Sheet feeding device and image forming apparatus

Abstract

The stacked sheets are separated one by one more reliably by using airflow. [Solution] The system includes an upstream air nozzle 71 that is movably supported on a side restricting member 61 and blows air from the sheet width direction to clear at least the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a, and an air supply unit 73 that supplies air to the upstream air nozzle 71. The upstream air nozzle 71 is positioned as a first air nozzle that blows air to a first blowing position when the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a is in a first sheet position, and as a second air nozzle that blows air to a second blowing position below the first blowing position when the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a is in a second sheet position below the first sheet position.

Description

Technical Field

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

Background Art

[0002] Conventionally, in image forming devices such as copiers and printers, various separation methods have been adopted to separate and feed the sheets stacked and supported on the sheet support portion one by one. For example, a retard separation method is widespread in which a pickup roller is brought into contact with and pressed against the uppermost sheet of the stacked sheet bundle to feed it out, and a feed roller and a retard roller arranged on the downstream side in the sheet conveyance direction prevent double feeding of the sheet. In recent years, with the diversification of recording media, there has been an increasing demand to form images on sheets such as coated paper obtained by applying a coating process to the surface of the sheet. However, in the case of coated paper, especially when the sheets are stacked in an environment of high humidity, the sheets have a property of being easily adsorbed to each other, so there is a risk of feeding failures such as non-feeding and double feeding in the retard separation method.

[0003] Therefore, in order to eliminate such strong adsorption between the sheets, a separation method has been proposed that includes air-disposing means for preliminarily disposing of the sheets by blowing air from the side surface of the sheet bundle, and performs feeding after disposing of the sheets one by one (see Patent Document 1). According to this configuration, the uppermost sheet can be picked up in a state where the adsorption between the sheets is reduced by blowing air from the side surface of the sheet bundle, and the sheets can be separated one by one by a separation unit provided downstream thereof. In such a separation method using air-disposing means, compared with a device using only the retard separation method without air-disposing means, even for sheets with strong adsorption force, the sheets are disposed before feeding to eliminate the adsorption, so it is possible to reliably separate and feed the sheets one by one from the sheet bundle.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-5643 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Incidentally, in order to reliably separate each sheet in a sheet bundle just before feeding, it is desirable to concentrate the airflow only near the top sheet of the sheet bundle just before feeding. This is because if air is blown over the entire sheet bundle, the bundle will float up as a clump at the top, making it difficult to separate each sheet properly and potentially causing feeding problems.

[0006] However, in the image forming apparatus shown in Patent Document 1, the air nozzle does not lower in response to the decrease in the stacking capacity of the sheet bundle, which lowers the height of the top sheet. As a result, the air is not always blown only near the top sheet of the sheet bundle, and there was a possibility that the sheets could not be properly handled one by one. This resulted in feeding problems such as non-feeding and double feeding.

[0007] The present invention aims to provide a sheet feeding device and an image forming apparatus that can more reliably separate stacked sheet bundles one by one by air handling. [Means for solving the problem]

[0008] One aspect of the present invention is a sheet feeding device comprising: a support section having a support surface for stacking and supporting sheets; a feeding section for feeding the uppermost sheet from a sheet bundle supported on the support surface; a side edge restricting section for restricting the end position of the sheet in the sheet width direction of the sheet supported on the support surface; an air nozzle movably supported by the side edge restricting section and blowing air from the sheet width direction to handle at least the uppermost sheet from the sheet bundle supported on the support surface; and an air supply section for supplying air to the air nozzle, wherein the air nozzle is located in a first air nozzle position that blows air to a first blowing position when the uppermost sheet from the sheet bundle supported on the support surface is located in a first sheet position, and is located in a second air nozzle position that blows air to a second blowing position lower than the first blowing position when the uppermost sheet from the sheet bundle supported on the support surface is located in a second sheet position lower than the first sheet position.

[0009] Furthermore, one aspect of the present invention is an image forming apparatus characterized by comprising the above-described sheet feeding device and an image forming unit for forming an image on a sheet. [Effects of the Invention]

[0010] According to the present invention, stacked sheet bundles can be separated one by one more reliably by air circulation. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view showing an image forming apparatus according to the first embodiment. [Figure 2] This is a perspective view showing the sheet feeding unit according to the first embodiment. [Figure 3] This is a cross-sectional view showing the sheet feeding unit according to the first embodiment, where (a) is in a state where the unit is full of sheets and (b) is in a state where there are only a few sheets remaining. [Figure 4] This is a perspective view showing the sheet feeding unit according to the second embodiment. [Figure 5]This is a cross-sectional view showing the sheet feeding unit according to the second embodiment, where (a) is in a state where the unit is full of sheets and (b) is in a state where there are only a few sheets remaining. [Figure 6] This is a cross-sectional view showing the sheet feeding unit according to the third embodiment, where (a) is in a state where the unit is full of sheets and (b) is in a state where there are only a few sheets remaining. [Modes for carrying out the invention]

[0012] <First Embodiment> Hereinafter, a first embodiment of the present invention will be described in detail with reference to Figures 1 to 3(b). In this embodiment, as an example, an electrophotographic monocolor printer is used as the image forming apparatus 10. However, the present invention is not limited to an electrophotographic monocolor printer image forming apparatus 10, and may also be full color, and may be applied to tandem or inkjet recording image forming apparatuses.

[0013] [Image forming apparatus] The schematic configuration of the image forming apparatus 10 will be described with reference to Figure 1. Figure 1 is a cross-sectional view of the image forming apparatus 10 according to this embodiment. In this embodiment, the image forming apparatus 10 has an image reading device 100. Hereinafter, the position facing the unshown operation section where the user makes various inputs / settings to the image forming apparatus 10 will be defined as the "front side" of the image forming apparatus 10, and the back side will be defined as the "back side". In other words, Figure 1 shows the internal configuration of the image forming apparatus 10 as seen from the front side.

[0014] The main body of the device 10a includes an image forming unit 11 that forms an image on a sheet S, which is a recording medium, and a sheet feeding unit 12 that feeds the sheet S to the image forming unit 11. The sheet feeding unit 12 includes a plurality of sheet storage units 1 that can store sheets of different sizes, and a manual feed tray 51. In this embodiment, there are four different sheet storage units 1, but since the other components are the same except for the arrangement position and the size of the sheets stored, they will be described using the same reference numerals. Each sheet storage unit 1 is detachable from the main body of the device 10a. The sheets S stored in each sheet storage unit 1 are fed out by a pickup roller 2. Then, they are separated one by one by a feed roller 3 and a retard roller 4 and passed to the corresponding transport roller pair 31. The sheets S are then passed sequentially to a plurality of transport roller pairs 31 arranged along the sheet transport path, and are transported to a registration roller pair 36.

[0015] The manual feed tray 51 is provided to the main body 10a so as to be openable and closable, and when open, it loads and supports the sheets S. The sheets S placed on the manual feed tray 51 by the user are fed into the main body 10a by the pickup roller 52, separated one by one by the feed roller 53 and retard roller 54, and transported to the registration roller pair 36.

[0016] The registration roller pair 36 stops the leading edge of the sheet S to correct its skewness and resumes transporting the sheet S in accordance with the progress of the image formation operation, which is the toner image formation process by the image forming unit 11.

[0017] The image forming unit 11 forms an image on the sheet S based on the information of the image read by the image reading device 100. The image forming unit 11 is an electrophotographic unit including a photosensitive drum 21 which is a photoreceptor. The photosensitive drum 21 is rotatable along the conveyance direction of the sheet S, and a charger 18, an exposure device 23, a developing unit 24, a transfer charger 25, a separation charger 26, and a cleaner 27 are arranged around the photosensitive drum 21. The charger 18 uniformly charges the surface of the photosensitive drum 21. The exposure device 23 exposes the photosensitive drum 21 based on the image information input from the image reading device 100 or the like, and forms an electrostatic latent image on the photosensitive drum 21.

[0018] The developing unit 24 contains a two-component developer including toner and a carrier, and develops the electrostatic latent image into a toner image by supplying charged toner to the photosensitive drum 21. The toner image carried on the photosensitive drum 21 is transferred to the sheet S conveyed from the registration roller pair 36 by the bias electric field formed by the transfer charger 25. The sheet S to which the toner image is transferred is separated from the photosensitive drum 21 by the bias electric field formed by the separation charger 26, and is conveyed toward the fixing unit 29 by the pre-fixing conveyance unit 28. In addition, the attachments such as the residual transfer toner remaining on the photosensitive drum 21 without being transferred to the sheet S are removed by the cleaner 27, and the photosensitive drum 21 is prepared for the next image forming operation.

[0019] The sheet S conveyed to the fixing unit 29 is sandwiched between the fixing roller pair, pressurized while being heated, and the image is fixed by melting and fixing of the toner. When the image output is completed, the sheet S on which the fixed image is obtained is discharged to the discharge tray 30 protruding outside the apparatus main body 10a via the discharge roller pair 32. When forming an image on the back surface of the sheet S in double-sided printing, the sheet S that has passed through the fixing unit 29 is reversed between the front and back surfaces by the reversing unit 39, and is conveyed to the registration roller pair 36 by the double-sided conveyance unit 38. Then, the sheet S on which the image is formed again by the image forming unit 11 is discharged to the discharge tray 30.

[0020] [Image Reading Device] The image reading device 100 disposed above the device main body 10a of the image forming apparatus 10 includes a scanner unit 101 and an ADF 102 (Auto Document Feeder), and optically scans a document to read image information. The image information converted into an electrical signal by the image reading device 100 is transferred to a control unit 13 provided in the device main body 10a via a controller (not shown). Thereby, the image forming apparatus 10 forms an image on a recording medium based on the image information read by the image reading device 100. Note that the control unit 13 includes a CPU which is a central processing unit, a ROM which is a read only memory, and a RAM which is a random access memory. A control program for realizing the operations of each unit is stored in the ROM, and input data and working data are stored in the RAM.

[0021] [Sheet Feeding Unit] Next, referring to FIGS. 2 to 3(b), the configuration of the sheet feeding unit 12 in the present embodiment will be described. As described above, the sheet feeding unit 12 has four sheet storage units 1 and a manual feed tray 51, but here, one sheet storage unit 1 will be described. The sheet feeding unit 12 is an example of a sheet feeding device, and includes a sheet storage unit 1 having a sheet support surface 1a for stacking and supporting a sheet S, a pickup roller 2, a feed roller 3, and a retard roller 4. The pickup roller 2 picks up and feeds the sheet S stacked and supported in the sheet storage unit 1. The pickup roller 2 is an example of a feeding unit, and feeds the uppermost sheet S among the sheet bundle supported by the sheet support surface 1a. The pickup roller 2 is biased downward toward the sheet S by a biasing spring (not shown). The feed roller 3 conveys the picked-up sheet S. The retard roller 4 is provided to be in pressure contact with the feed roller 3, and separates and conveys the uppermost sheet S from a plurality of stacked sheets S into a single sheet.

[0022] The sheet storage section 1 is an example of a support section and consists of a roughly casing-shaped sheet cassette with an open top. A movable loading section 40, which is a sheet loading member for loading sheets S, is provided in the area extending from approximately the center to the downstream side in the sheet transport direction Df at the bottom of the sheet storage section 1. The movable loading section 40 is roughly plate-shaped and is provided so as to be rotatable in the vertical direction relative to the sheet storage section 1, with a pivot shaft 40a provided on the upstream side of the sheet transport direction Df as a support shaft. That is, the movable loading section 40 is an example of a lifting member and moves up and down relative to the sheet storage section 1 and has a lifting region 40b which is part of the sheet support surface 1a.

[0023] In the bottom of the sheet storage section 1, a fixed loading section 41 is formed in the area extending from approximately the center to the upstream side in the sheet transport direction Df, and is fixed to the bottom surface of the sheet storage section 1 and does not move up and down. That is, the sheet S is supported on the downstream side of the sheet transport direction Df by the movable loading section 40 and on the upstream side by the fixed loading section 41. The fixed loading section 41 is part of the sheet support surface 1a and has a fixed region 41a that is fixed vertically to the fixed loading section 41. That is, the sheet support surface 1a has a fixed region 41a and a lifting region 40b that is continuous with the fixed region 41a and supports the sheet S together with the fixed region 41a.

[0024] The sheet feeding unit 12 has a lifting unit 42 that raises and lowers the movable loading unit 40. The lifting unit 42 is driven by a command from the control unit 13. The lifting unit 42 has a rotatable lifter 43 and a drive mechanism 44 including an electric motor and gears that rotate the lifter 43. The lifter 43 is roughly plate-shaped and is positioned below the downstream part of the movable loading unit 40 in the sheet transport direction Df, and is supported by the drive mechanism 44 so as to be rotatable in the vertical direction. As a result, when the drive mechanism 44 is driven, the lifter 43 rotates vertically around the upstream side of the sheet transport direction Df, lifting the movable loading unit 40 from below and positioning the vertical position of the movable loading unit 40. That is, the movable loading unit 40 is rotatable vertically around a pivot axis 40a, and the lifter 43 rotates it upward around the pivot axis 40a according to the remaining amount of sheet S, pressing the sheet S against the pickup roller 2.

[0025] In this embodiment, the movable loading section 40 is located in a first lifting position when the thickness of the sheet bundle supported in the lifting region 40b is a first thickness t1 (see Figure 3(a)). Furthermore, the movable loading section 40 is located in a second lifting position above the first lifting position when the thickness of the sheet bundle supported in the lifting region 40b is a second thickness t2, which is thinner than the first thickness t1 (see Figure 3(b)). That is, the lifting region 40b moves up and down in accordance with the position of the uppermost sheet S among the sheet bundle supported on the sheet support surface 1a.

[0026] The sheet feeding unit 12 has side regulating members 61 and 62 that regulate the end positions of the sheet S supported on the sheet support surface 1a in the sheet width direction W. The sheet width direction W is the horizontal direction perpendicular to the sheet transport direction Df. The side regulating members 61 and 62 are examples of side end regulating parts and are provided at both ends in the sheet width direction W. Side regulating member 61 is an example of a first side end regulating part, and side regulating member 62 is an example of a second side end regulating part that regulates the end position of the sheet S supported on the sheet support surface 1a in the sheet width direction W opposite to that of side regulating member 61.

[0027] The side regulating member 61 has a regulating surface 61a that abuts against the end of the sheet S in the sheet width direction W supported on the sheet support surface 1a, and a first opening 611 and a second opening 612 formed on the regulating surface 61a. The first opening 611 is positioned upstream of the second opening 612 in the sheet transport direction Df. The sheet feeding unit 12 is movably supported on the side regulating member 61 and has an upstream air nozzle 71 and a downstream air nozzle 72 that blow air from the sheet width direction W to handle at least the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a. The upstream air nozzle 71 is exposed from the first opening 611 toward the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a. The downstream air nozzle 72 is exposed from the second opening 612 toward the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a. The upstream air nozzle 71 is an example of a fixed-area air nozzle and a first air nozzle, and blows air toward the uppermost sheet S of the sheet bundle supported in the fixed area 41a. The downstream air nozzle 72 is an example of a lifting-up area air nozzle, and blows air from the sheet width direction W so as to handle at least the uppermost sheet S of the sheet bundle supported in the lifting-up area 40b.

[0028] The sheet feeding section 12 has an air supply section 73 that supplies air to the upstream air nozzle 71 and the downstream air nozzle 72. The air supply section 73 is supported by the sheet storage section 1 and has a fan 74 that blows out air and a connecting duct 75 that connects the fan 74 and the upstream air nozzle 71 to allow air to circulate. The connecting duct 75 is designed to expand and contract to maintain the connection when the distance between the fan 74 and the upstream air nozzle 71 changes due to the movement of the upstream air nozzle 71. As for the expansion and contraction mechanism, an appropriate configuration can be applied, such as one that deforms into a bellows shape or one in which an outer cylinder and an inner cylinder fitted together slide and expand and contract. The air supply section 73 also has a fixed duct (not shown) that connects the fan 74 and the downstream air nozzle 72 to allow air to circulate.

[0029] On the other hand, the sheet feeding unit 12 is movably supported by the side restricting member 62 and has an upstream air nozzle 76 and a downstream air nozzle 77 that blow air from the sheet width direction W to handle the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a. The upstream air nozzle 76 is exposed from a first opening (not shown) toward the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a. The downstream air nozzle 77 is exposed from a second opening (not shown) toward the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a. The upstream air nozzle 76 is an example of a fixed area side air nozzle and a second air nozzle, and blows air toward the uppermost sheet S of the sheet bundle supported on the fixed area 41a. The downstream air nozzle 77 is an example of a lifting area side air nozzle, and blows air from the sheet width direction W to handle at least the uppermost sheet S of the sheet bundle supported on the lifting area 40b. Furthermore, an air supply unit (not shown) similar to the air supply unit 73 is provided for the upstream air nozzle 76 and the downstream air nozzle 77.

[0030] The downstream air nozzles 72 and 77 are fixed to the side restricting member 62 and are positioned to be at a height near the uppermost sheet S. On the other hand, the upstream air nozzles 71 and 76 are supported so as to be vertically movable relative to the side restricting member 61. The upstream air nozzles 71 and 76 and the lifting unit 42 are connected by a drive train 45 having gears and belts. As a result, the upstream air nozzles 71 and 76 move up and down in conjunction with the rotation of the lifter 43 by the drive of the lifting unit 42. At this time, in the portion of the sheet bundle supported by the fixed area 41a, as the number of sheets loaded decreases due to the feeding operation, the height of the uppermost sheet S decreases. Therefore, the gear ratio of the drive train 45 is set so that the height of the upstream air nozzles 71 and 76 follows the height of the uppermost sheet Sa.

[0031] Specifically, the upstream air nozzles 71 and 76 are positioned as first air nozzles that blow air to the first spraying position when the uppermost sheet S in the sheet bundle supported on the sheet support surface 1a is in the first sheet position (see Figure 3(a)). Furthermore, the upstream air nozzles 71 and 76 are positioned as second air nozzles that blow air to the second spraying position, which is below the first spraying position, when the uppermost sheet S in the sheet bundle is in the second sheet position, which is below the first sheet position (see Figure 3(b)).

[0032] In this embodiment, the upstream air nozzles 71 and 76 blow air substantially horizontally toward the uppermost sheet S of the sheet bundle supported in the fixed area 41a, and the blowing angle is fixed. Furthermore, the upstream air nozzles 71 and 76 move up and down relative to the side regulating member 61, and the second air nozzle position is located below the first air nozzle position.

[0033] The drive train 45 is an example of a second interlocking unit, and moves the upstream air nozzles 71 and 76 in conjunction with the raising and lowering of the lifting and lowering area 40b. The drive train 45 positions the upstream air nozzles 71 and 76 at the first air nozzle position when the uppermost sheet S of the sheet bundle supported on the sheet support surface 1a is at the first sheet position and the movable loading unit 40 is at the first lifting and lowering position (see Figure 3(a)). The drive train 45 also positions the upstream air nozzles 71 and 76 at the second air nozzle position when the uppermost sheet S of the sheet bundle is at the second sheet position and the movable loading unit 40 is at the second lifting and lowering position, which is above the first lifting and lowering position (see Figure 3(b)).

[0034] Next, the sheet feeding operation of the sheet feeding unit 12 in this embodiment will be described. First, as shown in Figure 3(a), when the sheet storage unit 1, which is fully loaded with sheets S, is attached to the main body 10a of the device, the control unit 13 drives the lifting unit 42, and the movable loading unit 40 rotates upward by the lifter 43, causing the uppermost sheet S to come into contact with the pickup roller 2. The operation of the lifter 43 is controlled by the control unit 13 based on the detection result of a sheet height detection sensor (not shown) so that the height of the pickup roller 2 that comes into contact with the sheet S remains approximately constant. As such a sheet height detection sensor, for example, a sensor flag attached to a pickup roller holder that holds the pickup roller 2 and swings together with it, and a photo interrupter fixedly supported on the frame of the main body 10a can be used.

[0035] Next, air is blown onto the sheet S from the upstream air nozzles 71, 76 and the downstream air nozzles 72, 77 to disperse it, and the pickup roller 2 is rotated to feed out the sheet S. At this time, the upstream air nozzles 71, 76 and the downstream air nozzles 72, 77 are positioned to concentrate the air blow only near the top sheet S of the stacked sheet bundle, so that the sheet S immediately before feeding can be dispersed with high precision.

[0036] Furthermore, the sheets S of the sheet bundle loaded in the sheet storage section 1 are sequentially fed out by the pickup roller 2, causing the number of sheets S to decrease. Figure 3(b) shows the state when the amount of loaded sheets S has decreased. In the portion of the sheets S loaded in the movable loading section 40, the lifter 43 is controlled so that the height of the pickup roller 2 is approximately constant, so the height of the uppermost sheet S remains approximately constant. Therefore, the downstream air nozzles 72 and 77 fixed to the side restricting member 62 can always concentrate air only near the uppermost sheet S.

[0037] On the other hand, as the number of sheets S decreases, the height of the top sheet S decreases as the number of sheets S decreases. In response to this, the upstream air nozzles 71 and 76 are configured to move downward in conjunction with the rotational movement of the lifter 43, so that air can always be concentrated and blown only near the top sheet S.

[0038] As described above, according to the sheet feeding unit 12 of this embodiment, the upstream air nozzles 71 and 76 are positioned as a first air nozzle position that blows air to a first spraying position when the uppermost sheet S in the sheet bundle is in the first sheet position. Furthermore, when the uppermost sheet S in the sheet bundle is in the second sheet position, which is below the first sheet position, the upstream air nozzles 71 and 76 are positioned as a second air nozzle position that blows air to a second spraying position, which is below the first spraying position. As a result, the air blowing position from the upstream air nozzles 71 and 76 can always be kept near the uppermost sheet in the sheet bundle, making it possible to more reliably separate the stacked sheet bundle one sheet at a time by air handling.

[0039] In other words, even when the sheet storage section 1 includes a fixed loading section 41, air can always be concentrated and blown only near the top sheet S, so that sheets with strong adhesive properties, such as coated paper, can be reliably separated and fed one by one from the sheet bundle. Therefore, feeding problems such as sheets not being fed or double-feeding can be prevented.

[0040] In the above-described embodiment, air is supplied from a single air supply unit 73 to the upstream air nozzle 71 and the downstream air nozzle 72, but this is not the only configuration. For example, air may be supplied to the upstream air nozzle 71 and the downstream air nozzle 72 by independent supply means. In this case, for example, air can be blown from only one of the upstream air nozzle 71 or the downstream air nozzle 72. Therefore, for example, if the length Df in the sheet transport direction of the stacked sheets S is short and the air blown from the upstream air nozzle 71 does not reach the sheet bundle, the air blowing from the upstream air nozzle 71 can be stopped.

[0041] <Second Embodiment> Next, a second embodiment of the present invention will be described in detail with reference to Figures 4 to 5(b). This embodiment differs from the first embodiment in that it does not have a movable loading section 40. However, the other components are the same as in the first embodiment, so the same reference numerals are used and detailed descriptions are omitted.

[0042] [Sheet feeding unit] In the first embodiment, the sheet feeding unit 12 has four sheet storage units 1 and a manual feed tray 51, but here we will describe the case in which the present invention is applied to the manual feed tray 51. The sheet feeding unit 12 has a manual feed tray 51 having a sheet support surface 51a for loading and supporting sheets S, a pickup roller 52, a feed roller 53, and a retard roller 54. The configurations of the pickup roller 52, feed roller 53, and retard roller 54 are the same as in the first embodiment, so we will omit their description. The pickup roller 52 is raised and lowered by an electric motor based on the detection result of a sheet load amount detection (not shown). As a result, the pickup roller 52 is controlled to raise and lower in accordance with the position of the uppermost sheet S in the sheet bundle supported on the sheet support surface 51a.

[0043] The manual feed tray 51 is an example of a support part and is formed in a roughly plate shape. The manual feed tray 51 does not have a movable loading part, and a sheet support surface 51a for supporting the sheet S is formed on a part of its upper surface. In this embodiment, the entire sheet support surface 51a is a fixed area 41a fixed in the vertical direction relative to the manual feed tray 51.

[0044] The sheet feeding unit 12 has side restricting members 161 and 162 that restrict the end positions of the sheets S supported on the sheet support surface 51a in the sheet width direction W. Side restricting member 161 is an example of a first side end restricting member, and side restricting member 162 is an example of a second side end restricting member. The sheet feeding unit 12 has an air nozzle 171 that is movably supported on the side restricting member 161 and blows air from the sheet width direction W to handle at least the uppermost sheet S of the sheet bundle supported on the sheet support surface 51a. Air nozzle 171 is an example of a first air nozzle. The sheet feeding unit 12 has an air nozzle 176 that is movably supported on the side restricting member 162 and blows air from the sheet width direction W to handle at least the uppermost sheet S of the sheet bundle supported on the sheet support surface 51a. Air nozzle 176 is an example of a second air nozzle.

[0045] The sheet feeding unit 12 has an air supply unit 173 that supplies air to the air nozzle 176. The air supply unit 173 is supported by the manual feed tray 51 and has a fan 174 that blows out air and a connecting duct 175 that connects the fan 174 and the air nozzle 176 to allow air to circulate. The connecting duct 175 is made movable up and down by a movable unit 144. The movable unit 144 has an electric motor and gears and is controlled by the control unit 13 to move the air nozzle 176 relative to the side restricting member 162. The air nozzle 171 is also provided with an air supply unit and a movable unit (not shown) similar to the air supply unit 173 and the movable unit 144.

[0046] As a result, the air nozzles 171 and 176 are positioned as first air nozzles that blow air to the first spraying position when the uppermost sheet S in the sheet bundle supported on the sheet support surface 51a is in the first sheet position (see Figure 5(a)). Also, when the uppermost sheet S in the sheet bundle is in the second sheet position which is below the first sheet position, the air nozzles 171 and 176 are positioned as second air nozzles that blow air to the second spraying position which is below the first spraying position (see Figure 5(b)).

[0047] Next, the sheet feeding operation of the sheet feeding unit 12 of this embodiment will be described. First, as shown in Figure 5(a), when a sheet S is loaded onto the manual feed tray 51, the pickup roller 52 contacts the sheet S by an electric motor (not shown). Based on the detection result of the sheet load detection (not shown), the electric motor controls the air nozzles 171 and 176 to be near the top sheet S of the sheet bundle. Furthermore, air is blown onto the sheet S from the air nozzles 171 and 176 to disperse it, and the pickup roller 52 is rotated to feed out the sheet S. At this time, the position of the air nozzles 171 and 176 is controlled so that air is concentrated only near the top sheet S of the loaded sheet bundle, so that the sheet S immediately before feeding can be handled with high precision.

[0048] Furthermore, the sheets S of the sheet bundle loaded on the manual feed tray 51 are sequentially fed out by the pickup roller 52, causing the number of sheets S to decrease. Figure 5(b) shows the state when the amount of sheets S has decreased. As the number of sheets S decreases, the height of the top sheet S decreases. In response to this, the motor M controls the position of the air nozzles 171 and 176 to be near the top sheet S of the sheet bundle, based on the detection result of the sheet load detection (not shown). Therefore, air can always be concentrated and blown only near the top sheet S.

[0049] As described above, according to the sheet feeding unit 12 of this embodiment, the air nozzles 171 and 176 are positioned as a first air nozzle position that blows air to a first spraying position when the uppermost sheet S in the sheet bundle is in the first sheet position. Furthermore, when the uppermost sheet S in the sheet bundle is in the second sheet position which is below the first sheet position, the air nozzles 171 and 176 are positioned as a second air nozzle position that blows air to a second spraying position which is below the first spraying position. As a result, the air blowing position from the air nozzles 171 and 176 can always be kept near the uppermost sheet in the sheet bundle, making it possible to more reliably separate the stacked sheet bundle one sheet at a time by air handling.

[0050] In other words, even when the manual feed tray 51 does not have a movable loading section, air can always be concentrated and blown only near the top sheet S, so that sheets with strong adhesive properties, such as coated paper, can be reliably separated and fed one by one from the sheet bundle. Therefore, feeding problems such as sheets not being fed or double feeding can be prevented.

[0051] In the above-described embodiment, the case in which the air nozzles 171 and 176 are raised and lowered using a dedicated electric motor as the drive source was explained, but this is not the only case. For example, an interlocking unit 146 may be provided as a first interlocking unit that moves the air nozzles 171 and 176 in conjunction with the raising and lowering of the pickup roller 52. In this case, the interlocking unit 146 positions the air nozzles 171 and 176 at the first air nozzle position when the uppermost sheet S in the sheet bundle is at the first sheet position and the pickup roller 52 is at the first feeding position (see Figure 5(a)). The interlocking unit 146 positions the air nozzles 171 and 176 at the second air nozzle position when the uppermost sheet S in the sheet bundle is at the second sheet position and the pickup roller 52 is at the second feeding position which is lower than the first feeding position (see Figure 5(b)). With this configuration, the moving unit 144 can be omitted.

[0052] <Third Embodiment> Next, a third embodiment of the present invention will be described in detail with reference to Figure 6. This embodiment differs from the second embodiment in that it does not have a fixed area on the sheet support surface. However, the other components are the same as in the second embodiment, so the same reference numerals are used and detailed descriptions are omitted.

[0053] [Sheet feeding unit] At the bottom of the manual feed tray 51, which is an example of a fixed member, is a movable loading section 140, which is a sheet loading member for loading sheets S. The movable loading section 140 is an example of a lifting member, and is substantially plate-shaped. It is provided so as to be able to rotate vertically relative to the manual feed tray 51, with a pivot shaft 140a located on the upstream side of the sheet transport direction Df as a support shaft. In this embodiment, the movable loading section 140 forms the entire sheet support surface 51a.

[0054] The sheet feeding unit 12 has side restricting members 161 and 162 that restrict the end positions of the sheet S in the sheet width direction W of the sheet S supported on the sheet support surface 51a (see Figure 4). Side restricting member 161 is an example of a first side end restricting member, and side restricting member 162 is an example of a second side end restricting member (see Figure 4). The sheet feeding unit 12 has an air nozzle 171 that is movably supported on the side restricting member 161 and blows air from the sheet width direction W to handle at least the uppermost sheet S of the sheet bundle supported on the sheet support surface 51a (see Figure 4). Air nozzle 171 is an example of a first air nozzle. The sheet feeding unit 12 also has an air nozzle 176 that is movably supported on the side restricting member 162 and blows air from the sheet width direction W to handle at least the uppermost sheet S of the sheet bundle supported on the sheet support surface 51a. Air nozzle 176 is an example of a second air nozzle.

[0055] The sheet feeding unit 12 has an air supply unit 173 that supplies air to the air nozzle 176. The air supply unit 173 is supported by the manual feed tray 51 and has a fan 174 that blows out air and a connecting duct 175 that connects the fan 174 and the air nozzle 176 to allow air to circulate. The connecting duct 175 is made movable up and down by a movable part (not shown). The movable part has an electric motor and gears and is controlled by the control unit 13 to move the air nozzle 176 relative to the side restricting member 162. The air nozzle 171 is also provided with an air supply unit and a movable part (not shown) similar to the air supply unit 173 and the movable part.

[0056] As a result, the sheet support surface 51a is located at the first support position when the thickness of the supported sheet bundle is a first thickness t1 (see Figure 6(a)). Also, when the thickness of the supported sheet bundle is a second thickness t2 which is thinner than the first thickness t1, the sheet support surface 51a is located at the second support position, which is above the first support position (see Figure 6(b)).

[0057] As described above, according to the sheet feeding unit 12 of this embodiment, the air nozzles 171 and 176 are positioned as a first air nozzle position that blows air to a first spraying position when the uppermost sheet S in the sheet bundle is in the first sheet position. Furthermore, when the uppermost sheet S in the sheet bundle is in the second sheet position which is below the first sheet position, the air nozzles 171 and 176 are positioned as a second air nozzle position that blows air to a second spraying position which is below the first spraying position. As a result, the air blowing position from the air nozzles 171 and 176 can always be kept near the uppermost sheet in the sheet bundle, making it possible to more reliably separate the stacked sheet bundle one sheet at a time by air handling.

[0058] In the embodiments described above, the case in which air nozzles are provided on both sides of the side regulating member in the sheet width direction W has been explained, but this is not the only case, and they may be provided on only one side.

[0059] Furthermore, in the embodiments described above, the air nozzle is shaped to blow air horizontally from a raised or lowered position, but this is not limited to this. For example, it may have a swivel mechanism so that the air nozzle itself does not move up or down but swivels vertically to raise or lower only the direction of the airflow. [Explanation of Symbols]

[0060] 1...Sheet storage section (support section), 1a...Sheet support surface (support surface), 2...Pickup roller (feeding section), 10...Image forming apparatus, 11...Image forming section, 12...Sheet feeding section (sheet feeding device), 40...Movable loading section (lifting member), 40b...Lifting area, 41...Fixed loading section (fixing member), 41a...Fixed area, 45...Drive train (second interlocking section), 51...Manual feed tray (support section, fixing member), 51a...Sheet support surface (support surface), 52...Pickup roller (feeding section), 61...Side regulating member (side end regulating section, first side end regulating section), 61a...Regulating surface, 62...Side regulating member (side end regulating section, second side end regulating section), 71...Upstream air nozzle (air nozzle, fixed area 72... Downstream air nozzle (lifting area side air nozzle), 73... Air supply unit, 74... Fan, 75... Connecting duct, 76... Upstream air nozzle (air nozzle, fixed area side air nozzle, second air nozzle), 77... Downstream air nozzle (lifting area side air nozzle), 140... Movable loading unit (lifting member), 144... Moving unit, 146... Interlocking unit (first interlocking unit), 161... Side regulating member (side end regulating unit, first side end regulating unit), 162... Side regulating member (side end regulating unit, second side end regulating unit), 171... Air nozzle (first air nozzle), 173... Air supply unit, 176... Air nozzle (second air nozzle), 611... First opening (opening)

Claims

1. A support section having a support surface for loading and supporting sheets, A feeding unit that feeds the uppermost sheet from the sheet bundle supported on the aforementioned support surface, A side edge restricting portion that restricts the end position in the sheet width direction of the sheet supported on the support surface, An air nozzle is movably supported by the side end restricting portion and blows air from the sheet width direction to separate at least the uppermost sheet of the sheet bundle supported on the support surface, The system includes an air supply unit that supplies air to the air nozzle, The aforementioned air nozzle is When the uppermost sheet of the sheet bundle supported on the support surface is located at the first sheet position, the first air nozzle position is located to blow air to the first spraying position. When the uppermost sheet of the sheet bundle supported on the support surface is located at a second sheet position lower than the first sheet position, a second air nozzle position is located to blow air at the second spraying position lower than the first spraying position. A sheet feeding device characterized by the following features.

2. The support portion has a fixing member, The support surface has a fixing region that is fixed in the vertical direction with respect to the fixing member. The sheet feeding device according to feature 1.

3. The air nozzle blows air toward the uppermost sheet of the sheet bundle supported in the fixed area. The sheet feeding device according to feature 2.

4. A moving part for moving the air nozzle relative to the side end restricting part, The system includes a control unit for controlling the moving part, The control unit, When the uppermost sheet of the sheet bundle supported on the support surface is located at the first sheet position, the air nozzle is positioned at the first air nozzle position. When the uppermost sheet of the sheet bundle supported on the support surface is located at the second sheet position, the moving part is controlled so that the air nozzle is located at the second air nozzle position. The sheet feeding device according to feature 2.

5. The feeding unit moves up and down in accordance with the position of the uppermost sheet among the sheet bundle supported on the support surface. The air nozzle is provided with a first interlocking unit that moves in conjunction with the raising and lowering of the supply unit, The first interlocking unit is, When the uppermost sheet of the sheet bundle supported on the support surface is located at the first sheet position and the feeding unit is located at the first feeding position, the air nozzle is positioned at the first air nozzle position. When the uppermost sheet of the sheet bundle supported on the support surface is located at the second sheet position, and the feeding unit is located at a second feeding position lower than the first feeding position, the air nozzle is positioned at the second air nozzle position. The sheet feeding device according to feature 2.

6. The support portion has a lifting member that moves up and down relative to the fixed member. The support surface is positioned on the lifting member and has a lifting region that is continuous with the fixed region and supports the sheet together with the fixed region. The aforementioned lifting and lowering area is When the thickness of the sheet bundle supported in the lifting region is a first thickness, it is located at the first lifting position, When the thickness of the sheet bundle supported in the lifting region is a second thickness that is thinner than the first thickness, the second lifting position is located above the first lifting position. The sheet feeding device according to feature 2.

7. The air nozzle is a fixed-area side air nozzle that blows air toward the uppermost sheet of the sheet bundle supported in the fixed area. The lifting region side air nozzle is fixedly supported to the side end restricting portion and blows air from the sheet width direction to handle at least the uppermost sheet of the sheet bundle supported in the lifting region. The sheet feeding device according to feature 6.

8. The lifting region moves up and down in accordance with the position of the uppermost sheet among the sheet bundle supported on the support surface. The air nozzle is provided with a second interlocking unit that moves in conjunction with the raising and lowering of the lifting and lowering area. The second interlocking unit is, When the uppermost sheet of the sheet bundle supported on the support surface is located at the first sheet position and the lifting area is located at the first lifting position, the air nozzle is positioned at the first air nozzle position. When the uppermost sheet of the sheet bundle supported on the support surface is located at the second sheet position, and the lifting area is located at a second lifting position above the first lifting position, the air nozzle is positioned at the second air nozzle position. The sheet feeding device according to feature 6.

9. The support portion comprises a fixed member and a lifting member that moves up and down relative to the fixed member. The support surface is formed entirely on the lifting member. When the thickness of the sheet bundle supported on the support surface is a first thickness, it is located at the first support position, When the thickness of the sheet bundle supported on the support surface is a second thickness that is thinner than the first thickness, the second support position is located above the first support position. The sheet feeding device according to feature 1.

10. The aforementioned air supply unit is A fan, supported by the aforementioned support section, blows out air, The device includes a connecting duct that connects the fan and the air nozzle to allow air to circulate, and which expands and contracts to maintain the connection when the distance between the fan and the air nozzle changes due to the movement of the air nozzle, The sheet feeding device according to feature 1.

11. The side end restricting portion has a restricting surface that abuts the end of the sheet in the sheet width direction supported by the support surface, and an opening formed in the restricting surface. The air nozzle is exposed from the opening toward the uppermost sheet of the sheet bundle supported on the support surface. The sheet feeding device according to feature 1.

12. The air nozzle moves up and down relative to the side end restricting portion. The second air nozzle position is located below the first air nozzle position. The sheet feeding device according to feature 1.

13. The aforementioned side end restricting portion is a first side end restricting portion, The air nozzle is a first air nozzle, A second side end restricting portion that restricts the end position of the sheet supported on the support surface in the sheet width direction opposite to the first side end restricting portion, The device comprises a second air nozzle supported by the second side end restricting portion and facing the upper sheet of the sheet bundle supported by the support surface, The sheet feeding device according to feature 1.

14. A sheet feeding device according to any one of claims 1 to 13, It comprises an image forming unit that forms an image on a sheet, An image forming apparatus characterized by the following features.

Images