JP3780786B2 - Fixing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a heating roller and a pressure roller that is in pressure contact with the heating roller, a transfer material on which a toner image is transferred is passed between the heating roller and the pressure roller, and the toner image is transferred to the transfer material. The present invention relates to a fixing device that performs heat fixing.
[0002]
[Prior art]
FIG. 7 is a configuration diagram of a conventional fixing device. In the figure, the fixing device 1000 includes a heating roller 1003 having a heating unit 1001 extending in the direction of the rotation axis, and a pressure roller 1005 in pressure contact with the heating roller 1003. A transfer material on which a toner image is transferred is passed between rollers 1005, and the toner image is thermally fixed to the transfer material.
[0003]
When the fixing device having such a configuration is a center reference, for example, when a transfer material having a small size such as A4R is continuously fixed, the temperature of both end portions in the rotation axis direction of the heating roller rises, and the heating roller 1003 Therefore, a cooling means 1100 for cooling both end portions of the heating roller 1003 is provided.
[0004]
The cooling means 1100 shown in the figure is substantially perpendicular to the rotating shaft of the heating roller 1003, the blowing means 1101 provided on a line passing through the approximate center in the width direction of the heating roller 1003, and one end of the blowing means 1101. Connected to the blower port, the other end side is divided into two, and the first opening 1103 on one end side of the fork is near the surface on the one end side in the rotation axis direction of the heating roller 1003. The second opening 1105 on the other end side is located in the vicinity of the surface of the other end portion in the rotation axis direction of the heating roller 1003, respectively, and a duct 1107 for guiding the wind from the blowing means 1101 to the surface of the heating roller 1003; It is made up of.
[0005]
[Problems to be solved by the invention]
However, in the cooling unit 1100 of the fixing device 1000 having the above configuration, as shown in FIG. 8, in each of the openings 1103 and 1105, the outside of the openings has a wind speed distribution in which the wind speed suddenly increases. There is a problem that each end portion of the can not be uniformly cooled.
[0006]
Further, the heating roller 1003 is provided with a first heating means for mainly heating both end portions in the direction of the rotation axis and a second heating means for mainly heating the center portion in the direction of the rotation axis. There may be a case where temperature detection means (for example, a thermostat) for detecting the temperature of the surface of the heating roller is provided at the overlapping heating portion between the means and the second heating means.
[0007]
The overlapping heating part of the first heating means and the second heating means is in the inner part of the duct opening.
Therefore, when a thermostat is provided around 100 mm of the second opening in FIG. 8, the wind speed of the wind hitting the heating roller portion facing the thermostat is slow, and the temperature of most of the heating roller facing the opening of the duct is sufficiently high. Although it is low, the thermostat may be sensitive.
[0008]
The present invention has been made in view of the above problems, and an object thereof is to provide a fixing device capable of uniformly cooling an end portion of a heating roller.
[0009]
[Means for Solving the Problems]
The invention according to claim 1, which solves the above problem, includes a heating roller and a pressure roller that is in pressure contact with the heating roller, and passes a transfer material on which a toner image is transferred between the heating roller and the pressure roller. A fixing device for thermally fixing the toner image to the transfer material, wherein the air blowing means and one end portion are connected to the air blowing port of the air blowing means, and the other end side is a first air passage, The first air passage has a first opening in the vicinity of the surface on one end side in the rotation axis direction of the heating roller, and the first air passage has a first opening. Two openings are located in the vicinity of the surface of the other end of the heating roller in the rotation axis direction, a duct for guiding the air from the blowing means to the surface of the heating roller, and an air passage provided inside the duct. a rib for dividing, provided in the heating roller, contact the rotation axis A first heating means that mainly heats both end portions, a second heating means that is provided on the heating roller and mainly heats a central portion in the rotation axis direction, the first heating means, and the first heating means. In the fixing device, the temperature detecting means for detecting the temperature of the surface of the heating roller is provided in a heating portion overlapping with the heating means of No. 2, and the rib is arranged in the vicinity of the outside of the temperature detecting means. is there.
[0010]
By providing ribs that divide the air path inside the duct, the wind speed distribution of the wind coming out of each opening is leveled compared to the case without ribs, and the end portion of the heating roller can be cooled uniformly.
Further, by arranging the rib in the vicinity of the outside of the temperature detecting means, the speed of the wind hitting the surface of the heating roller facing the temperature detecting means becomes faster, the temperature of the heating roller part facing the temperature detecting means becomes lower, and the temperature Sensitive response of the detection means is eliminated.
[0011]
According to a second aspect of the present invention, the air blowing means according to the first aspect of the present invention is provided on a line that is substantially perpendicular to the rotating shaft of the heating roller and passes through a substantially center in the width direction of the heating roller, and the duct is The fixing device is substantially Y-shaped.
[0012]
The blower means is provided on a line that is substantially perpendicular to the rotation axis of the heating roller and passes through the approximate center in the width direction of the heating roller, and the duct is formed from a first opening by forming a substantially Y shape. The total wind volume of the wind and the total wind volume of the wind coming out of the second opening are substantially equal, so that both end portions of the heating roller can be cooled uniformly.
[0013]
According to a third aspect of the present invention, the air blowing means according to the first aspect of the present invention is provided on the other end side in the rotation axis direction of the heating roller, and the duct is substantially F-shaped, and the heating roller The fixing device is characterized in that the cross-sectional area of the first air passage that guides the air to one end portion of the first air passage is set to be larger than the step area of the second air passage.
[0014]
The air blowing means is provided on the other end side in the rotation axis direction of the heating roller, and the duct is substantially F-shaped and guides wind to one end portion of the heating roller. By setting the cross-sectional area of the road so as to be larger than the step area of the second air passage, the total air volume of the wind coming out of the first opening and the total air volume of the air coming out of the second opening are substantially equal. Thus, both end portions of the heating roller can be uniformly cooled.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
(overall structure)
First, the overall configuration of the image forming apparatus provided with the fixing device of the present embodiment will be described with reference to FIG.
[0018]
In the figure, an image forming apparatus 1 processes an automatic document feeder (commonly called ADF) A, a document image reading unit B for reading a document image conveyed by the automatic document feeder A, and a read document image. An image control unit C, a writing unit D including a writing unit 12 for writing on the image carrier 10 made of a photosensitive drum in accordance with data after image processing, a charging electrode 14 and a magnetic brush around the image carrier 10 and the periphery thereof. A plurality of image forming portions E including image forming means such as developing means 16, transfer electrode 18, separation electrode 20, cleaning means 21, and a tray that accommodates transfer material (hereinafter referred to as recording paper) P. Storage section F for sheet storage means (hereinafter referred to as a paper feed tray or tray) 22, 24.
[0019]
The automatic document feeder A mainly includes a document placing table 26, a roller group including a roller R1, and a document transport processing unit 28 including a switching unit for appropriately switching a document moving path.
[0020]
The document image reading unit B is located under the document glass G and has two mirror units 30 and 31 that can reciprocate while maintaining the optical path length, a fixed imaging lens (hereinafter referred to as a lens) 33, a line-shaped image sensor ( The writing unit D includes a laser light source 40, a polygon mirror (polarizer) 42, and the like.
[0021]
The principle of the automatic document feeder A is different from that of the conventional automatic document feeder, but the principle is well known, and the document image reading section B, writing section D, image processing means (on the image carrier 10). Since an image forming apparatus and an image forming process provided with a means for forming a toner image on the sheet and transferring the toner image onto the sheet are well known, description thereof will be simplified.
[0022]
Note that R10 shown on the front side of the transfer electrode 18 is a registration roller, and H shown on the downstream side of the separation electrode is a fixing device (details will be described later). The heating roller 91 and the pressure applied to the heating roller 91 are pressed against each other. The recording paper P onto which the toner image is transferred is fixed between the heating roller 91 and the pressure roller 92, so that the toner image is thermally fixed on the recording paper P.
[0023]
In the above configuration, the process of forming a toner image on the image carrier 10 and transferring it onto a sheet and then discharging it to a paper discharge tray is as follows.
In the present specification, a transfer region having a transfer electrode may be referred to as an image recording unit.
[0024]
One sheet of document (not shown) placed on the document table 26 is conveyed in the document conveyance processing unit 28, and slit exposure is performed by the exposure means L while passing under the roller R1.
[0025]
In this embodiment, the document placed on the document placement table 26 is set as the center reference.
The reflected light from the document is coupled and read on the CCD via the mirror units 30 and 31 and the lens 33 at fixed positions.
[0026]
The image information read by the document image reading unit B is processed by the image processing means, encoded, and stored in a memory on the image control board C.
The image data is called according to the image formation, the laser light source 40 in the writing unit D is driven according to the image data, and the image carrier 10 is exposed.
[0027]
Prior to this exposure, the image carrier 10 rotating in the direction of the arrow (counterclockwise) is given a predetermined surface potential by corona discharge of the charging electrode 14, but the potential of the exposed portion depends on the exposure amount by exposure. As a result, an electrostatic latent image corresponding to the image data is formed on the image carrier 10.
[0028]
The electrostatic latent image is reversely developed by the developing means 16 to be a visible image (toner image). On the other hand, before the leading edge of the toner image on the image carrier 10 reaches the transfer region, for example, one sheet P in the sheet feeding tray 22 is fed and conveyed to the registration roller R10, and the leading edge. It is regulated.
[0029]
The sheet P is conveyed toward the transfer region by a registration roller R10 that starts rotating in synchronization with the toner image, that is, the image region on the image carrier 10 so as to overlap.
[0030]
In the transfer area, the toner image on the image carrier 10 is transferred onto the sheet P by the urging of the transfer electrode, and then the sheet P is separated from the image carrier 10 by the urging of the separation electrode 20.
[0031]
Thereafter, the toner powder that forms the toner image is melted and fixed on the sheet P by heating and pressurizing the fixing device H, and the sheet P is discharged onto the discharge tray T via the discharge path 78 and the discharge roller 79. Paper.
(Fixing device)
The configuration of the fixing device H will be described in detail with reference to FIGS. FIG. 1 is a side view of the fixing device, and FIG. 2 is a configuration diagram viewed from the X direction of FIG.
[0032]
In FIG. 1, reference numeral 191 denotes a cylindrical cored bar (roller base) of the heating roller 91 whose both end faces are open.
A release layer 194 is formed on the outer peripheral surface of the cored bar 191.
[0033]
In this embodiment, the core metal 191 is made of aluminum or iron, and the release layer 194 is made of PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) or tetrafluoroethylene. A resin having good releasability such as
[0034]
Furthermore, the thickness of the cored bar 191 is 2.0 mm or less, the thickness of the releasable layer 194 is about 20 μm, and a thin-walled structure is obtained.
Inside the heating roller 91, in the cross section, the first halogen heater lamp 210 as the first heating means is provided on one side across the rotation axis O, and the second heating means is provided on the other side. The second halogen heater lamp 220 is provided.
[0035]
The sheet P is nipped and conveyed in the direction of the arrow R by the heating roller 91 and the pressure roller 92.
As shown in FIG. 2, the first halogen heater lamp 210 mainly heats both end portions (L1) in the rotation axis direction of the heating roller 91, and the second halogen heater lamp 220 has a rotation axis of the heating roller 91. The central part (L2) is mainly heated in the direction.
[0036]
The pressure roller 92 has a structure in which a PFA tube is covered on the circumferential surface of foamed silicon rubber, and the surface hardness (Asker C hardness) is set to 35 to 75.
The pressure roller 92 presses the heating roller 91 with a total load of 49 to 245 N by the urging force of the spring 90, so that the nip pressure between the pressure roller 92 and the heating roller 91 becomes 19600 Pa to 196000 Pa. The transit time is 20-40msec.
[0037]
In the fixing device H of the present embodiment, as shown in FIG. 2, the surface temperature of the heating roller 91 is predetermined at the overlapping heating portion of the first halogen heater lamp 210 and the second halogen heater lamp 220. A thermostat 350 is provided as temperature detecting means that responds when the temperature exceeds the above temperature.
[0038]
Further, a cooling means 800 for cooling both end portions of the heating roller 91 is provided. The cooling means 800 shown in the drawing is substantially perpendicular to the rotation axis of the heating roller 91 and is provided on a line passing through the approximate center of the heating roller 91 in the width direction. The other end side is divided into a bifurcated shape consisting of a first air passage 811 and a second air passage 812, and the first opening 802 of the first air passage 811 is connected to the heating roller 91. The second opening 803 of the second air passage 812 is positioned near the surface of the other end of the heating roller 91 in the rotation axis direction, near the surface on one end side in the rotation axis direction. And a substantially Y-shaped duct 807 that guides the air to the surface of the heating roller 91. Also, ribs that divide the air paths are provided inside the first air path 811 and the second air path 812 of the duct 807. 821 and 822 are provided.
[0039]
Further, the position of the rib 822 of the second air passage 812 is set to be near the outside of the thermostat 350.
According to the above configuration, the following effects can be obtained.
[0040]
(1) By providing the ribs 821 and 822 that divide the air path inside the duct 807, as shown in FIG. 4, the wind speed at the openings 802 and 803 is leveled as compared to FIG. 8 where no rib is provided. Thus, the end portion of the heating roller 91 can be cooled uniformly.
[0041]
(2) The fan 801 is provided on a line that is substantially perpendicular to the rotation axis of the heating roller 91 and passes through the approximate center of the heating roller 91 in the width direction, and the duct 807 has a substantially Y-shape to thereby form the first opening. The total air volume of the air coming out of 802 and the total air volume of the air coming out of the second opening 803 are substantially equal, so that both end portions of the heating roller 91 can be cooled uniformly.
[0042]
(3) By providing the rib 822 near the outside of the thermostat 350, the wind speed of the wind striking the surface of the heating roller 91 facing the thermostat 350 increases as shown in FIG. This reduces the temperature of the thermostat 350 and eliminates the sensitive response of the thermostat 350.
<Second Embodiment>
This will be described with reference to FIG. 5 for explaining the second embodiment. The difference between the present embodiment and the first embodiment is the cooling means of the fixing device, and the other parts are the same as those of the first embodiment. Are denoted by the same reference numerals, and redundant description is omitted.
[0043]
In the figure, a fan 901 as a blowing means is provided on the other end side in the rotation axis direction of the heating roller 91.
The duct 911 is substantially F-shaped, and the other end portion of the heating roller 91 close to the fan 901 has a cross-sectional area of the first air passage 921 that guides the air to one end portion of the heating roller 91 away from the fan 901. It is set to be larger than the step area of the second air passage 922 for guiding the wind to the part.
[0044]
In the present embodiment, the sectional area of the first air passage 921: the step area of the second air passage 922 = 2: 1.
In addition, ribs 931 and 932 that divide the air passage into three are provided in the first air passage 921 of the duct 911, and ribs 933 and 934 that divide the air passage into three in the second air passage 922. Is provided.
[0045]
According to the above configuration, the following effects can be obtained.
(1) Ribs 931 and 932 that divide the air passage are provided inside the first air passage 921 of the duct 911, and ribs 933 and 934 that divide the air passage are provided in the second air passage 922. Accordingly, the wind speed distribution of the wind coming out from the first opening 923 of the first air passage 921 and the second opening 924 of the second air passage 922 is leveled compared to the case where there is no rib, and the end of the heating roller 91 is Parts can be cooled uniformly.
[0046]
(2) The fan 901 as the air blowing means is provided on the other end side in the rotation axis direction of the heating roller 91, and the duct 911 is substantially F-shaped and is one end of the heating roller 91 away from the fan 90. The cross-sectional area of the first air passage 921 that guides the air to the portion is set to be larger than the step area of the second air passage 922 that guides the air to the other end portion of the heating roller 91 close to the fan 901. .
[0047]
6A shows a case where the first air passage 921 and the second air passage 922 have the same cross-sectional area, and FIG. 6B shows a cross-sectional area of the first air passage 921: the second air passage. It is a figure which shows the wind speed distribution in the 1st opening 923 and the 2nd opening 924 when the step area of the path | route 922 = 2: 1. As can be seen from these figures, the wind speed distributions in the first opening 923 and the second opening 924 are substantially equal, that is, the total air volume of the wind coming out of the first opening 923 and the second opening 924 The total air volume of the generated air becomes substantially equal, and both end portions of the heating roller 91 can be cooled uniformly.
[0048]
【The invention's effect】
As described above, according to the invention described in claim 1, by providing the rib for dividing the air passage inside the duct, the wind speed distribution of the wind coming out of each opening is leveled compared to the case where there is no rib. Thus, the end portion of the heating roller can be uniformly cooled.
Further, by arranging the rib in the vicinity of the outside of the temperature detecting means, the speed of the wind hitting the surface of the heating roller facing the temperature detecting means becomes faster, the temperature of the heating roller part facing the temperature detecting means becomes lower, and the temperature Sensitive response of the detection means is eliminated.
[0049]
According to the invention of claim 2, the air blowing means is provided on a line that is substantially perpendicular to the rotation shaft of the heating roller and passes through the approximate center in the width direction of the heating roller, and the duct is substantially Y By forming a letter shape, the total air volume of the air coming out of the first opening and the total air volume of the air coming out of the second opening become substantially equal, and both end portions of the heating roller can be cooled uniformly.
[0050]
According to a third aspect of the present invention, the air blowing means is provided on the other end side in the rotation axis direction of the heating roller, and the duct is substantially F-shaped, and one end portion of the heating roller. By setting the cross-sectional area of the first air passage that guides the wind to the part to be larger than the step area of the second air passage, the total air volume of the air coming out of the first opening and the second opening The total amount of air coming from the air becomes substantially equal, so that both end portions of the heating roller can be uniformly cooled.
[Brief description of the drawings]
FIG. 1 is a side view of a fixing device according to a first embodiment.
FIG. 2 is a configuration diagram viewed from the X direction in FIG. 1;
FIG. 3 is a diagram illustrating an overall configuration of an image forming apparatus provided with a fixing device according to an exemplary embodiment.
FIG. 4 is a diagram for explaining the effect of the first embodiment.
FIG. 5 is a side view of a fixing device according to a second embodiment.
FIG. 6 is a diagram for explaining the effect of the second embodiment.
FIG. 7 is a configuration diagram of a conventional fixing device.
FIG. 8 is a diagram illustrating a problem of a conventional fixing device.
[Explanation of symbols]
91 Heating roller 92 Pressure roller 801 Fan (air blowing means)
802 1st opening 803 2nd opening 811 1st air path 812 2nd air path 821,822 Rib

Claims (3)

A heating roller and a pressure roller that is in pressure contact with the heating roller; a transfer material having a toner image transferred between the heating roller and the pressure roller is passed therethrough, and the toner image is thermally fixed to the transfer material. A fixing device,
Air blowing means;
One end is connected to the air outlet of the air blowing means, and the other end is divided into a bifurcated shape consisting of a first air passage and a second air passage, and the first opening of the first air passage Is located near the surface on one end side in the rotational axis direction of the heating roller, and the second opening of the second air path is located near the surface on the other end portion in the rotational axis direction of the heating roller. A duct for guiding the air from the blowing means to the surface of the heating roller;
A rib provided inside the duct and dividing the air passage ;
A first heating means provided on the heating roller for mainly heating both end portions in the rotation axis direction;
A second heating means provided on the heating roller for mainly heating a central portion in the rotation axis direction;
A temperature detecting means for detecting a temperature of the surface of the heating roller at an overlapping heating portion of the first heating means and the second heating means;
Provided,
Further, the fixing device is characterized in that the rib is arranged near the outside of the temperature detecting means .   The air blower is provided on a line that is substantially perpendicular to the rotation shaft of the heating roller and passes through a substantially center in the width direction of the heating roller, and the duct has a substantially Y-shape. Fixing device.   The air blowing means is provided on the other end side in the rotation axis direction of the heating roller, and the duct is substantially F-shaped and guides wind to one end portion of the heating roller. The fixing device according to claim 1, wherein a cross-sectional area of the road is set to be larger than a step area of the second air path.

Images