JP3548489B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to a configuration for reducing the size of an image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image forming apparatus such as a copier, a facsimile, and a printer includes a sheet conveying device for conveying a sheet stored in a sheet storing unit to an image forming unit and discharging the sheet on which an image is formed. ing.
[0003]
Here, as such an image forming apparatus, for example, as shown in FIG. 4, a sheet feed tray 101 (101a, 101b, 101c, 101d) as four sheet storage units, an image forming unit 120, The image forming apparatus includes a sheet conveying unit 121 that conveys a sheet (not shown) stored in the sheet feeding tray 101 to the image forming unit 120, a fixing unit 104, and a sheet reversing unit 105 that discharges or reverses a sheet.
[0004]
In such an image forming apparatus, the sheet stored in the paper feed tray 101 is conveyed to the image forming unit 120 by the sheet conveying unit 121, and then the toner image formed in the image forming unit 120 is formed on the sheet. The image is transferred by the transfer unit 102. The sheet on which the toner image has been transferred is thereafter conveyed to a fixing unit 104 by a conveying belt 103, and the image is fixed by the fixing unit 104.
[0005]
By the way, after the image is fixed in this way, in the case of the straight discharge, the sheet is discharged through the conveyance path 105a, the conveyance path 105f and the post-processing device 140 provided in the sheet discharge reversing unit 105. It has become so.
[0006]
Further, at the time of double-sided copying, the sheet is reversed by the reversing path 105A composed of the conveying path 105a, the conveying path 105b, the conveying path 105d, the conveying path 105c, and the conveying path 105g, and is again transmitted to the image forming section 120 by the sheet conveying section 121. It is designed to be transported. Then, the sheet conveyed to the image forming unit 120 in this manner is transferred so that the toner image is transferred, and then the sheet is discharged through the conveyance belt 103, the fixing unit 104, the conveyance path 105a, and the conveyance path 105f. Has become.
[0007]
On the other hand, in recent years, digital copiers have been advanced, and multifunction peripherals having functions such as a printer and a facsimile have been increasing. In particular, in a device that emphasizes a printer function, a sheet can be sequentially output from a top page. Are reversed and the page order is adjusted.
[0008]
In the case of such a device, the sheet that has passed through the fixing unit 104 is conveyed to the conveyance path 105a, the conveyance path 105b, and the conveyance path 105d, and is then switched back to the conveyance path 105d, the conveyance path 105e, and the conveyance path 105f. After passing through, it is discharged with its back side up.
[0009]
By the way, in such a conventional image forming apparatus, when the transport paths 105d and 105c are formed along the left side surface of the apparatus main body 122 as shown in the figure, when a jam occurs in the transport path 105d or the transport path 105c. After the post-processing device 140 mounted on the left side of the apparatus main body 122 is moved, the open / close door (not shown) is opened to take out the jammed sheet.
[0010]
However, in the case where the jam processing is performed in this manner, when installing the image forming apparatus, in addition to the space for the transport path, a space for moving the post-processing apparatus 140 and an opening and closing door for opening and closing the opening and closing door are provided. Space and the like are required, and the occupied area becomes large.
[0011]
Therefore, conventionally, as shown in FIG. 5, there is a case in which the transport path 105d is provided substantially in parallel between the transport path 105a and the transport path 105g, thereby achieving space saving in the lateral direction of the apparatus main body. . Further, in such an image forming apparatus, a portion including the transport path 105d and the transport path 105g surrounded by a broken line is a drawer-type unit (hereinafter, referred to as a double-sided unit) U that is pulled out from the apparatus main body 122 to the front. In this way, it is possible to ensure the jam handling property.
[0012]
In addition, in the figure, 131 is a guide member which forms the lower surface of the transport path 105d and the upper surface of the transport path 105g, and 132 is a guide plate which configures the lower surface of the transport path 105g. Reference numerals 101e and 101f denote paper feed trays arranged below the duplex unit U, and 133 and 134 denote guide members that form a transport path 106b for transporting the sheets S stored in the paper feed tray 101f. The sheet S stored in the tray 101f passes through the transport paths 106b and 106c and is transported to the image forming unit 120.
[0013]
Here, when the jam occurs, if the double-sided unit U configured as described above is pulled out, the sheet on the transport path 105d can be easily removed because the upper part of the transport path 105d is open. The sheet on the transport path 105g can be removed by opening the opening / closing guide 131. Further, by forming the opening / closing guide 131 with a material such as a transparent resin, the sheet on the transport path 105g can be easily visually checked.
[0014]
[Problems to be solved by the invention]
However, in such a conventional image forming apparatus, the transport path 105g and the transport path 106c are linear as shown in FIG. The height dimension increases, and the height dimension of the apparatus main body also increases, making it difficult to reduce the size of the apparatus.
[0015]
On the other hand, the conveyance path 105g and the conveyance path 106c are provided with a sheet end detection mechanism for detecting a sheet passing through the conveyance path 105g and the conveyance path 106c during double-sided copying. The CPU (not shown) provided in the apparatus main body performs control to move the sheet to a predetermined position for forming the image on the second side in response to the detection signal from. However, when such a sheet end detection mechanism is provided in the conveyance paths 105g and 106c, the height of the duplex unit becomes large.
[0016]
In recent years, the conveyance speed has been further increased due to the pursuit of higher productivity, and after fixing various kinds of sheets, the curled paper and especially the basis weight of 200 g / m ² The transport stability is required in all of the processes up to the transport during the double-sided copying of the thick paper that reaches the maximum thickness.
[0017]
In such high-speed transport of thick paper, transportability at the curved portion connecting the transport path 105d and the transport path 105g is of the greatest concern. Here, it is important to reduce the curvature of the curved transport section in order to ensure the transportability in such a curved section, but in order to reduce the curvature of the curved transport section in this way, the curved diameter must be increased. In this case, when the curved diameter is made large, the height of the double-sided unit becomes large.
[0018]
Accordingly, the present invention has been made in view of such a situation, and an object of the present invention is to provide an image forming apparatus that can be made compact.
[0019]
[Means for Solving the Problems]
The present invention is configured such that an image forming unit that forms an image on a sheet, a sheet storage unit that stores the sheet, and the image forming unit that is mounted between the image forming unit and the sheet storage unit have an image formed on one surface. A reversing unit for reversing the sheet, a reversing path for conveying the sheet reversed by the reversing unit to the image forming unit, and a sheet merging with the reversing passage and conveying the sheet stored in the sheet storage unit to the image forming unit A conveyance unit having a conveyance path arranged in the up-down direction, wherein the reversing path of the conveyance unit is bent in a direction away from the sheet storage unit to increase the interval between the sheet storage unit and the reversal path, and the interval is increased. Detecting means for detecting a position of a sheet passing through the reversing passage in a direction perpendicular to a sheet conveying direction is provided between the spread sheet storage portion and the reversing passage. Is shall.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the materials, shapes, relative arrangements, and the like of the components described in the embodiment are not intended to limit the scope of the present invention only to them unless otherwise specified.
[0023]
FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention.
[0024]
In FIG. 1, reference numeral 50 denotes an image forming apparatus, 51 denotes an image forming apparatus main body (hereinafter, referred to as an apparatus main body), 1 (1a, 1b, 1c, 1d) denotes a sheet feeding tray serving as a sheet storage section, and 1e denotes a sheet feeding deck. It is. Reference numeral 52 denotes an image forming unit, and the sheet S stored in the sheet feeding tray 1 or the sheet feeding deck 1 e is conveyed to the image forming unit 52 via the conveying path 7 by the sheet feeding devices 53 to 56, and then the image is formed. The transfer section 2 transfers the toner image formed in the forming section 52.
[0025]
After the toner image is thus transferred, the sheet S is conveyed to the fixing unit 4 by the conveying belt 3, and heated and pressed by the heat roller 4a and the pressure roller 4b constituting the fixing unit 4, so that the toner image is formed. It has become established.
[0026]
By the way, after the image is fixed as described above, in the case of the straight discharge, the sheet S is discharged through the transport paths 5a and 5f constituting the discharge path provided in the discharge reversing section 5. The paper is discharged onto a paper tray 52.
[0027]
In the case of double-sided copying (double-sided image formation), after passing through the conveyance path 5a, the conveyance path 5b, and the conveyance path 5d, the sheet enters a conveyance path 5h which is a reversing unit for reversing a sheet. The sheet is conveyed again to the image forming section 52 in a reversed state by a reversing path 5A constituted by a conveying path 5j, a conveying path 5g, and conveying paths 6a and 6c. Then, after the toner image is transferred, the sheet S conveyed to the image forming unit 52 passes through the conveyance belt 3 and the fixing unit 4 and then passes through the conveyance paths 5a and 5f to be discharged straight. It is supposed to be paper.
[0028]
On the other hand, in the figure, UA is a double-sided reversing unit which is a transport unit detachably mounted on the apparatus main body 51, and connects the transport path 5c, the transport path 5h and the transport path 5g. The outer peripheral surface having a curvature substantially the same as the curvature of the conveying path 5j, the reversing path 5A, and the later-described conveying path 6b and the conveying path 5j that join the reversing path 5A, that is, the inner surface of the curved conveying path is described. A large-diameter roller 25 which is a transport roller having an outer peripheral surface and which can be rotated forward and backward. The large-diameter roller 25 includes two driven rollers 26a and 26b that rotate integrally with the large-diameter roller 25.
[0029]
On the other hand, FIG. 2 is a diagram showing a sheet conveyance path after the fixing unit 4, and in FIG. 2, reference numeral 51 denotes a first sheet discharge flapper for performing path switching for straight sheet discharge, reverse sheet discharge, and duplex copying. The path of the first paper discharge flapper 51 is switched by driving means such as a solenoid (not shown).
[0030]
Reference numeral 52 denotes a sheet that prevents the upwardly directed sheet from flowing backward in the direction of the transport path 5b due to the reversal (clockwise rotation) of the large-diameter roller 25 during the reverse discharge, which will be described later. The second discharge flapper for guiding the sheet to the transport path 5f is urged leftward by a spring (not shown) or its own weight.
[0031]
Reference numeral 21 denotes a double-sided first flapper serving as a switching unit for guiding the sheet S guided to the transport path 5b by switching the first sheet discharge flapper 51 to the transport path 5c or the transport path 5d. Is switched by driving means such as a solenoid (not shown).
[0032]
Reference numeral 22 denotes a case where the sheet guided to the conveyance path 5d by the double-sided first flapper 21 in the state shown by the broken line during the double-sided copying described later enters the conveyance path 5h, and then the large-diameter roller 25 described later is turned over (reversed). This is a double-sided second flapper that prevents the sheet S heading leftward in the figure from flowing backward in the direction of the transport path 5d by the clockwise rotation) and guides the sheet S to the transport path 5j. Like the second paper discharge flapper 52, it is urged downward by a spring (not shown) or its own weight.
[0033]
Reference numeral 27a denotes a sheet detecting means provided downstream of the driven roller 26a. The sheet detecting means 27a switches the two-sided first flapper 21 and rotates the large-diameter roller 25 in a counterclockwise direction when the sheet is reversed and discharged. , And the sheet S drawn into the conveyance path 5g by the rotation of the driven roller 26a is detected.
[0034]
Reference numeral 27b denotes a sheet detecting unit provided downstream of the driven roller 26b. By the sheet detecting unit 27b, switching of the double-sided first flapper 21 and rotation of the large-diameter roller 25 in the clockwise direction are performed during double-sided copying. The sheet S drawn into the conveyance path 5h by the driven roller 26b is detected.
[0035]
Although not shown in detail as the sheet detecting means 27a and 27b, for example, a flag protruding on the conveyance path and having a center of rotation outside the conveyance path is rotated by contact of the leading end of the sheet, and is provided in the flag. For example, it is possible to use one having a configuration that senses that the provided shielding plate shields the light emitting and receiving unit of the photo interrupter.
[0036]
When the sheet detecting means 27a, 27b detects the leading edge of the sheet, it outputs a detection signal to a CPU (not shown) provided in the apparatus main body 51. Then, the CPU determines the stop and reversal timing of the large-diameter roller 25 based on the detection signals from the sheet detection means 27a and 27b and information on the length of the sheet in the conveyance direction input from an operation unit (not shown). I have to.
[0037]
In the present embodiment, in the case of reverse discharge, the CPU determines that the rear end of the sheet has passed through the second discharge flapper 52 and has not reached the double-side reversing unit UA, and that the double-sided copy has been performed. In this case, the large-diameter roller 25 is stopped at a position before the rear end of the sheet has passed through the second-side second flapper 22 and before reaching the driven roller 26b, and thereafter, is reversed. In the case of a sheet having a long length in the conveyance direction, the CPU drives the conveyance rollers 28a and 28b in synchronization with the large-diameter roller 25 so that the longer sheet is drawn into the conveyance paths 5g and 5g.
[0038]
On the other hand, in the figure, reference numeral 31 denotes an opening / closing guide which is a first guide member constituting the lower surface of the conveying path 5h and the upper surfaces of the conveying paths 5g, 6a and 6c. Etc., and is rotatably held by the double-sided reversing unit UA.
[0039]
By using the opening / closing guide 31 having such a configuration, the jam sheet can be visually recognized even when a jam occurs in the transport path 5g, the transport path 6a, and the transport path 6c, so that the jam processing is reliably performed. Can be. Further, at the time of jam clearance, the sheet can be easily removed by rotating the opening / closing guide 31 upward as shown in FIG.
[0040]
Reference numeral 32 denotes a lower guide plate that forms the lower surfaces of the conveyance paths 6b and 6c, which are conveyance paths for conveying the sheets S stored in the sheet feeding tray 1b. Reference numeral 33 denotes a lower surface that forms the upper surface of the conveyance path 6b and the lower surface of the conveyance path 6a. The second guide member is an upper guide plate, and the upper guide plate 33 is formed of a material such as a transparent resin. By forming the upper guide plate 33 with a material such as a transparent resin in this way, even if a jam occurs in the transport path 6b, the jam sheet in the transport path 6b can be visually recognized, and the jam processing can be reliably performed. Can be done.
[0041]
Reference numeral 35 denotes a sheet end detection mechanism which is a detection unit provided upstream of the conveyance roller pair 28b. The sheet end detection mechanism 35 is a sheet re-conveyed to the image forming unit 52 for duplex copying. To detect a sheet position in a direction perpendicular to the conveying direction of the sheet. When the sheet edge detection mechanism 35 detects a sheet, it outputs position information to the CPU, and based on the information from the sheet edge detection mechanism 35, the CPU The control for moving to a predetermined position for forming is performed.
[0042]
By the way, in the present embodiment, the reversing passage 5A is bent in a direction away from the sheet feeding tray 1b, and the bending of the reversing passage 5A in this manner allows the reversing passage 5A and the sheet feeding tray 1b to be bent. The interval can be widened.
[0043]
By providing the sheet edge detection mechanism 35 between the reversing passage 5A and the sheet feeding tray 1b having such a wide interval as shown in FIG. 3, the height of the duplex reversing unit UA can be increased. Instead, the sheet edge detection mechanism 35 can be provided below the transport path 6a.
[0044]
In addition, by increasing the distance between the reversing path 5A and the sheet feeding tray 1b and joining the bent portion 5B of the reversing path with the transport path 6a, the height of the double-sided reversing unit UA is not increased. The transport path 6b can be merged with the transport path 6a.
[0045]
As a result, the space in the vertical direction of the duplex reversing unit UA depends only on the size of the curved transport path (transport path 5j) having the minimum radius of curvature for achieving transport stability. The unit UA and the apparatus main body 51 can be made compact.
[0046]
Next, the sheet conveying operation after the fixing unit 4 of the image forming apparatus 51 thus configured will be described in detail with reference to FIG.
[0047]
First, the case of straight discharge will be described. In the case of the straight discharge, the sheet that has passed through the fixing unit 4 is discharged through the transport path 5a and the transport path 5f by the first discharge flapper 51 switched to the position indicated by the broken line.
[0048]
Next, the case of the reverse discharge will be described. In the case of the reverse discharge, the first discharge flapper 51 is switched to the position shown by the solid line, whereby the sheet enters the conveyance path 5b, and the both sides are reversed while pressing the second discharge flapper 52 rightward in the drawing. Head to unit UA. At this time, the double-sided first flapper 21 has been switched to the position shown by the solid line, whereby the sheet is guided to the transport path 5c by the double-sided first flapper 21 and further transported by the large-diameter roller 25 rotating counterclockwise. Pulled up to 5g.
[0049]
When the sheet detecting means 27a detects the sheet moving in this way, the CPU detects that the rear end of the sheet passes through the second paper discharge flapper 52 based on the detection signal from the sheet detecting means 27a and the length information in the conveying direction. Then, the large-diameter roller 25 is stopped at a position before reaching the double-sided reversing unit UA, and thereafter, is reversed.
[0050]
In addition, after the rear end of the sheet has passed, the second sheet discharge flapper 52 prevents the sheet from flowing backward in the direction of the conveyance path 5b and guides the sheet to the conveyance paths 5e and 5f. It is returning due to its own weight. As a result, the sheet passes through the transport path 5a, the transport path 5c, the transport path 5e, and the transport path 5f, and is discharged in an inverted state.
[0051]
Next, the case of double-sided copying will be described. In the case of double-sided copying, the sheet is guided to the transport path 5d via the transport path 5b by the first discharge flapper 51 switched to the position shown by the solid line and the first double flapper 21 switched to the position shown by the broken line. I will
[0052]
Thereafter, the sheet is pulled up to the conveyance path 5h by the clockwise rotation of the large-diameter roller 25 and the driven roller 26b while pushing the double-sided second flapper 22 upward. When the sheet detecting means 27b provided downstream of the driven roller 26b detects the moving sheet, the CPU detects the leading edge of the sheet based on the leading edge detection signal from the sheet detecting means 27b and information on the length of the sheet in the conveying direction. After the end has passed through the second-side second flapper 22, the large-diameter roller 25 is stopped and reversed at a position before reaching the driven roller 26b.
[0053]
After the rear end of the sheet has passed, the double-sided second flapper 22 prevents the sheet from flowing backward in the direction of the conveyance path 5d due to its own weight and returns to the position where the sheet is guided to the conveyance path 5j. In this state, the sheet is guided to the conveyance path 5j.
[0054]
Thereafter, the sheet is conveyed along a conveyance path (conveyance path 5j, conveyance path 5g) along the large-diameter roller 25, and then conveyed along the conveyance paths 6a, 6c by the conveyance roller pairs 28a, 28b, 28c. It joins the transport path 7 and is transported to the transfer unit 2 to form an image on the second side.
[0055]
Here, as described above, since the outer peripheral surface of the large-diameter roller 25 also serves as the inner wall surface on the inner diameter side of the curved conveyance path 5j, the sheet conveyed along this conveyance path 5j has its own conveyance speed and This means that the inner wall surface of the transport path is moving at the same speed.
[0056]
In general, the conveyance resistance of a sheet conveyed on a curved portion (particularly, a portion that changes direction by about 180 degrees or more) is highly dependent on the frictional resistance of the inner wall surface. Friction resistance increases. In addition, in recent years, there is a tendency that the curvature of the curved portion is suppressed to be small due to a demand for downsizing the device.
[0057]
Therefore, by adopting a configuration in which the inner wall surface (the large-diameter roller 25) of the transport path is moved at the same speed as the transport speed of the sheet, the frictional resistance of the inner wall surface can be made substantially zero. As a result, a great effect can be achieved for reducing the sheet conveyance resistance.
[0058]
Furthermore, in recent years, strong firm weight 200 g / m required in the market. ² It is possible to ensure the conveyance stability of such a sheet even during high-speed conveyance. The driving system is simplified by driving one large-diameter roller 25 having a plurality of driven rollers 26a and 26b as compared with a case where several conveying roller pairs are driven and sequentially conveyed. It has many advantages in terms of cost and operation noise. Further, since the guide member on the inner peripheral surface of the curved portion can be omitted, the cost can be reduced.
[0059]
By the way, as shown in the drawing, the upper surface of the transport path 5h is substantially open, and when a jam occurs, when the double-sided reversing unit UA is pulled out from the apparatus main body 51 to the front, the sheet on the transport path 5h is It can be easily removed.
[0060]
As described above, the opening / closing guide 31 constituting the upper surface of the transport path 5h and the lower surface of the reversing path 5A (the transport path 5g, the transport path 6a, and the transport path 6c) is made of a transparent material that can be opened and closed. Therefore, when the duplex reversing unit UA is pulled out, the sheet on the reversing path 5A can be easily visually confirmed from above the duplex reversing unit UA.
[0061]
Thus, the sheet can be confirmed by pulling out the duplex reversing unit UA, and the jam sheet can be reliably processed by opening the opening / closing guide 31 after confirming the sheet.
[0062]
Further, in the present embodiment, the upper guide plate 33 constituting the lower surface of the transport path 6a and the upper surface of the transport path 6b is also formed of a transparent material. The sheet left in the road 6b can be easily visually checked from above. Then, after visually confirming the sheet in this way, for example, if the conveying roller pair 28d is manually rotated, the jammed sheet can be easily processed.
[0063]
By forming the upper guide plate 33 of a transparent material in this way, when the reversing passage 5A is opened by the opening / closing guide 31, the inside of the transport path 6b can be visually recognized. As a result, it is possible to prevent the user from forgetting to remove the jam sheet, and it is possible to reduce the burden on the user when clearing the jam.
[0064]
By the way, in recent years, it has been confirmed that as a factor of heat curl of a sheet, the influence of the conveying posture of the heated sheet is large. Therefore, when the sheet passes through a curved conveyance path or the like after being heated by the fixing unit 4 as in the present embodiment, the heat curl is further increased in the bending direction.
[0065]
For this reason, the purpose is to remove the heat applied to the sheet as quickly as possible so as not to bend the sheet as much as possible while the heat remains in the sheet. May be blown to the sheet.
[0066]
Note that, in the present embodiment, as described above, unlike the transport path (the transport path 5a, the transport path 5b, the transport path 5d, and the transport path 5h) during the duplex copying, the sheet transport path during the reverse discharge The (conveying path 5a, conveying path 5b, conveying path 5c) is a conveying path that, after passing through the fixing unit 4, bends approximately 90 degrees from the conveying path 5a to the conveying path 5b, and then linearly conveys.
[0067]
By forming the conveyance path at the time of reversal discharge in this way, it is possible to minimize the factors that affect the heat curl of the heated sheet. In particular, in the case of small-sized sheets, which are often stacked in a large amount (about 1000 to 3000 sheets) after being discharged, a small heat curl has a great effect on each sheet. The effect of the substantially straight transport path (the transport path 5b and the transport path 5c) that fits in a substantially linear manner is great.
[0068]
Further, among various kinds of sheets, there is a sheet having a different sheet curl size and its direction even under the same heating and pressing conditions. In order to cope with such a sheet, the sheet is conveyed along a curved conveying path (conveying path 5b, conveying path 5d) while the sheet temperature is high at the time of sheet reversal discharge, and a curve formed by the conveying path 5b and the conveying path 5d is heated. Curls have been corrected.
[0069]
Here, the correction of the sheet curl of the sheet by such a curved transport path (the transport path 5b and the transport path 5d) can be easily dealt with only by changing the switching control of the double-sided second flapper 21.
[0070]
In such a configuration, the transport path can be arbitrarily changed by operating and setting an input unit (not shown) by a user, a service person, or the like. 1a to 1d), it is also possible to automatically select (substantially straight or curved) a transport path at the time of reverse discharge according to the selected paper feed tray. It is also effective to use a sheet thickness detecting means and automatically select a transport path based on the sheet thickness information of the thickness detecting means.
[0071]
【The invention's effect】
As described above, according to the present invention, the reversing path provided in the transport unit is bent in a direction away from the sheet storage unit, and the transport path merges at the bent portion of the reversing path, thereby achieving compactness. , And the stable conveyance of the sheet becomes possible. Also, the sheet reversing path of the transport unit is bent in a direction away from the sheet storage section to widen the gap between the sheet storage section and the reversing path, and the sheet passing through the reversing path between the widened sheet storage section and the reversing path. By providing the detecting means for detecting, the device can be made compact.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a sheet conveyance path after a fixing unit of the image forming apparatus.
FIG. 3 is a diagram showing a state in which a jam sheet is removed by the double-sided reversing unit.
FIG. 4 is a diagram illustrating a configuration of a conventional image forming apparatus.
FIG. 5 is a view showing the vicinity of a duplex unit of the conventional image forming apparatus.
[Explanation of symbols]
1 (1a, 1b, 1c, 1d) paper feed tray
1e Paper deck
5a to 5h, 5j transport path
5A Inversion passage
5B bending part
6a-6c transport path
35 Sheet edge detection mechanism
50 Image forming apparatus
51 Image Forming Apparatus Main Body
52 Image forming unit
S sheet
UA Double-sided reversing unit

Claims (1)

An image forming unit that forms an image on a sheet,
A sheet storage unit for storing the sheet,
A reversing unit mounted between the image forming unit and the sheet storage unit for reversing a sheet on which an image is formed on one side, and a reversing path for conveying the sheet reversed by the reversing unit to the image forming unit A conveyance unit in which a conveyance path that merges with the reversing path and conveys a sheet stored in the sheet storage unit to the image forming unit is vertically arranged,
With
The reversing path of the transport unit is bent in a direction away from the sheet storage section to increase the interval between the sheet storage section and the reversing path, and the reversing path is provided between the widened sheet storage section and the reversing path. An image forming apparatus provided with detecting means for detecting a position of a sheet passing through the sheet in a direction perpendicular to a sheet conveying direction .

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