Sheet transport device and image forming apparatus

Abstract

The present invention provides a sheet conveying device that allows for easy assembly of a biasing member into a downward-opening opening / closing unit. [Solution] A sheet conveying device comprising: an upper unit fixed to the main body of the device and equipped with an upper guide that forms a conveying path for conveying sheets; a lower unit positioned below the upper unit and equipped with a lower guide that together forms a conveying path for conveying sheets together with the upper guide, and rotatable downward relative to the upper unit; a biasing member whose one end is pivotably supported by the lower unit and biases the lower unit in a retracted state; and a moving member which pivotably supports the other end of the biasing member and moves the other end from a first position to a second position, wherein the biasing member has a first length when the other end is in the first position, and a second length shorter than the first length when the other end is in the second position, and the moving member is fixed with the other end in the second position.

Description

Technical Field

[0001] The present invention relates to a sheet conveying device for conveying a sheet and an image forming device for forming an image on the sheet.

Background Art

[0002] In an image forming apparatus, in order to remove a jammed sheet when the sheet jams, it is common to make the portion forming the conveyance path openable and closable so as to open the conveyance path of the sheet. In order to improve the operability of the opening and closing unit, it is known to assist the opening and closing using a biasing member. In Cited Document 1, a configuration for opening the opening and closing unit upward using a gas spring has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, depending on the relationship and arrangement of the space around the opening and closing unit, it may be necessary to open the opening and closing portion downward. In order for the biasing member to apply a force to the opening and closing unit in a state where the opening and closing unit is closed, it is necessary to compress the biasing member when attaching the biasing member to the opening and closing unit, which makes assembly difficult. Therefore, an object of the present invention is to provide a sheet conveying device and an image forming device including a downward-opening opening and closing unit that can be easily assembled with a biasing member.

Means for Solving the Problems

[0005] One aspect of the present invention is a sheet conveying device comprising: an upper unit fixed to the main body of the device and equipped with an upper conveying guide that forms a conveying path through which sheets are conveyed; a lower unit positioned below the upper unit and equipped with a lower conveying guide that together forms a conveying path through which sheets are conveyed together with the upper conveying guide and is rotatable downward relative to the upper unit; a biasing member whose one end is pivotably supported by the lower unit and biases the lower unit in a retracted state; and a moving member which pivotably supports the other end of the biasing member and moves the other end from a first position to a second position, wherein the biasing member has a first length when the other end is in the first position, and a second length shorter than the first length when the other end is in the second position, and the moving member is fixed with the other end in the second position. [Effects of the Invention]

[0006] According to the present invention, a biasing member can be easily assembled to a downward-opening opening / closing unit. [Brief explanation of the drawing]

[0007] [Figure 1] Cross-sectional view of an image forming system. [Figure 2] Perspective view of the sheet transport unit. [Figure 3] A cross-sectional view of the sheet transport unit, parallel to the sheet transport direction. [Figure 4] Cross-sectional view of a sheet transport unit with the lower unit in the closed position. [Figure 5] Cross-sectional view of a sheet transport unit with the lower unit in the open position. [Figure 6] Cross-sectional view of the sheet transport unit during gas spring assembly. [Figure 7] A diagram showing the movement of the shaft attached to the second support member. [Figure 8] Cross-sectional view of the sheet transport unit before assembly of the gas spring. [Modes for carrying out the invention]

[0008] The following description of this embodiment will be illustrated with reference to the figures. While the embodiments described below are preferred embodiments of the present invention and therefore subject to various technically advantageous limitations, the scope of the present invention is not unduly limited by the following description. Furthermore, not all of the configurations described in this embodiment are essential components of the present invention.

[0009] <First Embodiment> This embodiment describes a case where an image forming system is applied to an inkjet recording system 1000. Figure 1 is a schematic diagram showing an example of the general configuration of the inkjet recording system 1000. This inkjet recording system 1000 is a sheet-fed inkjet recording system that produces a recording material by forming an ink image on a sheet using two liquids, a reaction solution and ink.

[0010] The inkjet recording system 1000 of this embodiment consists of an image forming apparatus and a plurality of sheet transport devices. Here, a device that is self-supporting and independently housing-like, supported by undercarriage components such as casters or adjusters, will be referred to as a module.

[0011] The inkjet recording system 1000 consists of a paper feed module 100, a print module 200, a drying module 300, a fixing module 400, a cooling module 500, a reversing module 600, and a paper output and stacking module 700. Cut sheets supplied from the paper feed module 100 are transported along a transport path, processed in each module, and then discharged to the paper output and stacking module 700, which acts as a sheet discharge device.

[0012] A paper feeding module 100, which is an example of a sheet feeding device, has storage compartments 110a, 110b, and 110c for storing sheets. The storage compartments 110a, 110b, and 110c are configured to be pull-out from the front of the device. Sheets are fed one by one from each storage compartment 110a, 110b, and 110c by a separation belt and transport rollers (not shown) and transported to the print module 200. Note that the storage compartments 110a, 110b, and 110c are not limited to three, but may be one, two, or four or more.

[0013] The print module 200, an example of an image forming apparatus that forms an image on a sheet, includes a pre-image registration correction unit (not shown), a print belt unit 220, and a recording unit 230. The sheet transported from the paper feed module 100 has its tilt and position corrected by the pre-image registration correction unit and is then transported to the print belt unit 220. The recording unit 230 is positioned opposite the print belt unit 220 across the transport path. The recording unit 230 is a sheet processing unit that forms an image by performing a recording process (printing) on ​​the transported sheet from above using a recording head. Multiple recording heads are arranged along the transport direction. In this embodiment, in addition to the four colors Y (yellow), M (magenta), C (cyan), and Bk (black), there are a total of five line-type recording heads corresponding to the reaction solution. Note that the number of colors and recording heads are not limited to five.

[0014] The inkjet method can employ methods using heating elements, piezoelectric elements, electrostatic elements, MEMS elements, etc. Each color of ink is supplied to the recording head from an ink tank (not shown) via an ink tube. The sheet printed by the recording unit 230 is transported by a print belt unit 220, ensuring clearance with the recording head. The sheet printed by the recording unit 230 is detected for image misalignment and color density by an inline scanner (not shown) located downstream of the recording unit 230 in the transport direction. The detection results are used to correct the printed image. In this embodiment, the recording unit 230 is an example of an image forming unit.

[0015] The drying module 300 includes a decoupling section 320, a drying belt unit 330, and a hot air blowing section 340. It reduces the liquid component in the ink applied to the sheet by the recording section 230 of the print module 200, thereby improving the adhesion between the sheet and the ink. The sheet printed by the recording section 230 of the print module 200 is transported to the decoupling section 320 located within the drying module 300. In the decoupling section 320, the sheet can be transported by air pressure from above and friction of the belt. By loosely holding the sheet on the belt during transport, it prevents the sheet from shifting on the print belt unit 220, which forms the ink image. The drying belt unit 330 is located below the sheet being transported, and the hot air blowing section 340 is located above the sheet being transported, with the belt in between them.

[0016] The sheets conveyed from the decoupling unit 320 are transported by adsorption using the drying belt unit 330, and at the same time, the ink-applied surface is dried by hot air from the hot air blowing unit 340. In addition to the method of applying hot air, the drying method may also be configured by combining a method of irradiating the sheet surface with electromagnetic waves (such as ultraviolet or infrared rays) or a conductive heat transfer method by contact with a heating element.

[0017] The fixing module 400 has a fixing belt unit 410. The fixing belt unit 410 has an upper belt unit and a lower belt unit, and can fix the ink to the sheet by passing the sheet conveyed from the drying module 300 between the heated upper belt unit and the lower belt unit.

[0018] The cooling module 500 has a plurality of cooling parts 510 and cools the high-temperature sheet conveyed from the fixing module 400. The cooling part 510 is configured to take in outside air into the cooling box with a fan, increase the pressure in the cooling box, and blow the air ejected from the nozzles formed in the conveyance guide against the sheet to cool the sheet. The cooling parts 510 are arranged on both the upper side and the lower side with respect to the conveyance path, and cool the sheet from both sides.

[0019] Also, the cooling module 500 has a conveyance path switching part 520, and can switch the conveyance path of the sheet according to whether the sheet is conveyed to the reversing module 600 or conveyed to the duplex conveyance path used during duplex printing. During duplex printing, the sheet is conveyed to the conveyance path below the cooling module 500. In this case, the sheet is further conveyed along the duplex conveyance path of the fixing module 400, the drying module 300, the printing module 200, and the paper feeding module 100 from the cooling module 500. A first reversing part 420 for reversing the front and back of the sheet is provided in the duplex conveyance part of the fixing module 400. Then, it is conveyed to the pre-image registration correction part, the printing belt unit 220, and the recording part 230 of the printing module 200 again, and is printed by the recording part 230.

[0020] The reversing module 600 has a second reversing part 640, can reverse the front and back of the conveyed sheet, and can freely change the front and back orientation of the ejected sheet.

[0021] The paper discharge stacking module 700 has a top tray 720 and a stacking part 750, and aligns and stacks the sheets conveyed from the reversing module 600.

[0022] The control unit 10 includes a CPU, RAM, and ROM, and controls each part of the inkjet recording system 1000. Based on detection signals input from various sensors and information stored in ROM, the CPU outputs output signals to each electrical component to operate it at the desired timing and with the required control amount. ROM and RAM store information data necessary for controlling each part, and the CPU reads data from the information stored in ROM and writes data to RAM. In this embodiment, the control unit 10 may also control an external computer connected to the inkjet recording system 1000.

[0023] <Sheet transport unit> Sheet transport unit 1 and sheet transport unit 2 are located in the double-sided transport path below the print module 200. Sheet transport unit 1 and sheet transport unit 2 transport the sheets that have been image-formed and transported in the image forming unit back towards the image forming unit.

[0024] The sheet transport unit 1 and the sheet transport unit 2 are configured so that the sheet transport path can be released in case a sheet jams, allowing the user to remove the jammed sheet. In this embodiment, a print belt unit 220 and the like are positioned above the sheet transport unit 1 and the sheet transport unit 2, and there is not enough space to rotate the upper unit of the sheet transport unit upward relative to the lower unit. Therefore, the lower unit of the sheet transport unit is configured to rotate downward relative to the upper unit.

[0025] In this embodiment, sheet conveying unit 1 and sheet conveying unit 2 differ in the arrangement of rollers in the sheet conveying direction and in the unit width, but the configuration of the opening and closing mechanism of the sheet conveying unit is the same. Therefore, the opening and closing mechanism of the sheet conveying unit will be explained using sheet conveying unit 2.

[0026] Figure 2 shows a perspective view of the sheet conveying unit 2. Figure 3 shows a cross-sectional view of the sheet conveying unit 2 parallel to the sheet conveying direction. Figure 4 is a cross-sectional view of the sheet conveying unit viewed from the upstream side in the sheet conveying direction, perpendicular to the conveying direction.

[0027] The sheet conveying unit 2 comprises an upper unit 5 fixed to the main body of the device and a lower unit 6 positioned below the upper unit 5. Furthermore, the sheet conveying unit 2 comprises a gas spring 8, a first support member 12 fixed to the lower unit and supporting one end of the gas spring 8, a second support member 132 supporting the other end of the gas spring 8, and a cam lever 133 for moving the second support member.

[0028] The upper unit 5 includes an upper transport guide 41 for guiding the sheet being transported, a plurality of upper transport rollers 31, and an upper frame 51 that supports the upper transport guide 41 and the upper transport rollers. The lower unit 6 includes a lower transport guide 42 for guiding the sheet being transported, a plurality of lower transport rollers 32, and a lower frame 61 that supports the lower transport guide 42 and the lower transport rollers 32. When the sheet transport unit 2 is closed, the upper transport guide 41 and the lower transport guide 42 form a sheet transport path at a predetermined interval. As shown in Figure 3, a plurality of upper transport rollers 31 and lower transport rollers 32 are arranged in the sheet transport direction. The upper transport rollers 31 and lower transport rollers 32 form a transport roller pair, and the sheet is nipped by the upper transport rollers 31 and lower transport rollers 32 and transported along the transport direction D.

[0029] In this embodiment, the sheet conveying unit 2 is large, capable of conveying sheets with a size of B3. Furthermore, the frame 61 and other parts of the sheet conveying unit 2 are made of sheet metal. As a result, the sheet conveying unit 2 is very heavy, and when a user opens or closes the sheet conveying device 2 during jamming, the heavy lower unit 6 rotates with force, which is dangerous. In this embodiment, a gas spring 8 biases the lower unit 6 of the sheet conveying unit 2, reducing the operating force required when the user closes the lower unit 6 and cushioning the force with which the user opens the lower unit 6.

[0030] Figure 4 shows a cross-sectional view of the sheet conveying unit 2 with the lower unit in the closed position. Figure 5 shows the sheet conveying unit 2 with the lower unit in the open position. Figures 4 and 5 are cross-sectional views of the sheet conveying unit taken from the upstream side in the sheet conveying direction, perpendicular to the conveying direction.

[0031] One end of the gas spring 8 is pivotably supported on the first support member 12 via the first shaft 11, and the other end of the gas spring 8 is pivotably supported on the second support member 132 via the second shaft 131. In other words, the first shaft 11 connects one end of the gas spring 8 to the first support member 12, and the second shaft 131 connects the other end of the gas spring 8 to the second support member 132. As shown in Figure 3, the sheet conveying unit 2 has two gas springs 8 arranged parallel to the width direction of the sheet. E-shaped retaining rings 11a and 131a are provided at the ends of the first shaft 11 and the second shaft 131 as retaining members.

[0032] The lower unit 6 is rotatable and includes a hook 15 for hooking the lower unit 6 onto the upper unit, and a gripping part 14 for the user to grasp during jam processing. The hook 15 and the gripping part 14 are located on the front side of the lower unit 6. In this embodiment, the front side is the side on which the user stands when processing jam when the sheet conveying unit 2 is attached to the main body of the device (right side of Figure 5). In this embodiment, the back side is the side opposite to the side on which the user stands when processing jam (left side of Figure 5).

[0033] In Figure 4, the lower unit 6 is in a position where the upper transport guide 41 and the lower transport guide 42 are facing each other and parallel, and the upper transport roller 31 and the lower transport roller 32 nip together, allowing the sheet to be transported. In this embodiment, this position is defined as the closed position of the lower unit 6.

[0034] From the closed position of the lower unit 6 in Figure 4, the lower unit 6 is rotated downward around the rotation axis 7, and the lower transport guide 42 and lower transport roller 32 located on the lower unit 6 move away from the upper transport guide 41 and upper transport roller 31 located on the upper unit 5. As a result, a predetermined space is formed between the lower transport guide 42 and the upper transport guide 41, and between the lower transport roller 32 and the upper transport roller 31, allowing the user to remove the jammed sheet. This position is defined as the open position of the lower unit 6.

[0035] When a user performs jamming, they grasp the gripping part 14 and rotate the hook 15. Next, by rotating the gripping part 14 downwards, the sheet transport path is opened, and jamming of the sheet becomes possible. After the user removes the jammed sheet, they grasp the gripping part 14 and rotate the lower unit 6 upwards to close the lower unit 6, and then hook the hook 15 onto the upper unit 5 again. In this embodiment, the lower unit 6 can be stopped at any position between the open and closed positions.

[0036] The gas spring 8 biases the lower unit 6 in the direction of rotation, causing it to rotate from the open position to the closed position and close. This reduces the operating force required by the user when closing the lower unit 6 from the open position to the closed position, and also cushions the momentum of opening the lower unit 6 when opening it from the closed position to the open position.

[0037] <Gas spring support mechanism> In this embodiment, the lower unit 6 of the sheet transport unit is configured to rotate downward relative to the upper unit 5. In a downward-opening opening and closing unit, a large force is required to compress the gas spring 8 when attaching it, making assembly difficult.

[0038] In this embodiment, the rotating shaft 7 is located at the rear of the sheet conveying unit 2 and outside the sheet conveying path. The upper unit 5 has a rear frame 9 fixed to the upper frame 51. The rear frame 9 is located at the rear of the sheet conveying unit 2 and below the upper frame 51, and has a shaft 134. The gas spring 8 spans the rear frame 9 and the lower frame 61 of the lower unit 6 via the first support member 12 and the second support member 132.

[0039] The cam lever 133 has a cam surface 1331 that contacts a contact portion 1321 of the second support member 132, which will be described later. The cam lever 133 is pivotally supported on an axis 134 of the rear frame 9 and rotates around the axis 134. The second support member 132 has a contact portion 1321 that contacts the cam surface 1331 and an opening 1322 (Figure 8). The opening 1322 extends along the seat width direction, and the axis 134 passes through the opening 1322. That is, the axis 134 passes through the rear frame 9, the opening 1322 of the second support member, and the cam lever 133. Therefore, the second support member 132 is configured to slide in the seat width direction when assembling the gas spring, as the cam surface 1331 of the cam lever 133 contacts and presses against the contact portion 1321 of the second support member 132.

[0040] Next, the assembly of the gas spring 8 will be described. Figure 6 shows the state of the gas spring 8 during assembly. Figure 4 shows the state of the gas spring 8 after assembly. In this embodiment, the gas spring 8 is uncompressed during assembly, and compressed after assembly.

[0041] As shown in Figure 6, in the assembled state of the gas spring 8, the stroke is 0, meaning no reaction force is generated from the gas spring 8. This position of the second shaft 131 is designated as the first position. From this state, the user rotates the cam lever 133 upward. As the cam lever rotates by a predetermined angle, the cam surface 1331 is pressed against the contact portion 1321 of the second support member 132, causing the second support member 132 to slide in the seat width direction. As the second support member 132 slides due to the cam lever 133, the gas spring 8 is compressed to a predetermined stroke. This position of the second shaft 131 is designated as the second position. In other words, as the cam lever 133 rotates by a predetermined angle, the second shaft 131 of the second support member slides from the first position to the second position via the cam surface 1331 and is fixed in the second position. In this way, as the second shaft 131 moves from the first position to the second position, the gas spring 8 is compressed to a predetermined stroke, and the repulsive force of the gas spring 8 holds the lower unit 6 in the closed position.

[0042] In this embodiment, the gas spring 8 is an example of a biasing member, and the second support member 132 is an example of a moving member. However, in this embodiment, the cam surface 1331 presses against the contact portion 1321 of the second support member 132, causing the second support member 132 to move and compress the gas spring 8, but this is not limited to this. The other end of the gas spring 8 may be pivotably supported directly on the cam lever 133 via the second shaft 131, and the gas spring 8 may be compressed by the rotation of the cam lever.

[0043] Figure 7 shows the movement of the second shaft 131, with the second shaft 131 in its first position during assembly (Figure 6) and in its second position after assembly (Figure 4) placed side by side. By rotating the cam lever 133, the second shaft 131 moves from the first position to the second position by a distance S. This compresses the gas spring 8, supporting the closed position of the lower unit 6. Note that in the gas spring assembly shown in Figure 6 and the gas spring after assembly shown in Figure 4, the first shaft 11 is located at the far right of the slit 121 of the first support member 12 (Figure 7).

[0044] In this embodiment, the cam surface 1331 has a curved portion and a straight portion. Specifically, when the second support member 132 is in the first position, the curved portion of the cam surface 1331 abuts against the contact portion 1321, and when the second support member 132 is in the second position, the straight portion of the cam surface 1331 abuts against the contact portion 1321. In this way, when the second support member 132 is in the second position, the straight portion of the cam surface 1331 abuts against the straight-shaped contact portion 1321, thereby fixing the position of the second support member 132. That is, the cam lever 133 functions as a fixing means for fixing the second support member 132 in the second position. However, the invention is not limited to this, and when the second support member 132 is in the second position, the rear frame 9 and the second support member 132 may be fixed together with a fastening member.

[0045] Furthermore, when the lower unit 6 opens downwards, the position of the second shaft 131 remains in the second position. As a result, as the first shaft 11 rotates around the rotation axis 7 when the lower unit 6 opens downwards, the gas spring 8 is gradually compressed, and the repulsive force increases. This prevents the lower unit 6 from opening unexpectedly due to its own weight, allowing it to open safely.

[0046] Figure 8 shows the state of the gas spring before assembly as shown in Figure 6. In this embodiment, the gas spring 8 is installed in the state shown in Figure 8. The slit 121 of the first support member 12 extends along the sheet width direction. The slit 121 guides the first shaft 11, which supports one end of the gas spring 8, from the outside to the center in the sheet width direction.

[0047] As shown in Figure 8, before assembling the gas spring 8, the shaft 11 is attached to the slit 121 of the first support member 12 and one end of the gas spring 8, and the shaft 131 is attached to the second support member 132 and the other end of the gas spring 8. After attaching the shafts 11 and 131, the gas spring 8 and the second support member 132 are slid along the slit 121. Then, as shown in Figure 6, the cam lever 133 is attached to the second support member 132 in the first position. That is, the gas spring 8 is attached to the second support member 132 on the rear side of the frame 9 in the seat width direction, beyond the first position. Note that at this time, the gas spring 8 is not compressed.

[0048] Because the slit 121 extends along the width direction of the sheet, the gas spring 8 and the second support member 132 can be inserted from the back to the front of the sheet conveying unit 2, making installation easy. However, the first support member 12 may not have a slit 121, and a hole may be provided at the position where the first shaft 11 is located in the first support member 12 in Figure 6. In other words, the gas spring 8 may be attached with the second support member 132 in the first position.

[0049] The downward-opening sheet conveying unit 2 of this embodiment has a gas spring 8, which allows the user to easily operate the unit when closing it, as it provides sufficient force to counteract the weight of the unit and the reaction force of the roller pressure, resulting in comfortable operation. Furthermore, the gas spring 8 prevents the lower unit 6 from opening abruptly due to the unexpected opening of the opening / closing unit, making it safer for the user to operate and improving usability. In addition, no special tools are required to install or assemble the gas spring 8 that assists in opening and closing the unit in this embodiment, making installation and assembly easy and resulting in good maintainability.

[0050] In the embodiments described above, the case in which the image forming system is applied to an inkjet recording system 1 is described, but it is not limited to this and may also be applied to an electrophotographic image forming system.

[0051] In this embodiment, a gas spring is used as the biasing member, but this is not the only option. For example, a spring may be used as the biasing member.

[0052] In this embodiment, the first position was a state where the stroke of the gas spring 8 was 0, but this is not limited to this, and a stroke may occur at the first position. In other words, the first position is not limited to a position where no reaction force is generated by the biasing member, but a reaction force may occur at the first position. That is, when the other end of the biasing member is at the first position, the length of the biasing member is the first length, and when the other end is at the second position, the biasing member has a second length which is shorter than the first length, and the movable member is fixed when the other end is at the second position. The length of the biasing member is the distance from one end to the other end of the biasing member.

[0053] In other words, when the other end of the biasing member is in the first position, the amount of contraction of the biasing member is the first amount of contraction, and when the other end of the biasing member is in the second position, the amount of contraction of the biasing member is the second amount of contraction, which is greater than the first amount of contraction, and the movable member is fixed when the other end is in the second position. [Explanation of Symbols]

[0054] 5 Upper unit 6 Lower unit 8 Gas springs 9. Rear frame 12 First support member 132 Second support member 133 Cam lever

Claims

1. An upper unit fixed to the main body of the device, which includes an upper transport guide that forms a transport path through which the sheets are transported, A lower unit is provided, which is positioned below the upper unit and includes a lower transport guide that, together with the upper transport guide, forms a transport path through which the sheet is transported, and which is rotatable downward relative to the upper unit. A biasing member is supported at one end of the lower unit so as to be swingable, and biases the lower unit when it is retracted, A moving member that pivotably supports the other end of the biasing member and moves the other end from a first position to a second position, Equipped with, When the other end is in the first position, the biasing member has a first length; when the other end is in the second position, the biasing member has a second length which is shorter than the first length; and the movable member is fixed with the other end in the second position. A sheet conveying device characterized by the following features.

2. The biasing member is a gas spring. The sheet conveying device according to feature 1.

3. The gas spring supports the lower unit by biasing it in the closing direction when its other end is in the second position, and cushions the opening of the lower unit when it is rotated from the closed position to the open position. The sheet conveying device according to feature 2.

4. The other end of the biasing member is positioned below the lower unit. The sheet conveying device according to feature 1.

5. The moving member has a rotatable cam that contacts the moving member, As the cam rotates, the other end moves from the first position to the second position. The sheet conveying device according to feature 1.

6. The cam has a lever portion that is grasped by the user. The sheet conveying device according to feature 5.

7. The cam has a curved portion and a straight portion. As the cam rotates with the curved portion of the cam in contact with the moving member, the other end moves from the first position to the second position. The straight portion of the cam comes into contact with the moving member, thereby fixing the other end to the second position. The sheet conveying device according to feature 5.

8. The upper unit comprises the upper transport guide and the upper transport roller. The lower unit comprises the lower transport guide and the lower transport roller. With the lower unit in the closed position, the sheet to be transported is nipped by the upper and lower transport rollers, and the sheet is transported. The sheet conveying device according to feature 1.

9. It has a rear frame that is fixed to the upper unit and positioned at the rear of the main body of the device, The moving member moves in the seat width direction relative to the rear frame. The sheet conveying device according to feature 1.

10. The other end of the biasing member is connected to the movable member, and the end of the shaft that pivotably supports the biasing member is fitted with a retaining mechanism, The retaining element is attached with the other end in the first position. The sheet conveying device according to feature 1.

11. The lower unit has a support member that pivotably supports one end of the biasing member, The support member has a slit that extends along the width direction of the sheet, The slit guides one end of the biasing member from the outside to the center in the sheet width direction. The sheet conveying device according to feature 1.

12. The lower unit is equipped with a gripping portion that is held by the user when opening and closing the lower unit. The sheet conveying device according to feature 1.

13. The sheet transport device is arranged in a double-sided transport path that transports the sheet, which has an image formed on it in the image forming unit, back to the image forming unit. The sheet conveying device according to feature 1.

14. A sheet conveying device according to claim 1, An image forming unit that forms an image on a sheet, An image forming apparatus characterized by having the following features.

Images