JP4189465B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that forms images on both sides of a recording sheet.
[0002]
[Prior art]
In general, an image forming apparatus that forms images on both sides of a recording sheet forms an image on the other side of the recording sheet that has been formed on one side and then turned upside down and re-fed to the image forming position.
[0003]
An image forming apparatus equipped with a reversing conveyance unit for reversing and re-feeding recording paper is widely used as a copying machine, a printer, a facsimile, and the like.
[0004]
The reversal conveyance unit includes a stack type in which recording sheets are stacked in the middle of the conveyance unit and a non-stack type in which recording sheets are not stacked. In digital image forming apparatuses, a non-fuck type is generally used.
[0005]
In the image forming apparatus having the non-stack type reversing conveyance unit, as shown in FIG. 1A, the number M of recording sheets that can be accommodated in the circulation path R including the reversal conveyance unit is a conveyance distance in the circulation path R. It is determined by the circulation length L and the size S of the recording paper P (length in the transport direction). As shown in FIG. 1B, which is a development view of the circulation path R, the circulation length L is the sum of the length L1 of the conveyance path that returns from the registration rollers and returns to the registration rollers and the length L2 of the switchback portion. The length L2 of the switchback unit is a length that accommodates one sheet of recording paper.
[0006]
In the continuous double-sided image forming process, as shown in FIG. 1C, the front surface image formation and the back surface image formation are alternately performed in units of the number M. Note that the double-sided image forming process shown in FIG. 1C is an example, and there are several methods other than FIG. The circulation path R is a conveyance unit that returns to the registration roller from the registration roller. In the following description, the number M of recording sheets that can be accommodated in the circulation path R is referred to as the circulation number.
[0007]
The control unit of the image forming apparatus manages the number of circulating sheets M based on the size S information and controls the conveyance timing of the recording paper when the fraction is less than the circulating sheet number M.
[0008]
In Patent Document 1, two reversing sections are provided, and two reversing conveyance sections are used alternately, thereby eliminating the waiting time for the recording paper in the previous stage of the reversing conveyance section and reducing the time required for double-sided image formation. An image forming apparatus that has been shortened and improved in productivity has been proposed.
[0009]
[Patent Document 1]
JP 2000-143103 A
[Problems to be solved by the invention]
In order to increase the productivity of image formation, that is, the efficiency of image formation, it is desirable to shorten the conveyance distance L of the circulation path R and reduce the number of circulation sheets M.
[0011]
If the circulation number M is large, it is necessary to prepare a large amount of image data prior to the start of image formation, and the time required for creating the image data becomes long. For this reason, the start time of image formation is delayed, and as a result, productivity is lowered.
[0012]
For example, when the number of circulating sheets is 5, it is necessary to prepare image data for 10 pages before image formation. In a copying machine, the time from the start of image reading to the start of image formation becomes longer. In the printer, the time from the reception of the print command to the start of image formation becomes longer.
[0013]
In addition, in order to store a large amount of image data, a large-capacity memory is required, which increases costs.
[0014]
Furthermore, if the number of circulating sheets M is large, the workability of jam removal is deteriorated and the machine becomes difficult to use.
[0015]
In order to solve such a problem, when measures such as reducing the number of circulating sheets M or increasing the conveying speed in the reversing conveying unit, the conveying unit having a small curvature radius in the circulation path, that is, the recording paper is strengthened. Problems arise, such as the conveyance section being bent, and the stability of the conveyance being lowered.
[0016]
Such a problem in conveyance is highly likely to occur in double-sided image formation using special paper such as thick paper or small-size paper.
[0017]
In the prior art, there is no means for satisfying such conflicting conditions at the same time, and intermediate measures have been taken.
[0018]
However, in recent years, the electrophotographic image forming apparatus is used for light printing, and as the field of use expands, the need for improvement in productivity has increased, and high-productivity that can use special paper such as cardboard without any trouble. Things are desired.
[0019]
An object of the present invention is to provide an image forming apparatus capable of satisfying such needs and capable of forming an image with high productivity using recording paper having various attributes. The purpose is to do.
[0020]
[Means for Solving the Problems]
The above object can be achieved by the following invention.
[0021]
1. An image forming unit that forms an image on one side of the recording paper, a first reverse conveying unit that reverses the front and back of the recording paper after image formation on one side, and refeeds the image forming position of the image forming unit and a second reverse A control unit and an operation unit that perform either side image formation by selecting any one of a transport unit, the first reverse transport unit, and the second reverse transport unit, and the first reverse transport unit includes the second reverse transport unit. The length of the circulation path is shorter than that of the printing unit, and the first reverse conveyance unit conveys the recording paper at a higher conveyance speed than the second reverse conveyance unit, and the first reverse conveyance unit Compared with the second reversal conveyance unit, the control unit has a conveyance unit with a small radius of curvature, and the control means is configured to control the first reversal conveyance unit or the first reversal unit based on a recording paper setting condition in the operation unit. 2. An image forming apparatus, wherein a reversing conveyance unit is selected.
[0022]
2. An image forming unit that forms an image on one side of the recording paper, a first reverse conveying unit that reverses the front and back of the recording paper after image formation on one side, and refeeds the image forming position of the image forming unit and a second reverse A control unit configured to form a double-sided image by selecting any one of a transport unit, the first reverse transport unit, and the second reverse transport unit, and a recording paper storage unit, wherein the first reverse transport unit includes the second reverse transport unit; The length of the circulation path is shorter than that of the reverse conveyance unit, and the first reverse conveyance unit conveys the recording paper at a higher conveyance speed than the second reverse conveyance unit, and the first reverse conveyance unit The control unit has a transport unit having a smaller radius of curvature than the second reverse transport unit, and the control means is configured to control the first reverse transport unit or the first reversal transport unit based on information from the recording paper storage unit. An image forming apparatus, wherein the second reverse conveying unit is selected.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 2 shows an image forming apparatus according to an embodiment of the present invention.
[0031]
The image forming apparatus includes an automatic document feeder A, an image reading section B, an image forming section C, a fixing device D, a transport section E, reverse transport sections F1 and F2, a recording paper storage section G, an operation section H, and a communication interface J. Composed.
[0032]
The automatic document feeder A conveys a large number of documents one by one to an image reading position and accumulates the scanned documents, and has a single-sided scanning mode and a double-sided scanning mode.
[0033]
The image reading unit B reads the original conveyed by the automatic original conveying apparatus A or the original placed on the original table B1, and generates image data.
[0034]
The image forming unit C forms an image on the recording paper P by an electrophotographic method, and includes a drum-shaped photoconductor 1, a charging device 2, an exposure device 3, a developing device 4, a transfer device 5, and a cleaning device 6. . The photosensitive member 1 is charged by the charging device 2, the photosensitive member 1 is exposed according to the image data by the exposure device 3, and developed by the developing device 4 to form a toner image on the photosensitive member 1. The formed toner image is transferred onto the recording paper P by the transfer device 5. The recording paper P to which the toner image has been transferred passes through the fixing device D and is fixed.
[0035]
The conveyance unit E includes sheet feeding units 11A, 11B, and 11C, conveyance rollers 121, 122, 123, and 124, a registration roller 13, and a conveyance belt 125.
[0036]
In the double-sided image formation, the reverse conveying unit that reverses the recording paper on which image formation has been performed on one side and feeds it to the registration roller 13 has the first reverse conveying unit F1 having a short circulation path and the circulation path having a short length. It consists of a long second reverse conveying section F2.
[0037]
The first reverse conveyance unit F1 receives the recording paper P that has passed through the fixing device D downward, the conveyance roller 141 that conveys the recording paper P from the reverse roller 142, and the conveyance rollers 151 and 152 that horizontally convey the recording paper P, and the conveyance roller 151. It consists of a transport unit in which a transport roller 153 that receives the recording paper P and transports it upward and supplies it to the registration rollers 13 and a switchback unit in which a reverse roller 142 that transports the recording paper P up and down is disposed.
[0038]
The second reverse conveyance unit F2 includes conveyance rollers 141, 142, and 143 that convey the recording paper P that has passed through the fixing device D downward, and conveyance rollers 161 and 162 that receive the recording paper P from the reverse roller 144 and convey it horizontally. 163, transport rollers 121, 122, and 123 that receive the recording paper P from the transport roller 163 and transport the recording paper P upward; a transport unit in which a transport roller 124 that receives the recording paper from the transport roller 123 and supplies the recording paper to the registration roller 13; And a switchback portion on which the reverse roller 144 is disposed.
[0039]
The recording paper storage unit G includes paper feed trays 10A, 10B, and 10C, and the horizontal transport unit of the second circulation transport unit F2 includes a paper feed tray 10B and a paper feed tray 10C that is a lowermost large capacity tray. Arranged between.
[0040]
The operation unit H is a user interface that has various buttons for setting various image forming conditions and performs various displays. The operation unit H is used to specify the size of the recording paper P and to set modes such as single-sided / double-sided. Is called.
[0041]
The communication interface J is a unit that performs communication with an external device such as a personal computer, and receives an image forming command from the outside.
[0042]
In the single-sided mode, when the recording paper P fed from the paper feeding unit 10A, 10B or 10C passes between the photosensitive member 1 and the transfer device 5 via the transport unit D, the toner image is transferred to the fixing device. At D, the fixing process is performed and the paper travels straight and is discharged out of the apparatus.
[0043]
In the double-sided mode, the toner image is transferred, fixed by the fixing device D, and the image is formed on the surface. The toner image is guided downward by the guide member 171 and transported downward by the transport rollers 141 and 142. .
[0044]
In the double-side mode using the first reverse conveyance unit F1, the recording paper P that has been fixed by the fixing device D and has an image formed on the surface thereof is guided downward by the guide member 171, and the conveyance roller 141 and the reverse roller 142 Then, the sheet is conveyed upward by the reversing roller 142, guided horizontally by the guide member 172, conveyed by the conveying rollers 151, 152, and 153 and supplied to the registration roller 13.
[0045]
The image is formed between the photosensitive member 1 and the transfer device 5 by the registration roller 13 to form an image on the back surface.
[0046]
The recording paper P on which the image is formed on the back side passes through the fixing device D and is subjected to fixing processing, and then is discharged outside the apparatus.
[0047]
In the double-side mode using the second reverse conveyance unit F2, the recording paper P that has been fixed by the fixing device D and has an image formed on the surface thereof is guided downward by the guide member 171, and the conveyance rollers 141, 142, 143, and After being conveyed downward by the reverse roller 144, it is conveyed upward by the reverse roller 144, guided horizontally by the guide member 173, conveyed to the right by the conveyance rollers 161, 162, 163, and further conveyed by the conveyance rollers 121, 122, 123 is conveyed upward and supplied to the registration roller 23 via the conveyance roller 124.
[0048]
The recording paper P is further supplied between the photosensitive member 1 and the transfer device 5 by the registration roller 13, and an image is formed on the back surface.
[0049]
The recording paper P on which the image is formed on the back side passes through the fixing device D and is subjected to fixing processing, and then is discharged outside the apparatus.
[0050]
As shown in FIG. 3A, three recording sheets P are accommodated in the first circulation path R1 formed by the first reverse conveyance unit F1, but formed by the second reverse conveyance unit F2. As shown in FIG. 3B, five recording sheets P are accommodated in the circulation path R2.
[0051]
FIG. 4 shows a time when an image of 6 pages is formed on three sheets of recording paper using the first and second reverse conveying sections F1 and F2 shown in FIG.
[0052]
In the case of using the first reversing conveyance unit F1, double-sided image formation is completed in 6 tw as shown in the figure when the time required to form one image is tw. On the other hand, when using the 2nd inversion conveyance part F2, time of 8tw is required.
[0053]
In FIG. 4, image formation is started simultaneously in the case of the first reverse conveyance unit F <b> 1 and the second reverse conveyance unit F <b> 2, but in consideration of the relationship with image reading, the second image formation unit F <b> 2 is used. In some cases, it may be necessary to delay the start of image formation compared to the case of the first image forming unit.
[0054]
In the case of double-sided image formation, image reading starts when the copy button is pressed, but since the first page on the back side is formed after the last page on the front side, the timing of image formation on the first page on the back side is the last page on the front side. It will be regulated by the reading completion time.
[0055]
When double-sided image formation of 5 pages and 10 pages is performed using the first reversing conveyance unit F1, images are formed in the order of pages 1, 3, 5, 2, 4, 6, 7, 9, 8, 10 Is done. Until the reading of the first to fifth pages is completed, the image formation for the third five pages cannot be started.
[0056]
When double-sided image formation of 5 pages and 10 sheets is performed using the second reversing conveyance unit F2, images are formed in the order of pages 1, 3, 5, 7, 9, 2, 4, 6, 8, 10 Is done. The fifth 9-page image cannot be formed until the reading of the 1st to 9th pages is completed.
[0057]
As described above, the time from the time when the copy button is pressed to the time when the image formation is started is compared with the image formation start time t1 when the first reverse conveyance unit F1 is used, and the image formation when the second reverse conveyance unit F2 is used. The start time t2 is delayed, and the image formation completion time is also delayed when the second reverse conveyance unit is used.
[0058]
Therefore, as shown in FIG. 5, the time required to form the image of 5 sheets and 10 pages becomes longer when the second reversing conveyance unit F2 is used.
[0059]
Thus, in terms of productivity, a shorter circulation path is advantageous. And productivity can be raised further by raising the conveyance speed in a reverse conveyance part.
[0060]
However, by shortening the reverse conveyance section or increasing the conveyance speed, for example, as shown by FR in FIG. 2, a conveyance section having a small curvature radius, that is, a strongly bent conveyance section can be formed, or the conveyance speed is increased. In this case, there are disadvantages such as unstable conveyance. The means for increasing the conveyance speed in the reversal conveyance unit is a means taken by shortening the conveyance unit in addition to improving the productivity. That is, in the switchback unit of the reverse conveyance unit, the conveyance speed after the switchback is increased in order to prevent the front and rear recording sheets from colliding with each other.
[0061]
As shown in the figure, by providing and selectively using the first reversing transport unit F1 and the second reversing transport unit F2 having a short circulation length as the reversing transport unit, productivity is improved and stability and reliability are sufficient. The image forming apparatus secured in the above.
[0062]
Whether the double-sided image formation is performed using the first reverse conveyance unit F1 or the double-sided image formation using the second reverse conveyance unit F2 is selected according to the attribute of the recording paper.
[0063]
In the case of recording paper that has good transportability and is normally used, the first reverse transport section F1 is used. That is, in the case of regular plain paper, for example, A-series paper of A5 to A3, and B-series plain paper of B5, B4, the first reversing conveyance unit is used, and highly efficient double-sided image formation is performed.
[0064]
Also in the case of regular thin paper, the first reverse conveying unit F1 is selected. Thin paper is paper that is thinner than normal thickness.
[0065]
In the case of other series of standard paper such as an inch series, the first reverse conveyance unit F1 is selected.
Note that plain paper is used to mean paper normally used for office work.
[0066]
When using special size recording paper, special paper such as coated paper or printing paper with special paper thickness or paper properties, the second transport unit F2 is used. That is, in the case of irregular size paper, A3 or larger paper, thick paper, postcard, coated paper, printing paper, and the like, the second reverse conveyance unit F2 is used.
[0067]
Note that the A3 or larger paper includes a length of recording paper that cannot be transported by the first reversing transport unit F1, but the second reversal transport is performed when the recording paper has a size that exceeds the transport capacity. By using the portion F2, it becomes possible to convey, and it is possible to form a double-sided image using a large-size recording paper, which was impossible in the past.
[0068]
FIG. 6 is a block diagram of a control system of the image forming apparatus according to the embodiment of the present invention.
[0069]
The control means CR selects the first reverse conveyance unit F1 or the second reverse conveyance unit F2 based on information from the paper sensor PS, the operation unit H, the communication interface J, and the recording paper storage unit G.
[0070]
Specifically, the selection of the first and second reverse conveyance units F1 and F2 is executed by controlling the reverse rollers 142, 143, and 144 and the guide members 172 and 173. That is, when using the first reverse conveyance unit F1, the rotation direction of the reverse roller 142 is reversed when the upper end of the recording paper P passes through the guide member 172 and is held by the reverse roller 142, and recording is performed. The paper P is transported upward and guided to the transport roller 152 by the guide member 172.
[0071]
In the case of using the second reverse conveyance unit F2, the reverse rollers 142 and 143 are used as the conveyance rollers to convey the recording paper P downward, and the upper end of the recording paper P passes through the guide member 173, and the reverse roller The rotation direction of the reversing roller 144 is reversed while being held by the roller 144, the recording paper P is conveyed upward, and is guided to the conveying roller 162 by the guide member 173.
[0072]
The paper sensor PS is installed, for example, between the transport roller 124 and the registration roller 13 and detects the size and thickness of the paper passing therethrough, and the control means CR determines the special size and detects the normal paper based on the output of the sensor S. Determine whether paper or cardboard.
[0073]
The operator can set the regular plain paper or special paper using the operation unit H. In the operation unit H, the selection of the first reverse counterclaim unit F1 or the second reverse transfer unit F2 can also be directly selected.
[0074]
The paper size is detected based on sensors (not shown) provided in the paper feed trays 10A, 10B, and 10C of the recording paper storage unit G, and the control means CR is based on information from the recording paper storage unit G. It is discriminated whether it is regular plain paper or special paper.
[0075]
Based on the paper size information included in the image formation command received by the communication interface J, the control means CR determines whether the paper is regular plain paper or special paper.
[0076]
Based on these various information, the control means CR selects the first or second reversal transport unit F1 or F2 and executes the double-sided image forming process.
[0077]
FIG. 7 is a flowchart of such control.
In the case of single-sided image formation (no in S1), the single-sided image formation step is executed (S2), but in the case of double-sided image formation (Yes in S1), information on the attribute of the recording paper is read (S3). ). The attribute information is information from the paper sensor PS, the operation unit H, the recording paper storage unit G, and the communication interface J as described above.
[0078]
When the second reverse conveyance unit F2 is selected (Yes in S4), control corresponding to the second reverse conveyance unit F2 is executed.
[0079]
In the control corresponding to the second reversing conveyance unit F2, importance is attached to stable conveyance such as increasing the number of circulating sheets, increasing the interval between conveyed recording sheets, and making the conveying speed in the second reversing conveying unit F2 substantially equal to the process speed. Control.
[0080]
When the first reverse conveyance unit F1 is used (no in S4), control corresponding to the first reverse conveyance is executed. In the control corresponding to the first reverse conveyance unit F1, speed-oriented control is performed, and control such as narrowing the interval between the recording sheets to be conveyed and increasing the conveyance speed in the second reverse conveyance unit is executed.
[0081]
The control is executed as shown in FIG. FIG. 8 is a timing chart of double-sided image formation using the first and second reverse conveyance units F1 and F2, and FIG. 8A is a case where the first reverse conveyance unit F1 is used, and FIG. ) Is a case where the second reversal conveyance unit F2 is used. The vertical axis in the figure indicates the recording paper moving distance in the circulation path, and the horizontal axis indicates time. 8A and 8B, the process speed, that is, the rotation speed of the photosensitive member 1 and the recording paper conveyance speed in the fixing device D are the same. FIG. 8 shows an example in which image formation is performed in the order of pages 2, 4, 1, and 3.
[0082]
The conveyance timing of the recording paper in FIG. 8A is as follows.
Feeding of the first recording sheet is started at t1, feeding of the registration roller 13 is started at t2, and image formation for one page is started at t3. The recording paper on which the image is formed passes through the fixing device D and proceeds to the reverse conveyance unit F1.
[0083]
At t5, the rotation direction of the reversing roller 142 is reversed, and the reversal of the recording paper is started. The reversed recording paper is conveyed by the registration roller 13, and the paper feeding in the back side image formation is started at t6. At t7, image formation for two pages is started, and at t8, the first recording sheet is ejected to complete double-sided image formation on one recording sheet. A vertical thick solid line indicates the first recording paper, and a vertical thick dotted line indicates the second recording paper.
[0084]
The recording paper is conveyed at the process speed v1 from t2 to t5, but the recording paper is conveyed at a conveyance speed v2 higher than v1 from t5 to t6, which is reversed and conveyed by the reversing roller 142. As described above, the conveyance step speed in the first reversal conveyance unit F1 is increased to v2. In the continuous image formation, the interval between the recording sheets conveyed before and after is compressed as much as possible, and at the position of the guide member 172. This is for avoiding the collision of the front and rear recording papers. As is apparent from the figure, by increasing the transport speed in the first reverse transport section F1 to v2, the time required for the double-sided image formation is shortened. Improvement of productivity is realized.
[0085]
Double-sided image formation is performed on the second recording paper indicated by the dotted line in the same process.
[0086]
The conveyance of the recording paper in FIG. 8B is also the same as that described above with respect to the conveyance order, but as is apparent from the drawing, the conveyance speed v3 in the reverse conveyance from t5 to t6 is lower than v2. A value close to the conveyance speed v1 is set.
[0087]
The lengths of the transport unit at t4 to t5 and the transport unit at t5 to 16 are long in FIG. 9, that is, by adding the transport unit of the reverse roller 144 and the transport rollers 121 to 124 from the reverse roller 142 in FIG. As can be seen from the figure, the times t1 to t8 for forming the double-sided image on one sheet of recording paper are much shorter when the first reverse conveying unit is used.
[0088]
As described above, by appropriately selecting double-sided image formation with high productivity and double-sided image formation with high stability, an image forming apparatus with high productivity and high reliability can be obtained.
[0089]
It is possible to produce an image forming apparatus having the first reverse conveyance unit F1 as a standard equipment and the second reverse conveyance unit F2 as an optional equipment.
[0090]
By selling a standard machine and an optional machine as a product line, a user can acquire a desired machine at low cost.
[0091]
【The invention's effect】
According to the invention of any one of claims 1 to 2 , since the first reversing conveyance unit for the double-sided image forming mode with high productivity and the second reversing conveyance unit with high conveyance stability are provided, According to the purpose of image formation, it is possible to select the reverse conveying unit, and an image forming apparatus having both high productivity and high stability is realized. In the first reverse conveying section, it is possible to use a means for increasing the image forming speed such as increasing the conveying speed as compared with the conventional one. Since the stability of the 1-reverse conveying unit can be made higher than before, an image forming apparatus having higher stability and reliability than before can be realized. According to the first or second aspect of the invention, since the reverse conveying unit is selected according to the attribute of the recording paper to be used, double-sided image formation is performed according to the attribute of the recording paper, and the image forming apparatus has high stability. Is realized.
[0092]
According to the first or second aspect of the invention, an image forming apparatus that performs double-sided image formation at a higher speed than the conventional one is realized.
[0094]
According to the first or second aspect of the invention, since the recording paper that is likely to cause a conveyance failure such as special paper is also stably conveyed, a highly stable image forming apparatus is realized.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a double-sided image forming process.
FIG. 2 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram of a circulation path formed by two reversing conveyance units.
FIG. 4 is a diagram illustrating time required for image formation in the case of double-sided image formation using first and second reversal conveyance units.
FIG. 5 is a diagram illustrating time required for image formation in the case of double-sided image formation using the first and second reversal conveyance units.
FIG. 6 is a block diagram of a control system of the image forming apparatus according to the embodiment of the present invention.
FIG. 7 is a flowchart of control in the image forming apparatus according to the embodiment of the present invention.
FIG. 8 is a timing chart of double-sided image formation using the first and second reverse conveyance units F.
[Explanation of symbols]
F1 1st reverse conveyance part F2 2nd reverse conveyance part CR Control means PS Paper sensor H Operation part J Communication interface

Claims (2)

An image forming unit that forms an image on one side of the recording paper, a first reverse conveying unit that reverses the front and back of the recording paper after image formation on one side, and refeeds the image forming position of the image forming unit and a second reverse A control unit and an operation unit that perform either side image formation by selecting any one of a transport unit, the first reverse transport unit, and the second reverse transport unit, and the first reverse transport unit includes the second reverse transport unit. The length of the circulation path is shorter than that of the printing unit, and the first reverse conveyance unit conveys the recording paper at a higher conveyance speed than the second reverse conveyance unit, and the first reverse conveyance unit Compared with the second reversal conveyance unit, the control unit has a conveyance unit with a small radius of curvature, and the control means is configured to control the first reversal conveyance unit or the first reversal unit based on a recording paper setting condition in the operation unit. 2. An image forming apparatus, wherein a reversing conveyance unit is selected. An image forming unit that forms an image on one side of the recording paper, a first reverse conveying unit that reverses the front and back of the recording paper after image formation on one side, and refeeds the image forming position of the image forming unit and a second reverse A control unit configured to form a double-sided image by selecting any one of a transport unit, the first reverse transport unit, and the second reverse transport unit, and a recording paper storage unit, wherein the first reverse transport unit includes the second reverse transport unit; The length of the circulation path is shorter than that of the reverse conveyance unit, and the first reverse conveyance unit conveys the recording paper at a higher conveyance speed than the second reverse conveyance unit, and the first reverse conveyance unit The control unit has a transport unit having a smaller radius of curvature than the second reverse transport unit, and the control means is configured to control the first reverse transport unit or the first reversal transport unit based on information from the recording paper storage unit. An image forming apparatus, wherein the second reverse conveying unit is selected.

Images