JP6710580B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus that forms an image by an electrophotographic method.

The image forming apparatus includes a transfer roller that is arranged to face an image carrier such as a photoconductor drum and that transfers a toner image formed on the image carrier to a recording sheet. At a position immediately upstream of the transfer roller, a long-width transfer guide member made of resin or sheet metal for guiding the conveyed recording paper between the image carrier and the transfer roller is installed (for example, Patent Document 1).

JP, 2011-28212, A JP, 2008-241793, A JP, 2003-34521, A

By the way, since the recording paper is conveyed to the photosensitive drum while being in sliding contact with the transfer guide member, static electricity due to friction is generated on the surface of the transfer guide member and is charged. Since the transfer guide member is close to the photosensitive drum, the fog toner, the floating toner, and the paper powder from the photosensitive drum are electrostatically adsorbed on the surface of the transfer guide member and are further attached thereto. Therefore, there has been a problem that both sides and the back surface of the recording paper passing through are soiled with toner or the like. Therefore, in order to prevent the adhesion of toner and paper dust, measures have been taken to change the material and shape of the transfer guide member. However, there is a problem that, for example, a toner-repellent material coated is expensive and is not effective in view of peeling due to repeated rushing impact of the leading edge of the recording paper.

On the other hand, in the image forming apparatus, various technologies have been proposed in which the heat of the fixing unit is used in other components (for example, Patent Documents 2 and 3). Japanese Patent Application Laid-Open No. 2004-242242 describes a preheating unit that is provided immediately downstream of a pickup roller and sufficiently upstream of a transfer unit so as to preheat the recording paper by blowing the heat of the fixing unit through a duct. .. In Patent Document 3, the heat of the fixing unit is blown to the blade of the cleaning unit arranged around the photosensitive drum through the duct to prevent the physical property of the blade from being changed and maintain the cleaning property. Things are listed. However, these are not for suppressing or preventing the adhesion of toner and paper powder to the guide member of the transfer portion.

The present invention has been made in view of the above, and paying attention to the relationship between the amount of static electricity generated and the temperature characteristic, by using the heat of the fixing unit to heat the periphery of the guide member, An object of the present invention is to provide an image forming apparatus that suppresses adhesion of toner and paper dust.

The image forming apparatus according to the present invention is an image forming apparatus in which a toner image transferred onto a recording paper passing between a transfer member and an image carrier arranged in parallel with each other is heated and fused at a fixing unit. A transfer guide member arranged upstream of the transfer member, for guiding the conveyance of the recording paper between the image carrier and the transfer member, the transfer guide member having a width longer than the width of the recording paper; A warm heat supply unit that supplies warm heat to the guide member side, and the warm heat supply unit includes a blower that directs the warm heat of the fixing unit toward the guide member side by a wind force.

According to the present invention, the recording paper is suitably guided between the image carrier and the transfer member while slidingly contacting the transfer guide member, the toner image is transferred, and the recording paper is further transported to the fixing heat of the fixing unit. Then, the toner image is fused and fixed. On the other hand, static electricity is generated on the transfer guide member due to friction during conveyance between the recording paper and the transfer guide member, and fog toner, floating toner, and paper dust are electrostatically adsorbed and adhered to the surface of the transfer guide member to There is a problem that the side edges and the back surface of the are soiled. The present inventor has focused on the phenomenon that static electricity due to triboelectric charging or the like is less likely to occur when the temperature exceeds 25°C. Therefore, the fixing warming temperature of the existing fixing temperature was designed to be raised to about 25° C. (structurally or controllably) by directing the fixing warming heat to the guide member side by the blowing air force using a blower. As a result, generation of static electricity on the surface of the transfer guide member is suppressed, and adsorption or adhesion of the toner or paper powder is suppressed. The temperature for raising the temperature is preferably higher than 25° C. On the other hand, if the temperature is too high, a suitable range may be adopted in consideration of the thermal load on other members.

In addition, the fixing unit and the transfer guide member are communicated with each other, and a duct in which the air blown by the blower acts is provided inside, the duct has an outlet, and the outlet is the transfer guide member. It is characterized in that it is located on the upstream side of the recording paper conveyance direction. According to this configuration, the fixing heat of the fixing temperature is reliably supplied to the transfer guide member through the duct in which the wind force is applied, so that the indirect temperature increase can be efficiently performed.

Further, the blowout port is directed to at least positions on both sides in the width direction in the recording paper conveyance path. With this configuration, it is possible to effectively raise the temperature from both sides of the transfer guide member in the width direction.

Further, the fixing unit has a configuration in which a heating unit containing a heat source and a pressurizing unit are arranged in contact with each other, the duct has an intake port, and the intake port is the pressurizing unit. It is characterized in that it is arranged toward the side. With this configuration, since the temperature of the fixing unit is sufficiently higher than the temperature for suppressing static electricity, it is possible to indirectly introduce heat from the pressurizing unit side, which is relatively lower than the heating unit side. , Temperature control is easy.

Further, the transfer guide member has a plurality of openings in the width direction, and the blowout port is communicated with the opening. According to this structure, the transfer guide member is directly or indirectly heated. Further, by designing the opening position, it becomes possible to heat an appropriate position in the width direction.

Further, the blower operates in conjunction with driving of the fixing unit. According to this configuration, it is possible to prevent the inconvenience that a large amount of static electricity is inadvertently generated by blowing hot air having a temperature lower than 25°C.

Further, the transfer guide member is made of a high heat conductive material. With this configuration, the transfer guide member is heated to a more uniform temperature in the entire axial direction.

According to the present invention, the generation of static electricity on the surface of the transfer guide member can be suppressed by supplying the heat of the fixing unit, and the adhesion of toner and paper dust can be suppressed.

It is a schematic side view which shows 2nd Embodiment of the heat supply part of the image forming apparatus which concerns on this invention. It is the schematic which shows 2nd Embodiment of a heat supply part, and is a schematic front view containing arrangement|positioning of a duct. It is the schematic which shows 3rd Embodiment of a heat supply part, (a) is a schematic front view of a transfer part, (b) is a schematic side view containing the blowing outlet of a duct. It is each schematic front of the transfer guide explaining other embodiment. FIG. 5 is a schematic side view showing a relationship between a transfer guide and a duct for explaining the embodiment of FIGS. 4(a) and 4(e). It is a block diagram of a drive control unit of the fixing unit and the heat supply unit. It is a time chart explaining the drive timing of each part of a heat supply part.

The image forming apparatus 1 shown in FIG. 1 includes an image forming unit 10, a fixing unit 20, and a heat supply unit 30. Note that, in FIG. 1, a line indicated by a broken line indicates the conveyance path 40 of the recording paper, and the conveyance roller pair 41 is arranged at an appropriate position such as the upstream side (the lower side in FIG. 1) of the image forming unit 10. ing. The image forming unit 10 includes a photoconductor drum 11 that rotates at a constant speed as an image carrier, and a charger 12, an exposure unit 13, a developing unit 14, and a transfer unit that are arranged around the photoconductor drum 11 from the upstream side in the rotation direction. And at least part 15. The photoconductor drum 11 has a longer width than the maximum width of the recording paper used.

The charger 12 uniformly charges the peripheral surface of the photosensitive drum 11 to a constant potential. The exposure unit 13 forms an electrostatic latent image in the sub-scanning direction by performing an exposure operation in the peripheral main scanning direction (width direction) of the photosensitive drum 11 with a beam light obtained by optically modulating image data. .. The developing unit 14 includes a container that contains toner therein, and visualizes the electrostatic latent image formed by the exposing unit 13 as a toner image via a developing roller that faces the photosensitive drum 11.

In the present embodiment, the transfer section 15 has a transfer roller 151 that is long in the axial direction, and is arranged in parallel with the photoconductor drum 11 so as to face each other. The transfer roller 151 has a long dimension corresponding to the photoconductor drum 11, and is applied with a transfer bias to transfer the toner image formed on the photoconductor drum 11 onto the recording paper. The recording paper is conveyed between the transfer roller 151 and the photoconductor drum 11 by the conveyance path 40 including the pair of conveyance rollers 41, and after the transfer processing, the transfer toner image is heat-fused at the fixing unit 20 and discharged. It

The transfer unit 15 has a transfer guide 16. The transfer guide 16 is arranged in parallel with the transfer roller 151 at a position on the upstream side of the transfer path 40 with respect to the transfer roller 151, and preferably guides the recording paper between the transfer roller 151 and the photosensitive drum 11. The transfer guide 16 has a predetermined cross-section, an L-shape in the present embodiment, and has a width corresponding to the length of the transfer roller 151, as can be seen from the front view of FIG. 2 described later. Have. In addition, the transfer guide 16 is made of a metal having at least a high thermal conductivity and a high thermal conductivity material so as to prevent thermal deformation, and SUS or aluminum which is not magnetized is adopted.

The fixing unit 20 includes at least a heating belt 21 having a heat source 211, and a pressure roller 22 arranged in parallel with the heating belt 21 in a contact state. The fixing unit 20 applies heat from the heat source 211 to the recording paper passing between the heating belt 21 and the pressure roller 22 to fuse the toner. In the present embodiment, the fixing unit 20 is surrounded by the housing 21A on the heating side and the housing 22A on the pressurizing side, and prevents inadvertent radiation of the fixing heat to the outside. However, the housings 21A and 22A are not necessarily essential in a configuration in which warm heat can be efficiently discharged by an exhaust fan or the like. The temperature of the heat source 211 is higher than the melting temperature of the toner, generally about 180°C. The fixing unit 20 is controlled to a low preheating temperature state during standby, and when the printing instruction is received, the fixing unit 20 is temperature-controlled to the printing temperature and the temperature sensor 23 (FIG. 6) indicates that the temperature has risen to a preset printable temperature. ), the rotation drive unit, for example, the fixing motor 25 (FIG. 6) is turned on, and the heating belt 21 and the pressure roller 22 start rotating to enable the recording paper to be conveyed.

The heat supply unit 30 includes at least a duct 31 and a fan 32 that is a blower. The duct 31 communicates between the fixing unit 20 and the transfer guide 16, and sends the heat of the fixing unit 20 to the space around the transfer guide 16. The intake port 311 of the duct 31 faces the inside of the fixing unit 20, for example, from the outer side in the width direction of the housing 22A, and the blowing port 312 is directed toward the transport path 40 in the space immediately upstream of the transfer guide 16, or The openings are opened so as to face each other.

The heat supply unit 30 may supply heat from the housing 21A on the heat source 211 side to the transfer guide 16, but in the present embodiment, in order to keep the space of the transfer guide 16 at a temperature of about 25°C. The heat of the casing 22A, which has a relatively low temperature, is guided to the transfer guide 16. The shape of the duct 31, for example, the cross-sectional size and the blowing force of the fan 32 are designed in advance so that the blowing temperature on the transfer guide 16 side is around 25°C. In this case, a temperature sensor may be provided near the transfer guide 16 and the fan 32 may be turned on/off to control the temperature. The duct structure of the blowout port 312 and the opening shape of the blowout port 312 can be variously adopted and will be described later.

The fan 32 is arranged, for example, so as to face the intake port 311, guides a part of the heat of the fixing unit 20 into the duct 31, and blows it out from the blowout port 312. The fan 32 may be installed inside the duct 31.

(Second Embodiment of Heat Supply Unit)
The heat supply units 30 are not limited to one side in the width direction of the fixing unit 20, and may be arranged side by side in the width direction as shown in the schematic view of FIG. By supplying the heat from both sides in the width direction, it is possible to raise the temperature in at least both end regions of the space in the width direction of the transfer guide 16. The transfer guide 16 has a small amount of toner or paper powder adhered by the passage of the recording paper in the widthwise range where the recording paper passes, while the amount of toner or paper powder adhered on both outer sides where the recording paper does not pass is relatively large. There are many. Therefore, hot air is blown out from the air outlets 312 toward at least both sides to raise the temperature of this space and suppress the generation of static electricity on the surface of the transfer guide 16.

In addition, the outlets 312 of the duct 31 which are arranged on both sides in the width direction are arranged to face each other on both sides immediately downstream of the transfer guide 16. According to this configuration, it is possible to suppress the generation of static electricity on the surface of the transfer guide 16 by raising the temperature of the space around the transfer guide 16 outside the passage area of the recording paper P, and in this area. Adhesion of toner and paper powder to the transfer guide 16 is suppressed.

(Third Embodiment of Heat Supply Unit)
As shown in FIG. 3, the duct 31 has a blowout port 312 corresponding to the entire length in the width direction and opened in a direction intersecting with the transport path 40. According to this configuration, the warm air from the outlet 312 is blown to the leading edge, both side surfaces, and the back surface of the recording paper P that is passing, so that the recording paper P has the effect of suppressing the generation of static electricity in the space. Preheating makes it possible to improve the fixability. In addition, in this embodiment, the duct 31 may use only one side in the width direction or both sides in the width direction and may be merged into one in the middle.

(Other embodiments)
4 and 5 are views for explaining each embodiment of the plate-shaped transfer guide. 4(a) to 4(c) and 4(e) show an opening formed in the transfer guide, FIG. 5(a) is a side view of FIG. 4(a), and FIG. It is a side view of (e). It should be noted that FIG. 4D is characterized only by the shape of the transfer guide, and the above-described embodiments are applied to the heat supply unit 30.

In FIG. 4A, a pair of openings 1161 are formed at both ends of the transfer guide 116 in the width direction. A blowout port 312 of the duct 31 communicates with each opening 1161 (see FIG. 5A).

In FIG. 4B, a pair of two openings 2161 is formed at both ends of the transfer guide 216 in the width direction. The outlets 312 of the duct 31 communicate with the openings 2161. The outlet 312 is branched on the outlet side of the duct 31 and communicates with each opening 2161.

In FIG. 4C, a plurality of openings 3161 are formed in the width direction of the transfer guide 316 at a constant pitch, for example. The outlets 312 of the duct 31 communicate with the openings 3161. The outlet 312 is branched on the outlet side of the duct 31 and communicates with each opening 2161. Alternatively, the blowout port 312 may have a long shape corresponding to the entire length in the width direction, and may be in contact with the transfer guide 316.

In FIG. 4D, a plurality of ribs 4160 parallel to the width direction are formed at a constant pitch on the surface of the transfer guide 416 facing the transport path 40.

In FIG. 4E, a plurality of ribs 5160 parallel to the width direction are formed at a constant pitch on the surface of the transfer guide 516 facing the transport path 40. Further, a plurality of openings 5161 are formed in the width direction of the transfer guide 516 at a constant pitch, for example. Note that, as in FIG. 4D, the blowout port 312 of the duct 31 communicates with each opening 5161. Further, as shown in FIG. 5B, the ribs 4160 and 5160 have a shape in which the center is raised in the carrying direction, but various shapes can be adopted. By adopting the ribs 4160 and 5160 as shown in FIGS. 4D and 4E, even if toner or paper powder adheres to the surface on the side of the transport path 40, the cross-sectional area is small, and therefore the wind that blows between the ribs. It has the advantage that it is easy to peel off and it is hard to accumulate.

Further, in FIG. 4 and FIG. 5, since an opening is formed in a portion where a temperature rise is desired and hot air is supplied to that portion, it is possible to suppress the generation of static electricity on the surfaces of the transfer guides 116 to 516. Become.

FIG. 6 is a block diagram of the drive control units of the fixing unit 20 and the heat supply unit 30. The temperature sensor 23 detects the temperature near the heating belt 21 of the fixing unit. The control unit 24 is configured by a microcomputer or the like, and controls driving of the heat source 211, the fixing motor 25, and the fan 32 based on the detected temperature information and the like. The control unit 24 executes a control program stored in a storage unit (not shown) to drive the heat source 211, a heat source control unit 241, a rotation drive control unit 242 that controls ON/OFF of driving of the fixing motor 25, and It functions as a fan drive control unit 243 that controls on/off of driving of the fan 32.

FIG. 7 is a time chart for explaining the drive timing of the heat supply unit 30. When the temperature detected by the temperature sensor 23 rises to a predetermined temperature T0 (for example, 80° C.), a standby state is set, and when the temperature rises to 120° C., for example. The fixing motor 25 starts rotating, and the fan 32 is driven in conjunction therewith. The fan 32 turns on/off in conjunction with turning on/off of the fixing motor 25. In this way, since the fan 32 is driven and the heat is supplied to the transfer guide 16 in a state where the fixing unit 20 has risen to a predetermined temperature, the temperature is raised prior to printing and the occurrence of static electricity is suppressed in advance. You can The predetermined temperature T0 is a temperature at which the hot air of about 25° C. can be supplied to the transfer guide 16 even if the fan 32 is driven at this temperature. The fixing temperature reaches a certain high temperature and the heat is supplied to prevent the inconvenience that a large amount of static electricity is generated by supplying the transfer guide 16 with a temperature lower than 25° C. ..

In each of the above embodiments, the photoconductor drum 11 is used as the image carrier and the transfer roller 151 is used as the transfer unit 15. However, the present invention is not limited to this, and the secondary transfer unit in the color image forming apparatus is used as the image carrier. Alternatively, a transfer belt may be applied instead of the transfer roller 151.

Although the duct 31 is adopted in each of the above-described embodiments, the duct 31 may be omitted as long as the wind power of the fan 32 is obtained and the heat of the fixing unit 20 is directed to the transfer guide 16. For example, a space structure such as a passage of warm air may be provided between the fixing unit 20 and the transfer guide 16, or an appropriate number of wind direction guide side plates and the like may be arranged in the middle thereof. Therefore, the structure is simplified.

Further, the description of the above-described embodiments should be considered as illustrative in all points and not restrictive. The scope of the invention is indicated by the claims rather than the embodiments described above. Further, the scope of the present invention is intended to include meanings equivalent to the claims and all modifications within the scope.

1 image forming apparatus 11 photoconductor drum (image carrier)
15 Transfer unit (transfer member)
16, 116, 216, 316, 416, 516 Transfer guide (transfer guide member)
1161, 1621, 3161, 5161 Opening 4160, 5160 Rib 20 Fixing part 21 Heating belt (heating part)
22 Pressure roller (pressure unit)
30 Heat Supply Unit 31 Duct 311 Intake Port 312 Outlet Port 32 Fan (Blower)

Claims (5)

In an image forming apparatus for heating and fusing a toner image transferred onto a recording sheet, which has passed between a transfer member and an image carrier, which are arranged in parallel to each other, at a fixing unit,
A transfer guide member that is arranged on the upstream side of a long transfer member and that guides the conveyance of the recording paper between the image carrier and the transfer member, and has a width wider than the width of the recording paper.
A heat supply unit that supplies the heat of the fixing unit to the transfer guide member side;
The heat supply unit is provided with a blower that directs the transfer guide member side heat of the fixing portion by blowing force, further
The fixing portion and the transfer guide member are communicated with each other, and a duct in which the blown air force by the blower acts is provided inside,
The duct has an outlet,
The outlet is located upstream of the transfer guide member in the recording sheet conveyance direction,
The transfer guide member has a plurality of openings in the width direction,
The image forming apparatus is characterized in that the outlet is communicated with the opening . The image forming apparatus according to claim 1 , wherein the air outlets are oriented at positions on at least both sides in a width direction of the recording paper conveyance path . The fixing unit has a configuration in which a heating unit and a pressurizing unit that house a heat source are arranged in contact with each other,
The duct has an intake port,
The inlet opening is, the image forming apparatus according to claim 1 or 2, characterized in that said being disposed toward the pressure portion side. The blower is an image forming apparatus according to any one of claims 1 to 3, characterized that you work in conjunction with the driving of the fixing unit. The transfer guide member, the image forming apparatus according to any one of claims 1-4, characterized in the high thermal conductivity material der Rukoto.

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