JPH0324672B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application of the Invention] The present invention relates to a heat fixing device that is installed in a recording device such as an electrophotographic device or an electrostatic recording device and heats and fixes an object to be fixed such as an unfixed image. [Prior Art] Conventionally, heating devices that use heat have difficulty achieving uniform heating and power consumption. In particular, in a heat roller fixing device, which is a typical type of fixing device, heat from a heating source installed in an image forming device or a fixing device is transmitted through the surface of the heat roller and is lost without affecting fixing. There was a problem that was mentioned earlier. As a result, heat loss increases at the ends of the heat roller, resulting in a significant decrease in fixing performance. On the other hand, in conventional technology, in order to compensate for the temperature drop at the end of the heat roller or the end region of the pressure roller that comes into pressure contact with the heat roller, the heat generation distribution of the heating source is configured to be stronger in the end region. was. However, with this method, the amount of heat lost from the end of the heat roller increases further, which causes the temperature inside the image forming apparatus to rise, causing toner blocking in the cleaner and developer, and causing damage to the plastic inside the apparatus. may cause thermal deformation of molded parts. Another solution is to provide a heat insulating sleeve only between the frame member holding the heat roller and the heat roller in order to reduce the heat loss mentioned above, but this is not a satisfactory solution. Otherwise, the heat loss will be large and the temperature at the end will sag. As a countermeasure to the above, the heat distribution is generally strengthened on the end side of the heater, so the overall power consumption is almost the same as in the conventional method. The above conventional method not only wastes electricity but also
This also causes the temperature to rise in other parts of the main body, causing various problems. [Object of the Invention] The present invention aims to improve the above-mentioned conventional drawbacks, and it is an object of the present invention to provide a heat fixing device that can perform a good heat fixing process even with a small amount of electric power. [Summary of the Invention] The present invention, which achieves the above object, includes a rotating body that comes into contact with an unfixed toner image and is heated by a heating means;
A support frame for supporting the rotating body, a drive gear made of a heat insulating material provided for the rotating body, and a heat insulating member provided between the rotating body and the support frame on the driving gear side. In the heating fixing device, the heat insulating member is a sliding bearing that rotatably supports the rotating body. [Embodiments of the Invention] The present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing one embodiment of the present invention, and is a sectional view of a heat fixing device that heats and fixes a toner image T formed by electrophotography onto plain paper P. 1 is a heating roller having a heating heater 3 such as a halogen heater inside, and a driving motor (not shown).
It rotates in the direction of the arrow in response to the driving force from. 2
is a pressure roller with a built-in heater 3' for low heating.
It comes into pressure contact with the heating roller 1 and rotates slidingly. This heating roller 1 has a heat-resistant, mold-releasing resin layer, such as a polytetrafluoroethylene resin, provided on the outer peripheral surface of a hollow roller core made of metal such as aluminum, stainless steel, or copper, to a thickness of 20 to 80 μm. The pressure roller 2 is rotatably supported by bearings 15, 15'. This roller 2 is pressed against the heating roller 1 by a known pressure means at least during fixing, and a relatively thick layer of elastic material such as silicone rubber, fuso rubber, fluorosilicone rubber, etc. is provided on the outer peripheral surface of the metal roller core. It is something that One purpose of this configuration is to secure a pressure contact area d with the heating roller. heating roller 1
A temperature sensing element 4 such as a thermistor or thermocouple is installed on the outer peripheral surface of the
are arranged in contact with each other, and the detection signal thereof is guided to a known control means (not shown) to control the temperature of the outer peripheral surface of the heating roller 1 (by controlling the output of the heater 33 or the applied voltage, etc.) The toner image is maintained at the melting temperature. Reference numeral 6 denotes a cleaning member for removing foreign matter such as offset toner and paper powder adhering to the surface of the heating roller from the roller surface, and a cleaning web ₆₁ made of a heat-resistant nonwoven fabric such as Nomex or Himeron is used. The cleaning web 6 ₁ is brought into contact with the heating roller by an elastic pressing roller 6 ₃ .
Further, this web 6 ₁ is moved by a driven take-up roller 6 ₅ (not shown) from the supply roller 6 ₂ so as to change its contact position little by little, so that a new surface of the cleaning web 6 ₁ is always heated. Contact with the roller. This web 6 ₁ moves on the roller 6 ₄ interposed after the pressing roller 6 ₃ , is reversed toward the supply roller 6 ₂ , and is wound around the winding roller 6 ₅ with the front and back sides reversed. Further, if the cleaning web ₆₁ is impregnated with an offset prevention liquid such as dimethyl silicone oil, the cleaning effect can be further enhanced. Reference numeral 7 denotes a curved reflection plate having heat reflection properties, which is provided close to the periphery of the heating roller 1 and over the entire length of the heating roller 1 in the hand direction. Further, the reflecting plate 7 has a width so as to cover the space between the position of the pressing roller 6 ₃ on the circumferential surface of the heating roller 1 and the entrance opening for the paper P.
Reference numeral 8 denotes a thick cover for preventing heat radiation, which is provided in close contact with the entire convex surface of the reflecting plate 7 to prevent wasteful radiation of heat from the reflecting plate 7. Reference numeral 16 denotes a casing member on the upper side of the fixing device, which surrounds the cleaning member 6, the reflection plate 7, the cover 8, and the temperature sensing element 4. The temperature detection part of the temperature sensing element 4 is a reflection plate 7
It is on the roller 1 side. On the other hand, on the pressure roller 2 side, a reflection plate 9 similar to the reflection plate 7 and a cover 10 similar to the cover 8 are provided so as to cover most of the circumferential surface of the pressure roller 2, respectively. By providing these reflective plates 7, 9 and covers 8, 10, it is possible to reduce wasteful heat from the surfaces of the heating roller and pressure roller, and to improve the temperature measurement performance of the temperature sensing element 4. can be stabilized. Furthermore, temperature control for the set temperature of the heating roller 1 can be stabilized and power consumption can be reduced. 22 is a guide plate that guides the paper P toward the heating roller 1 side;
It is provided close to the heating roller 1 so as to be located between one end of each of the reflecting plates 7 and 9. 2
Reference numeral 4 denotes a support plate that supports the pressure roller, and the pressure roller is pressed against the fixing roller by a spring 23. Now, plain paper P having an unfixed toner image T is conveyed while being sandwiched between both heating and pressure rollers 1 and 2, and the toner image T is fixed by applying heat due to the surface temperature of the rollers 1 and 2. Paper ejection rollers 20, 21
It is ejected from the device while being held between the two. On the discharge port side of the heating roller, a plurality of separation claws 5 are provided in contact with the roller surface along the roller axis direction in order to reliably separate the plain paper P from the heating roller. Further, a separation claw ₅₁ is provided on the discharge port side of the pressure roller 2 so as to be in contact with the surface of the roller 2. The separation claw 5 is held by a support plate 18 that is separated from the casing member 16, and the separation claw ₅₁ is also held by the support plate 18 that is separated from the casing member 17 on the lower side of the fixing device.
It is held at ₁ . The casing member 17 is spaced apart from the reflector 9 and cover 10 of the pressure roller 2 and is provided so as to cover them. The reflective plates 7 and 9 are preferably made of a metal with a glossy surface, such as an aluminum plate with a polished surface, a copper plate, or an iron plate with a surface treatment such as _Cr plating. Further, the shape of the reflecting plates 7 and 9 is preferably one having a curvature concentric with the circumferential surface of the roller, and the thickness thereof is preferably relatively thin. The covers 8 and 10 include glass wool,
Preferably, the material is made of rock wool, ceramic fiber, or a foam such as phenol foam or epoxy foam, or a composite material. Next, the structure of the end portion of the heating roller 1 will be described in detail with reference to FIG. 2, which is an explanatory diagram of the fixing device taken along the line X-X' in FIG. 1. 12 and 12' are respectively heat-insulating sliding bearings,
The frame body 1 of the fixing device slidingly supports the heating roller 1.
3 and 13', respectively. Heat-resistant gears 14 and 14' are made of heat-insulating heat-resistant resin, and are fitted onto the rotating shafts 1 ₁ and 1' of the heating roller 1, respectively, and transmit the driving force from the driving source M. This heating roller 14' is connected to another drive transmission gear 2.
5 and rotates together with the heating roller 1 in response to driving force. A gear 26 ₁ of a manual knob 26 is meshed with the heat-resistant gear 14 to transmit manual driving force. Since the heat-resistant gears 14, 14' are made of a heat-insulating material, heat is not dissipated from the heating roller 1 through the gears 14, 14' to other drive transmission members such as gears. do not have. This gear improves the heat retention of the heating roller 1. Further, the slide bearings 12, 12' are also heat-insulating materials, and prevent heat loss due to heat transfer from the ends of the heating roller 1 to the frames 13, 13'. Therefore, the heat loss from the end of the heating roller 1 can be reduced compared to the conventional one by the heat-resistant gears 14, 14', and can be further reduced significantly or almost completely eliminated by adding the plain bearings 12, 12'. I was able to do it. Generally, the heat-resistant gears 14, 14' are often provided with a number of other drive transmission members in conjunction with each other. Therefore, conventional heat losses account for the majority in such drive systems. On the other hand, in the embodiments described above, heat loss to the drive system can be reduced or eliminated, so thermal efficiency can be greatly improved and power consumption can be reduced. Furthermore, in the above embodiment, since the sliding bearings 12, 12' are used in addition to the heat-resistant gears 14, 14', heat loss from the roller ends to the frames 13, 13' can be prevented, further improving thermal efficiency. can. In the above embodiment, the heating roller 1 is provided at both ends, but at least the heating roller 1 is provided at both ends.
It is only necessary to provide a heat insulating portion between the roller 1 and the side that receives the driving force of the member that transmits the driving force to the roller 1. Further, the sliding bearing 12' made of a heat insulating resin and the heat resistant gear 14' are constructed separately. Since the resin material has a large thermal expansion, temperature fluctuations cause stress in the roller thrust direction and circumferential direction in the sliding bearing 12', and stress in the radial direction in the heat-resistant gear 14'. As mentioned above, the sliding bearing 12' and the heat-resistant gear 1
Since 4' is a separate body, different stress will not be applied to the resin material and damage it. Further, in this embodiment, the sliding bearing 12 and the heat-resistant gear 14 are also made separate. Furthermore, since the sliding bearing 12 is used, the heat insulation and the bearing can be performed in one part. The gears 14, 14' are made of polyimide,
It is preferable to use a heat-resistant resin material with good heat insulation properties, such as polyamide-imide, PPS, modified phenol, or tetrafluoroethylene with a reinforcing filler added. As mentioned above, the heating roller 1 has a sliding bearing 1
2 and 12' and the heat-resistant gears 14 and 14', the machine body and the frame bodies 13 and 13' are thermally elevated, and the heat loss transmitted through these is extremely small. Next, specific numerical examples of embodiments according to the present invention will be explained. In the fixing device with the above configuration, the heating roller 1 has an outer diameter of φ60, an aluminum core with a wall thickness of 7 mm, and a surface layer with a thickness of 35 μm.
As a PEA-coated roller and pressure roller 2,
A roller with a heat-vulcanized silicone rubber coating of 5 mm thick on a stainless steel core metal with an outer diameter of 60 mm and 50 mm was used. The heater 3 in the heating roller is a 650W halogen heater and is normally turned on, and the heater 3' in the pressure roller is a 70W sheathed heater and is turned on only when copying is not being done. Further, the pressing area d was 11 mm, and the heating roller surface temperature was 180°C. FIG. 3 is a diagram illustrating a change in the surface temperature of each roller over time for the experiment of the above specific example. When the power is turned on at time t=0, heater 3
And the heater 3' is turned on. The heating roller surface temperature increases as shown in the figure, and the heating roller surface temperature reaches 150°C.
℃ (point A), both rollers 1, which had stopped,
2 begins to rotate under pressure, and the surface temperature of the pressure roller also rises rapidly. When the heating roller surface temperature reaches 180℃ (point B)
The state becomes ready for fixing, and both rollers 1 and 2 stop rotating. The heating roller 1 is maintained at a surface temperature of about 180° C. by a control means (not shown). On the other hand, since the pressure roller 2 is no longer supplied with heat from the fixing roller, its surface temperature decreases. Approximately 5 minutes after the fixing-enabled state (point C), the pressure roller temperature reaches its lowest temperature, and then gradually rises as it receives heat from the heater 3' from inside. Therefore, C
The fixation ability at the point is the lowest. Therefore, if continuous copying is performed at this point C, it is extremely preferable as a comparative experiment of fixing properties. This figure shows the temperature change during continuous copying of 99 copies at point C, including the time when 99 copies were completed (point D). The experimental results shown below were conducted under the following common conditions between CD and CD. In other words, in an environment of 10℃, copy speed 405mm/sec (A3 size paper, 35 sheets/min), weight 80g/m ² A solid black of φ24 is formed on A3 paper, 1, 6,
11th, 16th, 8 12 every 10th from 21 to 91
The paper was selected, and nine locations on each paper were used as experimental subjects. The fixation of these 12 sheets, 9 points each, for a total of 108 points, was evaluated using a Kojin wiper (product name, Kojin Co., Ltd., Paper Waste) and rubbed 10 times at a pressure of 40 g/cm ² , and the density before and after rubbing. The difference was measured and quantified using a Macbeth reflection densitometer. In other words, ΔD=D−D′/D×100(%) D: Reflection density before rubbing the φ24 solid chrome image (1.0≦D≦1.1 D′: After rubbing ΔD: Density reduction rate Image (Adjust the density.) Table 1 below shows the structural requirements of each fixing device.

[Table] Uniform wire-wound heaters with a heat generation length of 330 mm were used as the uniform heaters 3 of fixing devices No. 1 to 5. The 200% heater of fixing device No. 6 is a heater with a large heat distribution in the center as shown in FIG. 4 (similar to the configuration of heater 3 shown in FIG. 2). Also,
In place of the 200% heater, a uniformly wound wire heater with a heat generation length of 297 mm or less (that is, a heater that is less than or equal to the maximum paper passing width, preferably 20 mm to 80 mm shorter than the maximum paper passing width) can be used to obtain approximately the same effect as described below. Ta. Table 2 shows the results of the fixing performance of each of the above-mentioned fixing devices. ).

[Table] As is clear from Table 2, fuser No. 1 to No. 6
The fixing properties become better as more favorable conditions are added. Particularly noticeable differences can be seen between No. 1 and No. 2, comparison between No. 4 and No. 7, No. 4 and No. 5, and No. 5 and No. 6. is the effect of providing the heat radiation prevention member and the reflective member, is the effect of establishing a heat barrier, and is the effect of the heat generation distribution of the heater. Further, when comparing fixing devices No. 3 and No. 4, it is understood that No. 4 is more effective in preventing heat loss in the drive system. Also, fuser No. 2 and No.
Comparing No. 3 and No. 4, the effect of providing an additional thermal barrier is confirmed, and in No. 5 and No. 6, the establishment of that thermal barrier is what gives an additional effect.

〔Effect of the invention〕

As described above, according to the present invention, heat loss can be significantly reduced, uniform heating of the object to be fixed can be easily achieved, power saving can be achieved, and thermal efficiency from the heating source to the object to be fixed can be improved. can be done.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a heat fixing device according to an embodiment of the present invention, and FIG.
X′ sectional view, Figure 3 is a diagram of the change in roller surface temperature over time, Figure 4 is a heat generation distribution diagram of the 200% heater of fuser No. 6, and Figure 5 is a diagram of fuser No. 1 and fuser No. 6. 6
Figures 6 and 7 are explanatory diagrams of temporal changes in the amount of heat dissipated with
The figure is an explanatory diagram of main parts of another embodiment according to the present invention. 1... Heating roller, 2... Pressure roller, 3,
3'... Heater, 4... Temperature sensing element, 6... Cleaning member, 7, 9... Reflector, 8, 10... Cover, 11, 11'... Heat resistant sleeve, 12,
12', 15, 15'...Bearing, 13,1
3'...Frame body, 14,14'...Heat-resistant gear.

Claims (1)

[Scope of Claims] 1. A rotating body that is in contact with an unfixed toner image and heated by a heating means, a support frame for supporting this rotating body, and a heat insulating material provided for the rotating body. A heat fixing device comprising: a driving gear; and a heat insulating member provided between the rotary body and a support frame on the drive gear side, the heat insulating member being a sliding member that rotatably supports the rotary body. A heat fixing device characterized by a bearing.