Sheet feeding device and image forming system

Abstract

To provide a sheet feeding device which can reduce sheet feeding failure of a sheet by surely feeding a sheet regardless of its basis weight.SOLUTION: A sheet feeding device 2 comprises a separation sheet feeding mechanism 33 which includes a sheet feeding roller 52 and a separation roller 53 brought into pressure-contact with the sheet feeding roller in order to separate the sheets at the uppermost position at a delivery position one by one from a loading tray 38 to feed the sheet to an image formation apparatus 1. The loading tray can be vertically moved so as to be arranged at a second delivery position P2 below a tip in a sheet feeding direction of a sheet guide 58 extended toward a nip part of the sheet feeding roller and the separation roller from the loading tray when the sheet to be loaded is a thin sheet, and so as to be arranged at a first delivery position P1 above the second delivery position when the sheet is a sheet thicker than the thin sheet.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a sheet feeding device that feeds sheets to an image forming apparatus that forms an image on the sheets, and further to an image forming system including such a sheet feeding device. [Background technology]

[0002] Conventionally, image forming apparatuses such as copiers and printers have been equipped with a built-in or external sheet feeding device that feeds sheets to an image forming section. Generally, the sheet feeding device includes a storage case capable of storing a large amount of sheets, for example several thousand sheets, a stacking tray for stacking the sheets in the storage case, and a separation and feeding mechanism that separates and feeds the sheets on the stacking tray one by one starting from the top.

[0003] The separation feed mechanism includes a feed roller that contacts the top surface of the sheets stacked on the stack tray to feed the sheet, and a separation mechanism consisting of a feed roller and a separation roller. The separation mechanism is configured such that when two or more sheets overlap and are nipped in the nip between the feed roller and the separation roller, the separation roller reverses or stops to feed only the top sheet and prevent the feeding of other sheets (for example, see Patent Document 1).

[0004] In such a separation mechanism, when the leading edge of the next sheet hits and is stopped by the separation roller that is stopped or rotating in the reverse direction, there is a risk that the leading edge of the sheet may curl up, causing a feeding error. In order to prevent such curling of the leading edge of the sheet and a feeding error, the sheet feeding device described in Patent Document 1 is provided with a sheet guide that extends from the leading edge of the stack tray in the paper feeding direction toward the nip portion to the vicinity of the nip portion, and is configured to reliably guide the leading edge of the sheet to the nip portion. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-322095 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the above-mentioned conventional separation mechanism may not be able to adequately prevent paper feeding failures when feeding thin paper with a small basis weight, particularly thin coated paper, the demand for which has been increasing in recent years. Some coated papers contain slippery components to give the surface a glossy appearance, and these components increase the adhesive force between the sheets of paper, increasing the possibility of double feeding.

[0007] Furthermore, if this component adheres to the surface of the separation roller and its coefficient of friction decreases, the separation roller may reverse even when there is only one sheet or no sheet sandwiched in the nip. In this case, since thin paper has lower stiffness than regular paper, its leading edge may hang down from the leading edge of the sheet guide and come into contact with the reversing separation roller, becoming caught in it and possibly causing curling.

[0008] The present invention has been made in consideration of the above-mentioned problems of the prior art, and Type and To provide a sheet feeding device capable of reliably feeding sheets regardless of the basis weight and reducing sheet feeding failures.

[0009] It is a further object of the present invention to provide an image forming system equipped with such a sheet feeding device. [Means for solving the problem]

[0010] In order to solve the above problems, a sheet feeding device according to the present invention comprises: A loading tray for loading sheets; a sheet feeding means for contacting an upper surface of a top sheet of the sheets stacked on the stacking tray and feeding the sheet; A separating means for separating the sheets fed by the feeding means into one sheet; a guide member having an inclined portion for guiding the sheet sent out by the sending means to the separating means; a moving means for moving the stacking tray up and down to a sending-out position where the sheet is sent out by the sending-out means, the moving means being configured to move the stacking tray, when the sheet stacked on the stacking tray is a predetermined sheet having a coating layer and a predetermined basis weight or less, to a sending-out position lower than the sending-out position when the sheet stacked on the stacking tray is a sheet other than the predetermined sheet; a sensor for detecting a top surface of the sheet on the stack tray which is moved up and down by the moving means, the moving means, when the sheet sent out from the stacking tray is a sheet other than the specified sheet, moves the stacking tray in response to the sensor detecting the top surface of the sheet on the stacking tray so that the top sheet is located at a first sending position, and when the sheet sent out from the stacking tray is the specified sheet, moves the stacking tray in response to the sensor detecting the top surface of the sheet on the stacking tray so that the top sheet is located at a second sending position lower than the first sending position. It is characterized by:

[0011] According to another aspect of the present invention, there is provided an image forming system including the sheet feeding device of the present invention described above, and an image forming apparatus that forms an image on a sheet fed from the sheet feeding device. Effect of the Invention

[0012] According to the sheet feeding device of the present invention, Type and To reliably feed sheets regardless of the basis weight and reduce sheet feeding failures. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating the overall configuration of an image forming system including a sheet feeding device according to a preferred embodiment of the present invention. [Diagram 2] 2 is a schematic diagram showing the internal configuration of the sheet feeding device from the front side (the front side in FIG. 1). [Diagram 3] 13A and 13B are partial enlarged views for explaining the operation of the separation and feeding mechanism accompanying the lifting of the stacking tray. [Figure 4] FIG. 11 is an explanatory diagram showing a sheet sending position in a normal mode. [Diagram 5] FIG. 13 is an explanatory diagram showing a sheet sending position in a thin coated paper mode. [Figure 6] FIG. 11 is a flow chart showing the operation of the loading tray. [Figure 7]13A and 13B are explanatory diagrams showing a sheet feeding operation in a thin coated paper mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0015] 1 shows the overall configuration of an image forming system 100 of this embodiment. The image forming system 100 includes an image forming apparatus 1 and a sheet feeding device 2. The sheet feeding device 2 is connected to one side surface 1a of the image forming apparatus 1 (the right side in FIG. 1). A document reading device 3, a document feeding device 4, and a sheet stacking device 5 are integrally mounted on the image forming apparatus 1.

[0016] (Image forming device) The image forming apparatus 1 is equipped with a paper feed cassette 6 (two paper feed cassettes 6a and 6b in the illustrated embodiment) capable of storing a predetermined number of sheets (for example, about 100 sheets) therein. The sheet feed device 2 is configured to have a relatively large capacity so as to be able to accommodate a larger number of sheets than the paper feed cassettes 6a and 6b.

[0017] The image forming apparatus 1 forms an image on a sheet supplied from a paper feed cassette 6a, 6b or a sheet feeder 2 based on image data read from the original sheet by the original reading device 3, and accumulates and stores the image-formed sheet in a sheet accumulation device 5. The original reading device 3 can also automatically feed an original sheet by an original feeding device 4. Here, the sheets handled in the image forming system 100 include plain paper of small sizes such as A6, B5, A4, etc. and large sizes such as B4, A3, long sheets of non-standard sizes, sheets of different basis weights (thicknesses) such as plain paper, cardboard, thin paper, etc., and special sheets such as overhead projector sheets, tracing paper, and coated paper.

[0018] The image forming device 2 is, for example, a copier, a printer, a facsimile, etc., and can employ various known image forming mechanisms as long as it can form an image on a sheet, and is installed, for example, on a floor surface. The image forming device 2 of the illustrated embodiment employs an electrostatic image forming mechanism as the image forming mechanism, but is not limited to this, and it is also possible to employ an inkjet image forming mechanism, an offset image forming mechanism, etc.

[0019] 1 includes a light projector (laser head or the like) 7, a photosensitive drum 8, a developing unit 9, a transfer charger 10, and a fixing roller 11. The sheets stored in each of the paper feed cassettes 6a and 6b are fed by a feed roller 12 in contact with the uppermost surface of the paper feed cassette, separated one by one by a separation roller pair 13, and fed to the transfer charger 10 along a conveying path 15 by a conveying roller pair 14. A sheet conveyed from the sheet feeder 2 is similarly fed to the transfer charger 10 along the conveying path 15 by the conveying roller pair 14.

[0020] Toner that has been attached by a developing unit 9 to an electrostatic latent image (still image) formed by a projector 7 on the surface of a photosensitive drum 8 is transferred by a transfer charger 10 onto a sheet supplied from paper feed cassettes 6a, 6b or the sheet feeder 2. The sheet onto which the toner has been transferred is sent to a fixing roller 11 disposed downstream, where the toner on the sheet is heated and fixed, and then the sheet is discharged to the sheet stacking device 5 by a pair of paper discharge rollers 16.

[0021] A first platen 17 and a second platen 18 made of transparent glass are arranged side by side in the horizontal direction above the document reading device 3. The first platen 17 is used to read documents that are manually placed, and is sized to accommodate a document of the largest size that can be supported. The second platen 18 is used to read documents that are fed from the document feeding device 4 and move at a predetermined speed.

[0022] Inside the document reading device 3, a first reading carriage 19, a second reading carriage 20, and a photoelectric conversion means having a condenser lens 21 and a photoelectric conversion element 22 are provided. The first reading carriage 19 and the second reading carriage 20 are driven by a carriage motor (not shown) to reciprocate in the sub-scanning direction below the first platen 17. When reading a document placed on the first platen 17, light is irradiated from a lamp of the first reading carriage 19 to an image of the document on the first platen 17 while the first reading carriage 19 and the second reading carriage 20 are moving, and the reflected light from the document is guided from the mirrors of the first reading carriage 19 and the second reading carriage 20 to the photoelectric conversion element 22 via the condenser lens 21 and converted into an electrical signal to generate image data.

[0023] The document feeder 4 includes a paper feed tray 23, a sheet transport mechanism 24, and a paper discharge tray 25. The documents placed on the paper feed tray 23 are transported one by one by the sheet transport mechanism 24, pass over the second platen 18, and are discharged to the paper discharge tray 25. When reading a document fed from the document feeder 4 and passing over the second platen 18, the first reading carriage 19 and the second reading carriage 20 are stopped below the second platen 18 in advance, and image data is generated from the document passing over the second platen 18.

[0024] (Sheet feeding device) Next, the structure of the sheet feeding device 2 will be described in detail with reference to FIGS. The sheet feeding device 2 is provided with a housing 31 that houses the entire device, and includes a storage compartment 32 that stores sheets to be supplied to the image forming device 1, a separation and feeding mechanism 33 that separates the sheets in the storage compartment 32 one by one and supplies them to the image forming device 1, and a lifting mechanism 34.

[0025] The storage case 32 has a roughly box-like shape with an opening at the top, and inside the storage case 32, a stacking tray 38 is provided so as to be movable up and down by a lifting mechanism 34. The stacking tray 38 is made of a plate member, and is capable of stacking sheets of a predetermined size in their entirety on its substantially flat upper surface. The storage case 32 can be pulled out from the housing 31 in a front direction (the front side in FIG. 1) perpendicular to the sheet feeding direction in which sheets are supplied from the sheet feeding device 2 to the image forming apparatus 1, and in this pulled-out state, sheets can be loaded and stacked on the stacking tray 38 through the opening at the top.

[0026] In the space (hereinafter referred to as the "loading tray storage space") inside the storage 32 that accommodates the loading tray 38, there are provided left and right side end regulating members (not shown) positioned to sandwich the sheets on the loading tray 38 from both sides in the width direction (direction perpendicular to the paper feed direction), and a rear end regulating member 43 positioned on the rear end side (end farther from the image forming apparatus 1 in the paper feed direction) of the sheets on the loading tray 38. The positions of both side ends in the width direction of the sheets S on the loading tray 38 are regulated by the side end regulating members, and the position of the rear end in the paper feed direction is regulated by the rear end regulating member 43.

[0027] The side end regulating members are erected on the bottom of the storage 32 so as to be slidable in the width direction of the sheets in cooperation with each other by, for example, a rack and a pinion. The rear end regulating member 43 is erected on the bottom of the storage 32 so as to be slidable in the sheet feed direction. Both the side end regulating members and the rear end regulating member 43 extend through a window portion (not shown) provided in the stacking tray 38 so as not to interfere with the stacking tray 38. With this configuration, the side end regulating members and / or the rear end regulating member 43 can be moved on the bottom of the storage 32 according to the size of the sheets loaded on the stacking tray 38 to regulate the side end position and / or the rear end position.

[0028] The loading tray 38 is supported by the lifting mechanism 34 so that it can be raised and lowered in the vertical direction within the storage 32. The loading tray 38 has four support parts 45 (only two are illustrated in FIG. 2 for simplicity) that protrude outward in the width direction from positions near the corners of both sides in the width direction. The lifting mechanism 34 is composed of four wires 46 as hanging members each having one end fixed to each support part 45 of the loading tray 38, four winding pulleys 47 that wind up the corresponding wires 46, a plurality of intermediate pulleys 48 around which the wires 46 extending between each winding pulley 47 and the corresponding support part 45 are wound, and a lifting motor M1 that rotates and drives the winding pulley 47.

[0029] For example, when the lift motor M1 is driven in the forward direction, the four winding pulleys 47 rotate simultaneously and wind up the wires 46, so that the four support parts 45 of the stacking tray 38 are pulled up simultaneously, and the stacking tray 38 rises while maintaining a substantially horizontal state. When the lift motor M1 is driven in the reverse direction, the four winding pulleys 47 are driven to rotate in the direction opposite to that when the stacking tray 38 was raised, and the wires 46 are unwound, so that the stacking tray 38 falls by its own weight while maintaining a substantially horizontal state. The lift mechanism 34 may be any mechanism capable of raising and lowering the stacking tray 38 while maintaining a substantially horizontal state in this manner, and is not limited to that of this embodiment.

[0030] The separation and feeding mechanism 33 includes a feed roller 51 that contacts the uppermost surface of the sheets stacked on the stacking tray 38 to feed the sheet, and a separation and conveying means that separates the fed sheets one by one and conveys them to the image forming apparatus 1. The separation and conveying means is composed of a feed roller 52 and a separation roller 53 that is in pressure contact with the feed roller to prevent the second and subsequent sheets from being fed. A conveying roller pair 54 is provided downstream of the separation and conveying means to feed the sheet into the conveying path 15 of the image forming apparatus 1.

[0031] The delivery roller 51 is rotated by the paper feed motor M2, and delivers the topmost sheet from the stacking tray 38. The paper feed roller 52 is similarly driven to rotate by the paper feed motor M2 via a plurality of gears and a timing belt (not shown), and delivers the sheet delivered from the stacking tray 38 by the delivery roller 51 in the paper feed direction. The transport roller pair 54 is rotated by the transport motor M3, and supplies the sheet delivered from the paper feed roller 52 to the image forming apparatus 1.

[0032] As shown in Fig. 3(a), the rotation shaft of the feed roller 51 is rotatably supported at the tip of an arm member 55 which is attached so as to be freely rotatable around the rotation shaft of the feed roller 52. The feed roller 51 hangs down due to its own weight. When the stack tray 38 rises, the feed roller 51 comes into contact with the top sheet on the stack tray, and is pushed up as the top sheet further rises. This causes the arm member 55 to rotate around the rotation shaft of the feed roller 52 as a fulcrum.

[0033] A sensor flag 56, which will be described later, is provided on the arm member 55 so as to rotate integrally with the arm member 55. As shown in Fig. 3(a), the sensor flag 56 in this embodiment extends from the rotation axis of the arm member 55 in approximately the opposite direction with respect to the arm member.

[0034] The feed roller 51 can be configured to be rotationally driven by the rotation of the rotation shaft of the feed roller 52 by the feed motor M2 being transmitted via multiple gears. In this case, for example, the bracket can be swung around the rotation shaft of the feed roller 52 by a solenoid, and the feed roller 51 can be moved between the operating position and the standby position.

[0035] As shown in FIG. 2, the separation roller 53 has a torque limiter 57 attached to its rotation shaft. As a result, when two or more sheets are overlapped and nipped in the nip portion where the feed roller 52 and the separation roller 53 are pressed against each other, the separation roller 53 stops and prevents the second and subsequent sheets from being fed. For example, when a plurality of overlapping sheets enter the nip portion between the feed roller 52 and the separation roller 53, the driving force of the feed roller 52 is transmitted to the top sheet, while the rotation of the separation roller 53 is stopped, so that the top sheet and the sheets below it slip, and only the top sheet is separated from the sheets below it and fed out. Of course, the separation roller 53 may be replaced with another member such as a separation pad.

[0036] 3, a sheet guide 58 is provided immediately downstream in the paper feed direction of the separation and conveyance means. The sheet guide 58 has a guide surface that is inclined upward from the tip side of the stacking tray 38 along the paper feed direction in order to guide the sheet sent out from the stacking tray 38 to the nip portion between the paper feed roller 52 and the separation roller 53. The sheet guide 58 can be formed, for example, by a flat plate member fixed to the storage 32 side.

[0037] It is preferable to position the leading edge of the sheet guide 58 in the sheet feeding direction as close as possible to the nip portion. This makes it possible to prevent the leading edge of the sheet sent from the stack tray 38 from hanging down from the leading edge of the sheet guide 58 and coming into contact with the separation roller 53, thereby preventing the leading edge of the sheet from curling up.

[0038] (Sensor means) The sheet feeding device 2 includes a lower limit detection means 61 and an upper surface detection means 64 in order to detect the positions of the stacking tray 38 and the sheet in the lifting and lowering direction. As shown in Fig. 2, the lower limit detection means 61 is disposed at the lower limit position in the lifting range of the stacking tray 38. The upper surface detection means 64 detects that the uppermost sheet S on the stacking tray 38 has reached a height position PU at which the sheet S can be fed by the separation sheet feeding mechanism 33 toward the image forming apparatus 1.

[0039] The upper surface detection means 64 includes a sheet contact sensor 65 for detecting the contact position between the feed roller 51 and the uppermost sheet on the stacking tray 38, and a sensor flag 56 that rotates integrally with the arm member 55. The sheet contact sensor 65 is disposed within the rotation range of the sensor flag 56 that rotates integrally with the arm member 55, as shown in FIG. 3(a).

[0040] In this embodiment, the arm member 55 is pushed up by the top sheet on the stacking tray 38 and rotates upward counterclockwise in the figure, the sensor flag 56 rotates downward counterclockwise to a certain rotation angle position, and the sheet contact sensor 65 turns on, thereby detecting the height position of the top sheet in contact with the pay-out roller 51.

[0041] Furthermore, the sheet feeding device 2 has a sheet detection means 66 arranged near the sheet exit of the paper feed roller 52, i.e., immediately downstream in the paper feed direction. The sheet detection means 66 detects the sheet sent from the paper feed roller 52 to the transport roller pair .

[0042] (Control unit) The sheet feeding device 2 includes a control unit 70 for controlling the operation thereof. The control unit 70 is made up of a central processing unit (CPU), and is connected to a ROM, which is a read-only memory, and a RAM, which is a rewritable memory. The ROM stores control procedures, which will be described later, in advance. The RAM is a main storage device used for storing input data and as a working storage area, etc.

[0043] The control unit 70 is connected to the lower limit detection means 61, the upper surface detection means 64, and the sheet detection means 66, and receives detection signals from each of these sensors in real time. The control unit 70 is also connected to the lift motor M1, the paper feed motor M2, and the transport motor M3, and the CPU controls the operation of these motors based on the detection signals from each of the detection means. The control unit 70 is also connected to an operation panel 74 of the image forming apparatus 1 that is operated by the user.

[0044] (Loading tray lifting operation) 3 to 5 and the flow chart of Fig. 6, the lifting and lowering operation of the stacking tray 38 in the sheet feeding device 2 will be described below. When the sheet feeding device 2 is started, or when a detection sensor (not shown) detects that the storage case 32, which has been pulled out from the housing 31, is accommodated in the housing 31, the sheet feeding device 2 drives the lifting motor M1 to lift the stacking tray 38.

[0045] Furthermore, when the sheets are sequentially fed from the stack tray 38 by the feed roller 51 and the position of the top sheet falls to a set position, the sheet feeding device 2 also drives the lift motor M1 to lift the stack tray 38. Note that the fact that the position of the top sheet on the stack tray 38 falls to the set position is determined when the sheet contact sensor 65 no longer detects the sensor flag 56 and turns off.

[0046] In the lifting operation of the stacking tray 38, the lifting motor MT1 is driven in the forward direction (step ST1). This rotates the winding pulley 47 to wind up the wire 46, and the stacking tray 38 is lifted. As shown in Fig. 3(a), after the top surface of the sheet on the stacking tray 38 abuts against the feed roller 51, when the stacking tray 38 is further lifted, the top surface of the sheet pushes up the feed roller 51, and the arm member 55 rotates upward in the counterclockwise direction in the figure.

[0047] 3(b), the sheet contact sensor 65 detects the sensor flag 56 rotating integrally with the arm member 55 and turns it on (step ST2). When the sheet contact sensor 65 turns on, it is detected that the upper surface of the uppermost sheet S on the stacking tray 38 has reached the reference position PU. When the sheet contact sensor 65 turns on, the control unit 70 determines whether the sheet feed mode is the "normal mode" or the "thin coated paper mode" (step ST3).

[0048] Here, the thin coated paper mode refers to a case where the sheets on the stacking tray 38 are thin coated paper, and the normal mode refers to a case where the sheets on the stacking tray 38 are sheets other than thin coated paper. In this embodiment, whether the sheets on the stacking tray 38 are thin coated paper or not is determined by the control unit 70 based on information related to the sheet type input in advance by the user from the operation unit 74.

[0049] In the normal mode (step ST4), the stacking tray 38 is raised by a first set amount from the position where the sheet contact sensor 65 is turned on, and the lifting motor MT1 is stopped (step ST6). As a result, the top surface of the sheet is placed at the first sending position P1 as shown in FIG.

[0050] In the thin coated paper mode (step ST5), the stacking tray 38 is raised by a second set amount from the position where the sheet contact sensor 65 is turned on, and the lifting motor MT1 is stopped (step ST6). The second set amount is set to a value smaller than the first set amount. As a result, as shown in FIG. 5, the top surface of the sheets on the stacking tray 38 is positioned at a second delivery position P2 that is lower than the first delivery position P1.

[0051] In this embodiment, the first output position P1 is set to be at approximately the same height as the leading edge of the sheet guide 58 in the paper feed direction, and the second output position P2 is set to a position slightly lower than that. In this embodiment, the second output position P2 is set to a position 0.5 mm lower than the leading edge of the sheet guide 58 in the paper feed direction. The difference in height between the second output position P2 and the first output position P1 can be determined taking into account, for example, the difference in thickness between thin coated paper and plain paper.

[0052] In this embodiment, the first and second set amounts for lifting the stacking tray 38 are set by the number of drive pulses of the lift motor MT1. In this case, the lift motor MT1 counts the number of drive pulses from the start of its drive, and is controlled to stop driving when the number reaches a preset number of pulses.

[0053] In the above embodiment, the paper feed mode is set to either the normal mode or the thin-coated paper mode depending on whether the sheets on the stack tray 38 are thin-coated paper or not. In another embodiment, multiple paper feed modes can be set simply depending on the basis weight of the sheets.

[0054] In the thin coated paper mode, when the stacking tray 38 rises by the second set amount and stops (steps ST5 and ST6) and the top surface of the sheets on the stacking tray 38 is located at the second delivery position P2, the feed motor M2 is driven with the feed roller 51 in contact with the top surface of the sheets on the stacking tray 38 as shown in Fig. 4. This causes the feed roller 51 to rotate and feed the topmost thin coated paper Ss on the stacking tray 38 in the feed direction as shown in Fig. 7. The fed sheets Ss are separated and transported one by one by the feed roller 52 and the separation roller 53, and are sent to the image forming apparatus 1 by the transport roller pair 54.

[0055] As shown in the figure, the topmost sheet Ss is fed out while its leading edge is pushed up obliquely from the lower second feed-out position P2 along the upward inclined surface of the sheet guide 58. As a result, the leading edge side portion of the sheet Ss is supported by the upward inclined surface of the sheet guide 58, compensating for its weak stiffness, i.e., low rigidity, and is prevented from sagging from the leading edge of the sheet guide 58 toward the separation roller 53. This eliminates or significantly reduces the risk of the leading edge of the sheet Ss fed out of the stacking tray 38 by the feed roller 51 coming into contact with the reversing separation roller 53 and curling up, causing a paper feeding failure.

[0056] Although the sheet feeding device and the image forming system including the same according to the present invention have been described above with reference to the embodiments of the accompanying drawings, the present invention is not limited to the embodiments shown in the drawings. [Explanation of symbols]

[0057] 1. Image forming device 2 Sheet Feeder 32 Storage 33 Separation feed mechanism 34 Lifting mechanism 38 Loading Tray 51 Payout roller 52 Paper feed roller 53 Separation roller 55 Arm parts 56 Sensor Flag 58 Seat guide 64 Upper surface detection means 65 Seat Contact Sensor 70 Control section 100 Image forming system M1 Lifting motor

Claims

1. A loading tray for loading sheets; a sheet feeding means for contacting an upper surface of a top sheet of the sheets stacked on the stacking tray and feeding the sheet; A separating means for separating the sheets fed by the feeding means into one sheet; a guide member having an inclined portion for guiding the sheet sent out by the sending means to the separating means; a moving means for moving the stacking tray up and down to a sending-out position where the sheet is sent out by the sending-out means, the moving means being configured to move the stacking tray, when the sheet stacked on the stacking tray is a predetermined sheet having a coating layer and a predetermined basis weight or less, to a sending-out position lower than the sending-out position when the sheet stacked on the stacking tray is a sheet other than the predetermined sheet; a sensor for detecting a top surface of the sheet on the stack tray which is moved up and down by the moving means, the moving means, when the sheet sent out from the stacking tray is a sheet other than the specified sheet, moves the stacking tray in response to the sensor detecting the top surface of the sheet on the stacking tray so that the top sheet is located at a first sending position, and when the sheet sent out from the stacking tray is the specified sheet, moves the stacking tray in response to the sensor detecting the top surface of the sheet on the stacking tray so that the top sheet is located at a second sending position lower than the first sending position. A sheet feeding device comprising:

2. the separating means includes a feeding roller for feeding the sheet fed by the feeding means, and a separating roller that is pressed against the feeding roller; 2. The sheet feeding device according to claim 1, wherein the inclined portion guides the sheet fed by the feeding means toward the feeding roller.

3. 3. The sheet feeding device according to claim 1, wherein the stacking tray is moved by the moving means so that the output position of the specified sheet when it is output is located below the downstream end of the inclined portion in the sheet transport direction by the output roller.

4. A sheet feeding device according to any one of claims 1 to 3, an image forming apparatus that forms an image on the sheet fed from the sheet feeding apparatus;

Images