Sheet discharging device and image forming apparatus

Abstract

To provide a sheet discharge device having functions of detecting the sheet and supporting the sheet under inversion transportation, with a compact structure in the height direction.SOLUTION: A sheet discharge device has a loading part for loading sheets, inversion means transporting the sheet in the second transportation direction opposite to a first transportation direction after projecting the sheet to the first transportation direction from a device body, a support member supporting an undersurface of the sheet transported by the inversion means, discharge means discharging the sheet from the device body, an upward turning member arranged above the loading part, positioned under the support member in a state not abutting on the sheet and turning upward by abutting of the sheet, and a detection part structured to allow detection signal to change according to a turning angle of the turning member. When seen in the sheet width direction perpendicular to the first transportation direction, a part of a turning locus of the turning member overlaps on the support member.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a sheet discharging device that discharges sheets and an image forming device that forms images on sheets.

Background Art

[0002] Image forming devices such as printers, copiers, and multifunction devices form images on sheets, which are recording media, and then discharge the sheets outside the device body and stack them on a stacking unit such as a discharge tray. In addition, an image forming device having a function of forming images on both sides of a sheet is provided with a reversing mechanism that performs sheet reverse conveyance (switchback) in order to convey the sheet on which an image has been formed on the first side back to the image forming unit again to form an image on the second side.

[0003] As a reversing mechanism, after protruding a sheet from the device body toward the space above the discharge tray by a pair of reversing rollers, the pair of reversing rollers is reversed before the rear end of the sheet passes through the pair of reversing rollers to reverse the conveyance direction of the sheet. Patent Document 1 describes an image forming device provided with a support member (reversing tray) that supports a part of the sheet protruding from the device body from below to prevent the sheet from sagging during reverse conveyance by a pair of reversing rollers.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the configuration described in the above document, a full-load detection flag for detecting that the discharge tray is in a full-load state is disposed above the discharge tray and below the support member. However, the fact that the full-load detection flag and the support member are arranged vertically one above the other has been an obstacle to downsizing the image forming apparatus in the height direction. Further, for example, if the position of the support member is moved downward in an attempt to reduce the size in the height direction, the position of the full-load detection flag also moves downward, resulting in a limitation on the loading amount of sheets that can be loaded on the discharge tray. Therefore, it has been required to achieve a compact configuration in the height direction and realize a function of detecting sheets and a function of supporting sheets during reverse conveyance. It has been required to arrange them.

[0006] Therefore, an object of the present invention is to provide a sheet discharge device and an image forming apparatus capable of realizing a function of detecting sheets and a function of supporting sheets during reverse conveyance with a compact configuration in the height direction.

Means for Solving the Problems

[0007] One aspect of the present invention includes a loading unit on which sheets discharged from the apparatus main body are loaded, a reversing unit that projects a sheet from the apparatus main body in a first conveyance direction toward a space above the loading unit and then conveys the sheet in a second conveyance direction opposite to the first conveyance direction, a support member that is disposed above the loading unit so as to project downstream in the first conveyance direction from the apparatus main body and supports the lower surface of the sheet conveyed by the reversing unit, a discharging unit that discharges sheets from the apparatus main body and is arranged such that the discharged sheets pass below the support member, a rotating member that is disposed above the loading unit, is positioned below the support member when not in contact with the sheet, and rotates upward when in contact with the sheet, and a detection unit configured such that a detection signal changes according to the rotation angle of the rotating member. A regulating portion that abuts on the rotating member and regulates the rotating member from protruding upward from the support member; A sheet discharge device characterized in that, when viewed in the sheet width direction perpendicular to the first conveyance direction, a part of the rotation locus of the rotating member overlaps with the support member.

Effects of the Invention

[0008] According to the present invention, it is possible to realize a function of detecting a sheet and a function of supporting a sheet during reverse conveyance with a compact configuration in the height direction.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings.

[0011] <First Embodiment> The overall configuration of the printer 100 as an image forming apparatus according to the first embodiment will be described with reference to FIG. 1. As shown in FIG. 1, the printer 100 is an electrophotographic laser beam printer having an image forming unit 102 that forms an image on a sheet S, a sheet feeding device 113, a fixing device 96, and a sheet discharging device 118. When an execution instruction (print instruction) for image formation including image information is input from an external device (not shown) to the controller 103, the printer 100 forms an image based on the image information on the sheet S and discharges it as a finished product. As the sheet S as a recording material, various sheet materials with different sizes and materials can be used, such as paper such as plain paper and thick paper, plastic film, cloth, sheet materials with surface treatment such as coated paper, and special-shaped sheet materials such as envelopes and index paper.

[0012] The image forming unit 102 as an image forming means includes four process cartridges 7a, 7b, 7c, and 7d that form toner images of four colors: yellow, magenta, cyan, and black, and a scanner unit 3 as an exposure device. These four process cartridges 7a, 7b, 7c, and 7d are arranged side by side in a substantially horizontal direction.

[0013] Note that the four process cartridges 7a, 7b, 7c, and 7d have substantially the same configuration except that the colors of the toner used for forming the toner image are different. Each of the process cartridges 7a to 7d has a photosensitive drum 1, a charging roller 2, a developing unit 4, a toner unit 5, and a drum cleaning blade 8. The photosensitive drum 1 as an image carrier is an electrophotographic photoreceptor formed in a drum shape. The photosensitive drum 1 is a member in which an organic photoconductive layer is formed on the outer periphery of, for example, an aluminum cylinder, and rotates in the clockwise direction in the figure by a drive motor (not shown). The developing unit 4 has a developing roller 40 and a developer coating roller 40a, and is connected to the toner unit 5. The toner unit 5 contains a developer containing toner.

[0014] Above the process cartridges 7a to 7d, an intermediate transfer belt 108 as an intermediate transfer member is disposed. The intermediate transfer belt 108 is stretched between a driving roller 110 and a secondary transfer opposing roller 109, and is conveyed in the counterclockwise direction in the figure by the rotation of the driving roller 110. Inside the intermediate transfer belt 108, primary transfer rollers 112 are disposed at positions facing the respective photosensitive drums 1 with the intermediate transfer belt 108 therebetween. Also, a secondary transfer roller 116 is disposed at a position facing the secondary transfer opposing roller 109 with the intermediate transfer belt 108 therebetween. The intermediate transfer belt 108 and the secondary transfer roller 116 form a secondary transfer nip as a transfer portion (secondary transfer portion 115) where an image is transferred to the sheet S. The fixing device 96 is a heat fixing type fixing unit using a heating means such as a ceramic heater or a halogen lamp in which a heating resistor is disposed on a ceramic substrate. The fixing device 96 of the present embodiment includes a fixing roller 96a heated by a heater and a pressure roller 96b pressed against the fixing roller 96a. The sheet feeding device 113 is provided below the printer 100 and houses the sheet S.

[0015] The sheet discharging device 118 includes a flap-shaped switching member 31, a pair of discharging rollers 21 as discharging means provided in the discharging path R1, a pair of reversing rollers 34 as reversing means provided in the reversing path R2, and a discharging tray 121. The switching member 31 is a member that switches the conveyance path of the sheet S between the discharging path R1 and the reversing path R2. The discharging tray 121 as a stacking portion is provided on the upper surface of the apparatus main body 101 of the printer 100.

[0016] Further, the printer 100 includes a controller 103 as control means for controlling the operation of the printer 100. The controller 103 includes a storage device such as a ROM that stores a control program and data for controlling the printer 100, and a CPU that reads and executes the control program from the storage device. The controller 103 executes an image forming operation described below and performs control based on, for example, a detection signal from a full-load detection sensor 26 described later. Further, the controller 103 receives display of information via a screen of an operation panel as a user interface (operation unit) provided in the printer 100, and setting operations for the printer 100 via the operation panel.

[0017] Next, the image forming operation of the printer 100 configured as described above will be described. When a print instruction is input from an external device to the controller 103, the photosensitive drum 1 and the intermediate transfer belt 108 are driven, and an image signal (video signal) based on the image information is transmitted to the scanner unit 3. The scanner unit 3 irradiates the photosensitive drum 1 of each process cartridge 7a to 7d with laser light modulated based on the image signal. The surface of the photosensitive drum 1 is uniformly charged to a predetermined polarity and potential in advance by a charging roller 2. An electrostatic latent image is formed on the surface of the photosensitive drum 1 by irradiation with laser light from the scanner unit 3. The electrostatic latent image formed on the photosensitive drum 1 is developed by the developing unit 4, and a toner image is formed on the photosensitive drum 1. In the developing unit 4, toner as a developer is applied to the developing roller 40 by a developer application roller 40a with a uniform thickness, and the toner is supplied from the developing roller 40 to the photosensitive drum 1, so that the electrostatic latent image is developed as a toner image.

[0018] The above-described image forming process proceeds in parallel in each of the process cartridges 7a to 7d, and yellow, magenta, cyan, and black toner images are formed on the four photosensitive drums 1. The toner images formed on each photosensitive drum 1 are transferred to the intermediate transfer belt 108 by the primary transfer roller 112 and conveyed to the secondary transfer roller 116 by the intermediate transfer belt 108 conveyed by the driving roller 110. Note that the image forming processes for the respective colors are synchronized so that the downstream toner image overlaps the upstream toner image primarily transferred onto the intermediate transfer belt 108. Further, after the toner image is transferred, the toner remaining on the surface of the photosensitive drum 1 is removed by the drum cleaning blade 8.

[0019] In parallel with this image forming process, the sheet S accommodated in the cassette 111 of the sheet feeding device 113 is fed out by the pickup roller 9 and separated one by one by the separation roller pair 10. The separation roller pair 10 includes a conveyance roller that conveys the sheet S and a separation roller that abuts against the conveyance roller to form a separation nip and applies a frictional force to the sheet S to prevent double feeding of the sheet S. Note that the separation roller may be configured such that a driving force in a direction opposite to the rotation of the conveyance roller is input via a torque limiter, or the sheet S may be separated by a pad-shaped friction member instead of the separation roller.

[0020] The skew of the sheet S sent out from the separation roller pair 10 is corrected by the registration roller pair 117. Further, the registration roller pair 117 conveys the sheet S to the secondary transfer unit 115 at a timing synchronized with the image forming process in the image forming unit 102. Then, by applying a transfer voltage to the secondary transfer roller 116, the toner image on the intermediate transfer belt 108 is transferred to the sheet S in the secondary transfer unit 115. The sheet S onto which the toner image has been transferred is subjected to a fixing process in which heat and pressure are applied to the toner image on the sheet S while being nipped and conveyed by the fixing roller 96a and the pressure roller 96b of the fixing device 96.

[0021] In the case of single-sided printing, the sheet S that has passed through the fixing device 96 is guided to the discharge path R1 by the switching member 31 and discharged to the discharge tray 121 as a stacking unit by the discharge roller pair 21. When forming images on both sides of the sheet S, the sheet S with an image formed on the first side is guided to the reverse path R2 by the switching member 31. After the trailing edge of the sheet S has passed through the switching member 31, it is reversely conveyed (switched back) by the reverse roller pair 34, guided by the switching member 31, and conveyed to the double-sided conveyance path R3. As a result, the sheet S is conveyed again toward the secondary transfer unit 115 in a state where the front end and the trailing edge are swapped, and the first side and the second side are swapped. Thereafter, the sheet S has an image transferred to the second side in the secondary transfer unit 115, undergoes a fixing process in the fixing device 96, and is then discharged to the discharge tray 121 by the discharge roller pair 21.

[0022] Note that the above-described image forming unit 102 is an example of an image forming means, and a direct transfer type image forming unit that transfers the toner image formed on the image carrier to the sheet S without passing through an intermediate transfer body may be used. Further, instead of the electrophotographic method, the configuration of the sheet discharge device described below may be applied to an image forming apparatus equipped with an image forming unit such as an inkjet method or an offset printing method as an image forming means.

[0023] [Sheet Discharge Device] Next, the sheet discharge device 118 will be described in detail. FIGS. 2(a, b) are perspective views of the sheet discharge device 118. FIG. 2(a) shows a state in which the full-load detection flag 24 described later is located at the home position, and FIG. 2(b) shows a state in which the full-load detection flag 24 has rotated upward from the home position. FIG. 3 is a side view of the sheet discharge device 118 viewed from the downstream side in the sheet discharge direction D1 (see FIG. 1). FIG. 4 is a cross-sectional view showing a cross-section of the sheet discharge device 118 cut by a plane perpendicular to the sheet width direction D3 at the cutting position indicated by line IV-IV in FIG. 3.

[0024] As shown in FIG. 4, in addition to the discharge tray 121, the discharge roller pair 21, the reverse roller pair 34, and the switching member 31 described above, the sheet discharge device 118 includes a reverse tray 22, a full-load detection flag 24, a full-load detection sensor 26, and a top cover 23.

[0025] In the following description, among the conveyance directions of the sheet by the discharge roller pair 21 and the reverse roller pair 34, the direction in which the sheet is discharged toward the discharge tray 121 (the left direction in FIGS. 1 and 4) is defined as the "sheet discharge direction D1", and the opposite direction is defined as the "reverse direction D2". The horizontal direction orthogonal to the sheet discharge direction D1 and the reverse direction D2 is defined as the "sheet width direction D3". Also, the vertical direction when the printer 100 is installed on a horizontal plane is defined as the "up-down direction D4". The sheet width direction D3 is also the main scanning direction (the direction of the rotation axis of the photosensitive drum 1) of the image forming process by the image forming unit 102. The up-down direction D4 can also be said to be the thickness direction of the sheet being nipped and discharged by the discharge roller pair 21. The sheet discharge direction D1 is the direction (the first conveyance direction) in which the reverse roller pair 34 as a reversing means projects the sheet from the apparatus main body toward the space above the stacking unit, and the reverse direction D2 is the second conveyance direction opposite to the first conveyance direction.

[0026] As shown in FIG. 3, the discharge roller pair 21 has a plurality of first rollers 21a and a plurality of second rollers 21b fixed to two drive shafts 21c and 21d extending in the sheet width direction D3, respectively. The discharge roller pair 21 as the first roller pair has three first rollers 21a and four second rollers 21b arranged alternately in the sheet width direction D3. The first roller 21a and the second roller 21b slightly overlap each other in the up-down direction D4. That is, when viewed in the sheet width direction D3, the outer peripheral surface of the first roller 21a and the outer peripheral surface of the second roller 21b partially overlap (FIG. 4). For this reason, when passing through the discharge roller pair 21, the sheet S3 is in a state of being curved in a wave shape when viewed from the downstream side in the sheet discharge direction D1. That is, the discharge roller pair 21 as the first roller pair is configured such that the sheet sent out from the first roller pair is in a state of undulating in the up-down direction along the sheet width direction when viewed from the downstream side in the first conveyance direction.

[0027] Due to such corrugations, the bending stiffness of the sheet S3 increases (it becomes more rigid), so that the leading end (free end) of the sheet S3 fed out from the discharge roller pair 21 is less likely to hang downward. As a result, it is possible to suppress the sagging sheet S3 from rubbing against the sheet S1 already loaded on the discharge tray 121 and disturbing its alignment, and improve the sheet loading property on the discharge tray 121. Note that the discharge means capable of discharging while making the sheet S3 more rigid is not limited to this. For example, the first roller 21a and the second roller 21b of the discharge roller pair 21 may be arranged in contact with each other, and a pressing member (rigidifying member) for pressing the sheet S3 upward or downward between the first rollers 21a arranged in the sheet width direction D3 may be provided.

[0028] As shown in FIG. 4, the discharge tray 121 is provided on the upper surface (outer surface) of the apparatus main body 101, and at least a part of the discharge tray 121 is configured as an inclined surface inclined upward toward the downstream in the sheet discharge direction D1. Further, the apparatus main body 101 has a rear end regulating surface 122 that rises upward from the upstream end of the discharge tray 121 in the sheet discharge direction D1. The rear end regulating surface 122 extends in the vertical direction D4 and the sheet width direction D3 between the opening (discharge port 41) through which the sheet S3 discharged by the discharge roller pair 21 passes in the vertical direction D4 and the discharge tray 121. With such a configuration, the sheet S3 discharged onto the discharge tray 121 by the discharge roller pair 21 slides upstream in the sheet discharge direction D1 along the inclination of the discharge tray 121 due to its own weight and is aligned by contacting the rear end regulating surface 122.

[0029] The reversing roller pair 34 is located inside the apparatus main body 101 (upstream side in the sheet discharge direction D1) compared to the discharge roller pair 21, and is disposed upstream of the rear end regulating surface 122 in the sheet discharge direction D1. The reversing path R2 passes above the discharge path R1 and opens to the outside of the apparatus main body 101 at an opening (reversing port 42) above the discharge port 41. The reversing port 42 is a space through which the sheet S2 formed under the top cover 23 on the extension line of the rear end regulating surface 122 can pass. The reversing roller pair 34 as the reversing means can convey the sheet S2 in the sheet discharge direction D1 as the first conveyance direction and the reversing direction D2 as the second conveyance direction opposite to the first conveyance direction. As the reversing roller pair 34, a roller pair (second roller pair) that sandwiches and conveys the sheet with a nip portion where the outer peripheral surfaces contact each other can be used. Since the sagging of the sheet protruding from the apparatus main body 101 during reverse conveyance is regulated by the following reversing tray 22, there is little need for the reversing roller pair 34 to perform sheet backing. By using a roller pair with outer peripheral surfaces that contact each other as the reversing roller pair 34, there is an advantage that skewing of the sheet is less likely to occur during reverse conveyance.

[0030] The reversing tray 22 protrudes downstream in the sheet discharge direction D1 from the apparatus main body 101 above the discharge port 41. For this reason, the discharge roller pair 21 is arranged such that the discharged sheet passes under the reversing tray 22 as a support member. The reversing tray 22 protrudes at least downstream of the rear end regulating surface 122 in the sheet discharge direction D1. Above the reversing tray 22, a top cover 23 that forms a part of the upper surface of the apparatus main body 101 is provided. The top cover 23 is provided along the reversing tray 22 above the reversing tray 22 and covers the upstream portion of the reversing tray 22 in the sheet discharge direction D1 from above.

[0031] The downstream portion of the reversing tray 22 in the sheet discharge direction D1 protrudes in the sheet discharge direction D1 beyond the downstream end of the top cover 23 and is exposed from the top cover 23 when viewed from above. That is, the reversing tray 22 as a support member protrudes further downstream than the downstream end of the first cover member in the first conveyance direction. Also, when viewed in the sheet width direction, the reversing tray 22 is inclined upward toward the downstream in the sheet discharge direction D1 on the downstream side of the downstream end of the top cover 23 in the sheet discharge direction D1. With such a configuration, while using the reversing tray 22 having an inclination capable of effectively suppressing the sagging of the sheet, the height of the top cover 23 can be made as low as possible to reduce the size of the printer 100 in the height direction. As an example, the height of the lower surface (guide surface of the reversing path R2) of the top cover 23 at the downstream end in the sheet discharge direction D1 may be set to be equal to or lower than the height of the upper end (the following tip portion 22a) of the reversing tray 22. Note that the top cover 23 may be configured to cover the entire reversing tray 22 and the following full-load detection flag 24 from above.

[0032] The full-load detection flag 24 rotates about a rotation shaft 25 extending in the sheet width direction D3 between the discharge roller pair 21 and the reversing tray 22 as shown in FIG. 4. The full-load detection flag 24 is disposed above the discharge tray 121 as a stacking portion, and is a rotating member that is located below the reversing tray 22 as a support member when not in contact with the sheet and rotates upward when brought into contact with the sheet. The full-load detection sensor 26 is a detection unit configured such that a detection signal changes according to the rotation angle of the full-load detection flag 24. As the full-load detection sensor 26, for example, a photo sensor (photo interrupter) in which a voltage value as a detection signal changes by being blocked by a light-shielding portion (flag) attached to the end of the rotation shaft 25 of the full-load detection flag 24 can be used.

[0033] The controller 103 (FIG. 1) as the control means determines the full state of the discharge tray 121 based on the detection signal of the full-load detection sensor 26. That is, as the sheet S1 is loaded on the discharge tray 121, the full-load detection flag 24 is pressed by the uppermost sheet of the loaded sheets S1, and the full-load detection flag 24 rotates clockwise in the drawing upward around the rotation axis 25. When the full-load detection flag 24 rotates by a predetermined angle or more from the home position, the detection signal output by the full-load detection sensor 26 is switched, and a signal indicating that the discharge tray 121 is in the full state is output. In other words, the position of the full-load detection flag 24 at which the detection signal of the full-load detection sensor 26 is switched defines the loading amount (maximum loading amount) of the sheet S1 that can be loaded on the discharge tray 121 in the present embodiment. When the controller 103 detects that the discharge tray 121 is full, it interrupts the ongoing image forming operation, issues a screen display, an audio alert, etc. on the operation panel, and notifies the user of information prompting the removal of the sheet S1 from the discharge tray 121.

[0034] Also, in the present embodiment, the full-load detection flag 24 and the full-load detection sensor 26 are also used for the purpose of monitoring the discharge of the sheet S3 by the discharge roller pair 21. That is, when the sheet S3 is normally discharged by the discharge roller pair 21, the full-load detection flag 24 rotates by the sheet S3 at a predetermined timing, and the detection signal of the full-load detection sensor 26 changes. The predetermined timing is the timing at which the full-load detection flag 24 should rotate by a predetermined angle or more by the sheet S3 when the conveyance of the sheet S3 proceeds normally based on the time point when the sheet S3 is detected by a sensor upstream of the discharge roller pair 21.

[0035] When the discharge tray 121 is not in a full-load state, the full-load detection flag 24 returns to the home position during the period (so-called paper interval) from when the discharge roller pair 21 completes the discharge of the preceding sheet until the discharge of the subsequent sheet starts. When the discharge tray 121 is not in a full-load state, the full-load detection sensor 26 outputs a detection signal indicating that it is detecting the sheet while the sheet S3 is being discharged from the discharge roller pair 21, and outputs a detection signal indicating that it is not detecting the sheet during the paper interval. The home position is the position (a position positioned by its own weight, a lower position) when the full-load detection flag 24 is not in contact with either the sheet S3 being discharged or the stacked sheet S1.

[0036] The controller 103 as the control means determines a jam of the sheet S3 based on the detection signal of the full-load detection sensor 26. Specifically, when the detection signal of the full-load detection flag 24 does not change to a state of detecting the sheet even after the elapse of the above-described predetermined timing, the controller 103 determines that a conveyance failure (jam) of the sheet has occurred. When the controller 103 detects a jam of the sheet, it interrupts the ongoing image forming operation, issues a screen display and an audio alert on the operation panel, and notifies the user of information prompting the removal of the jammed sheet in a predetermined procedure.

[0037] [Shape of the reversing tray] As shown in FIGS. 2(a, b), 3, and 4, the inversion tray 22 as a support member is formed to slope upward toward the tip portion 22a. That is, at least a part (downstream portion, tip portion) of the inversion tray 22 slopes upward toward the downstream of the sheet discharge direction D1. The inversion tray 22 is formed in a trapezoidal shape in a range including the central position X0 (FIG. 3) of the discharge roller pair 21 in the sheet width direction D3, where the side on the tip side is shorter than the side on the base end side (device main body 101 side). Among the inversion tray 22, the central portion 22b including the tip portion 22a protrudes toward the top cover 23 side (that is, upward). Note that the central position X0 of the discharge roller pair 21 in the sheet width direction D3 is the intermediate position between the end position on one side and the end position on the other side in the sheet width direction D3 within the range where any of the plurality of first rollers 21a and the plurality of second rollers 21b contacts the sheet.

[0038] Further, an opening hole 22c having a substantially triangular shape is provided in the central portion 22b of the inversion tray 22. The opening hole 22c is an opening that forms a space penetrating from the upper surface to the lower surface of the inversion tray 22. Also, the opening hole 22c is a hole surrounding the central protruding portion 24a of the following full-load detection flag 24. The inversion tray 22 includes protruding portions that protrude toward the downstream side in the sheet discharge direction D1 on both sides of the opening hole 22c in the sheet width direction D3, and a connecting portion that connects these protruding portions in the sheet width direction D3 on the downstream side of the opening hole 22c in the sheet discharge direction D1. The opening hole 22c has a hole shape surrounded by these protruding portions and the connecting portion.

[0039] The central portion 22b of the reversing tray 22 supports the lower surface of the sheet S2 while sliding on the sheet S2 that is reversely conveyed by the reversing roller pair 34, and restricts the leading end portion of the sheet S2 in the sheet discharge direction D1 from hanging down due to its own weight. At this time, since the reversing tray 22 is arranged in the central region in the sheet width direction D3 and is inclined upward toward the downstream in the sheet discharge direction D1, the sagging of the sheet S2 during reverse conveyance is more effectively restricted. That is, the sheet S2 supported by the lower surface at the central portion 22b of the reversing tray 22 is in a curved state where the central portion in the sheet width direction D3 bulges upward, and the bending rigidity (stiffness) in the direction along the sheet discharge direction D1 is improved.

[0040] [Shape of full-load detection flag] Next, the shape of the full-load detection flag 24 will be described. As shown in FIG. 3, the full-load detection flag 24 has a central protruding portion 24a located at the central portion in the sheet width direction D3, and side protruding portions 24b and 24c located at both end portions in the sheet width direction D3. These central protruding portion 24a and side protruding portions 24b and 24c protrude radially outward (downstream side in the sheet discharge direction D1) from the rotation shaft 25.

[0041] The central protruding portion 24a is an inner portion of the rotating member according to the present embodiment provided at a position corresponding to the opening hole 22c of the reversing tray 22 in the sheet width direction D3. The central protruding portion 24a is formed in a shape similar to but slightly smaller than the opening hole 22c of the reversing tray 22. That is, the inner portion of the rotating member has a shape similar to the opening of the support member, and the outer periphery of the inner portion is configured to face the inner periphery of the opening with a predetermined gap therebetween.

[0042] The side protruding portions 24b and 24c are outer portions of the rotating member according to the present embodiment provided on both outer sides of the support member in the sheet width direction. The side protruding portions 24b and 24c of the present embodiment are formed in a rectangular shape when viewed from above.

[0043] Also, as shown in FIG. 3, a stopper 49 is provided in the apparatus main body 101 as a restricting portion that restricts the rotation of the full-load detection flag 24. The stopper 49 abuts against a protrusion 24d provided on the rotation shaft 25 of the full-load detection flag 24, thereby restricting the full-load detection flag 24 from rotating upward beyond a predetermined upper limit position (upper position) and protruding above the inversion tray 22. The upper limit position of the full-load detection flag 24 shall be at least the same as or higher than the position where the detection signal of the full-load detection sensor 26 switches. Note that the position and shape of the stopper 49 are merely examples, and can be appropriately changed as long as the rotation of the full-load detection flag 24 can be restricted at a predetermined upper limit position. For example, a protrusion provided integrally with the central protrusion 24a of the full-load detection flag 24 may abut against the lower surface of the inversion tray 22.

[0044] When the full-load detection flag 24 is positioned at the home position, as shown in FIG. 4, the central protrusion 24a or the side protrusions 24b, 24c of the full-load detection flag 24 are positioned below the inversion tray 22. When the stacking amount of the sheet S1 in the discharge tray 121 increases and the central protrusion 24a or the side protrusions 24b, 24c are pushed up by the stacked sheet S1, the full-load detection flag 24 rotates upward from the home position. Also, when the sheet S3 is discharged by the discharge roller pair 21, the full-load detection flag 24 is pushed up by the discharged sheet S3 and rotates upward from the home position (FIG. 5). When the protrusion 24d of the full-load detection flag 24 abuts against the stopper 49, the upward rotation of the full-load detection flag 24 is restricted, and the full-load detection flag 24 is held at an upper limit position where it does not protrude above the inversion tray 22.

[0045] As shown in FIG. 5, at least when the full-load detection flag 24 is in the upper limit position, when viewed in the sheet width direction D3, the central protrusion 24a and the side protrusions 24b, 24c of the full-load detection flag 24 overlap the inversion tray 22. Also, when the full-load detection flag 24 is in the upper limit position, the upper surface of the full-load detection flag 24, together with the upper surface of the inversion tray 22, forms substantially the same plane.

[0046] Also, in a state where the full-load detection flag 24 is positioned at the upper limit position, the central protruding portion 24a of the full-load detection flag 24 enters the opening hole 22c of the inversion tray 22. That is, in the present embodiment, the support member is provided with an opening that penetrates the support member in the vertical direction, and the rotating member has an inner portion that enters the inside of the opening in a state where the rotating member overlaps the support member when viewed in the sheet width direction. In this state, the central protruding portion 24a of the full-load detection flag 24 closes at least a part of the opening region of the opening hole 22c of the inversion tray 22, and it is possible to suppress the water vapor coming out from the discharge port from escaping to the upper surface side of the inversion tray 22. By making it difficult for the water vapor to escape to the upper surface side of the inversion tray 22, it is possible to reduce the possibility that the sheet reversely conveyed by the inversion roller pair 34 gets wet and image defects occur during the formation of the image on the second surface.

[0047] Further, the central protruding portion 24a of the full-load detection flag 24 has a shape similar to the opening hole 22c of the inversion tray 22 and is formed to be slightly smaller than the opening hole 22c. That is, the inner portion of the rotating member has a shape similar to the opening of the support member, and the outer periphery of the inner portion is formed to face the inner periphery of the opening with a predetermined gap therebetween. Thereby, while effectively suppressing the water vapor from escaping to the upper surface side of the inversion tray 22, it is possible to reduce the possibility that the full-load detection flag 24 comes into contact with the inversion tray 22 when it rotates upward and generates a sudden sound (collision sound). The predetermined gap is a margin set so that the central protruding portion 24a does not contact the opening hole 22c in consideration of component tolerances, assembly tolerances, etc.

[0048] (Summary of this embodiment) As described above, as shown in FIG. 5, at least when the full-load detection flag 24 is located at the upper limit position, when viewed in the sheet width direction D3, the central protruding portion 24a and the side protruding portions 24b and 24c of the full-load detection flag 24 overlap the reverse tray 22. That is, in the present embodiment, when viewed in the sheet width direction perpendicular to the first conveyance direction, a part of the rotation locus of the rotating member overlaps the support member. In this way, in the present embodiment, the vertical positions of the rotating member for detecting the sheet and the support member for supporting the sheet during reverse conveyance are arranged to allow partial overlap. As a result, it is possible to realize a function of detecting a sheet and a function of supporting a sheet during reverse conveyance with a compact configuration in the height direction.

[0049] As a comparative example, assume a printer in which the entire rotation locus of the full-load detection flag 24 is located below the reverse tray 22 when viewed in the sheet width direction D3. Compared with this comparative example, by applying the configuration of the present embodiment, for example, the position of the reverse tray 22 can be moved downward while maintaining the position of the full-load detection flag 24. In this case, by moving the top cover 23 etc. downward in accordance with the reverse tray 22, it is possible to reduce the size of the printer in the height direction (vertical direction). At this time, since the position of the full-load detection flag 24 does not change, the loading amount of the sheet S1 that can be loaded on the discharge tray 121 does not decrease. Also, if the position of the full-load detection flag 24 is moved upward while maintaining the position of the reverse tray 22 compared with the comparative example, it is possible to increase the loading amount of the sheet S1 that can be loaded on the discharge tray 121 without increasing the size of the printer. That is, with the configuration of the present embodiment, it is possible to achieve both miniaturization of the image forming apparatus in the height direction (vertical direction) and the loading amount of sheets in the loading section.

[0050] Also, when the full-load detection flag 24 is located at the upper limit position, the upper surface of the full-load detection flag 24, together with the upper surface of the reverse tray 22, substantially constitutes the same surface. In other words, in the present embodiment, in a state where the rotating member is in contact with the regulating portion, the upper surface of the rotating member and the upper surface of the support member overlap when viewed in the sheet width direction.

[0051] In addition, during double-sided printing, the trailing end of the sheet S2 (the leading end in the sheet discharge direction D1) drawn in the reverse direction D2 by the reverse roller pair 34 and the leading end of the sheet S3 discharged by the discharge roller pair 21 pass by each other near the full-load detection flag 24, and passing conveyance is performed. In the present embodiment, since the rotation angle of the full-load detection flag 24 is regulated by the stopper 49, it is possible to suppress the generation of noise and rubbing marks due to the full-load detection flag 24 colliding with the sheet S2 during passing conveyance.

[0052] Note that the reverse tray 22 of the present embodiment is provided in the central region in the sheet width direction D3 and is inclined upward toward the downstream in the sheet discharge direction D1. Therefore, the possibility that the sheet S2 being reversed contacts the sheet S3 being discharged while sagging during passing conveyance is reduced. Further, the side protrusions 24b and 24c of the full-load detection flag 24 are interposed between the sheets S2 and S3 in the region outside the reverse tray 22 in the sheet width direction D3, so that the possibility that the side ends of the sheets S2 and S3 contact and rub against each other during passing conveyance can be reduced.

[0053] <Second Embodiment> Next, the second embodiment will be described. Hereinafter, elements denoted by the same reference numerals as those in the first embodiment have substantially the same configuration and operation as those described in the first embodiment, and the parts different from the first embodiment will be mainly described.

[0054] As shown in Fig. 6, the inversion tray 52 as a support member according to the present embodiment has a notch 52c as an opening instead of the opening hole 22c in the first embodiment. That is, when viewed from above, the opening in the present embodiment has a concave shape in which a part in the sheet width direction D3 at the downstream end of the support member in the sheet discharge direction D1 (first conveyance direction) is recessed toward the upstream side of the sheet discharge direction D1. The full-load detection flag 54 has a central protrusion 54a (inner part) located at the central portion in the sheet width direction D3 and side protrusions 54b and 54c (outer parts) located at both ends in the sheet width direction D3. The central protrusion 54a has substantially the same shape (rectangular shape) as the notch 52c of the inversion tray 52 and is formed with a width slightly narrower than the inner width of the notch 52c.

[0055] As shown in Fig. 7, when the sheet S3 is discharged in the sheet discharge direction D1 by the discharge roller pair 21, the full-load detection flag 54 is pressed by the sheet S3 and rotates to a position lifted upward as shown by the broken line. At this time, the central protrusion 54a of the full-load detection flag 54 enters the inside of the notch 52c of the inversion tray 52, and a part of the full-load detection flag 54 overlaps the inversion tray 52 when viewed in the sheet width direction D3. That is, also in the present embodiment, when viewed in the sheet width direction perpendicular to the first conveyance direction, a part of the rotation locus of the rotating member overlaps the support member. As a result, it is possible to realize a function of detecting a sheet and a function of supporting a sheet during inversion conveyance with a compact configuration in the height direction. As a result, it is possible to achieve both miniaturization in the height direction (vertical direction) of the image forming apparatus and an increase in the sheet loading amount in the loading unit. Further, since the notch 52c as the opening is provided, it is possible to reduce the possibility that the full-load detection flag 54 collides with the inversion tray 52 when rotating and sudden noises or the like are generated.

[0056] Note that the tip 52a of the inversion tray 52 may extend over the entire sheet width direction D3. Further, the notch 52c of the inversion tray 52 may have an arbitrary size and may be located at a position where it does not overlap the central protrusion 54a and the side protrusions 54b and 54c of the full-load detection flag 54, and there may be a plurality of them.

[0057] (Other Embodiments) In the above-described embodiment, the full-load detection flag 24 also serves as a rotating member for detecting the discharge of the sheet. However, a rotating member for detecting the discharge of the sheet may be provided separately from the detection mechanism for detecting the full-load state of the discharge tray 121. That is, the "rotating member" may be used for only one of the purposes of detecting the discharged sheet or detecting the sheet on the stacking unit. Even in that case, by applying each embodiment, it is possible to realize a function of detecting a sheet and a function of supporting a sheet during reverse conveyance in a compact configuration in the height direction.

[0058] Further, in the above-described embodiment, the change in the detection signal of the full-load detection sensor 26 corresponding to the presence or absence of sheet discharge does not necessarily have to be the same as the change in the detection signal of the full-load detection sensor 26 corresponding to whether the discharge tray 121 is in a full-load state. For example, a detection unit may be used that combines a sensor whose detection signal changes when the full-load detection flag 24 rotates to a first angle with reference to the home position, and a sensor whose detection signal changes when the full-load detection flag 24 rotates to a second angle greater than the first angle.

[0059] Also, the specific configurations such as the full-load detection flag and the reverse tray described in the above-described embodiment are merely examples, and the shape, arrangement, etc. can be appropriately changed. For example, the reverse tray may be provided over the entire area of the reverse path R2 in the sheet width direction D3. Also, it is conceivable to omit either the central protruding portion (inner portion) or the side protruding portion (outer portion) of the full-load detection flag.

[0060] Also, in the above-described embodiment, the sheet discharge device that discharges a sheet from the apparatus main body of the image forming apparatus has been described. However, for example, the present technology may be applied to a sheet discharge device of an optional device that is detachably installed on the upper part of an image forming apparatus (the part equipped with an image forming unit).

Explanation of Reference Numerals

[0061] 1…Image forming apparatus (printer) / 21…Discharging means (discharging roller pair) / 22, 52…Supporting member (reverse tray) / 24, 54…Rotating member (full-load detection flag) / 26…Detection unit (full-load detection sensor) / 34…Reversing means (reverse roller pair) / 49…Restricting unit (stopper) / 101…Apparatus main body / 121…Loading unit (discharge tray) / D1…First conveyance direction (sheet discharge direction) / D2…Second conveyance direction (reverse direction) / D3…Sheet width direction

Claims

1. A loading section on which the sheet discharged from the apparatus main body is loaded; Inverting means for projecting the sheet from the apparatus main body in a first conveyance direction toward the space above the loading section and then conveying the sheet in a second conveyance direction opposite to the first conveyance direction; A support member disposed above the loading section so as to project downstream in the first conveyance direction from the apparatus main body and supporting the lower surface of the sheet conveyed by the inverting means; Discharging means for discharging the sheet from the apparatus main body, the discharging means being disposed such that the discharged sheet passes below the support member; A rotating member disposed above the loading section, positioned below the support member when not in contact with the sheet, and rotating upward when contacting the sheet; A detection section configured such that a detection signal changes according to the rotation angle of the rotating member; A restricting section that contacts the rotating member and restricts the rotating member from protruding above the support member; characterized by comprising: A sheet discharging device, wherein when viewed in the sheet width direction perpendicular to the first conveyance direction, a part of the rotation locus of the rotating member overlaps the support member.

2. The sheet discharging device according to Claim 1, wherein when viewed in the sheet width direction with the rotating member in contact with the restricting section, the upper surface of the rotating member and the upper surface of the support member overlap.

3. The sheet discharging device according to Claim 1 or 2, wherein the support member is provided with an opening penetrating in the vertical direction; the rotating member having an inner portion that enters inside the opening in a state where the rotating member overlaps the support member when viewed in the sheet width direction.

4. The sheet discharging device according to Claim 3, wherein the opening is a hole surrounding the periphery of the inner portion of the rotating member when viewed from above.

5. The sheet discharging device according to Claim 4, wherein the inner portion of the rotating member has a shape similar to the opening of the support member, and the outer periphery of the inner portion is formed to face the inner periphery of the opening with a predetermined gap therebetween.

6. The sheet discharging device according to Claim 3, The sheet discharging device is characterized in that, when viewed from above, a part of the downstream end of the support member in the sheet width direction in the first conveyance direction is concave in a shape recessed toward the upstream side in the first conveyance direction.

7. In the sheet discharging device according to any one of Claims 1 to 6, the support member is provided over a range including the central position of the discharging means in the sheet width direction, the sheet discharging device is characterized in that the rotating member has outer portions provided on both outer sides of the support member in the sheet width direction.

8. In the sheet discharging device according to any one of Claims 1 to 7, the sheet discharging device further includes a cover member that constitutes the upper surface of the device body, the support member protrudes further downstream than the downstream end of the cover member in the first conveyance direction, the sheet discharging device is characterized in that, when viewed in the sheet width direction, on the downstream side of the downstream end of the cover member in the first conveyance direction, the upper surface of the support member is inclined upward toward the downstream in the first conveyance direction.

9. In the sheet discharging device according to any one of Claims 1 to 8, the sheet discharging device further includes control means for determining a full-load state of the stacking unit based on a detection signal of the detection unit.

10. In the sheet discharging device according to any one of Claims 1 to 8, the sheet discharging device further includes control means for determining a sheet jam based on a detection signal of the detection unit.

11. In the sheet discharging device according to any one of Claims 1 to 9, the discharging means has a first pair of rollers that sandwich and convey a sheet, and is configured such that, when the sheet fed out from the first pair of rollers is viewed from the downstream side in the first conveyance direction, the sheet is in a state of undulating in the vertical direction along the sheet width direction, the sheet discharging device is characterized in that the reversing means has a second pair of rollers having a nip portion where outer peripheral surfaces contact each other, and sandwiches and conveys a sheet at the nip portion.

12. an image forming means for forming an image on a sheet; the sheet discharging device according to any one of Claims 1 to 11, which discharges the sheet on which an image has been formed by the image forming means; An image forming apparatus characterized by comprising the above.

Images