Sheet feeding device and image forming device

Abstract

To provide an air handling mechanism configured to feed a sheet such as a coat sheet exhibiting a high inter-sheet adhesive force while blowing air, prevent staying of air by providing no air outlet to an air blow tip, and reduce the inter-sheet adhesive force with a minimum air blowing amount, thereby addressing the problems of deterioration of geometric characteristics of a product, an adverse effect on an image, and the increase of an operation sound or power consumption caused by the increase of an air blowing amount when air handing efficiency is not high.SOLUTION: This sheet feeding device comprises: a loading unit that can load a sheet bundle; blowing means for blowing air to the end of the sheet bundle of the loading unit; and air blowing means for reducing an adhesive force between the sheets. The air blowing means is provided on both sides at least one each in a sheet conveying direction. At least one of the air blowing means is disposed at a position shifted from above a straight line of an air flow line generated from another air blowing means.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a sheet feeding device capable of blowing air onto a sheet stack being fed, and an image forming apparatus including the sheet feeding device. [Background technology]

[0002] In recent years, electrophotographic image forming devices such as copying machines, printers, and facsimiles have become widespread. In addition, the types of recording media that can be output by these image forming devices are expanding, and it is becoming common for them to support recording media with smoother surfaces than fine paper, such as coated paper made of pulp with a coating applied to the surface.

[0003] However, with sheets that have a smooth surface, the air flow between the sheets is prevented, so the adhesion between the sheets is strong, making it difficult to separate and transport each sheet from the sheet stack. Therefore, an air handling method has been proposed that reduces the adhesion between sheets by providing an air blowing section that blows air onto the end of the sheet stack to lift the sheets (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 04-023747 Summary of the Invention [Problem to be solved by the invention]

[0005] In a configuration provided with an air handling mechanism as described above, increasing the amount of air blown to further reduce the adhesion force between sheets causes problems such as deterioration of geometric characteristics due to sheet disturbance, effects on images due to uneven air blowing, increased power consumption and operating noise, etc. Therefore, an efficient method for sufficiently reducing the adhesion force between sheets without increasing the amount of air blown is desirable.

[0006] In Patent Document 1, a sheet holding member is provided to control the floating posture of the sheet in order to efficiently reduce the adhesion force between sheets. However, in cases where it is difficult to provide the holding member at a desired position in manual paper feed, or where there are significant restrictions on operating noise and the amount of air blowing cannot be increased, it is difficult to obtain a sufficient air handling effect.

[0007] The object of the present invention is to provide a sheet feeding device or image forming apparatus that realizes an efficient air handling mechanism that prevents losses due to air stagnation by not providing an air outlet at the destination of the air blown, and can reduce the adhesion force between sheets with a minimum amount of air blown. [Means for solving the problem]

[0008] In order to achieve the above object, the sheet feeding device or image forming apparatus of the present invention is a sheet feeding device having a stacking section 5 on which a stack of sheets can be placed, air blowing means (15a-15g) for blowing air onto the ends of the stack of sheets in the stacking section 5, and air blowing means (16a-16g) for reducing the adhesion between the sheets, characterized in that the air blowing means (16a-16g) are provided at least one on each side in the sheet conveying direction Y, and at least one of the air blowing means (16a-16g) is positioned at a position offset from the straight line of the air flow lines (A1-A9) generated from the other air blowing means (16a-16g). Effect of the Invention

[0009] According to the present invention, by not providing an air outlet at the destination of the air blowing, it is possible to prevent losses due to air stagnation, and to realize an efficient air handling mechanism that can reduce the adhesion force between sheets with a minimum amount of air blowing. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an image forming apparatus including a sheet feeding device according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a block diagram of an embodiment of the present invention. [Diagram 3] 1 is a diagram illustrating a sheet feeding device according to a first embodiment of the present invention. [Figure 4] FIG. 13 is a diagram illustrating a sheet feeding device according to a second embodiment of the present invention. [Diagram 5] FIG. 13 is a diagram illustrating a sheet feeding device according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A sheet feeding device according to an embodiment of the present invention and an image forming apparatus including the same will be described with reference to FIGS.

[0012] (Image forming device) FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 201 according to an embodiment of the present invention, and FIG. 2 is a block diagram.

[0013] The image forming apparatus 201 is a tandem type intermediate transfer type laser beam printer that utilizes an electrophotographic process. The image forming apparatus 201 can form and output a full-color or monochrome image corresponding to print image data output from a host device 900 connected to the control unit 100 on a sheet S, which is a recording medium.

[0014] 2 is a control unit that controls the overall operation of the image forming apparatus 201, and transmits and receives information to and from a host device 900 and an operation unit 730. The control unit 100 also performs signal processing and sequence control for various process devices. Here, the host device 900 is a personal computer, an image scanner, a facsimile, or the like.

[0015] In Fig. 1, 201 is an image forming apparatus, 201A is an image forming apparatus main body, and 201B is an image forming section that forms an image on a sheet. 202 is an image reading apparatus installed substantially horizontally above the image forming apparatus main body 201A, and a discharge space V for discharging sheets is formed between this image reading apparatus 202 and the image forming apparatus main body 201A.

[0016] Reference numeral 230 denotes a cassette feeding section that feeds a sheet S from a feeding cassette 1 that is a sheet storage means for storing the sheet S. The cassette feeding section 230 includes a pickup roller 2 that is a sheet feeding means, and a separation section that includes a feed roller 3 and a retard roller 4 for separating the sheet S fed from the pickup roller 2. Reference numeral 235 denotes a manual feeding section that feeds a sheet S from a manual feed tray 5 that is a means for holding the sheet S. Like the cassette feeding section 230, it includes a pickup roller 502 that is a sheet feeding means, and a separation section that includes a feed roller 503 and a retard roller 504 for separating the sheet S fed from the pickup roller 502.

[0017] The image forming unit 201B, which is an image forming means, is of a four-drum full-color type and includes a laser scanner 210 and four process cartridges 211 that form toner images of four colors, yellow (Y), magenta (M), cyan (C), and black (K). Here, each process cartridge 211 includes a photosensitive drum 212, a charger 213 that is a charging means, and a developer 214 that is a developing means. In addition, the image forming unit 201B includes a secondary transfer unit 201D and a fixing unit 201E that are disposed above the process cartridges 211. Reference numeral 215 denotes a toner cartridge for supplying toner to the developer 214.

[0018] The secondary transfer section 201D includes a transfer belt 216 wound around a drive roller 216a and a tension roller 216b. A primary transfer roller 219 is provided on the inside of the transfer belt 216, which contacts the transfer belt 216 at a position facing the photosensitive drum 212. The transfer belt 216 rotates in the direction of the arrow by a drive roller 216a driven by a drive unit (not shown). A secondary transfer roller 217 that transfers a color image formed on the transfer belt 216 to a sheet S is provided at a position facing the drive roller 216a of the secondary transfer section 201D. Furthermore, a fixing section 201E is disposed above the secondary transfer roller 217, and a first discharge roller pair 225a, a second discharge roller pair 225b, and a double-sided reversing section 201F are disposed at the upper left of the fixing section 201E. The double-sided reversing section 201F is provided with a pair of reversible reversing rollers 222 and a re-conveying path R for conveying the sheet S having an image formed on one side thereof again to the image forming section 201B.

[0019] An operation panel 730 for receiving operations from a user is provided on the upper portion of the image forming apparatus 201. Recently, the operation panel is generally of the touch panel type that not only displays but also has an input function.

[0020] (Operation of image forming device) Next, the image forming operation of the image forming apparatus 201 will be described. First, when the image forming apparatus 201 receives image data of an original to be printed, the image information is subjected to image processing, converted into an electric signal, and transmitted to a laser scanner 210 of the image forming section 201B. In the image forming section 201B, the surface of the photosensitive drum 212, the surface of which is uniformly charged to a predetermined polarity and potential by a charger 213, is sequentially exposed to a laser. As a result, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photosensitive drum of each process cartridge 211, respectively.

[0021] Thereafter, the electrostatic latent images are developed and visualized with toner of each color, and the toner images of each color on each photoconductor drum are transferred in sequence onto the transfer belt 216 in a superimposed manner by a primary transfer bias applied to the primary transfer roller 219. As a result, a toner image is formed on the transfer belt 216.

[0022] In parallel with this toner image forming operation, the sheets S are conveyed one by one by the cassette feeding section 230 or the manual paper feed section 235 to the pair of registration rollers 240, and the skew is corrected by the pair of registration rollers 240. After the skew is corrected, the sheet S is conveyed to the secondary transfer section 201D by the pair of registration rollers 240, and in the secondary transfer section 201D, the toner images are transferred all at once onto the sheet S by a secondary transfer bias applied to the secondary transfer roller 217. Next, the sheet S onto which the toner images have been transferred is conveyed to the fixing section 201E, and in the roller nip section formed by the pressure roller 220a and the heating roller 220b, the toners of the respective colors are melted and mixed under heat and pressure, and are fixed onto the sheet S as a color image. The sheet S on which the image has been fixed is discharged to the discharge space V by a first discharge roller pair 225a and a second discharge roller pair 225b provided downstream of the fixing unit 201E, and is stacked on a stacking unit 223 protruding from the bottom surface of the discharge space V. When images are formed on both sides of the sheet S, after the images are fixed, the sheet S is transported to a re-conveying path R by a reversing roller pair 222, and is transported again to the image forming unit 201B. [Example of the sheet feeding device of the present invention]

[0023] An example of a sheet feeding device of the present invention will be described below with reference to the sheet feeding device shown in FIGS. EXAMPLES

[0024] A first embodiment of the present invention will be described with reference to Fig. 3. Fig. 3 is a schematic top view of a manual paper feeder 235 to which the present invention is applied.

[0025] (Explanation of manual paper feeder with air blowing unit and paper feeding operation) The manual feed section 235 includes a feed tray 5 which is a sheet storage means, a pickup roller 502 which is a sheet feeding means, and a separation section which includes a feed roller 503 and a retard roller 504 for separating the sheet S sent out from the pickup roller 502.

[0026] The manual feed tray 5 is provided with side edge regulating plates (14a, 14b) for regulating the position in a direction (paper width direction) perpendicular to the sheet conveying direction arrow Y. The side edge regulating plates (14a, 14b) are provided with fan motors (15a, 15b, 15c) that are capable of blowing air to the sheets via blowing nozzles (16a, 16b, 16c). By blowing air from the fan motors (15a, 15b, 15c) toward the ends of the sheets along the flow lines (A1, A2, A3), the upper sheets of the sheet stack are lifted, and the adhesion between the sheets is reduced.

[0027] When the start button is pressed, paper feeding begins. When sheets with high inter-sheet adhesion, such as coated paper, are set, the fan motors (15a, 15b, 15c) of the side end regulating plates (14a, 14b) are operated to blow air onto the widthwise ends of the sheets through the blowing nozzles (16a, 16b, 16c). After a predetermined time, the topmost sheet S, in which the adhesive force between the sheets has been reduced, is sent to a separation section consisting of a feed roller 503 and a retard roller 504 by the rotation of a pickup roller 502. The leading edge of the separated sheet S is detected by a paper detection sensor 505. The sheet S is then sent to a pair of registration rollers 240 by a pair of conveying rollers 506.

[0028] (Explanation of the configuration of the air blowing section) In order to efficiently reduce the adhesion between sheets using air, it is desirable to provide air blowing ports on both sides in the conveying direction. This is because if there are only air blowing ports on one side, sufficient air will not reach the other side, and sufficient adhesion between sheets will not be obtained. Furthermore, when providing air blowing ports on both sides, it is desirable to arrange them in such a way that the air streamlines do not collide with each other. This is because if the air streamlines collide, the air that would normally flow evenly within the surface to reduce the adhesion between sheets will stagnate at the collision point and will not easily contribute to reducing the adhesion between sheets, resulting in a decrease in handling efficiency.

[0029] 3, in the first embodiment of the present invention, the blowing nozzles (16a, 16b, 16c) are arranged so as not to be positioned on the straight lines of the flow lines (A1, A2, A3) of the air generated from each of the air blowing nozzles (16a, 16b, 16c). This allows the air generated from each of the air blowing nozzles (16a, 16b, 16c) to flow uniformly within the surface without stagnating, effectively reducing the adhesion force between the sheets.

[0030] Moreover, the blowing nozzles (16a, 16b, 16c) are disposed upstream of the pickup roller 502 in the transport direction Y. This is because, if the blowing nozzles are disposed downstream of the pickup roller 502, the leading edge of the sheet S is likely to float, which pushes up the pickup roller and prevents it from operating at the intended position, resulting in poor sheet transport. Also, in terms of handling efficiency, it is known that blowing air onto the leading edge of the sheet pushed down by the pickup roller 502 provides little handling effect relative to the amount of air blown. EXAMPLES

[0031] A second embodiment of the present invention will be described with reference to FIG. 4. In the first embodiment, three air blowing nozzles (16a, 16b, 16c) are provided in a configuration shifted in parallel to the conveying direction Y, but in the second embodiment, an example in which the air blowing nozzles are arranged opposite each other will be described. As shown in FIG. 4, in the second embodiment, the air blowing nozzles (16d, 16e) are provided opposite each other, but while in the first embodiment, the air blowing nozzles are provided so that the air hits them vertically, in the second embodiment, the air blowing nozzles are arranged at an angle α. As a result, the air streamlines (A4, A5) generated from the air blowing nozzles (16d, 16e) do not collide with each other, and uniform air is provided within the surface. In the second embodiment, the air blowing nozzles (16d, 16e) are provided at the same angle α, but they may be at different angles. EXAMPLES

[0032] A third embodiment of the present invention will be described with reference to FIG. 5. In the first and second embodiments, all the air blowing nozzles are arranged so as not to be positioned on the straight lines of the respective air streamlines (A1, A2, A3), but the present invention is not limited to this. As shown in FIG. 5, some of the air streamlines may be positioned on a straight line. In the example of the third embodiment, the air streamlines A6 and A9 are positioned on straight lines. Therefore, the efficiency of handling is inferior compared to the case where all the air streamlines (A6, A7, A8, A9) are not positioned on straight lines, but it is more efficient than, for example, the case where two pairs of air streamlines A6 and A8, and A7 and A9 are positioned opposite each other on straight lines. In the first and second embodiments, a configuration in which one air streamline is generated through an air blowing nozzle for one fan motor has been described, but the present invention is not limited to this. As shown in FIG. 5, two or more air streamlines may be generated for one fan motor.

[0033] In this embodiment, the manual paper feed has been described, but the present invention is not limited to this. For example, the present invention can be applied to cassette paper feed or other paper feed stages that use an air handling mechanism. [Explanation of symbols]

[0034] 14a, 14b Side end regulating plate 15a, 15b, 15c, 15d, 15e, 15f, 15g Fan motor 16a, 16b, 16c, 16d, 16e, 16f, 16g Spray nozzle 201 Image forming device 201A Image forming apparatus body 230 Cassette Feeder 235 Manual feeder 502 Pickup roller 503 Feed Roller 504 Retard roller 506 Pull-out roller 505 Paper feed sensor S Seat

Claims

1. a loading section on which a sheet stack can be placed; a blowing means for blowing air onto an end of the sheet stack in the stacking section; An air blowing means for reducing the adhesion between the sheets; In a sheet feeding apparatus having At least one air blowing means is provided on each side in the sheet conveying direction Y, A sheet feeding device or an image forming apparatus, comprising: at least one air blowing means disposed at a position offset from a straight line of air flow generated by the other air blowing means.

2. 2. The sheet feeding device or image forming apparatus according to claim 1, further comprising a rotating body that picks up and feeds the sheets one by one from a stacking section, and the contact point between the rotating body and the sheets is positioned at a position offset from a straight line of the air flow generated by the air blowing means.

3. 2. An image forming apparatus comprising: the sheet feeding device according to claim 1; and an image forming section that forms an image on a sheet fed from the sheet feeding device.

Images