JP2019182615A - Sheet receiver and image forming apparatus - Google Patents

Abstract

To provide a sheet receiver and image forming apparatus capable of heating up and dehumidifying a sheet with good balance and reducing the occurrence of curling or rumpling in a sheet.SOLUTION: A sheet receiver comprises a cassette 102 for receiving a sheet and a dehumidification heater 2 arranged in a recess 1a of the cassette 102 and heating up the sheet received in the cassette 102. The dehumidification heater 2 has a frame 2a and a heating element generating heat and arranged along an outer periphery of the frame 2a at an inward of the frame 2a. The frame 2a has an upper surface area set equal to or greater than 1/4 of a sheet surface area of a maximum-sized sheet receivable in the cassette 102 and equal to or smaller than an upper surface area of a top plate 1.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sheet storage device that stores sheets and an image forming apparatus including the sheet storage device.

  Conventionally, as shown in FIG. 8, there has been proposed an image forming apparatus including an apparatus main body having a transfer unit for transferring an image to a sheet, and an optional paper feed cassette unit 3 mounted below the apparatus main body. (See Patent Document 1). The sheet feeding cassette unit 3 includes two stages of upper and lower sheet feeding cassettes 10 and 11 and a dehumidifying unit 17 that is detachably installed on the upper surface of the sheet feeding cassette 10.

  The dehumidifying unit 17 includes a heater body 14, a wiring portion 15 that supplies power to the heater body 14, and a panel portion 16 that supports the heater body 14 and the wiring portion 15 and transfers heat generated by the heater body 14. ing.

JP 2009-298523 A

  However, the heater main body 14 described in Patent Document 1 is disposed above and in the center of the paper feed cassette 10 and is configured to particularly heat the central portion of the sheet stored in the paper feed cassette 10. If the central portion of the sheet is dehumidified by the heater main body 14 and the outer edge portion is not dehumidified, the outer edge portion of the sheet curls or wrinkles when the sheet is heated in the fixing unit. There is a risk of getting lost.

  Further, if the amount of heat of the heater main body 14 is increased to sufficiently dehumidify the outer edge portion of the sheet, the bottom surface of the apparatus main body or the paper feed cassette 10 may be deformed by the heat of the heater main body 14. As described above, the dehumidifying unit 17 described in Patent Document 1 cannot dehumidify the sheet in a balanced manner.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet storage device and an image forming apparatus in which a sheet is heated and dehumidified in a balanced manner to solve the above-described problems.

  The present invention, in the sheet storage device, comprises a cassette capable of storing the sheet, and a dehumidification heater that is installed in a recess of the top plate of the cassette and heats the sheet stored in the cassette, the dehumidification heater, And a heating element that generates heat and is disposed along the outer periphery of the frame body inside the frame body, and the area of the upper surface of the frame body is a maximum that can be stored in the cassette. It is characterized by being set to ¼ or more of the area of the sheet surface of the size sheet and not more than the area of the top surface of the top plate.

  According to the present invention, the sheet can be heated and dehumidified in a balanced manner, and the occurrence of curling and wrinkles on the sheet can be reduced.

1 is an overall perspective view illustrating a printer according to an embodiment. 1 is an overall schematic diagram showing a printer main body. 5 is a flowchart illustrating an image forming process by an image forming unit. (A) is a perspective view which shows a cassette, (b) is a perspective view which shows the state which attached the dehumidification heater to the cassette. (A) is a wiring diagram of a heating element according to the present embodiment, and (b) and (c) are wiring diagrams showing other wiring examples of the heating element. (A) is a top view which shows the flow path between a laser scanner and a flame | frame, (b) is a top view which shows the flow path between each process cartridge and a photoreceptor and a flame | frame. (A) is a perspective view which shows the cassette deck which concerns on a modification, (b) is a perspective view which shows the state which attached the dehumidification heater to the cassette deck. The perspective view which shows the conventional dehumidification unit.

  Hereinafter, a sheet storage device and an image forming apparatus according to the present embodiment will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the following embodiments are not intended to limit the scope of application of the present technology only to those unless otherwise specified. .

[Schematic configuration of printer]
First, a schematic configuration of a printer 300 as an image forming apparatus will be described with reference to FIG. As shown in FIG. 1, the printer 300 includes a printer main body 100 and an image reading device 200. Specifically, the image reading apparatus 200 disposed above the printer main body 100 includes a reading unit 202 and an ADF 201, and optically scans a document to read image information. The document is a sheet such as a sheet of paper or an envelope, a plastic film such as an overhead projector sheet (OHT), or a cloth. Image information converted into an electrical signal by the image reading device 200 is transferred to a control unit (not shown) provided in the printer main body 100.

  As shown in FIG. 2, the printer main body 100 includes a main body portion 61 as an apparatus main body and an optional feeder 62 connected to the lower portion of the main body portion 61. The main body 61 includes an image forming unit 120 that forms an image on a sheet that is a recording medium, a fixing device 140, a discharge roller pair 150, and a feeding unit 130 that feeds the sheet to the image forming unit 120. is doing. The feeding unit 130 includes a main body cassette 101 that can store sheets, a pickup roller 131 that feeds the sheets stored in the main body cassette 101, a separation pad 132 that separates the sheets together with the pickup roller 131, have.

  Similarly, the feeder 62 includes a cassette 102 that can store sheets, a pickup roller 141 that feeds the sheets stored in the cassette 102, and a separation pad 142 that separates the sheets one by one together with the pickup roller 141. is doing. The main body cassette 101 and the cassette 102 have a middle plate (not shown) that supports the sheet and can be raised and lowered. However, the sheet is stacked on the bottom plate of the main body cassette 101 and the cassette 102 without providing the middle plate. May be.

  The image forming unit 120 includes four process cartridges 121Y, 121M, 121C, and 121K that form toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (K), respectively, and a laser scanner. 110. The four process cartridges 121Y, 121M, 121C, and 121K have the same configuration except that the colors of images to be formed are different. Therefore, only the configuration of the process cartridge 121Y and the image forming process will be described, and the description of the process cartridges 121M, 121C, and 121K will be omitted.

  The process cartridge 121Y includes a photosensitive drum 122 as an image carrier, a charging roller 123, and a developing roller 124. The photosensitive drum 122 is configured by applying an organic photoconductive layer to the outer periphery of an aluminum cylinder, and is rotated by a drive motor (not shown). An intermediate transfer belt 113 is disposed above the process cartridges 121Y, 121M, 121C, and 121K. The intermediate transfer belt 113 is stretched by a driving roller 113a, a tension roller 113b, and the like, and is rotated by the driving roller 113a. Inside the intermediate transfer belt 113, primary transfer rollers 125Y, 125M, 125C, and 125K are provided. A secondary transfer roller 127 is disposed on the opposite side of the driving roller 113a with the intermediate transfer belt 113 interposed therebetween.

  Next, an image forming operation of the printer 300 configured as described above will be described with reference to FIGS. 1 to 3. When an image signal is input to the laser scanner 110 from a personal computer (not shown) or the image reading apparatus 200, the laser beam corresponding to the image signal is emitted from the laser scanner 110 onto the photosensitive drum 122 of the process cartridge 121Y.

  At this time, the surface of the photosensitive drum 122 is uniformly charged to a predetermined polarity and potential in advance by the charging roller 123, and an electrostatic latent image is formed on the surface by irradiating the laser beam from the laser scanner 110. . The electrostatic latent image formed on the photosensitive drum 122 is developed by the developing roller 124, and a yellow (Y) toner image is formed on the photosensitive drum 122.

  Similarly, each photosensitive drum of the process cartridges 121M, 121C, and 121K is irradiated with laser light from the laser scanner 110, and magenta (M), cyan (C), and black (K) toner images are formed on the photosensitive drums. Is done. The toner images of the respective colors formed on the respective photosensitive drums are transferred to the intermediate transfer belt 113 by the primary transfer rollers 125Y, 125M, 125C, and 125K, and up to the secondary transfer roller 127 by the intermediate transfer belt 113 rotated by the driving roller 113a. Be transported. Note that the image forming process for each color is performed at the timing when the toner image is superimposed on the upstream toner image primarily transferred onto the intermediate transfer belt 113.

  In parallel with this image forming process, the sheets stored in the main body cassette 101 or the cassette 102 are sent out by the pickup rollers 131 and 141 and separated one by one by the separation pads 132 and 142. Then, the sheet is conveyed to the registration roller pair 133, and the skew is corrected by hitting the nip of the stopped registration roller pair 133.

  The registration roller pair 133 conveys the sheet according to the image transfer timing, and a full color toner image on the intermediate transfer belt 113 is transferred to the sheet by the secondary transfer bias applied to the secondary transfer roller 127. The The sheet on which the toner image has been transferred is applied with heat and pressure in the fixing device 140, and the toner is melted and fixed (fixed). The sheet that has passed through the fixing device 140 is discharged to the discharge tray 151 by the discharge roller pair 150.

  Here, an image forming process by the image forming unit 120 will be described with reference to a flowchart shown in FIG. The control unit of the printer 300 determines whether an image signal has been received (step S1). When the image signal is received (step S1: Yes), the control unit causes the laser scanner 110 to emit a laser corresponding to the image signal (step S2). Further, the control unit forms an electrostatic latent image on the photosensitive drum 122 by the laser emitted from the laser scanner 110 (step S3), and forms a toner image on the photosensitive drum 122 by the developing roller 124 (step S4).

  The toner images formed on the photosensitive drums 122 of the process cartridges 121Y, 121M, 121C, and 121K are transferred as full-color toner images to the intermediate transfer belt 113 by the primary transfer rollers 125Y, 125M, 125C, and 125K (step S5). . The image on the intermediate transfer belt 113 is transferred to the sheet by the secondary transfer roller 127 (step S6), and the image forming process by the image forming unit 120 is completed.

[Dehumidification heater]
Next, the dehumidifying heater 2 and its peripheral configuration will be described. As shown in FIG. 4A, the cassette 102 includes a cassette frame 102a and a drawer portion 102b supported so as to be able to be pulled out and attached to the cassette frame 102a. A sheet is supported on the drawer portion 102b.

  The cassette frame 102a has a top plate 1 that faces the printer main body 100 (see FIG. 2) and is disposed above the drawer portion 102b. The top plate 102c has a recess 1a that is recessed downward. ing. That is, the top plate 1 is arranged at a position overlapping the drawer portion 102b in plan view. As shown in FIG. 4B, the recess 1a is provided with a dehumidifying heater 2 that heats the drawer unit 102b and the sheet stored in the main body cassette 101. The conduction unit 1b continuous to the recess 1a includes Wiring (not shown) connected to the dehumidifying heater 2 is arranged.

  The dehumidifying heater 2 is configured in a flat plate shape so as to have a space inside, and a frame body 2a that transmits heat, and a heating element 70 that generates heat and is disposed inside the frame body 2a (FIG. 5A). Reference). As shown in FIG. 6A, the dehumidifying heater 2 is disposed at a position that does not overlap the pickup roller 141 as a feeding unit in a plan view, and as shown in FIG. It is arranged at the overlapping position. For this reason, the dehumidification heater 2 can be installed in the feeder 62 without enlarging the feeder 62 as a sheet storage device.

Further, as shown in FIG. 4B, the area of the upper surface 2b of the frame 2a of the dehumidifying heater 2 is equal to or more than 1/4 of the area of the sheet surface of the maximum size sheet that can be supported by the drawer portion 102b. Is set to be equal to or smaller than the area of the upper surface of 1. In the present embodiment, the area of the upper surface 2b of the frame 2a of the dehumidifying heater 2 is about 2/5 with respect to the area of the sheet surface of the maximum size sheet.
Furthermore, as shown to Fig.5 (a), the heat generating body 70 is arrange | positioned along the outer periphery of a frame in the inner side of the frame 2a.

  Thus, by determining the size of the frame 2a and the wiring of the heating element 70, the temperature variation between the central portion and the outer edge portion of the dehumidifying heater 2 can be reduced, and heat can be transferred in a balanced manner. And the sheet | seat accommodated in the main body cassette 101 and the drawer | drawing-out part 102b can be dehumidified with sufficient balance, and it can reduce that a curl and a wrinkle generate | occur | produce in a sheet | seat.

  Note that the wiring of the heating element 70 is not limited to one heating element as shown in the example of FIG. 5A. For example, as shown in FIG. 5B, the two heating elements 70 and 70a are framed. You may wire along the outer periphery of the body 2a. In this case, the outer edge portion of the dehumidifying heater 2 can be heated more than the central portion, and the inner side is more suitable for the main body cassette 101 and the cassette 102 having higher thermal conductivity than the outer side. Further, as shown in FIG. 5C, one heating element 70 may be wired along the outer periphery of the frame body 2a, and another heating element 70c may be wired in the central portion of the frame body 2a. In this case, the central portion and the outer edge portion of the dehumidifying heater 2 can be heated with good balance. Not only the wiring example of the heating element 70 shown in FIGS. 5 (a) to 5 (c), the wiring may be changed as appropriate, but the sheet may be dehumidified in a balanced manner according to the apparatus. It is good to wire as much as possible.

  As shown in FIGS. 6A and 6B, the dehumidifying heater 2 is disposed below the laser scanner 110 and the process cartridges 121Y, 121M, 121C, and 121K for each color and at a position overlapping in plan view. As shown in FIGS. 2 and 6A, a flow path A through which warm air heated by the dehumidifying heater 2 passes is formed between the frame 100a of the printer main body 100 and the laser scanner 110. . Further, as shown in FIGS. 2 and 6B, a flow path B through which the warm air passes is formed outside the process cartridges 121Y and 121K, and the warm air flows between the photosensitive drums 122. Passing channels C1, C2, C3 are formed. These flow paths B, C1, C2, and C3 are formed between the frame 100a, the process cartridges 121Y and 121K, and the photosensitive drums 122.

  Note that there is a space through which warm air can pass between the frame 100a and the top plate 1 and between the frame 100a and the main body cassette 101, and there is warm air on the bottom surface of the frame 100a, that is, the bottom surface of the printer main body 100. The hole that can pass through is clear. As shown in FIG. 2, the warm air heated by the dehumidifying heater 2 rises through these spaces and holes, and further through the conveyance path CP through which the sheet passes, and passes through the flow paths A, B, C1, C2, and C3. To do. Thereby, the inside of the printer main body 100 can be efficiently dehumidified. In particular, in the present embodiment, since the dehumidifying heater 2 extends to the vicinity of the pickup roller 141, the dehumidifying heater 2 and the conveyance path CP are arranged close to each other, and the warm air heated by the dehumidifying heater 2 is generated. It is configured to easily pass through the conveyance path CP.

  Further, as shown in FIGS. 2 and 6A, a dustproof glass 80 as a transparent member is disposed at the exit from which the laser of the laser scanner 110 is emitted. A laser for forming an electrostatic latent image passes through the dust-proof glass 80. For this reason, the emission port is closed with the dust-proof glass 80, and dust and the like can be prevented from flowing into the laser scanner 110, and the inside of the laser scanner 110 can be prevented from condensing. Further, since warm air passing through the flow path B passes in the vicinity of the dust-proof glass 80 and warm air passing through the flow paths C1, C2, and C3 passes in the vicinity of the photosensitive drums 122, the dust-proof glass 80 and the photosensitive drum 122 are used. Can be prevented from condensing. Accordingly, it is possible to prevent the toner image from being thinned by reducing the amount of toner that is supplied to the photosensitive drum 122 due to condensation of the dust-proof glass 80 and a decrease in the amount of laser transmission. Further, it is possible to prevent the toner image on the photosensitive drum 122 from flowing due to condensation on the photosensitive drum 122.

  As described above, in the present embodiment, the size of the dehumidifying heater 2 (the area of the upper surface 2b of the frame body 2a) is set to an area of 1/4 or more of the maximum size sheet that can be supported by the drawer portion 102b. The heating element 70 is wired along the outer periphery of the frame 2a of the dehumidifying heater 2. For this reason, the sheets stored in the main body cassette 101 and the cassette 102 can be dehumidified in a balanced manner, and the occurrence of curling and wrinkles on the sheets can be reduced.

  The feeder 62 in the present embodiment is an optional cassette connected to the lower part of the printer main body 100, but the target to which the dehumidifying heater 2 is attached is not limited to the feeder 62. For example, as shown in FIG. 7A, a cassette deck 520 having a top plate 501 is connected to the lower portion of the printer main body 100, and a recess 501a formed in the top plate 501 is connected to a recess 501a as shown in FIG. A dehumidifying heater 502 may be attached.

  Further, the dehumidifying heater 2 is not limited to the concave portion 1a of the top plate 1, and may be attached to the bottom plate of the printer main body 100 or the bottom plate of the cassette frame 102a, for example. In the above embodiment, the electrophotographic printer 300 has been described. However, the present invention is not limited to this. For example, the present invention can be applied to an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from a nozzle.

  1: Top plate / 1a: Recessed portion / 2: Dehumidifying heater / 2a: Frame body / 2b: Upper surface / 62: Sheet storage device (feeder) / 70: Heating element / 80: Transparent member (dust-proof glass) / 102: Cassette / 110: laser scanner / 120: image forming unit / 122: image carrier (photosensitive drum) / 141: feeding unit (pickup roller) / 100: apparatus main body (printer main body) / 300: image forming apparatus (printer) / A , B, C1, C2, C3: flow path

Claims (5)

A cassette that can store sheets,
A dehumidification heater that is installed in the recess of the top plate of the cassette and heats the sheet stored in the cassette;
The dehumidifying heater has a frame and a heating element that emits heat and is disposed along the outer periphery of the frame inside the frame,
The area of the upper surface of the frame is set to be not less than 1/4 of the area of the sheet surface of the maximum size sheet that can be stored in the cassette and not more than the area of the upper surface of the top plate,
A sheet storage device. A feeding unit that feeds the sheets stored in the cassette;
The dehumidifying heater is disposed at a position that does not overlap the feeding unit in a plan view and a position that overlaps the feeding unit in the vertical direction.
The sheet storage device according to claim 1. The sheet storage device according to claim 1 or 2,
An apparatus main body having an image forming unit that forms an image on a sheet fed from the sheet storage device,
An image forming apparatus. The image forming unit includes an image carrier that carries a toner image, and a laser scanner that emits a laser for forming an electrostatic latent image on the image carrier.
The apparatus main body includes a flow path through which warm air heated by the dehumidifying heater passes between the frame of the apparatus main body and the laser scanner and between the frame and the image carrier.
The image forming apparatus according to claim 3. The laser scanner has a transparent member through which the emitted laser passes,
The image forming apparatus according to claim 4.

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