JP2015215396A - Fixing apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing apparatus configured to reduce the amount of ultrafine particles to be discharged, with a simple configuration.SOLUTION: A fixing apparatus 36 includes: a fixing roller 71 and a pressure roller 72 for fixing an unfixed image carried on a sheet P; a fixing cover 73 having a sheet outlet B for discharging the sheet P with the image fixed thereon, and covering a fuser 75; and an opening/closing member 74 arranged in the sheet outlet B. The opening/closing member 74 is located in a closed position M1 for closing the sheet outlet B, and an open position M2 to be opened by the sheet P discharged from the sheet outlet B. When the opening/closing member 74 closes the sheet outlet B, fine particles generated from the fuser 75 are prevented from being leaked to the outside the fixing cover 73.

Description

  The present invention relates to a heat fixing type fixing device and an image forming apparatus including the same.

  In an image forming apparatus such as a printer, a copying machine, and a fax machine that forms a toner image (image) on a sheet with toner, generally, a fixing device having a fixing roller (heating member) and a pressure roller (pressure member) The toner image is melted and fixed (fixed) on the sheet.

  It is known that ultrafine particles are generated even when the toner image is fixed. It has been found that the ultrafine particles are volatile substances generated by heating silicone used to impart elasticity to a part of the fixing device.

  It is desirable that such ultrafine particles are not discharged outside the apparatus (outside of the image forming apparatus).

  Therefore, in the invention of Patent Document 1, air in the vicinity of the fixing device is guided to an exhaust duct by a fan, and ultrafine particles are aggregated and removed using a cyclone type dust collector provided in the exhaust duct. Furthermore, ultrafine particles that could not be removed by the dust collector are charged by discharge and collected by the dust collecting electrode for removal. As a result, the ultra fine particles discharged out of the machine are efficiently removed to reduce the discharge amount.

  In the invention of Patent Document 2, the air in the vicinity of the fixing device is guided to the exhaust duct by a fan, and the guided air is passed through the exhaust duct while being maintained at a high temperature by the heater. Thereby, the ultrafine particles are efficiently aggregated and removed.

JP 2010-2803 A JP 2013-3507 A

  However, according to the inventions of Patent Documents 1 and 2, a dedicated fan and an exhaust duct are required to reduce the amount of ultrafine particles generated in the fixing device to the outside of the machine, and the configuration is complicated accordingly. There was a problem of becoming. In addition, it is necessary to secure a space for providing a fan and an exhaust duct, and accordingly, there is a problem that space saving of the image forming apparatus is hindered.

  The present invention provides a fixing device capable of reducing the discharge amount of ultrafine particles while having a simple configuration, and an image forming apparatus including the same.

  The fixing device of the present invention includes a fixing unit that heats and fixes an unfixed image carried on a sheet, a sheet discharge port that discharges the sheet after image fixing, and a cover that covers the fixing unit; An opening / closing member disposed at the sheet discharge port to open and close the sheet discharge port, and the opening / closing member is opened from a state where the sheet discharge port is closed by a sheet discharged from the sheet discharge port. It is characterized by that.

  An image forming apparatus according to the present invention includes an image forming unit that forms an unfixed image on a sheet and fixes the unfixed image on the sheet, and the image forming unit includes the fixing device. Yes.

  According to the fixing device of the present invention, the amount of ultrafine particles discharged can be reduced by an opening / closing member having a simple configuration.

  According to the image forming apparatus of the present invention, the amount of discharge of ultrafine particles to the outside of the apparatus can be reduced by a fixing device having a simple configuration, and the image forming apparatus can be reduced in size because a fan and an exhaust duct are unnecessary. Can be

1 is a front view illustrating a schematic configuration of an image forming apparatus. (A)-(C) are the figures explaining the structure and operation | movement of a fixing device. (A) is the perspective view which looked at the opening-and-closing member of the state which removed the adsorption member from diagonally upward, (B) is the perspective view which looked at the opening-and-closing member of the state which attached the adsorption member from diagonally upward, (C ) Is a perspective view of the opening / closing member with the adsorbing member attached when viewed obliquely from below. (A), (B) is a figure explaining generation | occurrence | production, adsorption | suction, and discharge | emission of the ultrafine particle in a fixing device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the numerical value taken up by embodiment is a reference numerical value, Comprising: It is not a numerical value which limits this invention.

<First Embodiment>
A first embodiment of the present invention will be described with reference to FIGS. First, the schematic configuration of the image forming apparatus 1 will be described with reference to FIG. 1, and then the fixing device 36 will be described with reference to FIGS. In the following description, the case where the image forming apparatus is an electrophotographic printer, a thermal fixing printer, a copier, or a fax machine is described as an example, but the present invention is not limited thereto. The image forming apparatus may be, for example, a printer, a copier, or a fax machine of an electrophotographic system or an electrostatic recording system as long as it is of a thermal fixing system.

[Image forming apparatus]
FIG. 1 is a diagram of a schematic configuration of the image forming apparatus 1 as viewed from the front side (the side on which an operation panel (not shown) is located and the user is positioned during operation).

  As shown in FIG. 1, the image forming apparatus 1 includes a sheet feeding / conveying unit 2, an image forming unit 3, a sheet discharging unit 4, and an image reading unit 5 that are configured to be stacked in order from the lower side.

  Among these, the sheet feeding / conveying unit 2 includes a sheet feeding cassette 20, a pickup roller 21, and a feeding roller 22. A plurality of sheets P stored in a stacked state in the sheet feeding cassette 20 are taken out by the rotation of the pickup roller 21, and are fed to the upper registration roller pair 23 along the conveyance path P1 by the feeding roller 22. It is conveyed toward. Thereafter, the skew of the sheet P is corrected by abutting the leading end against the nip portion of the registration roller pair 23, and then the registration roller pair 23 rotates in synchronization with the rotation of the photosensitive drum 30 described later. The image is supplied to the image forming unit 3.

  Next, the image reading unit 5 will be described before the image forming unit 3 and the sheet discharge unit 4.

  The image reading unit 5 includes a flat base scanner unit 50, a document pressing plate 51 that covers the upper surface of the image reading unit 5 so as to be freely opened and closed, and an ADF (automatic document feeder) 52 mounted on the document pressing plate 51.

  The flat base scanner unit 50 is arranged on the upper surface, and is mounted with a document placement glass 53 on which the document D is placed with the image surface facing downward, and a light source, a mirror, a lens, and a CCD for reading the image surface. Scanning carriage 54. The scanning carriage 54 can reciprocate below the document placement glass 53.

  The document pressing plate 51 presses the document D from above to bring it into close contact with the document placement glass 53.

  The ADF 52 includes a document placement tray 55 on which the document D is set, a document transport unit 56 that transports the document D from here to the document reading position Pr, and transports the document D after reading, and a document after reading. And a document discharge tray 57 from which D is discharged.

  In the image reading unit 5, the scanning carriage 54 scans and moves in the direction of the arrow K 1, so that the image surface of the document D placed (fixed) on the document placing glass 53 is fixedly read or the document reading position Pr. The image plane of the document D passing through here is scanned and read. Thus, the image information of the image surface of the document D read by the image reading unit 5 is sent to the exposure unit 32 of the image forming unit 3 described below.

  The image forming unit 3 includes a photosensitive drum 30 and a plurality of process devices arranged substantially in order along the rotation direction thereof, that is, a charger 31, an exposure unit 32, a developing device 33, a transfer roller 34, and a cleaning device 35. And have. The image forming unit 3 further includes a fixing device 36 disposed on the downstream side of the photosensitive drum 30 along the sheet conveying direction (above the photosensitive drum 30 in FIG. 1).

  Among these, the photosensitive drum 30 is rotationally driven in a direction indicated by an arrow (clockwise in FIG. 1) by a drive motor (not shown). The surface of the photosensitive drum 30 is uniformly charged to a predetermined positive or negative potential by the charger 31. The charged surface of the photosensitive drum 30 is scanned and exposed by the laser beam emitted from the exposure unit 32, and the charge of the exposed portion is removed to form an electrostatic latent image. The laser light emitted from the exposure unit 32 is ON / OFF controlled based on the image information of the document D read by the image reading unit 5. The electrostatic latent image formed on the surface of the photosensitive drum 30 is visualized (developed) as a toner image with toner (developer) attached thereto by the developing device 33.

  The toner image formed (supported) on the surface of the photosensitive drum 30 is conveyed to the transfer nip portion between the photosensitive drum 30 and the transfer roller 34 by the rotation of the photosensitive drum 30. On the other hand, the sheet P is supplied from the registration roller pair 23 to the transfer nip portion in synchronization with the toner image conveyed to the transfer nip portion. Then, a transfer bias is applied to the transfer roller 34, whereby the toner image on the surface of the photosensitive drum 30 is transferred to the sheet P.

  Thus, the sheet P carrying the toner image (unfixed toner image) on the surface is conveyed to the upper fixing device 36, where the unfixed toner image is heated and pressed to be fixed (melted and fixed) on the surface. The fixing device 36 will be described in detail later.

  The sheet discharge unit 4 includes a discharge roller 40 and a discharge tray 41. The sheet P on which the toner image is fixed on the surface by the fixing device 36 described above opens an opening / closing member 74 (see FIG. 2), which will be described later, reaches the discharge roller 40 through the discharge path P2, and The sheet is discharged onto the discharge tray 41 by rotation (rotation in the sheet discharge direction).

  Next, a case where images (toner images) are formed on both surfaces (front and back surfaces) of the sheet P will be described.

  The discharge roller 40 stops in a state where the trailing edge is held before the trailing edge of the sheet P is completely pulled out, and then immediately reverses (rotates in the reverse feeding direction). At this time, since the rear end of the sheet P has already passed through the opening / closing member 74 described later, the opening / closing member 74 is disposed at the closed position M1 and closes the sheet discharge port B of the fixing device 36. Yes. For this reason, the sheet P reversely fed by the reverse rotation of the discharge roller 40 is guided by the opening / closing member 74 and guided from the discharge path P2 to the re-conveyance path P3. The sheet P guided to the re-conveying path P3 is conveyed downward by the re-conveying roller 60, and is guided to the registration roller pair 23 while being gently curved by the re-conveying roller 61 near the lower part. It is burned.

  In this way, the sheet P guided to the registration roller pair 23 is formed with the forward rotation of the discharge roller 40 after the toner image is formed on the back surface in the same manner as described above when the toner image is formed on the front surface. It is discharged to the discharge tray 41.

  Note that the sheet P relating to image formation is supplied from the manual feed tray 62 in addition to being supplied from the paper feed cassette 20 described above. The manual feed tray 62 is disposed at the lower part of one wall surface (the left wall surface in FIG. 1) of the image forming apparatus 1 so as to be opened and closed (in the figure, the closed state is illustrated). The sheet P can be transported to the registration roller pair 23 by the manual feed tray 62 opened in the direction of the arrow K2 and set thereon, and fed by the paper feed roller 63 and the above-described re-transport roller 61. An image can be formed on the sheet P in the same manner as described above.

  As described above, the image forming apparatus 1 that forms an image on one surface (front surface) or both surfaces (front surface and back surface) of the sheet P includes the heat fixing type fixing device 36 described below.

[Fixing device]
The fixing device 36 will be described with reference to FIGS. 2A to 2C are diagrams illustrating the configuration and operation of the fixing device 36. FIG. 3A is a perspective view of the opening / closing member 74 with the adsorption member 85 removed, as viewed obliquely from above, and FIGS. 3B and 3C show the opening / closing member 74 with the adsorption member 85 attached. It is the perspective view seen from diagonally downward from diagonally upward, respectively. 4A and 4B are diagrams for explaining generation, adsorption, and discharge of the ultrafine particles Q in the fixing device 36. FIG.

  As shown in FIG. 2, the fixing device 36 includes a fixing device 75 as a fixing unit, a fixing cover 73, and an opening / closing member 74. The fixing device 75 includes a fixing roller 71 and a pressure roller (pressure member) 72. The fixing device includes a configuration in which a fixing roller and a pressure roller are pressed against each other, and a configuration in which a film-like cylindrical member and a roller are pressed against each other. In this case, a heat source (heater) and a pressing member that presses the cylindrical member against the roller are housed in the film-shaped cylindrical member. Therefore, the fixing device is not limited to a configuration in which a pair of rollers are pressed against each other.

  The fixing roller 71 includes a metallic cylindrical member 71a and a heater (not shown) that is disposed inside the fixing roller 71 and heats the cylindrical member 71a. The fixing roller 71 is disposed so as to be rotatable in the arrow R1 direction with respect to the shaft 71b.

  The pressure roller 72 is formed in a cylindrical shape, and has an elastic layer 72a on the outer peripheral surface thereof. The pressure roller 72 is disposed so as to be rotatable in the direction of the arrow R2 with reference to a shaft 72b parallel to the shaft 71b of the fixing roller 71. The pressure roller 72 is disposed such that the elastic layer 72a abuts on the cylindrical member 71a of the fixing roller 71. Between the elastic layer 72a and the cylindrical member 71a, shafts 71b and 72b are provided. A fixing nip portion T extending long along the line is formed.

  At least one of the fixing roller 71 and the pressure roller 72 is rotationally driven by a motor (not shown). As a result, the sheet P carrying the unfixed toner image (unfixed image) is heated and pressurized while being nipped and conveyed by the fixing nip T, and is fused and fixed (fixed) on the sheet P. At this time, since the pressure roller 72 containing silicone may come into direct contact with the heated fixing roller 71, the silicone may volatilize and generate the ultrafine particles Q shown in FIG. .

  The fixing cover 73 is formed in a box shape, and houses the fixing roller 71 and the pressure roller 72 inside. A sheet supply port A for supplying the sheet P from the photosensitive drum 30 is formed below the fixing nip T in the fixing cover 73. A sheet discharge port B through which the sheet P is discharged after toner image fixing (after image fixing) is formed above the fixing nip T (pressure roller 72). Note that one (left side in the drawing) side wall 73a of the fixing cover 73 constitutes a part of the above-described re-transport path P3.

  The opening / closing member 74 is disposed so as to be swingable, and can take a closed position M1 shown in FIGS. 2 (A) and 2 (C) and an open position M2 shown in FIG. 2 (B).

  As shown in FIG. 3, the opening / closing member 74 includes a frame-like support portion 81 that is long in the front-rear direction, a plurality of short guide ribs 82 and long guide ribs 83 that are supported by the support portion 81 and arranged in the front-rear direction. A boss portion 84 serving as a moving center and a long plate-like adsorption member 85 are provided.

  The support portion 81 includes a base end support portion 81a and a tip end support portion 81b that are long in the front-rear direction and are parallel to each other, and a front end support portion 81c and a rear end support portion 81d that connect these front ends and rear ends. Thus, the frame is formed in a frame shape that is long in the front-rear direction.

  The short guide rib 82 is formed in a substantially rectangular long plate shape. On the other hand, the long guide rib 83 has a shape in which a claw portion 83 a is added to the distal end side of the short guide rib 82. Four long guide ribs 83 are disposed at the center portion of the support portion 81 along the front-rear direction, and two long guide ribs 83 are disposed at the front end portion and the rear end portion, respectively. Four short guide ribs 82 are disposed between the central portion and the front end portion and between the central portion and the rear end portion, respectively.

  The guide ribs 82 and 83 have long holes 82b and 83b extending in the longitudinal direction extending in the longitudinal direction. The base end support portion 81a penetrates in the front-rear direction on the base end side of the long holes 82b and 83b, and the tip support portion 81b penetrates on the front end side. A long plate-like suction member 85 is passed through the center of the long holes 82b and 83b. The guide ribs 82 and 83 are fixed to the proximal end support portion 81a and the distal end support portion 81b that pass through them, whereas the suction member 85 is detachable.

  The portions of the guide ribs 82 and 83 that protrude from the surface 85a of the suction member 85 are guide portions 82c and 83c that guide the sheet P. Similarly, portions of the guide ribs 82 and 83 that protrude from the back surface 85b of the suction member 85 are guide portions 82d and 83d that guide the sheet P.

  In the guide ribs 82 and 83, the entire upper end edges 82e and 83e including the upper end edges of the guide portions 82c and 83c are formed in a gentle convex shape upward by combining a plurality of straight lines. On the other hand, the guide ribs 82 and 83 are formed in a curved shape in which the lower end edges 82f and 83f including the lower end edges of the guide portions 82d and 83d are curved in a gentle convex shape upward. The reason why it is formed in a curved shape is that the lower end edges 82f and 83f are brought into contact with almost the entire sheet P including the leading end of the sheet P to guide the conveyance of the sheet P.

  The opening / closing member 74 has the guide portions 82c, 83c, 82d, and 83d in which the guide ribs 82 and 83 protrude from the front surface 85a and the back surface 85b of the suction member 85 in this way, so that the sheet P directly contacts the suction member 85. To prevent it.

  The boss portion 84 is disposed so as to protrude from the base end side of the front end support portion 81c and the rear end support portion 81d of the support portion 81 to the front side and the rear side, respectively. These boss portions 84 are rotatably supported by the upper end portion of the side wall 73a of the fixing cover 73 shown in FIG. As a result, the entire opening / closing member 74 can swing with respect to the boss portion 84.

  The adsorbing member 85 as the adhering member is, for example, a filter impregnated with silicon oil, and is formed in a long plate shape that is long in the front-rear direction as described above. When the portion excluding the adsorbing member 85, that is, the support portion 81, the guide ribs 82 and 83, and the boss portion 84 are used as the open / close member main body from the components of the open / close member 74, the adsorbing member 85 is detachable from the open / close member main body. It is. In other words, in this embodiment, the adsorption member 85 becomes a part of the constituent elements of the opening / closing member 74 when attached to the opening / closing member main body. On the other hand, as will be described later, the opening / closing member 74 occupies a large area from the viewpoint of closing the sheet discharge port B of the fixing device 36. The suction member 85 can be replaced together with the opening / closing member 74.

  Next, the operation of the opening / closing member 74 will be described with reference to FIG.

  The opening / closing member 74 is normally disposed at the closed position M1 shown in FIGS. At this time, the opening / closing member 74 has a gentle inclined posture in which the distal end side is engaged with a part of the discharge path P2 from above, and the distal end side is positioned higher than the proximal end side. Further, at this time, the opening / closing member 74 mainly closes (closes) the sheet discharge port B by the support portion 81 and the suction member 85 without any gap.

  For this reason, as shown in FIG. 4A, the ultrafine particles Q generated from the pressure roller 72 cannot exit from the sheet discharge port B and are confined in the fixing cover 73. Further, heat is trapped in the fixing cover 73. Thereby, in the fixing cover 73, the density of the ultrafine particles is increased, the aggregation is advanced by heat, and the number of fine particles having a particle diameter exceeding 1000 nm is increased. These ultrafine particles and fine particles can be efficiently adsorbed by the adsorbing member 85 of the opening / closing member 74.

  On the other hand, when the sheet P is discharged, the opening / closing member 74 is disposed at the open position M2 shown in FIG. When the sheet P is nipped and conveyed by the fixing roller 71 and the pressure roller 72 and the fixing proceeds, the sheet P is brought into contact with the opening / closing member 74 from below. As a result, the opening / closing member 74 is pushed up so that the leading end thereof is in contact with a part of the discharge path P2, and is disposed at the opening position M2 having a larger inclination angle than the closing position M1, and the trailing end of the sheet P has finished passing. This open position M2 is maintained until. For this reason, as shown in FIG. 4B, the ultrafine particles Q and the fine particles are discharged from the sheet discharge port B together with the air discharged from the sheet discharge port B, and are further discharged outside the apparatus. However, since the ultrafine particles Q in the air discharged from the sheet discharge port B are reduced as described above, the ultrafine particles discharged outside the apparatus are also reduced. Although the amount of ultrafine particles discharged outside the machine may decrease, the fine particles may increase. However, the fine particles are relatively removed from the ultrafine particles by, for example, a dust removing device disposed outside the machine. Cheap.

  When the rear end of the sheet P has passed, the opening / closing member 74 moves from the open position M2 shown in FIG. 2 (B) to the closed position M1 shown in FIG. 2 (C), and closes the sheet discharge port B again. Cover.

  If the weight of the opening / closing member 74 is set appropriately, when the sheet P is discharged, the opening / closing member 74 is easily moved from the closed position M1 to the open position M2 by the contacted sheet P. By its own weight, it is possible to satisfactorily return from the open position M2 to the closed position M1.

  The opening / closing member 74 described above also functions as a switching member that switches the conveyance path of the sheet P. As described above, when an image is also formed on the back surface of the sheet P, the rear end of the sheet P having the toner image fixed on the front surface passes through the opening / closing member 74 and the rear end passes through the discharge roller 40. Before finishing, the discharge roller 40 is stopped and reversely rotated to be reversely fed. At this time, the opening / closing member 74 has moved from the open position M2 to the closed position M1 shown in FIG. 2C, and connects the discharge path P2 and the re-transport path P3 and closes the sheet discharge port B. . For this reason, the sheet P that is fed back through the discharge path P2 does not enter the sheet discharge port B, and is guided by the upper end edges 82e and 83e of the guide ribs 82 and 83 of the opening / closing member 74 to be attracted to the suction member 85. It is smoothly guided to the re-transport path P3 without contact.

  According to the fixing device 36 described above, it is possible to reduce the ultra fine particles discharged outside the apparatus while having a simple configuration that does not require a fan or an exhaust duct. Furthermore, since a space for providing a fan and an exhaust duct is not required, the image forming apparatus 1 can be reduced in size accordingly.

  In the above description, the case where the heating member of the fixing device 36 is the cylindrical fixing roller 71 and the pressure member is the cylindrical pressure roller 72 has been described as an example. Instead of this, for example, an endless belt-like fixing belt or fixing film may be used as the heating member. In this case, the same effect as described above can be obtained.

  B ... sheet discharge port, M1 ... closed position, M2 ... open position, P ... sheet, Q ... ultra fine particles, 1 ... image forming apparatus, 3 ... image forming section, 36 ... fixing apparatus, 71 ... fixing roller (heating member) , 72... Pressure roller, 73... Fixing cover, 74. Opening / closing member, 75... Fixing device (fixing means), 82 and 83... Guide rib, 82 c and 83 c.

Claims (7)

Fixing means for heating and fixing an unfixed image carried on the sheet;
A cover having a sheet discharge port for discharging a sheet after image fixing, and covering the fixing unit;
An opening / closing member disposed at the sheet discharge port to open and close the sheet discharge port,
The opening and closing member is opened from a state in which the sheet discharge port is closed by a sheet discharged from the sheet discharge port.
A fixing device. The sheet discharge port is disposed above the fixing unit.
The fixing device according to claim 1. The opening / closing member has an adhesion member to which ultrafine particles adhere,
The fixing device according to claim 1, wherein The attachment member is formed in a plate shape covering the sheet discharge port,
The fixing device according to claim 3. The opening / closing member includes guide ribs having guide portions protruding from the front surface and the back surface of the adhesion member,
The fixing device according to claim 4. The attachment member is replaced with the opening / closing member.
The fixing device according to any one of claims 3 to 5, wherein An image forming unit for forming an unfixed image on a sheet and fixing the unfixed image on the sheet;
The image forming unit includes the fixing device according to any one of claims 1 to 6.
An image forming apparatus.

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