Sheet feeding apparatus, image forming apparatus, and extension support unit

Abstract

To easily attach and detach an extension support unit and to prevent it from easily falling off after mounting.SOLUTION: An image forming apparatus includes an extension unit 60 detachably attached to a side D1 in an attachment / detachment direction with respect to a manual feed unit 50. The manual feeding unit 50 includes the insertion portion 54 having the projection portion 64 and the abutment surface 56. The extension unit 60 includes the frame 63 that has the opening portion D1 larger than the insertion portion 54 when viewed from the attachment / detachment direction 63a, and the insertion portion 54 is inserted into the opening portion 63a in the attached state. The frame body 63 includes the recessed portion 55 that is configured to be engageable with and disengageable from the protruding portion 64 in the sheet-width direction and is engaged with the protruding portion 64 in the attached state to position the extension unit 60 with respect to the manual feeding unit 50 at the D1 in the attachment / detachment direction, the abutted surface 65 that abuts against the abutting surface 56 at the D3 in the loading direction in the attached state, and the urging portion 66 that urges the abutting surface 56 toward the abutted surface 65 at the D3 in the loading direction.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device that feeds sheets, an image forming apparatus including the sheet feeding device, and an extension support unit that is applied to the sheet feeding device. [Background technology]

[0002] In recent years, the types of media used in image forming devices have been increasing year by year. Long sheets are one example of this, and it is desirable to be able to print on long sheets of approximately 1000 mm in length, such as promotional banners. When feeding such long sheets, a configuration is known in which a separate extension sheet tray (extension support unit) is attached to the manual feed tray to enable support of long sheets (see Patent Document 1). In this configuration, a loading platform formed by bending a rod into a roughly U-shape is elastically deformed to be detachable from a frame member supported on the device body.

[0003] Extension sheet trays tend to be large in the longitudinal direction of sheets in order to accommodate long sheets. If the extension sheet tray remains attached when not feeding long sheets, it may obstruct traffic or make it difficult to clear jams. Therefore, it is desirable for users to be able to easily attach and detach the extension sheet tray as needed. On the other hand, if the extension sheet tray is easily detachable, there is a risk that the extension sheet tray may come into contact with something and fall off the manual feed tray. For this reason, the extension sheet tray needs to be held by the manual feed tray with enough force to prevent it from easily falling off. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-127753 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the extension sheet tray described in Patent Document 1 is configured to attach the loading platform to the frame member by elastically deforming it, which makes it difficult to attach or detach the tray, as the loading platform must be elastically deformed.Furthermore, depending on the position and direction of an external force acting on the attached loading platform, the loading platform may be elastically deformed and fall off.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet feeding device, an image forming apparatus, and an extension support unit that are easily detachable and that will not easily fall off once attached. [Means for solving the problem]

[0007] A first aspect of the present invention is a sheet support unit having a sheet support surface that supports a sheet, a feeding section that feeds the sheet supported on the sheet support surface, and an extension support unit that is detachably attached to the sheet support unit in a first direction and has an extension support surface that is located upstream of the sheet support surface in the sheet feeding direction and supports the sheet when attached to the sheet support unit, wherein the sheet support unit has an insertion section that has an engagement section and an abutment section, and the extension support unit has an opening that is larger than the insertion section when viewed from the first direction, This sheet feeding device is characterized in that it has an inserted portion into which the insertion portion is inserted in the opening in an attached state, the inserted portion being configured to be engageable and detachable with the engaging portion in a second direction intersecting the first direction, an engaged portion that engages with the engaging portion in the attached state to position the extension support unit in the first direction relative to the sheet support unit, an abutted portion that abuts against the abutting portion in a third direction intersecting the first direction and the second direction in the attached state, and a biasing portion that biases the abutting portion toward the abutted portion in the third direction.

[0008] A second aspect of the present invention is an image forming apparatus including the above-mentioned sheet feeding device and an image forming section that forms an image on a sheet.

[0009] A third aspect of the present invention is an extension support unit that is detachably attached in a first direction to a seat support unit having a sheet support surface that supports a seat, and that, when attached to the sheet support unit, is provided with an extension support surface that is located upstream of the sheet support surface in the sheet feed direction and supports the sheet, and an inserted portion that has an opening that is larger than the insertion portion of the sheet support unit when viewed from the first direction, and into which the insertion portion is inserted in the attached state, and the inserted portion is configured to be engageable and detachable with an engaging portion of the insertion portion of the seat support unit in a second direction that intersects the first direction, and that positions the extension support unit in the first direction relative to the seat support unit by engaging with the engaging portion in the attached state, an abutted portion that abuts against an abutting portion of the insertion portion of the seat support unit in a third direction that intersects the first direction and the second direction in the attached state, and a biasing portion that biases the abutting portion toward the abutted portion in the third direction. [Effects of the Invention]

[0010] According to the present invention, the extension support unit can be easily attached and detached, and once attached, it will not easily fall off. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing an image forming apparatus according to an embodiment; [Figure 2] FIG. 2 is a block diagram showing a control system of the image forming apparatus according to the embodiment. [Figure 3] FIG. 2 is a plan view showing a manual feeding unit according to the embodiment. [Figure 4] 4A and 4B are diagrams showing a manual feeding unit according to an embodiment, in which (a) is a front view and (b) is a cross-sectional view taken along line AA in FIG. 3. [Figure 5] FIG. 2 is a plan view showing an extension unit according to the embodiment. [Figure 6]6A and 6B are diagrams showing an extension unit according to an embodiment, in which (a) is a side view and (b) is a cross-sectional view taken along line BB in FIG. 5. [Figure 7] FIG. 3 is a cross-sectional view showing the internal space of the frame body according to the embodiment. [Figure 8] 1A is a cross-sectional view showing a manual feed unit and an extension unit according to an embodiment, in which (a) shows a detached state immediately before the extension unit is attached to the manual feed unit, (b) shows a state in which the extension unit is being attached to the manual feed unit, and (c) shows an attached state in which the extension unit is attached to the manual feed unit. [Figure 9] 8(c) in the manual feeding unit and the extension unit according to the embodiment. FIG. [Figure 10] FIG. 4 is a cross-sectional view showing a protrusion and a recess in an attached state according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present embodiment will be described below with reference to the drawings. First, the schematic configuration of an image forming apparatus 1 according to this embodiment will be described with reference to FIG. 1. FIG. 1 is a cross-sectional view of the schematic configuration of the image forming apparatus 1 according to this embodiment, as viewed from the front side. The image forming apparatus 1 is a tandem-intermediate transfer laser beam printer that uses an electrophotographic process. The image forming apparatus 1 can form and output a full-color or monochrome image corresponding to print image data output from a host device 24 (see FIG. 2) connected to a control unit 20 onto a sheet S, which is a recording medium.

[0013] [Image forming device] The image forming apparatus 1 has an apparatus main body 201A and an image forming section 201B that forms an image on a sheet S. An image reading device 202, which is installed substantially horizontally, is provided above the apparatus main body 201A. A discharge space V for sheet discharge is formed between the image reading device 202 and the apparatus main body 201A.

[0014] [Feeding unit] The sheets S are stored in feeding cassettes 7A and 7B of cassette feeding units 9A and 9B according to size, for example, or are supported in a manual feeding section 40.

[0015] The cassette feeding units 9A and 9B have feeding cassettes 7A and 7B that store sheets S, and feeding sections 6A and 6B that feed sheets S from the feeding cassettes 7A and 7B. The cassette feeding units 9A and 9B store sheets S of different sizes, but the feeding sections 6A and 6B have the same configuration, so only feeding section 6A will be described here. The feeding section 6A has a pickup roller 2 and a separation roller pair 5 consisting of a feed roller and a retard roller for separating the sheets S sent out from the pickup roller 2. The sheets S separated one by one by the separation roller pair 5 are transported by a first pre-registration roller pair (hereinafter referred to as the first pre-registration roller pair) 11 to a registration roller pair (hereinafter referred to as the registration roller pair) 13.

[0016] The manual feed section 40 is an example of a sheet feeding device and includes a manual feed unit 50, a feed section 41, and an extension unit 60. In this embodiment, the direction in which stacked sheets S are fed in the manual feed unit 50 is referred to as a sheet feed direction Df, a direction parallel to the sheet feed direction Df is referred to as a loading / unloading direction D1, and a width direction of the stacked sheets S is referred to as a sheet width direction D2. Furthermore, a direction intersecting (e.g., perpendicular to) a sheet support surface 52 (described later) is referred to as a sheet stacking direction D3, which is approximately a vertical direction in this embodiment. The loading / unloading direction D1, the sheet width direction D2, and the sheet stacking direction D3 are examples of a first direction, a second direction intersecting the first direction, and a third direction intersecting the first and second directions, respectively.

[0017] The manual feed unit 50 is an example of a sheet support unit and includes a manual feed tray 51 and a sheet support surface 52 formed on the upper surface of the sheet tray 51 to support the sheets S. The manual feed unit 50 can be opened and closed by rotating relative to the device main body 201A, and can be displaced between a closed position and an open position. The manual feed unit 50 is detachably provided to the device main body 201A. When open, the manual feed tray 51 supports the sheets S stacked on the sheet support surface 52. The manual feed tray 51 also has side restriction plates 53 that are disposed on the sheet support surface 52 and restrict the positions of both ends of the stacked sheets S in the sheet width direction D2. The side restriction plates 53 are provided with, for example, an air handling fan unit (not shown).

[0018] The feeding section 41 feeds the sheets S supported on the sheet support surface 52 of the manual feed tray 51 to a second pre-registration roller pair (hereinafter referred to as the second pre-registration roller pair) 12. The feeding section 41 has a pickup roller 42 and a separation roller pair 43 consisting of a feed roller and a retard roller for separating the sheets S sent out from the pickup roller 42. The sheets S separated one by one by the separation roller pair 43 are transported to the registration roller pair 13 by the second pre-registration roller pair 12.

[0019] The extension unit 60 is an example of an extension support unit, and is detachably attached to the manual feed unit 50 in the attachment / detachment direction D1. The extension unit 60 has an extension tray 61 that is located upstream of the manual tray 51 in the sheet feed direction Df when attached to the manual feed unit 50. The upper surface of the extension tray 61 has an extension support surface 62 that is located upstream of the sheet support surface 52 in the sheet feed direction Df when attached and supports the sheet S. The extension unit 60 will be described later.

[0020] In this embodiment, the extension unit 60 is described as being attached to the manual feed unit 50 and as part of the image forming apparatus 1. However, this is not limiting, and the extension unit 60 may be treated as an optional device that is not included in the image forming apparatus 1. In this embodiment, the state shown in FIG. 1 in which the extension unit 60 is attached to the manual feed unit 50 is referred to as an attached state. Also, the state in which the extension unit 60 is detached from the manual feed unit 50 is referred to as a detached state.

[0021] [Image forming section] The image forming unit 201B forms an image on a sheet S fed by a cassette feeding unit 230 or a manual feeding unit 50 and conveyed by a pair of registration rollers 13. The image forming unit 201B includes four process cartridges PY, PM, PC, and PK that form toner images in four colors: yellow (Y), magenta (M), cyan (C), and black (K), an exposure unit 30, and an intermediate transfer belt 36. The four process cartridges PY, PM, PC, and PK have the same configuration except for the colors of the images they form. Therefore, only the configuration and image forming process of the process cartridge PY will be described, and a description of the process cartridges PM, PC, and PK will be omitted. The image forming unit 201B also includes a secondary transfer unit 38 and a fixing unit 201E disposed above the process cartridges PY, PM, PC, and PK. A toner cartridge 35 supplies toner to a developing roller 34.

[0022] The process cartridge PY includes a photosensitive drum 32, which is a drum-shaped electrophotographic photosensitive member, a charging roller 33, and a developing roller 34. The photosensitive drum 32 is rotatably supported by the image forming apparatus 1 and is rotationally driven by a driving unit (not shown). The photosensitive drum 32 is configured by providing a photoconductive layer such as an OPC (organic photoconductor) on the outer surface of an aluminum cylinder. The charging roller 33 charges the photosensitive drum 32. The charging roller 33 is configured by a core metal and a conductive elastic member surrounding the periphery. The charging roller 33 is disposed in contact with the surface of the photosensitive drum 32 and rotates in response to the rotation, and a charging bias is applied to it by a power source (not shown). The developing roller 34 deposits toner of a different color (yellow, magenta, cyan, or black) onto the surface of the photosensitive drum 32 for each process cartridge PY, PM, PC, or PK. The developing roller 34 develops the electrostatic latent image on the surface of the photosensitive drum 32 by attaching toner to the electrostatic latent image, thereby forming a toner image on the surface of the photosensitive drum 32 .

[0023] The exposure unit 30 houses within its housing a laser light source that emits laser light and various optical members for deflection scanning by guiding the laser light emitted from the laser light source to the corresponding photosensitive drum 32. The exposure unit 30 irradiates the charged surface of the photosensitive drum 32 with laser light based on image information, forming an electrostatic latent image.

[0024] The secondary transfer unit 38 includes an intermediate transfer belt 36 wound around a drive roller 36a and a tension roller 36b. A primary transfer roller 39 is provided inside the intermediate transfer belt 36 and abuts against the intermediate transfer belt 36 at a position facing the photosensitive drum 32. The intermediate transfer belt 36 is rotated in the direction of the arrow by the drive roller 36a, which is driven by a drive unit (not shown). A secondary transfer roller 37 that transfers the color image formed on the intermediate transfer belt 36 onto the sheet S is provided at a position facing the drive roller 36a of the secondary transfer unit 38.

[0025] A fixing unit 201E is disposed above the secondary transfer roller 37, and above this fixing unit 201E, a first pair of discharge rollers 225a, a second pair of discharge rollers 225b, and a duplex inverting unit 201F are disposed. The duplex inverting unit 201F is an example of a re-conveying unit, and inverts the sheet S on which an image has been formed by the image forming unit 201B, conveys it upside down, and conveys it to the second pair of pre-registration rollers 12. The duplex inverting unit 201F has a pair of reversible reversing rollers 222 and a re-conveying path 224 that conveys the sheet S on which an image has been formed on its first side back to the image forming unit 201B. An operation unit 23 that accepts user operations is provided on the top of the image forming apparatus 1. The operation unit 23 is a touch panel type that combines display and input functions. The operation unit 23 is connected to the control unit 20 and accepts various user operations, such as various information related to the sheet to be used for printing (e.g., size information, basis weight information, surface property information), and instructions to start or stop printing.

[0026] [Control system] Next, the control unit 20 and control system of the image forming apparatus 1 will be described with reference to Fig. 2. The control unit 20 has various functional units, such as a CPU 21 (Central Processing Unit), a memory 22, an image formation control unit 25, a sheet conveyance control unit 26, and a sensor control unit 27. The CPU 21 executes predetermined control programs and the like to realize various processes performed by the image forming apparatus 1. The memory 22 is, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores various programs and various data in predetermined storage areas.

[0027] The image formation control unit 25 issues instructions to the image forming unit 201B, including the exposure unit 30, and controls image formation. The sheet transport control unit 26 issues instructions to the first pre-registration motor 101, the second pre-registration motor 102, the registration motor 103, etc., and controls the driving of various transport rollers to control the transport of the sheet S. The sensor control unit 27 controls the start or stop of detection by the sheet presence / absence sensor 104, etc., and receives the detection results of each sensor. Note that the system may also be configured to receive various information about the sheets used for printing via a host device 24, such as a personal computer, image scanner, or facsimile connected via a network.

[0028] [Image formation operation] Next, we will explain the image forming operation of the image forming apparatus 1. First, when the image forming apparatus 1 receives image data of an original to be printed, the image information is processed, converted into an electrical signal, and transmitted to the exposure unit 30 of the image forming section 201B. In the image forming section 201B, a laser is used to sequentially expose the surface of the photosensitive drum 32, the surface of which is uniformly charged to a predetermined polarity and potential by the charging roller 33. As a result, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photosensitive drum 32 of each process cartridge PY, PM, PC, and PK, respectively.

[0029] Thereafter, the electrostatic latent images are developed and visualized with toner of each color, and the toner images of each color on each photosensitive drum 32 are transferred in order onto the intermediate transfer belt 36 in a superimposed manner by a primary transfer bias applied to the primary transfer roller 39. As a result, a toner image is formed on the intermediate transfer belt 36.

[0030] In parallel with this toner image formation operation, sheets S are fed one by one from cassette feeding units 9A, 9B or manual feeding unit 50. The sheets S fed from cassette feeding units 9A, 9B pass through a first pre-registration roller pair 11 and are transported to a registration roller pair 13. The first pre-registration roller pair 11 and the registration roller pair 13 correct any skew of the sheets S. Specifically, the leading edge of the sheet S being transported is abutted against the nip portion of the registration roller pair 13, which is stopped. The first pre-registration roller pair 11 further transports the sheet S to form a loop, thereby correcting the skew. Similarly, the sheet S fed from manual feeding unit 50 passes through a second pre-registration roller pair 12 and is transported to the registration roller pair 13. The second pre-registration roller pair 12 and the registration roller pair 13 correct any skew of the sheet S. In this embodiment, the first pre-registration roller pair 11, the second pre-registration roller pair 12, and the registration roller pair 13 are collectively referred to as the skew correction unit 10.

[0031] The pair of registration rollers 13 transports the sheet S to the secondary transfer unit 38 in accordance with the timing at which the toner image on the intermediate transfer belt 36 is transferred onto the sheet S. In the secondary transfer unit 38, the toner image is transferred onto the sheet S all at once by a secondary transfer bias applied to the secondary transfer roller 37.

[0032] Next, the sheet S onto which the toner image has been transferred is transported to a fixing unit 201E, where the toners of each color are melted and mixed by heat and pressure in a roller nip formed by a pressure roller 220a and a heating roller 220b, and are fixed as a color image on the sheet S. The sheet S with the fixed image is discharged into a discharge space V by a first discharge roller pair 225a or a second discharge roller pair 225b provided downstream of the fixing unit 201E, and is stacked on a discharge tray 223 protruding from the bottom surface of the discharge space V.

[0033] On the other hand, when forming images on both sides of the sheet S, the sheet S is stopped once with the trailing edge of the sheet S remaining a predetermined distance from the pair of reversing rollers 222, and then the pair of reversing rollers 222 is rotated in the reverse direction, and the sheet S passes through the second pair of pre-registration rollers 12 via a re-conveyance path 224. Then, the sheet S is conveyed again to the pair of registration rollers 13, where skew correction is performed, and the image on the second side is formed and fixed in the image forming section 201B.

[0034] [Manual feed unit] Next, the manual feed unit 50 of the manual feed section 40 will be described with reference to FIGS. 3, 4(a), and 4(b). FIG. 3 is a plan view of the manual feed unit 50, FIG. 4(a) is a front view of the manual feed unit 50, and FIG. 4(b) is a cross-sectional view of the manual feed unit 50 taken along line AA in FIG. 3. The manual feed unit 50 has an insertion section 54 to which the extension unit 60 is attached. The insertion section 54 has a recess 55 recessed in the sheet width direction D2 and an abutment surface 56 that is at least a part of the upper surface. The insertion section 54 is configured by the upstream portion of the manual tray 51 in the sheet feed direction Df. The abutment surface 56 is an example of an abutment portion, and is positioned so as not to overlap the sheet support surface 51 in the sheet width direction D2 when viewed from the stacking direction D3 (see FIG. 3). In this embodiment, the abutment surfaces 65 are formed at both ends of the manual tray 51 in the sheet width direction D2. The recesses 55 are an example of an engagement portion, and are formed at both ends of the manual feed tray 51 in the sheet width direction D2, and have a shape recessed toward the center in the sheet width direction D2 of the manual feed tray 51. In the attached state, protrusions 64, which will be described later, fit into the recesses 55 in the sheet width direction D2 (see FIG. 8).

[0035] [Extension unit] Next, the extension unit 60 of the manual feed unit 40 will be described with reference to FIGS. 5 to 7. FIG. 5 is a plan view of the extension unit 60, FIG. 6(a) is a side view of the extension unit 60 as viewed from the downstream side in the conveying direction X of the sheet feed direction Df, and FIG. 6(b) is a cross-sectional view of the extension unit 60 taken along line BB in FIG. 5. FIG. 7 is a cross-sectional view showing the internal space S0 of the frame 63. The extension unit 60 has the frame 63 on the downstream side of the extension tray 61 in the sheet feed direction Df. The frame 63 is an example of an insertion receiving portion and has an opening 63a larger than the insertion portion 54 as viewed from the attachment / detachment direction D1. In the attached state, the insertion portion 54 is inserted into the opening 63a. As shown in FIG. 6(a), the frame 63 has a substantially rectangular shape as viewed from the downstream side in the conveying direction X of the sheet feed direction Df, with an opening at the center of the upper wall in the sheet width direction D2. The frame 63 also has an internal space S0 into which the insertion portion 54 is inserted. The internal space S0 is formed by a plurality of space-forming surfaces, which include at least an upper surface and a lower surface.

[0036] The frame 63 has a protrusion 64 that engages with the recess 55 of the manual feeding unit 50, an abutment surface 65 that abuts against the abutment surface 56 of the manual feeding unit 50, and an urging portion 66. The protrusions 64 are an example of an engagement portion and are arranged at both ends of the extension tray 61 in the sheet width direction D2. Each protrusion 64 is configured to be engageable with and detachable from the recess 55 in the sheet width direction D2, and by engaging with the recess 55 in the attached state, the extension unit 60 is positioned in the attachment / detachment direction D1 relative to the manual feeding unit 50. In this embodiment, the protrusion 64 has a cone shape that protrudes in the sheet width direction D2 toward the recess 55 in the attached state, and is arranged with the apex of the approximately cone shape facing the recess 55. The extension unit 60 has a urging spring 67 that is an example of a second urging spring. The biasing spring 67 is made of, for example, a compression coil spring, and is interposed between the protrusion 64 and the frame body 63 to bias the protrusion 64 toward the center in the seat width direction D2.

[0037] The contact surface 65 is an example of a contact portion, and in the attached state, it contacts the contact surface 56 of the manual feeding unit 50 in the stacking direction D3. The contact surface 65 is formed on the lower surface of the upper wall of the frame body 63, and is arranged at both ends of the frame body 63 in the sheet width direction D2. In other words, the contact surface 65 corresponds to the upper surface of the multiple space forming surfaces that form the internal space S0. The contact surface 65 is arranged at a position that does not overlap the extended support surface 62 in the second direction when viewed from the stacking direction D3.

[0038] The biasing portion 66 biases the contact surface 56 toward the contacted surface 65 in the stacking direction D3. In this embodiment, the biasing portion 66 is disposed below the insertion portion 54 in the attached state and biases the contact surface 56 toward the contacted surface 65 upward in the stacking direction D3. The biasing portion 66 has a biasing spring 68 and a pressing member 69. The biasing spring 68 is an example of a first biasing spring and is made of, for example, a compression coil spring, and is provided on the lower surface 63b of the space forming surfaces that form the internal space S0 in the frame 63. In the attached state, the pressing member 69 presses the insertion portion 54 with the biasing spring 68, thereby causing the contact surface 56 to contact the contacted surface 65.

[0039] 7, the partitioned space S1 defined by the pressing member 69 in the internal space S0 of the frame 63 includes a pressing space S2 and an introduction space S3. The pressing space S2 is a space in which the insertion portion 54 is located in the attached state, pressing the insertion portion 54 to press the contact surface 56 against the contacted surface 65 (see FIG. 8(c)). The introduction space S3 is located downstream of the pressing space S2 in the sheet feeding direction Df, and is a space whose downstream side is wider than its upstream side in the sheet feeding direction Df when viewed from the sheet feeding direction Df. The introduction space S3 is a space into which the upstream end of the insertion portion 54 in the sheet feeding direction Df is introduced when the insertion portion 54 is displaced from the detached state (FIG. 8(a)) in which it is detached from the frame 63 to the attached state (FIG. 8(c)).

[0040] The pressing member 69 has an upper surface portion 70 that faces the insertion portion side, i.e., the abutment surface 65, in the attached state. The upper surface portion 70 has a first region 71 and a second region 72. The first region 71 is a region that forms a pressing space S2 in the attached state. The second region 72 is a region that is provided downstream of the first region 71 in the sheet feeding direction Df, forms an introduction space S3, and is formed so that the downstream side is farther away from the abutment surface 65 than the upstream side in the sheet feeding direction Df. In this embodiment, the second region 72 is an inclined surface that is inclined with respect to the sheet feeding direction Df. However, the second region 72 is not limited to being a flat inclined surface, and may be an inclined curved surface as a whole.

[0041] [Attachment / detachment operation] Next, the operation of attaching and detaching the extension unit 60 to and from the manual feed unit 50 will be described with reference to FIGS. 8(a) to 10. As shown in FIG. 8(a), when the extension unit 60 is moved in an attachment direction D11 (sheet feed direction Df) for attachment to the manual feed unit 50, the second region 72 (FIG. 7) of the pressing member 69 of the extension unit 60 comes into contact with the tip of the insertion portion 54 of the manual feed unit 50. The pressing member 69 presses the biasing spring 68, causing an upward biasing force Fa to act on the insertion portion 54 of the manual feed unit 50. The biasing force Fa presses the manual feed unit 50 upward, and as shown in FIG. 8(b), the extension unit 60 can be moved in the attachment direction D11 while maintaining the abutment state between the abutting surface 56 of the insertion portion 54 and the abutted surface 65 of the extension unit 60.

[0042] Fig. 8(c) is a diagram showing the state after the attachment operation of the extension unit 60 is completed, and Fig. 9 is a cross-sectional view showing the state taken along line CC in Fig. 8(c). When the extension unit 60 is attached to the manual feed unit 50, the convex portion 64 of the extension unit 60 enters the concave portion 55 of the manual feed unit 50 due to the biasing force of the biasing spring 67, thereby holding the extension unit 60 in the manual feed unit 50. Furthermore, in the attached state, the extension support surface 62 is located on an extension of the sheet support surface 52. This allows the sheet S supported across the sheet support surface 52 and the extension support surface 62 to be supported flat and fed smoothly.

[0043] Here, if the urging portion 66 were not present, no upward urging force Fa would be generated on the manual feed unit 50 during the attachment operation of the extension unit 60, and therefore the relative positions of the extension unit 60 and the manual feed unit 50 in the vertical direction would not be uniquely determined. In this case, even if the extension unit 60 is moved all the way in the attachment direction D11, the convex portion 64 of the extension unit 60 and the concave portion 55 of the manual feed unit 50 may not be aligned in the vertical direction, resulting in a failure to engage. This could result in the extension unit 60 not being held by the manual feed unit 50. In contrast, in this embodiment, the provision of the urging portion 66 makes it easy to align the convex portion 64 and the concave portion 55 in the vertical direction, preventing the extension unit 60 from being held by the manual feed unit 50.

[0044] [Retention mechanism] Next, a configuration for holding the extension unit 60 attached to the manual feed unit 50 and preventing it from falling off will be described with reference to FIG. 10 . FIG. 10 is an enlarged view of a holding mechanism for the extension unit 60, which is formed by the protrusion 64 of the extension unit 60 and the recess 55 of the manual feed unit 50. When the extension unit 60 is moved in the removal direction D12 (the direction opposite to the sheet feeding direction Df) to remove it, the slope 64a of the protrusion 64 comes into contact with the edge of the recess 55. At this time, a force FB1 perpendicular to the slope 64a acts on the protrusion 64. The force FB1 can be divided into a component force FB2 parallel to the removal direction D12 and a component force FB3 perpendicular to the removal direction D12. The component force FB2 resists removal of the extension unit 60, and therefore the component force FB2 holds the extension unit 60 in place in the manual feed unit 50.

[0045] Furthermore, the component force FB3 is a force that presses the protrusion 64 against the biasing spring 67. If the component force FB3 is greater than the biasing force of the biasing spring 67 of the protrusion 64, the protrusion 64 can come out of the recess 55. In other words, the extension unit 60 can be removed by applying a force to the extension unit 60 that makes the component force FB3 greater than the biasing force of the protrusion 64, but the extension unit 60 cannot be removed by applying a force that makes the component force FB3 less than the biasing force of the protrusion 64. In other words, the protrusion 64 abuts against the edge of the recess 55, and when the extension unit 60 shifts from the attached state to the detached state, the sloped surface 64 a presses the protrusion 64 to the opposite side of the recess in the sheet width direction D2 against the biasing spring 67. In this way, the holding force of the extension unit 60 with respect to the manual feed unit 50 can be designed by changing the biasing force of the biasing spring 67 of the protrusion 64 and the gradient of the sloped surface 64 a of the protrusion 64.

[0046] As described above, according to the image forming apparatus 1 of this embodiment, the extension unit 60 can be attached and detached by the simple operation of simply inserting it into the manual feed unit 50, and once attached, the retention mechanism between the convex portion 64 and the concave portion 55 prevents it from easily falling off.

[0047] Furthermore, according to the image forming apparatus 1 of this embodiment, the frame 63 of the extension unit 60 has a biasing portion 66. This makes it possible to easily align the vertical positions of the convex portion 64 and the concave portion 55 when attaching the extension unit 60 to the manual feed unit 50, preventing the extension unit 60 from being held by the manual feed unit 50. In other words, by restricting the orientation of the extension unit 60 relative to the manual feed unit 50 when attaching it, it is possible to attach the extension unit 60 while guiding it so that the convex portion 64 of the extension unit 60 engages with the concave portion 55 of the manual feed unit 50.

[0048] <Other embodiments> In the above-described embodiment, the attachment / detachment direction D1 is parallel to the sheet feeding direction Df, but this is not limiting. For example, the attachment / detachment direction may be the stacking direction of the sheets S, not parallel to the sheet feeding direction Df. In addition, in the above-described embodiment, the extension unit 60 is provided with the convex portion 64, and the manual feeding unit 50 is provided with the concave portion 55. However, this is not limiting, and the extension unit 60 may be provided with the concave portion, and the manual feeding unit 50 may be provided with the convex portion. In addition, while a convex portion and a concave portion are given as an example of the engaging portion and the engaged portion, this is not limiting, and a wide range of general engaging shapes can be applied. [Explanation of symbols]

[0049] 1...image forming apparatus, 40...manual feeding section (sheet feeding device), 41...feeding section, 50...manual feeding unit (sheet support unit), 52...sheet support surface, 54...insertion section, 55...recessed section (engagement section), 56...contact surface (contact section), 60...extension unit (extension support unit), 62...extension support surface, 63...frame body (inserted section), 64...protruding section (engaged section), 64a...inclined section, 65...contact surface (contact section), 6 6...urging portion, 67...urging spring (second urging spring), 68...urging spring (first urging spring), 69...pressing member, 70...upper surface portion, 71...first region, 72...second region, 201B...image forming portion, D1...attachment / detachment direction (first direction), D2...sheet width direction (second direction), D3...sheet stacking direction (third direction), Df...sheet conveying direction, S...sheet, S0...internal space, S1...compartment space, S2...pressing space, S3...introduction space

Claims

1. a seat support unit having a seat support surface that supports a seat; a feeding section that feeds a sheet supported on the sheet support surface; an extension support unit that is detachably attached to the sheet support unit in a first direction, and has an extension support surface that is positioned upstream of the sheet support surface in the sheet feeding direction and supports the sheet when attached to the sheet support unit, the seat support unit has an insertion portion having an engagement portion and an abutment portion, the extension support unit has an opening that is larger than the insertion portion when viewed from the first direction, and an insertion portion into which the insertion portion is inserted in the opening in the attached state; The inserted portion is an engaged portion configured to be engageable with and disengaged from the engaging portion in a second direction intersecting the first direction, and to position the extension support unit in the first direction relative to the seat support unit by engaging with the engaging portion in the attached state; an abutted portion that abuts against the abutting portion in a third direction intersecting the first direction and the second direction in the attached state; a biasing portion that biases the contact portion toward the contacted portion in the third direction, A sheet feeding device characterized by:

2. the first direction is a direction parallel to the sheet feeding direction; 2. The sheet feeding device according to claim 1, wherein the sheet feeding device is a sheet feeding device.

3. the second direction is a sheet width direction, The third direction is a direction perpendicular to the sheet support surface.

3. The sheet feeding device according to claim 2, wherein the sheet feeding device is a sheet feeding device.

4. the contact portion is disposed at a position that does not overlap the sheet support surface in the second direction when viewed from the third direction, the abutment portion is disposed at a position that does not overlap the extended support surface in the second direction when viewed from the third direction, The extended support surface is located on an extension of the seat support surface in the attached state.

4. The sheet feeding device according to claim 3, wherein the sheet feeding device is a sheet feeding device.

5. the biasing portion is disposed below the insertion portion in the attached state and biases the contact portion toward the contacted portion in an upward direction in the third direction.

5. The sheet feeding device according to claim 4.

6. The biasing portion is a first biasing spring provided on a lower surface of a space forming surface that forms an internal space in the inserted portion into which the inserting portion is inserted; a pressing member that presses the insertion portion with the first biasing spring in the attached state, thereby causing the abutting portion to abut against the abutted portion, 6. The sheet feeding device according to claim 5, wherein the sheet feeding device is a sheet feeding device.

7. The compartment space partitioned by the pressing member in the internal space is a pressing space in which the insertion portion is located, the insertion portion pressing the contact portion against the contacted portion in the attached state; an introduction space that is located downstream of the pressing space in the sheet feeding direction, that is wider on the downstream side than on the upstream side in the sheet feeding direction as viewed from the sheet feeding direction, and that introduces an upstream end of the insertion portion in the sheet feeding direction into the pressing space when the insertion portion changes from a detached state in which it is detached from the insertion receiving portion to an attached state, 7. The sheet feeding device according to claim 6, wherein the sheet feeding device is a sheet feeding device.

8. the pressing member has an upper surface portion facing the insertion portion side in the attached state, The upper surface portion is a first region that forms the pressing space in the attached state; a second region that is provided downstream of the first region in the sheet feeding direction, that forms the introduction space, and that is formed so that a downstream side thereof is farther away from the abutment portion than an upstream side thereof in the sheet feeding direction, 8. The sheet feeding device according to claim 7, wherein the sheet feeding device is a sheet feeding device.

9. the second area is an inclined surface inclined with respect to the sheet feeding direction; 9. The sheet feeding device according to claim 8, wherein the sheet feeding device is a sheet feeding device.

10. the engaged portion is a convex portion that protrudes in the second direction toward the engaging portion in the attached state, the engaging portion is a recess into which the protruding portion is fitted in the second direction in the attached state; 4. The sheet feeding device according to claim 3, wherein the sheet feeding device is a sheet feeding device.

11. the extension support unit has a second biasing spring interposed between the protrusion and the inserted portion and biasing the protrusion in the second direction; the protrusion has an inclined surface portion that abuts against an edge of the recess and pushes the protrusion toward the opposite side to the recess in the second direction against the second biasing spring when the extension support unit is displaced from the attached state to a detached state in which the extension support unit is detached from the seat support unit.

11. The sheet feeding device according to claim 10.

12. The sheet feeding device according to claim 1 ; an image forming unit that forms an image on a sheet, An image forming apparatus characterized by:

13. An extension support unit that is detachably attached in a first direction to a seat support unit having a seat support surface that supports a seat, an extended support surface that is located upstream of the sheet support surface in a sheet feeding direction and supports the sheet when the sheet support unit is attached to the sheet support unit; an insertion portion having an opening larger than the insertion portion of the seat support unit when viewed from the first direction, and into which the insertion portion is inserted in the opening in the attached state; The inserted portion is an engaged portion configured to be engageable with and disengaged from an engaging portion of the insertion portion of the seat support unit in a second direction intersecting the first direction, and to position the extension support unit in the first direction relative to the seat support unit by engaging with the engaging portion in the attached state; an abutted portion that abuts against the abutting portion of the insertion portion of the seat support unit in the attached state in a third direction intersecting the first direction and the second direction; a biasing portion that biases the contact portion toward the contacted portion in the third direction, An extension support unit characterized by:

Images