b) and (4)) whose phases match with each other, and the image formation (FIG. 3 (b) and (1)) on the opposite surface of the first transfer sheet reversely conveyed at normal timing. No collision occurs. That is, the same sheet interval as usual is maintained.

In this case, normally, the place where three sheets should be retained is set to two sheets (the processing of changing the retention arrangement is executed).
Image formation on both sides in the document order such as 2, 3-4 is completed. For this reason, in the next image forming cycle, instead of forming the image of the eighth page of the original on the transfer sheet, the image of the sixth page of the original is started on the transfer sheet.
Therefore, the overall control board 100 changes the order of the images to be developed in the image memory 160 so as to match this state, and re-assigns the image forming order.

After the first transfer paper (FIG. 3 (c)) and the second transfer paper (FIG. 3 (c)) are fed from the paper feeder at a normal timing, the third transfer paper is transferred. It is assumed that a paper feeding failure (no feed: NF) occurs when paper is fed from the paper feeding unit. When this paper feed failure is detected by the paper feed sensor 261a, the retry is not executed for the third transfer paper, and the paper feed at the original timing is stopped.

As a result, the original feeding of the third transfer sheet is stopped, but no change occurs in other feeding timings (phases). Then, the first transfer sheet (FIG. 3 (c) (1)), which has been fed and conveyed at normal timing and has already formed an image on one side, is conveyed reversely, and the image on the other side is conveyed. It is conveyed to the image forming unit 50 for formation.

At this time, since the image formation at the timing (phase) that should be the third transfer paper is stopped, the opposite side of the first transfer paper reversely conveyed at the normal timing is stopped. In image formation (FIGS. 3 (b) and (1)),
No timing conflict occurs.

In this case as well, the place where three sheets should normally be retained is regarded as two sheets (the processing for changing the stay arrangement is executed).
Image formation on both sides in the original order such as 3-4 is completed.
For this reason, in the next image forming cycle, instead of forming the image of the eighth page of the original on the transfer paper, the sixth
The process is started from page image formation. Therefore,
In order to conform to this state, the overall control board 100 changes the order of the images to be developed in the image memory 160, and reassigns the image forming order.

As described above, according to the first embodiment, it is not necessary to increase the space between sheets to prevent a collision.
There is no need to provide a mechanism (such as a clutch or a control program) for stopping the transfer paper when a collision is likely to occur. For this reason, the apparatus and control timing can be kept simple, and the reliability can be kept extremely high.

Although n = 3 in the above description, the invention is not limited to this. If a paper feed failure occurs on the first transfer sheet, a retry may be performed to adjust the overall timing to that.
In this case, an effective effect can be obtained with the second to n-th transfer sheets.

[Second Embodiment] FIG. 6 shows an image formed by an image forming apparatus capable of forming an image on both sides of a transfer sheet while retaining three transfer sheets fed from a sheet feeding section in the apparatus. 5 is a time chart schematically showing formation timing.

Here,... Mean the first, second, third, and fourth transfer sheets, respectively.
Also, (2), (4), (6), (1), (5),
(3) and (8) are the image formation of the second page of the original, the image formation of the fourth page of the original, the image formation of the sixth page of the original, the image formation of the first page of the original, the image formation of the third page of the original, and the original, respectively. This means image formation on the fifth page and image formation on the eighth page of the document. By performing image formation in this order, image formation on both sides in original order such as 1-2, 3-4, and 5-6 on transfer paper is completed. In this case, FIG. 6A shows a normal timing.

Here, the first transfer paper (FIG. 6B)
When the second transfer sheet (FIG. 6B) is fed from the sheet feeding unit after the sheet is fed from the sheet feeding unit at a normal timing, a sheet feeding failure (no feed: NF) occurs. . If this paper feed failure is detected by the paper feed sensor 261a,
A retry is performed for the transfer sheet (FIG. 6B)
). Then, the feeding of the next transfer sheet at the original timing or at a delayed timing is stopped.

Then, the first transfer sheet (FIG. 6 (b) (1)), which has been fed and conveyed at normal timing and has already formed an image on one side, is conveyed reversely, and the other side is conveyed. The image is conveyed to the image forming unit 50 for image formation on the surface.

At this time, an image is formed at the timing (phase) that should be the third transfer paper (FIGS. 6A and 6).
6 (b) and (4)) whose phases match with FIG. 6 (b), and the image formation on the opposite surface of the first transfer sheet (FIG. 6 (b) (1)) reversely conveyed at normal timing. No collision occurs.

In this case, normally, the place where three sheets should be retained is set to two sheets (the process of changing the retention arrangement is executed).
-4, the image formation on both sides in the document order is completed. For this reason, in the next image forming cycle, instead of forming the image on the eighth page of the original on the transfer paper, the image on the sixth page of the original is started on the transfer paper. Therefore, the overall control board 100 changes the order of the images to be developed in the image memory 160 so as to match this state, and re-assigns the image forming order.

Although n = 3 in FIG. 6 described above, FIG. 7 shows the case where n> 3. That is, 2
Paper feeding failure and retry of the transfer sheet (FIG. 7B)
According to (4)), the image formation at the timing of the third transfer sheet is originally stopped, but the image formation at the timing corresponding to the original fourth and subsequent sheets is performed as usual (FIG. 7B).
(6)). That is, no change occurs in other feeding timings (phases) after the stop timing.

Then, the first transfer sheet (FIG. 7 (b) (1)), which has been fed and conveyed at normal timing and has already formed an image on one side, is conveyed reversely, and the other side is conveyed. The image is conveyed to the image forming unit 50 for image formation on the surface.

At this time, the timing (phase) that should be the fourth transfer paper following the timing when the paper supply is stopped
7 (FIG. 7 (a) and FIG. 7 (8)
(B) and (6)) and image formation on the opposite surface of the first transfer sheet conveyed reversely at normal timing (FIG. 7 (b)).
With (1)), no timing collision occurs. That is, the same sheet interval as usual is maintained.

In this case, normally, the place where four sheets should be retained is set to three sheets (the process of changing the retention arrangement is executed).
Image formation on both sides in the document order such as 2, 3, 4 and 5-6 is completed. Therefore, in the next image forming cycle,
Instead of forming the image of the 10th page of the original on the transfer paper, the transfer sheet is started with the image of the 8th page of the original. Therefore, the overall control board 100 changes the order of the images to be developed in the image memory 160 so as to match this state, and re-assigns the image forming order.

As described above, according to the second embodiment, there is no need to increase the space between sheets to prevent collision.
There is no need to provide a mechanism (such as a clutch or a control program) for stopping the transfer paper when a collision is likely to occur. For this reason, the apparatus and control timing can be kept simple, and the reliability can be kept extremely high.

In the above description, n = 3 and n = 4.
It is not limited to this. In this embodiment, since the feeding of the transfer paper immediately after the retry is stopped, when the number of stays is n, the effect that is effective for the first to (n-1) th transfer papers is not obtained. can get.

[0066]

As described above, according to the present invention, the following effects can be obtained.

(1) According to the first and sixth aspects of the present invention, images are formed on both sides of the transfer paper while the plurality of transfer papers fed from the paper feeding section are kept in the machine, and the transfer paper is formed. If a feeding failure occurs when feeding from the paper feeding unit, the feeding of the transfer paper in which the feeding failure has occurred is stopped, and the timing of feeding and transporting other transfer papers is not changed. Control is performed to execute image formation. For this reason, even if a paper feeding failure occurs, it is possible to avoid collision of the transfer paper without adjusting the paper interval or partially changing the transfer paper transport timing.

(2) According to the second and seventh aspects of the present invention, the n sheets of transfer paper fed from the paper feeding section are image-formed on both sides of the transfer paper while staying in the machine. If a feeding failure occurs when the transfer paper after the first feed is fed from the paper feeding unit, the feeding of the transfer paper with the feeding failure is stopped, and the timing of feeding and transporting the other transfer paper is stopped. Is controlled so as to execute image formation without changing the image data. For this reason, even if a paper feeding failure occurs, it is possible to avoid collision of the transfer paper without adjusting the paper interval or partially changing the transfer paper transport timing.

(3) According to the third and eighth aspects of the present invention, a plurality of transfer papers fed from the paper supply unit are formed in the machine while images are formed on both sides of the transfer paper while staying in the apparatus. If a feeding failure occurs when feeding from the paper feeding unit, the feeding of the transfer paper having the feeding failure is retried, and the feeding of the transfer paper next to the retried transfer paper is stopped. The image forming is controlled so as not to change the timing of feeding and transporting the other transfer paper. For this reason, even if a paper feeding failure occurs, it is possible to avoid collision of the transfer paper without adjusting the paper interval or partially changing the transfer paper transport timing.

(4) According to the fourth and ninth aspects of the invention, an image is formed on both sides of the transfer paper while the n transfer papers fed from the paper supply unit are kept in the machine. If a feeding failure occurs when feeding the first or previous transfer paper from the paper feeding unit, the feeding of the transfer paper having the feeding failure is retried and the next transfer of the retried transfer paper is retried. In addition to stopping paper feeding, control is performed so that image formation is performed without changing the timing of feeding and transporting other transfer paper. For this reason, even if a paper feeding failure occurs, it is possible to avoid collision of the transfer paper without adjusting the paper interval or partially changing the transfer paper transport timing.

(5) According to the fifth and tenth aspects of the present invention, in accordance with the stoppage of the feeding of defective transfer paper and the unchanging of the transfer timing of the remaining transfer paper (change processing of the stay arrangement), Since the image formation order is reassigned,
Even if a paper feeding failure occurs, it is possible to avoid the collision of the transfer paper without the necessity of adjusting the interval between the papers or partially changing the transfer paper transport timing.

[Brief description of the drawings]

FIG. 1 is a functional block diagram illustrating an electrical configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a mechanical configuration of the image forming apparatus according to the embodiment of the present invention;

FIG. 3 is a time chart showing the operation of the present embodiment.

FIG. 4 is an explanatory diagram showing an example of a state of recording paper passing during image formation.

FIG. 5 is an explanatory diagram illustrating an example of a state of recording paper passing during image formation.

FIG. 6 is a time chart showing the operation of the present embodiment.

FIG. 7 is a time chart showing the operation of the present embodiment.

FIG. 8 is a time chart showing the operation of the conventional device.

[Explanation of symbols]

 Reference Signs List 20 image reading unit 30 paper feeding unit 30a paper feeding cassette 30b paper feeding cassette 40 image writing unit 50 image forming unit 100 overall control board 110 CPU 120 CCD 130 index sensor 140 laser diode 150 operating unit 160 image memory 170 read image processing unit 180 Image memory 200 Engine drive board 210 CPU 261a Paper feed sensor 261b Paper feed sensor

Claims (10)

[Claims] 1. An image forming method for forming an image on both sides of a transfer sheet while retaining a plurality of transfer sheets fed from a sheet feeder in the apparatus, wherein the transfer sheet is fed when the transfer sheet is fed from the sheet feeder. When a feeding failure occurs, the feeding of the transfer paper in which the feeding failure has occurred is stopped, and image formation is performed without changing the timing of feeding and transporting the other transfer paper. Image forming method. 2. An image forming method for forming an image on both sides of a transfer sheet while n sheets of transfer paper fed from a sheet feeding section are retained in the apparatus, wherein any one of a second sheet to an n-th sheet is transferred. If a feeding failure occurs when feeding paper from the paper feed unit, stop feeding the transfer paper where the feeding failure has occurred, and change the timing of feeding and transporting other transfer paper. An image forming method, comprising: 3. An image forming method for forming an image on both sides of a transfer sheet while retaining a plurality of transfer sheets fed from a sheet feeder in the machine, wherein the transfer sheet is fed when fed from the sheet feeder. When a feeding failure occurs, the feeding of the transfer paper having the feeding failure is retried, and the feeding of the transfer paper next to the retried transfer paper is stopped.
An image forming method, wherein an image is formed without changing the timing of feeding and conveying another transfer sheet. 4. An image forming method for forming an image on both sides of a transfer sheet while retaining n sheets of transfer paper fed from a paper feeding unit in the machine, wherein any one of the (n-1) th or earlier transfer sheet If a paper feed failure occurs when feeding paper from the paper feed unit, retry feeding the transfer paper with the paper feed failure and stop feeding the next transfer paper after the retried transfer paper. And forming the image without changing the timing of feeding and conveying another transfer sheet. 5. The image forming method according to claim 1, wherein the image forming order is re-assigned in accordance with the stoppage of the feeding of the defective transfer paper. 6. An image forming apparatus for forming an image on both sides of a transfer sheet while retaining a plurality of transfer sheets fed from a sheet feeder in the apparatus, comprising: an image forming unit for forming an image; And transfer the transfer paper to the image forming means.
Transport means for transporting image formation on both sides, a paper feed sensor for detecting whether or not transfer paper is fed from a paper feed unit; control means for controlling the feed and transport and controlling image formation; The control means stops the feeding of the transfer sheet in which the feeding failure has occurred when the feeding sensor detects that the feeding failure of the transfer sheet has occurred, and feeds another transfer sheet. An image forming apparatus, which performs control for executing image formation without changing the timing of feeding, conveying, and image forming. 7. An image forming apparatus for forming an image on both sides of a transfer sheet while retaining n transfer sheets fed from a sheet feeder in the apparatus, comprising: an image forming means for forming an image; From the printer to the image forming means,
Transport means for transporting image formation on both sides, a paper feed sensor for detecting whether or not transfer paper is fed from a paper feed unit; control means for controlling the feed and transport and controlling image formation; The control means, when detecting that a feeding failure has occurred when feeding any of the second to n-th transfer papers from the paper feeding unit by the paper feeding sensor, An image forming apparatus which stops feeding of a transfer sheet in which a defect has occurred, and performs control for feeding and conveying another transfer sheet and executing image formation without changing the timing of image formation. . 8. An image forming apparatus for forming an image on both sides of a transfer sheet while retaining a plurality of transfer sheets fed from a sheet feeder in the apparatus, comprising: an image forming means for forming an image; And transfer the transfer paper to the image forming means.
Transport means for transporting image formation on both sides, a paper feed sensor for detecting whether or not transfer paper is fed from a paper feed unit; control means for controlling the feed and transport and controlling image formation; The control means, when the feeding sensor detects that the feeding failure of the transfer paper has occurred, retry feeding the transfer paper in which the feeding failure occurred and retrying the transfer paper. An image forming apparatus, comprising: stopping the feeding of the next transfer sheet, and performing control for feeding and conveying another transfer sheet and executing image formation without changing the timing of image formation. 9. An image forming apparatus for forming an image on both sides of a transfer sheet while retaining n transfer sheets fed from a sheet feeder in the apparatus, comprising: an image forming means for forming an image; From the printer to the image forming means,
Transport means for transporting image formation on both sides, a paper feed sensor for detecting whether or not transfer paper is fed from a paper feed unit; control means for controlling the feed and transport and controlling image formation; The control means, when it is detected by the paper feed sensor that any of the (n-1) th transfer paper is fed from the paper feed unit when a paper feed failure has occurred, Retrying the transfer of the transfer paper where the error occurred and stopping the feeding of the transfer paper next to the retried transfer paper without changing the timing of feeding and transporting the other transfer paper and the image forming. An image forming apparatus that performs control for executing image formation. 10. The image forming apparatus according to claim 1, wherein the control unit performs reassignment of an image forming order in response to the stoppage of the feeding of the defective transfer paper.
The image forming apparatus according to any one of claims 6 to 10, wherein: