JP2018077295A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that is excellent in collection of evaporated wax generated when an image formed by using a toner containing wax is heated.SOLUTION: An image forming apparatus comprises: an image forming part 10 that forms an image T on a recording material P by using a toner containing wax; and a fixing part 100 including nip part forming members 101 and 102 forming a nip part N that heats, while holding the recording material on which the image is formed to fix the image to the recording material. The image forming apparatus includes: a frame 120 that includes a conveyance port 121 for passing the recording material on which the image is formed through the nip part and an opening 122 provided at a position different from that of the conveyance port to store the nip part forming members; a fan 115 that draws air inside the frame from the opening; and a member 113 for urging collision of particles of evaporated wax generated when the image is heated provided between the opening and the fan.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer.

  An electrophotographic copying machine or printer includes an image forming unit that forms a toner image using toner as a recording material, and a fixing unit (fixing device) that fixes the toner image formed on the recording material to the recording material. I have. In the fixing device, a pressure rotator such as a roller is pressed against a heating rotator such as a sleeve or a roller to form a nip portion, and the recording material on which the toner image is formed is heated while being conveyed in the nip portion. The toner image is fixed on. Many toners contain wax. This is for the purpose of imparting effects such as adjusting the glossiness of the printed image and the dispersibility of the pigment, and is added to prevent fixing offset.

  The wax added to the toner is liquefied during the fixing process of the toner image by the fixing device, and most of the wax components are fixed to the recording material after being transferred together with the molten toner. Adhere to various places. For example, when a wax component adheres to the recording material conveyance guide or the conveyance roller, the conveyance of the recording material may be hindered or the friction coefficient of the conveyance roller may be reduced.

  Patent Document 1 discloses a method of collecting vaporized wax by a collecting member provided between a fixing nip forming member and a frame of a fixing device.

JP 2012-194576 A

  When the printing processing operation of the image forming apparatus is speeded up, not only the amount of vaporized wax per unit time is increased in the fixing device, but also an increase in airflow generated by the conveyed recording material is accompanied. Therefore, diffusion of the vaporized wax is promoted on the downstream side in the conveyance direction of the recording material of the fixing device.

  An object of the present invention is to provide an image forming apparatus excellent in collecting vaporized wax generated when an image formed using a toner containing wax is heated.

In order to achieve the above object, an image forming apparatus according to the present invention includes:
An image forming portion that forms an image on a recording material using toner containing wax, and a nip portion that fixes the image on the recording material by heating while sandwiching the recording material on which the image is formed are formed. In an image forming apparatus comprising a fixing unit having a nip forming member,
A transport port for allowing the recording material on which the image is formed to pass through the nip portion, a frame having an opening provided at a position different from the transport port, and housing the nip portion forming member; And a fan for drawing air inside the frame from the opening, and a member for promoting collision of vaporized wax particles generated when the image is heated between the opening and the fan. It is characterized by having.

  According to the present invention, it is possible to provide an image forming apparatus that is excellent in trapping vaporized wax that is generated when an image formed using a toner containing wax is heated.

Sectional drawing which shows schematic structure of the image forming apparatus which concerns on Example 1. FIG. Sectional view showing schematic configuration of fixing device The figure for demonstrating the flame | frame of a fixing device, and a cover member The figure for demonstrating the structure of the airflow of a fixing device FIG. 9 is a perspective view of a front cover of a frame in a fixing device of an image forming apparatus according to a second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Although the preferred embodiment of the present invention is an example of the best embodiment of the present invention, the present invention is not limited by the following examples, and various other configurations are within the scope of the idea of the present invention. It is possible to replace with.

[Example 1]
<Image forming apparatus 1>
With reference to FIG. 1, an image forming apparatus according to a first embodiment will be described. FIG. 1 is a cross-sectional view showing a schematic configuration of an example of an image forming apparatus (full color printer in the present embodiment) 1 using an electrophotographic recording technique.

  In the image forming apparatus 1, an image forming unit 10 that forms an image on a recording material using a toner containing wax has four image forming stations SY, SM, SC, and SK of yellow, magenta, cyan, and black. Each image forming station includes photosensitive drums 11Y, 11M, 11C, and 11K as image carriers, charging members 12Y, 12M, 12C, and 12K, and developing units 13Y, 13M, 13C, and 13K. Further, the image forming unit 10 includes a laser scanner 14, transfer members 15Y, 15M, 15C, and 15K, a belt 16 that carries a toner image transferred from each photosensitive drum by the transfer member, and a recording material P from the belt. And a secondary transfer member 17 for transferring the toner image to the head. Since the above-described operation of the image forming unit 10 is well known, detailed description thereof is omitted.

  Recording materials (not shown) stored in the cassette 21 in the image forming apparatus main body 1A are supplied to the rollers 26 one by one as the rollers 23 rotate. Alternatively, the recording material P set on the manual feed tray 22 provided in the image forming apparatus main body 1 </ b> A is supplied to the roller 26 via the roller 25 one by one by the rotation of the roller 24. Then, the recording material P is conveyed to the secondary transfer nip portion formed by the belt 16 and the secondary transfer member 17 by the rotation of the roller 26. The recording material P on which the toner image is transferred in the secondary transfer unit is sent to a fixing device 100 as a fixing unit, and the toner image is heated and fixed on the recording material by the fixing device. The recording material P exiting the fixing device 100 passes through the flapper 29 and is discharged to the tray 28 by the rotation of the roller 27.

  The above description of the printing operation is for single-sided printing.

  In the case of duplex printing, the conveyance path is switched by the flapper 29, and the recording material P is conveyed to the roller 30 side. The recording material P conveyed to the roller 30 side is reversely conveyed by the roller 30, passes through the rollers 25 and 26, the secondary transfer unit, and the fixing device 100, then passes through the flapper 29, and rotates on the roller 27 to the tray 28. Discharged.

<Fixing device 100>
Next, the fixing device 100 will be described with reference to FIGS. FIG. 2 is a cross-sectional view showing a schematic configuration of the fixing device 100, and FIG. 3 is a view for explaining a frame and a cover member of the fixing device 100.

  The fixing device 100 includes a heat resistant endless belt (hereinafter referred to as a sleeve) 101 having flexibility and a pressure roller 102 as a nip portion forming member. Further, the fixing device 100 includes a plate-like heater 103 as a heating body, a holder 104 as a support member, a pressure stay 105 as a pressure member, and a pair of left and right flanges 106L and 106R as restriction members, Have

  The heater 103 is supported by the holder 104 in the longitudinal direction perpendicular to the conveyance direction of the recording material P. The pressure stay 105 is placed on the holder 104 on the side opposite to the heater 103. The holder 104 is formed of a heat resistant resin having heat resistance and sliding properties such as a liquid crystal polymer. A sleeve 101 is fitted on the holder 104 that supports the heater 103 and on which the pressure stay 105 is placed. The sleeve 101 has substantially the same circumference as the pressure roller 102.

  The heater 103 has an elongated substrate 103a made of insulating ceramics. On the surface of the substrate 103a opposite to the holder 104, a heating resistor 103b that generates heat when energized is provided along the longitudinal direction of the substrate. Further, an insulating protective layer 103c is provided on the surface of the substrate 103a so as to cover the heating resistor 103b.

  In the longitudinal direction perpendicular to the conveyance direction of the recording material P, both end portions of the sleeve 101 are rotatably held on the outer periphery of the flanges 106L and 106R. Further, both end portions of the holder 104 are supported by the flanges 106L and 106R via the pressure stay 105. The flanges 106L and 106R are supported by the left and right side plate pairs 107L and 107R.

  The pressure roller 102 includes a cored bar 102a, an elastic layer 102b provided on the outer peripheral surface of the cored bar, and a release layer 102c coated on the outer peripheral surface of the elastic layer. In the longitudinal direction perpendicular to the conveyance direction of the recording material P, both ends of the cored bar 102a are rotatably supported by the side plate pairs 107L and 107R via bearings (not shown).

  In the longitudinal direction perpendicular to the conveyance direction of the recording material P, both flanges are sleeves 101 by pressure springs (not shown) provided between the spring receiving portions (not shown) of the pair of side plates 107L and 107R and the flanges 106L and 106R. The pressure is applied in the vertical direction perpendicular to the generatrix direction. In FIG. 3, the pressing direction of the flanges 106L and 106R is indicated by an arrow A.

  When the flanges 106L and 106R are pressed, the holder 104 presses the heater 103 against the inner peripheral surface (inner surface) of the sleeve 101, and the outer peripheral surface (surface) of the sleeve 101 becomes the outer peripheral surface (front surface) of the pressure roller 102. Press contact. As a result, the elastic layer 102b of the pressure roller 102 is crushed and elastically deformed, and a nip portion N having a predetermined width is formed by the surface of the sleeve 101 and the surface of the pressure roller 102. The nip portion N is an area where the recording material P on which the toner image T is formed is heated while being nipped and conveyed.

<Heat fixing processing operation>
The pressure roller 103 rotates in the direction of the arrow shown in FIG. 2 when a driving force of a motor (not shown) is transmitted to the core metal 103 a of the pressure roller 103. The sleeve 101 rotates in the direction of the arrow shown in FIG. 2 following the rotation of the pressure roller 102 while the inner surface of the sleeve 101 slides on the protective layer 103 c of the heater 103. When the heating resistor 102b is energized to cause the heating resistor 102b to generate heat, the heater 102b rapidly rises in temperature to heat the sleeve 101. The temperature of the sleeve 101 is detected by a temperature detection element (not shown), and a temperature control unit (not shown) controls the amount of power supplied to the heater 103 so as to maintain the temperature at a predetermined fixing temperature (target temperature).

  The recording material P on which the unfixed toner image T is formed is conveyed to the nip portion N. The recording material P is heated by the heat of the heater 103 while being conveyed at the nip portion N. As a result, the toner image T on the recording material P is fixed to the recording material.

<Configuration of frame 120>
The frame 120 of the fixing device 100 will be described with reference to FIGS.

  The side plate pairs 107L and 107R, the stay 108, and the base plate 109 are all sheet metal members. These three components constitute part of the frame 120 of the fixing device 100 to ensure the rigidity of the fixing device 100. In the longitudinal direction orthogonal to the conveyance direction of the recording material P, both ends of the stay 108 are connected to the side plate pairs 107L and 107R on the sleeve 101 side. Further, both ends of the base plate 109 are connected to the side plate pairs 107L and 107R on the pressure roller 102 side. The L-shaped front cover 112 is formed of a resin, and the lower part is in contact with the stay 108 and also functions as the frame 120 of the fixing device 100.

  That is, the frame 120 includes the side plate pairs 107L and 107R, the stay 108, the base plate 109, and the front cover 112. The frame 120 accommodates a sleeve 101 that encloses the heater 103, the holder 104, and the pressure stay 105, and a pressure roller 102 that forms a nip portion N together with the sleeve 101. In the conveyance direction of the recording material P, the frame 120 has a conveyance port 121 for allowing the recording material P to pass through the nip portion N. The conveyance port 121 introduces the recording material P from the stay 108 and the base plate 109 into the nip portion N between the pair of side plates 107L and 107R, and causes the recording material P that has left the nip portion N to pass between the front cover 112 and the base plate 109. It is formed to discharge from the space.

  Further, the pair of side plates 107L and 107R, the stay 108, and the base plate 109 are surrounded by the rear cover 110, the upper cover 111, the front cover 112, the left cover 117L, and the right cover 117R. That is, the base plate 109 is surrounded by the rear cover 110, and the side plate pairs 107L and 107R are surrounded by the left cover 117L and the right cover 117R. Between the side plate pairs 107L and 107R, the pressure roller 102 side of the side plate pairs 107L and 107R is surrounded by the upper cover 111, and the sleeve 101 side of the side plate pairs 107L and 107R is surrounded by the front cover 112. As a result, the user cannot touch the side plate pairs 107L and 107R, the stay 108, and the base plate 109 from the outside.

  On the surface of the front cover 112 facing the surface of the sleeve 101, an elongated opening 122 having a longitudinal dimension that intersects with the conveying direction of the recording material P is 16 mm and a longitudinal dimension that intersects with the conveying direction of the recording material P is 200 mm. Provided. That is, the opening 122 is provided at a position different from the conveyance port 121. A metal mesh 113 is fitted into the opening 122 as a member for promoting collision between vaporized wax particles. Air can freely move from the opening 122 into which the wire mesh 113 is fitted. The wire mesh 113 will be described in detail later.

<Composition of air flow>
Next, the airflow configuration of the fixing device 100 will be described with reference to FIG. 4A is a cross-sectional view showing a schematic configuration of the airflow, and FIG. 4B is a perspective view showing a schematic configuration of the airflow.

  The duct 114 formed of resin is a blower pipe installed in the apparatus main body 1A so as to connect the air flow path between the front cover 112 of the frame 120 and the fan 115. The fan 115 is a 30 angle axial flow fan installed in the apparatus main body 1 </ b> A, and exhausts air from the duct 114 to the electrical component 118. The vaporized wax generated in the sleeve 101 of the fixing device 100 by the duct 114 and the fan 115 passes through the mesh of the metal mesh 113 of the front cover 112 as shown by an arrow and passes into the duct 114, and the electric unit 118 is provided by the fan 115. To. In the duct 114 or the electrical component 118 on the vaporized wax flow path, the vaporized wax is adsorbed on the wall surfaces of these peripheral members.

  Here, a mechanism of generation of vaporized wax from the toner will be described with reference to FIG.

  Toners are stored in the developing devices 13Y, 13M, 13C, and 13K of each image forming station of the image forming unit 10 shown in FIG. This toner contains hydrocarbon waxes such as paraffin wax, polyethylene wax, and polypropylene wax.

  The wax is liquefied by heat and pressure when the toner image T passes through the nip N, and exudes from the inside of the toner to the toner surface. At this time, part of the wax is vaporized and released into the air. These vaporized wax becomes ultrafine particles and floats in the surrounding space by riding on the surrounding air current. These vaporized waxes tend to agglomerate if they are in a floating state for a long time, and are easily adsorbed to peripheral members. For this reason, it has been generally preferred to cover the periphery of the sleeve 101 with a collecting member to temporarily retain the vaporized wax immediately after the occurrence.

  However, as the speed of the image forming apparatus increases, the vaporized wax diffuses against the air current generated when the recording material P is conveyed, no matter how much the periphery of the sleeve 101 is covered with the collecting member. Then, the diffused vaporized wax is carried on the airflow by being carried on the airflow.

  For this reason, in the conveyance direction of the recording material P, vaporized wax adheres to the conveyance guide or the roller 27 or the roller 30 on the downstream side of the fixing device 100 to prevent the conveyance of the recording material P, or the friction of the rollers 27 and 30. It led to things like lowering the coefficient.

  On the other hand, in the airflow configuration of the present embodiment, the vaporized wax is actively carried to the electrical component 118 on the airflow indicated by the arrow in FIG. 4, so that the vaporized wax adheres to the conveyance guide or the rollers 27 and 30. That was gone.

<Configuration of wire mesh 113>
According to general gas kinetics, the higher the temperature, the higher the speed of the particles, and the higher the speed, the higher the collision frequency between the particles. The wire mesh 113 shown in the present embodiment utilizes this gas property. That is, it is intended to increase the collision frequency of vaporized wax to vaporized wax particles or peripheral members by increasing the temperature on the vaporized wax flow path, and to promote adsorption to the duct 114 or the electrical component 118. It is.

  The reason for using the wire mesh 113 will be described below.

  First, the use of the wire mesh 113 can increase the temperature on the flow path of the vaporized wax without requiring a new heating source. That is, the wire mesh 113 is heated by the convection of air from the sleeve 101, but the wire mesh 113 has a small heat capacity, so that the temperature quickly rises even when a certain distance is away from the sleeve 101, and the surrounding temperature is increased. Can do. This is because the metal mesh 113 is a metal having a specific heat smaller than that of a mold or the like, and the shape is knitted with fine wires, so the mass is small.

  Next, it is mentioned that the flow of air is not inhibited by using the wire mesh 113.

  For example, when a material with higher linear density such as steel wool is installed instead of the wire mesh 113, the vaporized wax flows out toward the conveyance path, and the effect is reduced. This is because, in the case of a material having a high linear density, the flow of air flowing from the sleeve 101 to the duct 114 or the electrical component 118 decreases due to the inhibition of the air flow. In particular, costly measures are required.

  On the other hand, in this embodiment, a wire net having a wire diameter of 0.1 to 0.3 and a mesh of 10 to 30 mesh / inch was used. In that case, the flow rate drawn by the fan 115 did not change greatly, and the air flow from the sleeve 101 to the duct 114 or the electrical component 118 was not obstructed.

  In this embodiment, from this point of view, the wire mesh 113 is made of material SUS304, wire diameter Φ0.25, mesh 20 mesh / inch, and is cut into a size of 20 mm × 220 mm and the opening 121 of the front cover 112 is used. The sleeve 105 was used for heat welding.

<Effect of Example>
In order to quantitatively confirm the effect of this example, the number of vaporized wax near the roller 27 was measured. For the measurement, a nanoparticle measuring machine FMPS (manufactured by TSI) was used, and the integrated values when printed for 10 minutes were compared. Table 1 shows the results. Table 1 also shows the results of Example 2 described later.

  The comparative example (Ref) is a case where a mold plate made of the same material as that of the front cover 112 is attached to the metal mesh 113 of the front cover 112 to close the opening 121. On the other hand, in the case of this example (Example 1), the number is half, and it was confirmed that the vaporized wax diffused by the airflow generated by the conveyance of the recording material P could be effectively reduced. .

  As described above, in the image forming apparatus of the embodiment, the air inside the frame 120 is drawn out through the opening 122 provided in the frame 120 of the fixing device 100 and the vaporized wax particles are exchanged between the metal meshes 113 installed in the opening 122. Collisions can be promoted. As a result, the vaporized wax can be collected efficiently.

[Example 2]
Another example of the image forming apparatus will be described. In the present embodiment, only the configuration different from the first embodiment will be described.

  In the first embodiment, the metal mesh 113 is used as a member for promoting collision between vaporized wax particles. In the present embodiment, a case where a metal spring 116 is used will be described.

  FIG. 5 is a perspective view of the front cover 112 of the frame 120 in the fixing device 100 of the image forming apparatus 1 of the present embodiment.

  The metal spring 116 is made of material SUS304, wire diameter Φ0.20, coil diameter Φ3, and number of windings 300. In the present embodiment, the three metal springs 116 are each extended to a length of 220 mm, and are installed by hooking both ends to projections (not shown) provided on the left and right inner surfaces of the opening 122 of the front cover 112. The reason for using the metal spring 116 is that it is a material that does not obstruct air flow as much as possible in the same manner as in the first embodiment, has a low heat capacity, and is easier to assemble than the wire mesh in the first embodiment.

  In order to quantitatively confirm the effect of this example, the number of vaporized wax near the roller 27 was printed for 10 minutes and measured in the same manner as in Example 1. As shown in Table 1, it was confirmed that the vaporized wax could be effectively reduced compared to the comparative example (Ref) although it did not reach the reduction rate of Example 1.

  As described above, the image forming apparatus according to the exemplary embodiment draws the air inside the frame F through the opening 122 provided in the frame 120 of the fixing device 100 and uses the metal spring 116 installed in the opening 122 to exchange the vaporized wax particles. Can promote collisions. As a result, the vaporized wax can be collected efficiently.

<Other embodiments>
In the image forming apparatuses according to the first and second embodiments, the metal mesh 113 and the metal spring 116 are installed in the opening 121 of the front cover 112. However, the present invention is not limited to this and may be installed in the duct 114. The present invention can be applied not only to a full-color image forming apparatus but also to a monochrome image forming apparatus. Further, the present invention can be applied not only to a fixing device using a sleeve but also to a fixing device having other configurations such as a heat roller type fixing device using a fixing roller.

10 image forming section, 100 fixing device, 101 sleeve, 102 pressure roller,
115 fan, 120 frame, 121 transport port, 122 opening, 113, 116 member, P recording material, T unfixed toner image

Claims (3)

An image forming portion that forms an image on a recording material using toner containing wax, and a nip portion that fixes the image on the recording material by heating while sandwiching the recording material on which the image is formed are formed. In an image forming apparatus comprising a fixing unit having a nip forming member,
A transport port for allowing the recording material on which the image is formed to pass through the nip portion, a frame having an opening provided at a position different from the transport port, and housing the nip portion forming member; And a fan for drawing air inside the frame from the opening, and a member for promoting collision of vaporized wax particles generated when the image is heated between the opening and the fan. An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the member is a wire mesh.   The image forming apparatus according to claim 1, wherein the member is a metal spring.