JP2009096605A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing dew condensation of conveyance guides wherein weight and cost are reduced. <P>SOLUTION: Contact parts 25a, 27a with which a recording material P of first and second conveyance guides 25, 27 for guiding transportation of the recording material P contacts are composed of a high thermal conductive wire material. Thus, dew condensation of the first and second transport guides 25, 27 is prevented and the compact, light weight and low cost image forming device can be provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a function of forming an image on a recording material such as a sheet, such as a copying machine, a printer, or a facsimile machine.

  In an image forming apparatus using electrophotographic technology such as a copying machine or a laser beam printer, an electrostatic latent image is formed on a surface of a latent image carrier having a photosensitive layer by laser irradiation. A visible image is formed by attaching toner to the electrostatic latent image, and an image is formed by transferring the toner image to a recording material by electrostatic force.

  On the other hand, the recording material is conveyed from the feed tray, transferred with a transfer means, and a toner image is transferred. The fixing means fixes the unfixed toner image by heat and pressure, and is discharged and stacked on the discharge tray. At this time, the recording material is guided by a conveyance guide that leads to each constituent means.

  In recent years, energy saving is highly demanded along with the colorization and speeding up of the market, and when image formation has not started, a configuration that uses as little power as possible has been installed.

  In such an image forming apparatus, since heat energy is not used particularly in a low temperature environment, the conveyance guide is held in a cold state.

  If this happens, when the job starts, the air in the machine rises in temperature due to the heat energy generated by driving electric parts such as motors, and water vapor in the air adheres to the transport guide that is not sufficiently warmed, causing condensation. There is.

  In particular, in the fixing unit, moisture contained in the sheet evaporates due to heating, and the water vapor is likely to adhere to a guide plate of a post-fixing guide disposed downstream of the fixing unit and cause condensation.

  If condensation occurs on the transport guide, water droplets may adhere to the sheet, or the sheet may adhere to the transport guide, resulting in poor sheet transport, image deterioration such as missing backside transfer, corner breakage of the sheet, and scratches at the tip. May cause trouble.

  In particular, in recent years, fixing devices with a low heat capacity have become mainstream from the viewpoint of quick start and energy saving, and it is important to solve the problem of dew condensation.

  Conventionally, in order to prevent condensation on the guide plate, for example, a heating element is arranged on the upper / lower guide plate that forms the sheet path, and a temperature sensor is provided in the vicinity of the guide plate to keep the guide plate at a constant temperature to prevent condensation. It has been proposed to prevent (see Patent Document 1).

  In addition, an exhaust fan is provided to exhaust the air in the part where condensation is likely to occur, and a heat transfer member is provided to the discharge guide part such as the guide plate, and heat is supplied from the fixing means to heat the guide part and prevent condensation. It has been proposed (see Patent Document 2).

JP-A-4-166968 JP-A-8-211819

  However, in order to prevent the dew condensation of the guide, if a heating element is arranged on the upper / lower guide plate and countermeasures are taken by controlling with the temperature sensor as in Patent Document 1, the cost is increased and the structure is complicated. To reduce the weight and size of the device.

  In addition, in the case of performing dehumidification using an exhaust fan as in Patent Document 2, the arrangement of the exhaust fans and the structure of the exhaust passage may be complicated in order to increase the exhaust efficiency. Increase, and obstruct the weight reduction and downsizing of the device. In addition, the air flow of the exhaust fan may cause a conveyance failure such as a sheet floating.

  The technical problem of the present invention has been made in view of the circumstances as described above, and the object thereof is to prevent the occurrence of condensation on the conveyance guide, and to achieve image formation that achieves weight reduction and cost reduction. Is to provide a device.

  In order to achieve the above object, a typical configuration according to the present invention includes a conveyance unit that conveys a recording material, a conveyance guide that guides conveyance of the recording material, and a toner image that is collectively transferred onto the recording material. In the image forming apparatus having a transfer unit and a fixing unit that is arranged on the downstream side of the transfer unit and fixes the toner image transferred to the recording material, the contact portion of the conveyance guide that contacts the recording material Is made of a wire.

  According to the present invention, since the conveyance guide is made of a wire material, the amount of heat generated when power is turned on is effectively used for the conveyance guide portion, and condensation of the conveyance guide is prevented. As a result, defects in images and conveyance can be avoided, and a reduction in weight and size and cost can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First embodiment]
FIG. 1 is a perspective view of a fixing device of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of FIG. 3 is a configuration diagram of the fixing device shown in FIG. 2, and FIG. 4 is a cross-sectional view of the conveyance guide shown in FIG.

(Configuration of fixing device)
1 to 4, the fixing device is a heating device of a fixing belt heating method and a pressurizing rotating body driving method (tensionless type). In the figure, reference numeral 20 denotes a fixing belt as a first rotating body (first fixing member), which is a cylindrical member (endless belt shape, sleeve shape) in which an elastic layer is provided on the belt-like member. Reference numeral 22 denotes a pressure roller as a second rotating body (second fixing member).

  Reference numeral 17 denotes a heater holder having heat resistance and rigidity of a substantially semicircular arc shaped cross section as a heating body holding member. Reference numeral 16 denotes a fixing heater as a heating body (heat source), which is disposed on the lower surface of the heater holder 17 along the length of the heater holder 17. The fixing belt 20 is loosely fitted to the heater holder 17 and its end is biased to the fixing flange 50.

  The pressure roller 22 is formed by forming a silicone rubber layer having a thickness of about 3 mm on a stainless steel core by injection molding and coating a PFA resin tube having a thickness of about 40 μm thereon. Above the pressure roller 22, a fixing belt unit including a fixing heater 16, a heater holder 17, a fixing belt 20, and the like is disposed in parallel with the pressure roller 22 with the fixing heater 16 facing downward.

  Then, both end portions of the heater holder 17 are urged in the axial direction of the pressure roller 22 with a force of 98 N (10 kgf) on one side and a total pressure of 196 N (20 kgf) by a pressure mechanism (not shown). As a result, the downward surface of the fixing heater 16 is pressed against the elastic layer of the pressure roller 22 through the fixing belt 20 with a predetermined pressing force against the elasticity, and a fixing nip portion having a predetermined width necessary for heat fixing is formed. Is formed. Note that the pressurizing mechanism has a pressure releasing mechanism, and has a structure in which the pressurization is released at the time of jam processing and the recording material P can be easily removed.

  The pressure roller 22 is rotationally driven at a predetermined peripheral speed by driving means (not shown). When the pressure roller 22 is rotationally driven, a rotational force is applied to the cylindrical fixing belt 20 by a pressure frictional force at a fixing nip portion between the outer surface of the pressure roller 22 and the fixing belt 20.

  As a result, the fixing belt 20 is driven to rotate around the heater holder 17 while the inner surface of the fixing belt 20 slides in close contact with the downward surface of the fixing heater 16. Note that grease is applied to the inner surface of the fixing belt 20 to ensure slidability between the heater holder 17 and the inner surface of the fixing belt 20.

(Operation of fixing device)
When the pressure roller 22 is driven to rotate, the cylindrical fixing belt 20 is driven and rotated. The fixing heater 16 is energized, the temperature of the fixing heater 16 is increased, and the temperature is raised to a predetermined temperature.

  In this state, the recording material P carrying the unfixed toner image is guided and introduced along the entrance guide 23 between the fixing belt 20 and the pressure roller 22 in the fixing nip portion. Then, the toner image carrying surface side of the recording material P is brought into close contact with the outer surface of the fixing belt 20, and the fixing nip portion is nipped and conveyed together with the fixing belt 20.

  In this nipping and conveying process, the heat of the fixing heater 16 is applied to the recording material P via the fixing belt 20, and the unfixed toner image on the recording material P is heated and pressurized on the recording material P and melted and fixed. The The recording material P that has passed through the fixing nip is separated from the fixing belt 20 by the curvature, guided by the first and second transport guides 25 and 27 disposed opposite to the downstream side, and discharged by the discharge roller 26 (FIG. 5). reference).

(Construction of transport guide)
The contact portions 25a and 27a with which the recording material P abuts in the first and second transport guides 25 and 27 are composed of base layers 25b and 27b made of a wire material. Thin heat-absorbing materials 25c and 27c made of a material that easily absorbs heat and has good thermal conductivity are deposited on the surfaces of the base layers 25b and 27b. The base layers 25b and 27b are formed of a material having high strength and high thermal conductivity such as metal.

  Further, as the endothermic materials 25c and 27c, for example, a black coating is used on an aluminum deposition surface deposited on the surface of the heat insulating layer, and the surfaces of the endothermic materials 25c and 27c are formed flat. The heat absorbing materials 25c and 27c may be made of a vapor deposition surface of a metal other than aluminum as long as it is made of a material having good thermal conductivity, or may be made of other materials.

  In the present embodiment, it is assumed that the first conveyance guide 25 and the second conveyance guide 27 are in contact with the recording material P, and both have the same configuration, but the recording is performed only on one of the conveyance guides. If the material P does not contact, the conveyance guide configuration of the present embodiment may be taken on only one side.

(Operation of transport guide)
Since the contact portions 25a and 27a of the first conveyance guide 25 and the second conveyance guide 27 configured in this manner have high heat conduction and low heat capacity, they easily absorb infrared rays generated from the fixing device, and instantaneously In addition, the temperatures of the first conveyance guide 25 and the second conveyance guide 27 rise.

  Therefore, the first and second transport guides 25 and 27 can be efficiently warmed before the recording material P reaches the fixing device, that is, while the fixing device is on standby.

  Therefore, by effectively utilizing the heat energy, it is possible to efficiently prevent the dew condensation generated in the first transport guide 25 and the second transport guide 27 by the water vapor generated from the recording material P.

  In addition, since the first and second transport guides 25 and 27 are made of wire rods, the apparatus main body can be reduced in weight and size and cost. Further, as shown in FIG. 5, the first and second transport guides 25 and 27 are spaces other than the wire material, so that the user visibility of the recording material P at the time of paper jam is improved.

[Second Embodiment]
Next, another fixing device of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same structural member as 1st embodiment, and the overlapping part is omitted.

(Configuration of fixing device)
Since the heat generated from the fixing device is transferred to the periphery of the fixing device, the power cost is likely to be high. For this reason, in order to increase the heat retaining property inside the fixing device where the toner image is fixed and prevent heat diffusion, a heat insulating cover surrounding the fixing device is conventionally provided. For example, there has been proposed one using a heat reflecting layer that reflects radiant heat on the surface of the heat insulating cover on the heating roll side (Japanese Patent Laid-Open No. 2006-251654).

  In addition, the heat insulating property of the heat insulating cover can be obtained by using a vacuum heat insulating material formed by vacuum-sealing a base material such as glass fiber having a low thermal conductivity in a laminated film bag as a material constituting the inside of the heat insulating cover. There has also been proposed a device for improving the above (Japanese Patent Laid-Open No. 2003-210444).

  In such a configuration, although the heat insulation effect is improved, it is difficult to exhaust the water vapor generated from the recording material P to the outside of the fixing device because the inside of the fixing device is sealed. difficult.

  In this embodiment, condensation is prevented while insulating the fixing device, and as shown in FIG. 6, heat insulating covers 10 and 11 are arranged outside the fixing belt 20 and the pressure roller 22. Yes.

(Construction of transport guide)
Since the contact portions 25a and 27a of the first transport guide 25 and the second transport guide 27 are the same as those in the first embodiment, description thereof is omitted. The first transport guide 25 and the second transport guide 27 shown in FIG. 6 are formed of a moisture absorbing material 30 except for the contact portions 25a and 27a.

  The material of the moisture absorbing material 30 is not particularly limited to the felt member based on the polyester resin, and the material and the material are not particularly limited as long as they can absorb moisture.

  Further, the shape is not limited to a sheet shape, and may be a thick shape. Furthermore, it is not limited to a felt-like structure, and for example, a foamed resin may be used.

(Operation of transport guide)
With the first conveyance guide 25 and the second conveyance guide 27 configured as described above, even if it is difficult to exhaust the water vapor generated from the recording material P, the moisture absorption material 30 is effective. Moisture is absorbed. Therefore, water vapor generated from the recording material P is condensed and liquefied, and does not fall on the recording material P and damage the image.

  Next, an image forming apparatus using the above-described conveyance guide will be described.

(Configuration of image forming apparatus)
In FIG. 7, the image forming apparatus is arranged in parallel, for example, four photosensitive drums a (yellow), b (magenta), c (cyan), which form toner images of colors of yellow, magenta, cyan, and black. d (black). Further, an intermediate transfer belt 2 is disposed above the photosensitive drums a to d so as to be cut longitudinally.

  The photosensitive drums a to d are driven by a motor (not shown), and a primary charger, a developing device, and a transfer charger are unitized as process cartridges 1 a to 1 d around the photosensitive drums a to d. In addition, transfer charging members 2a to 2d are provided on the photosensitive drums a to d, and an exposure device 6 including a polygon mirror is disposed below the photosensitive drums a to d. A cassette 4 is installed below the exposure device 6, and a recording material P is stored in the cassette 4.

  Laser light based on a yellow component color image signal of an original is projected onto the photosensitive drum a through a polygon mirror of the exposure device 6 to form an electrostatic latent image on the photosensitive drum a. Then, yellow toner is supplied from the developing device and developed, and the electrostatic latent image is visualized as a yellow toner image.

  The toner image arrives at a primary transfer portion where the photosensitive drum a and the intermediate transfer belt 2 come into contact with the rotation of the photosensitive drum a. Then, the yellow toner image on the photosensitive drum a is transferred to the intermediate transfer belt 2 by the primary transfer bias applied to the transfer charging member 2a (primary transfer).

  A portion of the intermediate transfer belt 2 carrying the yellow toner image moves to the image forming unit. By this time, a magenta toner image has been formed on the photosensitive drum b by the same method as described above in the image forming unit, and this magenta toner image is transferred from the yellow toner image to the intermediate transfer belt 2.

  Similarly, as the intermediate transfer belt 2 moves, the cyan toner image and the black toner image are transferred onto the yellow toner image and the magenta toner image at the respective primary transfer portions of the image forming unit.

  The recording material P is fed one by one from the cassette 4 by the pickup roller 8 and the timing is adjusted by the registration roller 9. Thereafter, the toner image of the four colors on the intermediate transfer belt 2 is collectively transferred onto the recording material P by the secondary transfer bias applied to the pair of secondary transfer rollers 3 serving as transfer means, reaching the secondary transfer site. (Secondary transfer).

  The recording material P onto which the four color toner images have been transferred is guided from the secondary transfer roller pair 3 to the conveyance guide 28 in the fixing roller pair 5 and conveyed to the fixing roller pair 5 as fixing means. Therefore, the toner image is fixed by receiving heat and pressure, whereby the toner of each color is melted and mixed to form a full-color print image fixed to the recording material P. Thereafter, the paper is discharged to the discharge tray 7 by a discharge conveyance roller pair 11 which is a discharge conveyance means provided downstream of the fixing roller pair 5.

  Further, when the double-sided image is formed, when the leading edge of the recording material P enters a reversing sensor flag (not shown), the reversing sensor flag swings around the rotation axis, thereby shielding a photo interrupter (not shown) and shielding the recording material P. Tip position information is obtained.

  Using this leading edge position information as a trigger, the timing at which the trailing edge of the recording material P exits the reverse flapper is obtained from information on the length of the recording material P and the conveyance speed of the recording material P. At this timing, the discharge conveyance roller pair 11 starts reversal, and the recording material P is conveyed to the double-side conveyance path by the guidance of the reverse flapper.

  Then, the toner image is re-fed to the registration roller 9 via the junction, and the toner image is formed on the recording material P and discharged by the above-described image forming operation as in the case of image formation on the first surface. Each rotating body described above is connected to a driving motor (not shown) to obtain a rotational driving force.

(Construction of transport guide)
The conveyance guide 28 functions as a conveyance guide for the recording material P from the registration roller 9 to the secondary transfer roller pair 3, and also functions as a conveyance guide for both surfaces of the recording material P. Since the contact portion 28a of the transport guide 28 is the same as that of the first embodiment, description thereof is omitted.

(Operation of transport guide)
With the above configuration, in the image forming apparatus according to this embodiment, the conveyance guide 28 can be efficiently warmed by the thermal energy generated from the drive motor or the like before the recording material P starts to be conveyed by the user pressing the copy start button. It becomes. Therefore, it is possible to efficiently prevent the condensation of the conveyance guide 28 that easily occurs in a low temperature environment.

  Further, since the transport guide 28 is made of a wire material, the apparatus main body is reduced in weight and size. Further, since the portion other than the wire rod of the conveyance guide 28 is a space, even if the door opening / closing configuration is as shown in FIG. 8, by opening the door 29, not only the double-sided conveyance path but also the conveyance path space 45 is formed. It can be visually recognized, and the user visibility of the recording material P is improved.

1 is a perspective view of a fixing device of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing of FIG. FIG. 3 is a configuration diagram of the fixing device in FIG. 2. It is sectional drawing of the contact part of the conveyance guide shown in FIG. FIG. 2 is a perspective view when a recording material is conveyed in the fixing device of FIG. 1. It is a block diagram of the other fixing apparatus of this invention. 1 is a cross-sectional view of an image forming apparatus of the present invention. FIG. 8 is a cross-sectional view of the image forming apparatus shown in FIG. 7 when the door is opened.

Explanation of symbols

16 Fixing heater
17 Heater holder
20 Fusing belt
22 Pressure roller
23 Entrance guide
25 First transport guide
25a, 27a Contact part
25b, 27b Base layer
25c, 27c endothermic material
26 Discharge roller
27 Second transport guide
30 Moisture absorbing material P Recording material

Claims (5)

A conveying means for conveying a recording material; a conveying guide for guiding the conveying of the recording material; a transferring means for transferring a toner image onto the recording material at a time; and a recording material disposed downstream of the transferring means. In an image forming apparatus having fixing means for fixing the toner image transferred to
An image forming apparatus, wherein a contact portion of the conveyance guide with which the recording material contacts is made of a wire.   The image forming apparatus according to claim 1, wherein the conveyance guide is located downstream of the fixing unit.   3. The image forming apparatus according to claim 1, wherein the contact portion of the conveyance guide with which the recording material contacts is made of a highly heat conductive wire.   The image forming apparatus according to claim 1, wherein a surface of the conveyance guide is formed of an endothermic material.   5. The image forming apparatus according to claim 1, wherein a portion excluding the contact portion of the conveyance guide is formed of a moisture absorbing material.

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