Sheet feeding device, laminating device, image forming device, and image forming system

Abstract

To provide a sheet feeding device capable of preventing double feeding or feeding failure due to the catching of burrs of a sheet.SOLUTION: A sheet feeding device 33 has a sheet loading part 32a, a sheet feeding roller 7, a separation roller pair 8, and elevation means 30 for elevating the sheet loading part 32a according to a loading amount of the sheet S. The sheet loading part 32a has a first loading face 32b provided facing the sheet feeding roller 7 and supporting the downstream side of the sheet S in a carrying direction, a second loading face 32c supporting the upstream side of the sheet S in the carrying direction, and a bent part 32d integrally connecting the first loading face 32b and the second loading face 32c so as to project upward. The sheet S is loaded on the sheet loading part 32a so that the center of gravity thereof is positioned above the first loading face 32b, and during the operation of the elevation means 30, the first loading face 32b and the second loading face 32c integrally displace in the sheet loading part 32a.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a sheet feeding device, a laminating processing device, an image forming device, and an image forming system.

Background Art

[0002] Conventionally, in image forming devices such as copiers, printers, facsimiles, and multi-functional devices thereof, a sheet feeding device has been used to separately feed one by one the sheets stacked in large numbers on a feeding tray toward an image forming unit, an image reading device, or a sheet processing device or the like. In this sheet feeding device, a feeding tray formed in a flat shape is used to facilitate the setting of the sheets to be fed, and a configuration is adopted in which the sheet width direction is guided by a pair of side guides.

[0003] However, when the sheet to be fed has a curved shape in which the central portion in its width direction is curled in the vertical direction compared to both ends, the sheet is fed with the positions in the width direction being uneven, so there is a problem that skew, double feeding, non-feeding, etc. occur in the fed sheet. Further, in a sheet feeding device adopting a separation pad method including a paper feeding roller and a separation pad, a structure for holding the sheet in an inclined state may be considered in order to reduce the installation area of the device.

[0004] In order to solve this problem, a sheet feeding device has been proposed in which the placement surface on which the sheet is placed includes a first flat portion and a second flat portion provided on a different plane with respect to the first flat portion (see, for example, "Patent Document 1"). According to this technique, since the first flat portion and the second flat portion of the sheet placed on the placement surface are provided on different planes, the end portion thereof is deflected in the direction of gravity due to its own weight, so the curl is corrected.

[0005] Furthermore, a sheet feeding device has been proposed in which the mounting surface on which the sheet is placed is inclined, and the rear of the mounting surface can be set to an inclined position or a horizontal position depending on the type of sheet (see, for example, "Patent Document 2"). According to this technology, by setting the mounting surface to an inclined position for sheets that are relatively non-slippery, and to a horizontal position for sheets that are relatively slippery, it is possible to prevent the sheet from moving downward due to its own weight. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In sheet feeding devices, when feeding sheets that have burrs on their edges, such as laminated sheets, there is a problem that multiple sheets may be fed at once due to the burrs getting caught, resulting in double feeding. Furthermore, when sheets with burrs are applied to the sheet feeding device disclosed in "Patent Document 2," the angle of the bend becomes gentler as the mounting surface is raised and lowered, causing the rear end of the sheet to sag less, making it easier for the burrs to get caught. In particular, when using resin sheets, burrs are more likely to occur on the cut surface due to the cutting process during manufacturing compared to paper, resulting in stronger burr-induced snagging and a greater likelihood of double feeding. The present invention aims to solve the above-mentioned problems and provide a sheet feeding device that can prevent double feeding or non-feeding from occurring due to burrs on the sheet getting caught. [Means for solving the problem]

[0007] The invention described in claim 1 comprises a sheet loading section on which sheets to be transported are loaded, a paper feed roller for feeding the sheets, a pair of separation rollers for separating the sheets fed by the paper feed roller into individual sheets, and a lifting mechanism for raising and lowering the sheet loading section according to the amount of sheets loaded, wherein the sheet loading section is provided opposite to the paper feed roller and has a first loading surface that supports the downstream side of the sheets in the transport direction, a second loading surface that supports the upstream side of the sheets in the transport direction, and a bent portion that integrally connects the first loading surface and the second loading surface such that the first loading surface and the second loading surface protrude upward, the sheets are placed on the sheet loading section such that their center of gravity is located above the first loading surface, and when the lifting mechanism is operated, the sheet loading section is displaced integrally with the first loading surface and the second loading surface. Furthermore, the first loading surface is inclined downward as it is directed downstream in the transport direction, and the paper feed roller and the separation roller pair are arranged in a direction tangential to the first loading surface of the sheet placed on the first loading surface. It is characterized by the following: [Effects of the Invention]

[0008] According to the present invention, a gap is formed between the topmost sheet and the sheet directly below it, making it less likely for burrs formed on the topmost sheet to get caught on the sheet directly below, thereby suppressing the occurrence of double feeding and non-feeding. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic front view of an image forming system to which one embodiment of the present invention can be applied. [Figure 2] This is a schematic diagram illustrating a laminating apparatus to which one embodiment of the present invention can be applied. [Figure 3] This is a schematic diagram illustrating the winding roller, switching claw, and peeling claw used in a laminating processing device. [Figure 4] This is a schematic diagram illustrating the series of processes involved in laminating sheets using a laminating processing device. [Figure 5] This is a schematic diagram illustrating a conventional paper feed tray. [Figure 6] This is a schematic diagram illustrating the rear end of a laminate sheet loaded into a conventional paper tray. [Figure 7] This is a schematic diagram illustrating a conventional paper feed tray with a split stacking surface. [Figure 8] This is a schematic diagram illustrating the state of a conventional paper feed tray with a split stacking surface when the number of sheets decreases. [Figure 9] This is a schematic diagram illustrating the state of a conventional paper feed tray with a split stacking surface when the amount of sheet deflection is excessive. [Figure 10] This is a schematic diagram illustrating a paper feed tray according to one embodiment of the present invention. [Figure 11] This is a schematic diagram illustrating the rear end of a laminate sheet loaded in a paper feed tray according to one embodiment of the present invention. [Figure 12] This is a schematic diagram illustrating the state of a paper feed tray when the number of sheets decreases, according to one embodiment of the present invention. [Modes for carrying out the invention]

[0010] Figure 1 shows an image forming system to which one embodiment of the present invention can be applied. This image forming system 1 includes a multifunction device 2 equipped with copying, printing, and facsimile functions, a laminating device 3, a post-processing device 4, etc. Of these components, the multifunction device 2 constitutes an image forming apparatus on its own, and the image forming apparatus 5 is also configured with the multifunction device 2 and the laminating device 3.

[0011] The multifunction printer 2 includes an image forming unit 2A, which has a well-known configuration for forming an image on a transfer sheet, which is the recording medium, and a paper feeding unit 2B that receives the transfer sheet for image formation and feeds it to the image forming unit 2A. The transfer sheet received by the paper feeding unit 2B and used for image formation includes the inner sheet used when lamination is performed by the laminating processing unit 3, which is enclosed between laminate sheets. The transfer sheet for which image formation has been performed by the multifunction printer 2 is discharged onto a relay device 2C, which also serves as the output tray. The transfer sheet discharged onto the relay device 2C is configured to be fed to the laminating processing unit 3 in the same state. Therefore, since the multifunction printer 2 can form an image on the inner sheet, the image forming device 5 can automatically perform a series of processes from feeding the laminate sheet, peeling, creating the inner sheet, inserting the inner sheet, and laminating. The post-processing device 4 will be described later.

[0012] The laminating apparatus 3 shown in Figures 1 and 2 is a device that performs lamination by inserting an inner sheet (paper, photograph, etc.) into a laminate sheet, which is a double-layered sheet formed by joining two sheets together on only one side, and then applying heat and pressure to join the laminate sheet containing the inner sheet. In the following description, the expression "joining the laminate sheet and the inner sheet" is used. Laminating sheets S used as sheets include, for example, those in which one side is made of a permeable material such as a polyester sheet and the other side is permeable or opaque, or laminate films. Inner sheets include ordinary paper, cardboard, postcards, envelopes, thin paper, coated paper, tracing paper, OHP sheets, etc.

[0013] The laminating processing device 3 includes a paper feed tray 6 for loading laminate sheets S, a paper feed roller 7 for feeding the laminate sheets S on the paper feed tray 6, and a pair of separation rollers 8 for separating the laminate sheets S fed by the paper feed roller 7 into individual sheets. The paper feed tray 6 is equipped with multiple sheet size detection sensors 9 for detecting the size of the laminate sheets S placed on it. The paper feed tray 6 has a sheet tray 6a as a liftable sheet loading section for loading laminate sheets S, and the sheet tray 6a is raised and lowered by a lifting means 30 described later, and is configured so that the uppermost laminate sheet S is pressed against the paper feed roller 7 with a predetermined pressure force. The separation roller pair 8 includes a feed roller 8a that is driven to rotate in conjunction with the paper feed roller 7, and a separate roller 8b that can stop or rotate in the opposite direction to the paper feeding direction (see Figure 2 for both). Both rollers 8a and 8b have a high friction resistance member on their surface, and when two or more laminate sheets S are fed, the difference between the friction resistance between the sheets and the friction resistance between the sheets and the rollers ensures that only one sheet is fed.

[0014] Downstream of the separation roller pair 8 in the sheet transport direction, a sheet transport detection sensor 10 is provided to detect the transport of the laminate sheet S. Below the sheet transport detection sensor 10, an inlet roller pair 11 is provided to receive the transfer sheet sent from the multifunction printer 2, and a sheet transport detection sensor 12 is provided to detect the transported transfer sheet. To the left of the inlet roller pair 11, an discharge roller pair 13 is provided to send the transfer sheet sent from the multifunction printer 2 to the post-processing device 4 if the lamination process is not performed by the lamination processing device 3.

[0015] Downstream of the separation roller pair 8 in the sheet conveying direction, there are a first conveying roller pair 14, a winding roller 15, a second conveying roller pair 16, a third conveying roller pair 17, a heating roller pair 18, a fourth conveying roller pair 19, a discharge roller pair 20, and the like. On the downstream side of the winding roller 15 in the sheet conveyance direction, a sheet position detection sensor 21 for detecting the positions of the laminate sheet S and the intermediate paper P, which is a transfer sheet, is provided. Further downstream in the sheet conveyance direction, a sheet state detection sensor 22 for detecting the state of the laminate sheet S is provided. Also, a sheet position detection sensor 23 for detecting the positions of the laminate sheet S and the intermediate paper P is provided on the downstream side of the second conveyance roller pair 16 in the sheet conveyance direction. Among the above-described configurations, the sheet feeding device 24 is constituted by a paper feed tray 6, a paper feed roller 7, a separation roller pair 8, and a lifting means 30.

[0016] In FIGS. 1 and 2, the first conveyance roller pair 14 and the second conveyance roller pair 16 each have a driving roller and a driven roller that are pressed against each other, and the driving roller is rotationally driven by a driving means (not shown) to sandwich and convey the laminate sheet S and the intermediate paper P. The first conveyance roller 14 is configured to be rotatable only in the conveyance direction of sending the sheet downward in FIG. 2, and the second conveyance roller pair 16 is configured to be rotatable in both the conveyance direction and the reverse conveyance direction opposite thereto.

[0017] Between the first conveyance roller pair 14 and the second conveyance roller pair 16, as shown in FIG. 3, a winding roller 15, a switching claw 25, a peeling claw 26, etc. are arranged. The winding roller 15 is rotationally driven by a driving means (not shown) and is rotatable in both the conveyance direction and the reverse conveyance direction, similar to the second conveyance roller pair 16. The winding roller 15 has a gripping member 15a for holding the laminate sheet S on its outer peripheral surface. The gripping member 15a is displaced by an opening / closing means (not shown) and selectively occupies the closed position shown by the solid line and the open position shown by the two-dot chain line in FIG. 3. In the closed position, the end portion of the laminate sheet S can be gripped, and in the open position, the end portion of the laminate sheet S that was being gripped is released. When the end portion of the laminate sheet S is gripped by the gripping member 15a, the end position of the laminate sheet S is detected by the sheet position detection sensor 21. <0000​Downstream of the sheet position detection sensor 21 in the sheet transport direction, a switching claw 25 is positioned, which is displaced by a displacement means (not shown) and selectively occupies a first position shown by a solid line and a second position shown by a dashed line in Figure 3. When the switching claw 25 occupies the first position, the leading edge of the laminate sheet S being transported between the winding roller 15 and the second transport roller pair 16 can pass in either the transport direction or the reverse transport direction. When the switching claw 25 occupies the second position, the leading edge of the laminate sheet S in the transport direction (the leading edge is located upstream of the switching claw 25 in the transport direction) can pass the switching claw 25 and be transported downstream. Also, when the switching claw 25 occupies the second position, the leading edge of the laminate sheet S in the reverse transport direction (the leading edge is located downstream of the switching claw 25 in the transport direction) is prevented from passing the tip of the switching claw 25 and moving upstream in the transport direction. At this time, the leading edge of the laminate sheet S in the reverse direction is separated into two by the peeling claw 26, and one of these is guided by the switching claw 25 and transported to the right in Figure 3. The other leading edge of the separated laminate sheet S in the reverse direction is guided by the guide plate 27 fixed to the main body of the laminating processing device 3 and transported to the left in Figure 3.

[0019] A pair of peeling claws 26 are positioned downstream of the switching claw 25 in the sheet transport direction, and are movable in the width direction of the laminate sheet S. The peeling claws 26 are selectively positioned between a standby position and a peeling position by a moving mechanism (not shown). The peeling claws 26 are formed with pointed tips, which are the inner ends of each claw facing each other, and are configured so that when they occupy the peeling position, each tip can be inserted between the overlapping sheets of the laminate sheet S. When the peeling claws 26 occupy the standby position, each tip is retracted outside the transport area of ​​the laminate sheet S, so as not to obstruct the transport of the laminate sheet S. A sheet state detection sensor 22 is positioned at a location corresponding to the leading edge in the transport direction of the laminate sheet S into which the peeling claw 26 is inserted.

[0020] In Figures 1 and 2, the third transport roller pair 17, the fourth transport roller pair 19, and the discharge roller pair 20 each have a drive roller and a driven roller pressed against each other, and the sheet is gripped and transported by the rotational drive of the drive roller by a drive means (not shown). Each roller pair 17, 19, and 20 is configured to be rotatable only in the transport direction. The heating roller pair 18 comprises a heating roller having a heater inside and being rotationally driven, and a pressure roller that is pressed against the heating roller and rotates in response, and applies heat and pressure to the laminate sheet S in which the inner paper P is inserted between two sheets to bond the laminate sheet S and the inner paper P. A storage tray 28 is provided on the downstream side of the discharge roller pair 20 in the sheet transport direction, for accommodating the finished laminated sheets SA that have been joined together after the insertion of the core paper P. The storage tray 28 accommodates the finished laminated sheets SA, which have been vertically transported downwards within the main body of the laminating processing device 3, in an upright position. The storage tray 28 has an opening 28a on the front of the main body of the device, making it easy to remove the stored finished laminated sheets SA.

[0021] Next, a series of operations of the laminating apparatus 3, namely the peeling of the laminating sheet S, the insertion of the interlining paper P into the laminating sheet S, and the joining of the laminating sheet S and the interlining paper P, will be explained based on Figure 4. The configuration of the winding roller 15, the switching claw 25, and the peeling claw 26 described above, as well as the operations described below, are disclosed in detail in well-known technology by the same applicant as the present applicant (for example, Japanese Patent Application Publication No. 2021-143072). As shown in Figure 2, the laminate sheets S on the paper feed tray 6 are set so that one side with a joint where two sheets are joined is located downstream in the sheet transport direction, and multiple sheets are stacked on the paper feed tray 6. Once the setting of the laminate sheets S is confirmed and a start key (not shown) is turned on, the laminating processing device 3 operates the paper feed roller 7 and the separation roller pair 8 to feed one laminate sheet S toward the first transport roller pair 14.

[0022] The first transport roller pair 14, having received the laminate sheet S from the separation roller pair 8, further transports the laminate sheet S downstream. Here, the leading end of the transported laminate sheet S has one side with a joint where two sheets are joined, and the trailing end has the other side with an overlapping section where two sheets are superimposed. The laminating processing device 3 then temporarily stops transporting the laminate sheet S when the trailing end of the laminate sheet S passes the winding roller 15 and the detection of the laminate sheet S by the sheet position detection sensor 21 is interrupted. Subsequently, the laminating processing device 3 activates an opening / closing mechanism (not shown) to displace the gripping member 15a from the closed position to the open position, as shown in Figure 4(a).

[0023] Next, the laminating apparatus 3 reverses the second transport roller pair 16 to reverse the laminating sheet S in a vertically upward direction. When the laminating apparatus 3 recognizes, based on the signal from the sheet position detection sensor 21, that the rear end (leading end in the reverse direction) of the laminating sheet S has been transported to a position where it can be gripped by the gripping member 15a which is in an open position, the reverse movement of the laminating sheet S is stopped. Subsequently, the laminating apparatus 3 activates an opening / closing mechanism (not shown) to displace the gripping member 15a from the open position to the closed position, as shown in Figure 4(b), thereby holding the laminate sheet S on the outer surface of the winding roller 15.

[0024] Next, the laminating apparatus 3 rotates the winding roller 15 clockwise in Figure 3, winding the laminate sheet S onto the outer surface of the winding roller 15. Once the laminate sheet S has been wound onto the outer surface of the winding roller 15 about once, the difference in circumference between the two overlapping sheets causes the inner sheet to have excess material compared to the outer sheet, resulting in slack at the joint on one side of the laminate sheet S. As a result, a space is created between each sheet, as shown in Figure 4(c), and this space is detected by the sheet state detection sensor 22. The transport control of the laminate sheet S during winding onto the winding roller 15 is performed based on a signal from the sheet position detection sensor 23. In the state shown in Figure 4(c), the laminate sheet S has one side S1, where the joint is located, positioned downstream in the reverse direction from the sheet position detection sensor 23.

[0025] Next, the laminating apparatus 3 activates a moving mechanism (not shown) to move the peeling claws 26 from the standby position to the peeling position, inserting the peeling claws 26 into the space created between each sheet from both sides in the width direction of the laminate sheet S, and ensuring that the created space is securely maintained by each peeling claw 26, as shown in Figure 4(d). Then, with the peeling claws 26 inserted between the sheets, the winding roller 15 is rotated counterclockwise in Figure 3, and the second transport roller pair 16 is rotated forward to move the space created by the peeling of each sheet to the rear end of the laminate sheet S in the transport direction. Along the way, when the laminate sheet S has moved a predetermined amount, the gripping member 15a is displaced to the open position, releasing the rear end of the laminate sheet S in the transport direction that was held by the winding roller 15. Subsequently, when the rear end of the laminate sheet S in the transport direction reaches a position corresponding to the peeling claw 26, the transport of the laminate sheet S is stopped and a displacement mechanism (not shown) is activated, causing the switching claw 25 to be displaced from the first position to the second position, resulting in the state shown in Figure 4(e).

[0026] Next, the laminating apparatus 3 reverses the second transport roller pair 16 to reverse the laminate sheet S. At this time, the two sheets separated from each other by the peeling claws 26 are guided to the right by the switching claw 25, which occupies the second position, as one of the sheets located on the right in Figure 4(e), and guided to the left by the guide plate 27 as the other sheet located on the left in Figure 4(e). During this operation, as the two separated sheets are guided in the left and right directions by the switching claws 25 and the guide plate 27, respectively, a moving mechanism (not shown) is activated, causing the peeling claws 26 to move from the peeling position to the standby position, resulting in the state shown in Figure 4(f). Furthermore, when the laminate sheet S is fed in reverse, the two separated sheets are peeled apart from each other over their entire length. When one side S1 of the laminate sheet S reaches a predetermined position, the reverse feeding of the laminate sheet S is temporarily paused. At this time, the joint portion of the laminate sheet S is held between the second transport roller pair 16, and the overlapping portion opens wide to the left and right. Subsequently, a displacement mechanism (not shown) is activated, and the switching claw 25 is displaced from the second position to the first position, resulting in the state shown in Figure 4(g).

[0027] Next, the inner paper P is fed from the multifunction printer 2 via the relay device 2C. The fed inner paper P is taken into the main body of the laminating processing device 3 via the entrance roller pair 11, detected by the sheet transport detection sensor 12, and then guided by a switching claw (not shown) to the first transport roller pair 14. After that, the inner paper P is transported further downward by the first transport roller pair 14, and its leading edge is inserted into the overlapping section of the laminate sheet S, which has large openings on the left and right, resulting in the state shown in Figure 4(h). Next, the laminating apparatus 3 transports the laminate sheet S with the insert paper P inserted vertically downwards, overlapping each sheet again and closing the opening. The laminate sheet S with the insert paper P inserted is then transported further downwards by the third transport roller pair 17 and then sent to the heating roller pair 18.

[0028] The core paper P and laminate sheet S, which are sent to the heating roller pair 18, are bonded together by the action of heat and pressure, and then cooled as they pass through the fourth conveying roller pair 19 and the discharge roller pair 20. The cooled and completed finished laminate sheet SA is discharged upright into the storage tray 28 by the discharge roller pair 20. In this way, the finished laminate sheet SA, which has been pressed together after passing through the heating roller pair 18, is discharged vertically downward, so that the heated finished laminate sheet SA can be stored in the storage tray 28 while suppressing bending due to external forces. In this configuration, the finished laminated sheets SA are discharged vertically downwards, so gravity and external forces that would deform them do not act on them. Furthermore, since the finished laminated sheets SA are sufficiently cooled before reaching the storage tray 28, deformation of the finished laminated sheets SA is suppressed even if the loading surface of the storage tray 28 is inclined.

[0029] Next, the post-processing device 4 will be described. In the case of image forming operation without lamination, the transfer sheet PA that is not used as the inner paper P discharged from the multifunction printer 2 is received by the inlet roller pair 11 of the laminating device 3, then transported horizontally by the discharge roller pair 13 to the post-processing device 4 connected to the downstream side of the laminating device 3. The post-processing device 4 can perform post-processing on the transfer sheet PA, such as stapling and sorting. The transfer sheet PA is loaded onto the output tray 29 of the post-processing device 4.

[0030] The image forming apparatus 5, which includes the laminating apparatus 3 described above, can automatically perform a series of laminating operations, including feeding the laminate sheet S, peeling it off, inserting the interleaving paper P, and bonding the laminate sheet S and the interleaving paper P by heating and pressurizing, thus improving convenience compared to conventional configurations. However, problems have also arisen in the image forming apparatus 5, which includes the laminating apparatus 3 described above. These problems are explained below.

[0031] Figure 5 shows a schematic diagram of the paper feed tray 6. The laminate sheets S, stacked in bundles on the sheet tray 6a within the paper feed tray 6, are held in a state where their leading edge in the sheet transport direction is pressed against the paper feed roller 7 with a predetermined pressure force as the sheet tray 6a rotates with its base end 6b, which is the upstream end in the sheet transport direction, as a pivot point. The sheet tray 6a is rotated by a lifting mechanism 30 consisting of a drive means such as a motor, and the laminate sheets S on the sheet tray 6a are raised and lowered. Next, the laminate sheets S are fed by the rotation of the paper feed roller 7, at which time the feed roller 8a also rotates in the same direction as the paper feed roller 7, and the separate roller 8b also stops or rotates in the opposite direction, so that only one laminate sheet S is separated and fed.

[0032] The separate roller 8b is equipped with a torque limiter (not shown), and when multiple laminate sheets S are fed between the feed roller 8a and the separate roller 8b (separation nip), the frictional force of the separate roller 8b suppresses the transport of the lower laminate sheets S, so that only the top laminate sheet S is fed. As the amount of sheets in the sheet bundle decreases due to sheet feeding, and the top sheet surface on the sheet tray 6a begins to descend, a sensor (not shown) detects the descent of the sheet surface, and the lifting mechanism 30 rotates the sheet tray 6a counterclockwise in Figure 5, using its base end 6b as a pivot point. As a result, the top sheet surface of the laminate sheets S stacked on the sheet tray 6a rises, and the top laminate sheet S is controlled to press against the paper feed roller 7 with a predetermined pressure.

[0033] Figure 6 shows an enlarged view of the state of the rear end of the laminate sheet S in the transport direction when the laminate sheet S is placed on the paper feed tray 6. As mentioned above, since the laminate sheet S is formed from a resin material such as a polyester sheet, burrs SB may be generated at the rear end of the sheet during formation. When laminate sheets S with such burrs SB are fed, the downward-facing burrs SB formed on the uppermost laminate sheet S catch on the second laminate sheet S, causing the second sheet to be fed together with the first sheet, resulting in double feeding. Double feeding occurs when the catching force of the burrs SB becomes greater than the separation force of the separation roller pair 8.

[0034] Conventional paper trays are known to have configurations that improve sheet separation during paper feeding, such as dividing the tray into two loading surfaces or having a part of the tray's bottom plate move up and down relative to the paper feed roller. Figures 7, 8, and 9 show a conventional paper feed tray with a split loading surface. The paper feed tray 31 has a sheet tray 31a which is a sheet loading section divided into two parts on which laminate sheets S are loaded. The sheet tray 31a has a first loading surface 31b and a second loading surface 31c. The second loading surface 31c is fixed to the tray body of the paper feed tray 31 in a nearly horizontal position, and the first loading surface 31b is configured to be rotatable with its base end 31d as a pivot point. The laminate sheets S on the sheet tray 31a are stacked in bundles such that their center of gravity is located above the first loading surface 31b. The first loading surface 31b rotates with its base end 31d as a pivot point, so that the leading edge in the sheet transport direction is held in contact with the paper feed roller 7 with a predetermined pressure. The first loading surface 31b is rotated by the lifting mechanism 30, and the laminate sheets S on the first loading surface 31b are raised and lowered.

[0035] Subsequently, the paper feed roller 7 and the separation roller pair 8 operate in the same manner as the paper feed tray 6, and only one laminate sheet S is separated and fed. In this paper feed tray 31, Figure 7 shows the state in which many laminate sheets S are stacked on the sheet tray 31a, and Figure 8 shows the state in which the number of laminate sheets S on the sheet tray 31a decreases, the lifting mechanism 30 operates, and the first stacking surface 31b is raised. In the state shown in Figure 7, if a burr SB is formed at the rear end of the laminate sheet S, the situation will be the same as in Figure 6, and there is a risk of double feeding. In the state shown in Figure 8, the bending angle between the first loading surface 31b and the second loading surface 31c is larger than in the state shown in Figure 7, and the sagging at the rear end of the laminate sheet S becomes less pronounced, making it easier for the burr SB to get caught. Furthermore, in the state shown in Figure 9, the bending angle is too steep for the physical properties of the laminate sheet S, and the sagging at the rear end of the sheet becomes too pronounced, increasing the transport resistance and leading to problems such as double feeding and non-feeding. The configuration of the present invention that prevents the occurrence of the above-mentioned problems is described below.

[0036] Figure 10 shows a paper feed tray according to one embodiment of the present invention, in which the paper feed tray 32 is used in place of the paper feed tray 6 in Figures 1 and 2. The paper feed tray 32 has a sheet tray 32a that serves as a liftable sheet loading section for loading laminate sheets S. The sheet tray 32a is raised and lowered by a lifting mechanism 30, and is configured so that the uppermost laminate sheet S is pressed against the paper feed roller 7 with a predetermined pressure. The sheet tray 32a is divided into two parts, and has a first loading surface 32b located on the downstream side in the sheet transport direction where laminate sheets S are mainly loaded, and a second loading surface 32c located on the upstream side in the sheet transport direction. The sheet tray 32a is connected by a bent portion 32d such that the first loading surface 32b and the second loading surface 32c protrude upward, and the loading surfaces 32b and 32c are integrally formed. The sheet tray 32a is configured to be rotatable with a base end 32e located at the upstream end in the sheet transport direction as a pivot point.

[0037] The laminate sheets S on the sheet tray 32a are stacked in bundles such that their center of gravity is located above the first loading surface 32b, and are held in a state where their leading edge in the sheet transport direction is pressed against the paper feed roller 7 with a predetermined pressure by rotating with the base end 32e as a pivot point. The sheet tray 32a is rotated by the lifting mechanism 30, and the laminate sheets S on the first loading surface 32b are raised and lowered. The first loading surface 32b extends upstream in the sheet transport direction from the center of gravity of the loaded laminate sheet S, and its main functions are to hold the laminate sheet S and to make contact with the paper feed roller 7. The bent portion 32d is positioned so that the rear end of the loaded laminate sheet S hangs down onto the second loading surface 32c, and the second loading surface 32c is positioned upstream of the bent portion 32d in the sheet transport direction so that the rear end of the laminate sheet S does not hang down too much.

[0038] The bending angle between the first loading surface 32b and the second loading surface 32c at the bent portion 32d is configured to be a predetermined angle θ. The formation position and predetermined angle θ of the bent portion 32d are determined by various conditions such as the material (physical properties), size, and thickness of the laminate sheet S used, and are determined in a manner in which the rear end of the sheet of the maximum or minimum size and maximum or minimum thickness of the laminate sheet S used undergoes elastic deformation as described later. Furthermore, setting the bending angle to an unnecessarily acute angle may result in excessive sagging at the rear end of the sheet, similar to the condition shown in Figure 9, potentially negatively impacting sheet transportability. Therefore, it is desirable to set the angle within an appropriate range.

[0039] Figure 11 shows an enlarged view of the state of the rear end of the laminate sheet S in the transport direction when the laminate sheet S is placed on the paper feed tray 32. In the configuration of the present invention, at the rear end of the sheet upstream of the bent portion 32d in the sheet transport direction, each sheet sags downward due to the effect of gravity, and a gap SC is created between each sheet. As a result of the gap SC being created between each sheet, burrs are formed on the uppermost laminate sheet S. SBThis makes it less likely for the paper to get caught on the lower laminate sheet S, suppressing the occurrence of double feeding and non-feeding. In the example shown in Figure 11, a gap SC is formed between each sheet. However, in order to achieve the effects of the present invention, namely to prevent double feeding and non-feeding, it is sufficient for a gap SC to be formed at least between the top sheet and the sheet directly below it. When the top sheet is fed and the sheet directly below it becomes the top sheet, a new gap SC is formed between the new top sheet and the sheet directly below it.

[0040] Figure 12 shows the paper feed tray 32 in a state where the amount of laminate sheets S loaded has decreased from the state shown in Figure 10. As the amount of sheets loaded decreases due to the feeding of the loaded laminate sheets S, the lifting mechanism 30 is activated and the sheet tray 32a rotates counterclockwise in the figure around the base end 32e, and is controlled to maintain the contact position between the uppermost laminate sheet S and the paper feed roller 7 at a constant height. Thus, when the amount of sheets loaded decreases, it is necessary to raise the sheet tray 32a, but the sheet tray 32a is constructed with each loading surface 32b, 32c integrally formed, and the base end 32e, which is the pivot point, is located near the upstream end in the transport direction of the second loading surface 32c. Of the above-described components, the sheet feeding device 33 is comprised of the paper feed tray 32, the paper feed roller 7, the separation roller pair 8, and the lifting mechanism 30. This allows the sheet tray 32a to be raised and lowered while maintaining a predetermined angle θ as the bending angle, and the sagging state at the rear end of the sheet can be kept constant regardless of the sheet load, thereby suppressing the occurrence of double feeding and non-feeding.

[0041] In the above configuration, the first loading surface 32b is provided in such a manner that it slopes downward as it moves downstream in the sheet transport direction. This reduces the installation area of ​​the device compared to when the first loading surface 32b is arranged horizontally. Furthermore, by arranging the paper feed roller 7 and the pair of separation rollers 8 in a direction tangential to the first loading surface 32b of the laminate sheet S placed on the first loading surface 32b, the laminate sheet S is positioned downstream in the transport direction by its own weight when placed on the first loading surface 32b, thus eliminating the need for an end fence and reducing costs.

[0042] In the above embodiment, an example was shown using a vertical transport type laminating apparatus 3 as the laminating apparatus to which the present invention can be applied, but the present invention can also be applied to a horizontal transport type laminating apparatus. Furthermore, an example was shown using an image forming apparatus 5 as the image forming apparatus to which the present invention can be applied, but the present invention is not limited to this and can also be applied to photocopiers, facsimile machines, multifunction printers, etc. Furthermore, in the above embodiment, a configuration was shown in which a transfer sheet is used as the inner paper S on which the image is formed, but this transfer sheet can also include cardboard, postcards, roll paper, envelopes, plain paper, thin paper, coated paper (such as coated paper or art paper), tracing paper, OHP sheets, OHP films, resin films, etc., and any sheet-like material capable of forming an image can be used.

[0043] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the spirit of the invention as described in the claims, unless otherwise specifically limited in the above description. The effects described in the embodiments of the present invention are merely illustrative of the most preferred effects that may arise from the present invention, and the effects of the present invention are not limited to those described in the embodiments. [Explanation of Symbols]

[0044] 1. Image forming system 2 Image forming device (multifunction device) 3. Laminating equipment 5 Image forming apparatus 7 Paper feed roller 8 Separation Roller Pairs 30 Lifting and lowering means 32a Seat loading section (seat tray) 32b First loading surface 32c Second loading surface 32d bend 32e Fulcrum (base end) 33 Sheet feeding device S Sheet (Laminate Sheet) [Prior art documents] [Patent Documents]

[0045] [Patent Document 1] Japanese Patent Publication No. 2008-133103 [Patent Document 2] Patent No. 3591175

Claims

1. A sheet loading section where the sheets to be transported are loaded, A paper feed roller for feeding the aforementioned sheet, A pair of separation rollers that separate the sheets fed by the aforementioned paper feed rollers into individual sheets, A lifting mechanism for raising and lowering the sheet loading section according to the amount of sheets loaded. Equipped with, The aforementioned sheet loading section is A first loading surface is provided opposite the paper feed roller and supports the downstream side in the conveying direction of the sheet, A second loading surface that supports the upstream side of the sheet in the transport direction, A bent portion integrally connects the first loading surface and the second loading surface such that the first loading surface and the second loading surface protrude upward. It has, The sheet is placed on the sheet loading section such that its center of gravity is located above the first loading surface. When the lifting mechanism is operated, the sheet loading section is displaced integrally with the first loading surface and the second loading surface. The first loading surface is inclined downward as it is directed downstream in the transport direction. A sheet feeding device in which the paper feeding roller and the pair of separation rollers are arranged in a direction tangential to the first loading surface of the sheet placed on the first loading surface.

2. In the sheet feeding device according to claim 1, A sheet feeding device characterized in that when the lifting means is operated, the sheet loading section is displaced by rotating around a pivot point, and the pivot point is located near the upstream end of the second loading surface in the transport direction.

3. A laminating apparatus comprising a sheet feeding device according to claim 1 or 2.

4. An image forming apparatus comprising the sheet feeding device according to claim 1 or 2.

5. An image forming apparatus comprising the laminating apparatus described in Claim 3.

6. An image forming system comprising the sheet feeding device according to claim 1 or 2.

Images