JP2727980B2 - Electrophotographic fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for electrophotography, and more particularly to a fixing device on which a toner image has been transferred, which is inserted between a heat-fixing section and a pressing section to transfer the toner image. The present invention relates to a fixing device for electrophotography for performing heat fixing on a sheet.

[0002]

2. Description of the Related Art An electrophotographic recording apparatus has been realized as a page printer having a small size, high speed, and excellent performance of image quality, and the price has been shifted to a low price range which can be purchased on an individual level. . However, in the conventional electrophotographic recording apparatus, a fixing device configured to fix a toner image transferred on a recording medium is 300 [W].
Since a large amount of power of up to 400 [W] is required, the power consumption is too large to be used in each home at the individual level, so that it is necessary to reduce this power consumption. Further, in view of the environment and global resources in recent years, reducing power consumption has become a condition for widespread use of this type of page printer on an individual level.

As shown in FIG. 4, a conventional electrophotographic fixing device has a heat generating roller 51 having a heat generating portion including a halogen lamp 51A, and operates in cooperation with the heat generating roller 51 to form a toner image. The main part is constituted by the pressure roller 52 for applying pressure to the medium to be fixed (recording medium). The recording medium P with the toner image T is inserted between the heat roller 51 and the pressure roller 52.

[0004] Such a conventional fixing device for electrophotography,
The heat generating roller 51 is heated from the inner surface by the radiant heat from the halogen lamp 51A, and the surface of the heat generating roller 51 is uniformly heated after about 30 to 50 seconds. For this reason, heat is generated also in portions other than the portion necessary for actual fixing, and heat is released on most surfaces other than the fixing region.

In order to prevent the heat generated in portions other than those necessary for fixing from escaping wastefully, as shown in FIGS. 5 and 6, the heating roller 51 is actually surrounded by a semi-sealed cover 53. Have been. Here, FIG.
6 shows a case where the toner image T is transferred to the lower surface of the recording medium P. FIG.
Reference numeral 54 denotes a cover for the pressure roller 52.

In any of the conventional examples shown in FIGS. 5 and 6, the heat-generating roller 51 side is the recording image surface (toner image forming surface).
Therefore, it is not permissible for the cover 53 or the like for sealing to come into contact with the image surface, and a gap for loading and unloading paper having a vertical width of 5 mm or more in consideration of the bending of the recording medium P or the like. (Openings 55 and 56) must be formed. As a result, the heat generated by the heat generating roller 51 is released into the main body case 60 through the openings 55 and 56 through which the recording medium P is inserted, and adversely affects the photosensitive member 61 that is weak to heat.

For this reason, in the above-described conventional example, it is necessary to release this heat to the outside of the main body case 60, and a part of the heat must be released to the outside by the fan motor 62 while generating heat for fixing. Had to be inefficient. As a result, the power consumption of the entire apparatus is increased, and the cost is increased due to the provision of the fan motor 62. Therefore, there is a disadvantage that the cost of the entire apparatus is hindered.

On the other hand, the heat generating roller 51 having the halogen lamp 51A therein cannot be reduced in thickness because a pressure is applied by the pressing roller 52, so that the heat capacity inevitably increases. For this reason, the temperature rise of the heat roller 51 becomes extremely slow, and the first print time, which is one of the important performance factors as a printer, becomes slow. Therefore, it is not possible to use the energy saving mode in which the operation of the fixing device is stopped except during printing. And the power consumption increases as a result.

Further, the portion where the heat generating roller 51 and the recording medium P are in contact with each other can be pressed by the pressing roller 52 is a part of the whole, and it is necessary to increase the temperature to increase the printing speed. From this point as well, this is one of the factors that increase power consumption.

In order to solve such a conventional problem, Japanese Patent Application Laid-Open No. H3-161783 discloses a heating roller 5.
A thin belt is used in place of 1, and a halogen lamp is inserted in the belt. Further, the halogen lamp is provided with a reflecting mirror having unidirectionality, so that the heating surface is reduced to 1 mm.
The surface is shown as a surface, and pressure is applied to the belt on the heating surface side by a pressure roller. In such a conventional example, the heating speed is high because the belt is a thin-walled belt and only the pressurized portion is heated, and since only the heating surface required for fixing is heated, heat release into the apparatus is reduced. .

[0011]

However, since the heater described in Japanese Patent Application Laid-Open No. H3-161783 uses a halogen lamp, an inrush current peculiar to the halogen lamp flows. As in the case of, a circuit to prevent inrush current is required.
Adding a unidirectional reflecting mirror to the halogen lamp complicates the configuration of the fixing device, and skew occurs during belt rotation due to stretching of the belt without loosening. This requires a skew correction mechanism, which also complicates the configuration of the fixing device, and as a result, there is an inconvenience that the price of the entire apparatus rises.

[0012] Furthermore, due to the increase in heat capacity caused by the need for a thick material for the heat generating roller, it takes time for the surface of the heat generating roller to rise to a fixable temperature, which delays the first print time. There was an inconvenience.

[0013]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a relatively inexpensive electrophotographic fixing device which can solve the disadvantages of the prior art and which has a good start-up at start-up and can save energy. Aim.

[0014]

The above object is achieved.
Therefore, the present invention includes a heating mechanism and a pressure mechanism for thermally fixing the medium to which the toner image has been transferred from the photosensitive drum by heat and pressure. Where the pressure mechanism
Section is connected to the drive roller via an endless belt described later.
One equipped with a pressure roller that comes into contact with the device is provided.

[0015] Also, the heating mechanism includes an endless belt rigidity thin having a width of more than the recording width of the recording paper is of a relatively large member, corresponding to the outer surface and retracting the side of the outer surface of the feed side of the endless belt A guide case, which is disposed on the endless belt, and is configured to guide the running of the endless belt and support the endless belt, the guide case including a heat-insulating member; a cylindrical driving roller provided in the endless belt for driving the endless belt; Outside of both ends of the drive roller in communication with the left and right openings
And a heat source provided in one of the space air chambers.

Further, a hot air circulation path is formed by the inside of the endless belt of the heating mechanism and the first and second space air chambers communicating with the endless belt, and the hot air circulation path is formed at a predetermined position in the hot air circulation path. It equipped with blowing means for forcibly circulating air in the hot air circulation path. Then, endless described above
The configuration is such that a thin tube is used as the belt .

[0017]

[Action] First, the heat generated by the heating resistor is a heat source, for example, as shown in FIG. 1, in a hot air by the blower fan 11 in the hot air circulation path 2, the heating resistor (originating
(A heat source ) 9 from the first space air chamber 7 through the one hot air circulation path 2 in the endless belt 4 to enter the second space air chamber 8 and then the other hot air circulation path 2 and returns to the first space air chamber 7. By repeating this operation, the hot air constantly moves in the endless belt 4, whereby the endless belt 4 is rapidly and uniformly heated.

That is, due to the circulation of the hot air, the endless belt 4 uses a thin tube and the heat capacity of the drive roller 6 and the guide case 5 is small, so that the surface of the endless belt 4 at the fixing opening 5A is short. The fixing temperature is reached in time.

As a result, the first print time, which is one of the performance factors of the recording apparatus, is reduced. On the other hand, the recording paper enters in parallel with the endless belt 4, which has already reached the fixing temperature, before entering the portion to be pressed between the pressure roller 3A and the drive roller 6,
During this approach process, the toner image on the recording medium is preheated and the toner is softened, so that the fixing performance is improved even when the pressurized portion passes for a short time. For this reason, even if the printing speed increases, it is not necessary to increase the fixing temperature, and the temperature can be reduced to 80 to 90% as compared with the conventional recording device of the same speed, and as a result, the power consumption of the recording device is reduced. it can.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

The embodiment shown in FIGS. 1 and 2 includes a heating mechanism 1 and a pressure mechanism 2 for applying heat and pressure to the recording paper P on which the toner image has been transferred from the photosensitive drum and sequentially fixing the recording paper. .

The heating mechanism section 1 includes an endless belt 4 made of a thin, relatively rigid member having a width equal to or larger than the recording width of the recording paper P, and an end face on the pay-out side and an end face on the feed-in side of the endless belt 4. And a guide case 5 formed of a heat insulating member that guides the running of the endless belt 4 and supports the endless belt 4, and a cylindrical case that is provided in the endless belt 4 and drives the endless belt 4. And the first and second space air chambers 7 and 8 which are disposed so as to communicate with the left and right openings of the endless belt 4, and one of the space air chambers 7. It comprises a heating resistor 9 as a mounted heat source. Reference numeral 6A indicates a drive shaft.

The pressing mechanism 3 includes a pressing roller 3A that comes into contact with the driving roller 6 via the endless belt 4. Further, the endless belt 4 of the heating mechanism 1 described above.
As a blowing means for forcibly circulating the air in the hot air circulating path 2 at a predetermined position of the hot air circulating path 2 formed by the inside of the hot air circulating path 2 formed by the first and second spatial air chambers 7 and 8 communicating therewith. Fan 11 is provided.

In the present embodiment, the cylindrical drive roller 6 is provided as shown in FIG.
As shown in the figure, the endless belt 4 is disposed at a central portion. In this case, the above-described blower fan 11 is provided on one side in the endless belt 4.

Here, the cylindrical drive roller 6 may be disposed on one side in the endless belt 4 as shown in FIG. In this case, the blower fan 1 described above is used.
Numeral 1 is provided on the other side of the endless belt 4. In this case, the hot air circulation path 2
Has a configuration in which the space inside the drive roller 6 is incorporated in a part thereof.

This will be described in more detail.

The endless belt 4 is made of a relatively thin metal plate, and has engagement holes 4a at both ends thereof at predetermined intervals along the rotation direction. Corresponding to the engagement holes 4a, engagement protrusions 6a are provided at both ends of the drive roller 6, and the engagement protrusions 6a are provided.
The endless belt 4 is engaged with the upper and lower surfaces by a driving roller 6 and held rotatably. The first and second space chambers 7 and 8 described above are set outside the both ends of the drive roller 6 so as to communicate with the openings at both ends of the endless belt 4.

The space in the endless belt 4 and the first and second space air chambers 7 and 8 constitute the hot air circulation path 2 described above, and a part of the hot air circulation path 2 described above. The blower fan 11 is provided in the endless belt 4 as described above.

The first air space 7 is provided with the heating resistor 9 as a heat source as described above. Code 9
Reference numerals a and 9b denote terminals for supporting the heating resistor 9.

In the guide case 5, a fixing opening 5A is formed along the driving roller 6 so that a part of the upper surface of the endless belt 4 is exposed, and the fixing opening 5A is formed in the fixing opening 5A. A pressure roller 3A is provided.
The pressure roller 3A comes into contact with the drive roller 6 via the endless belt 4 with a predetermined pressure. Reference numeral 3B indicates the pressure roller 3A.
2 shows a pressing spring that presses.

The pressing roller 3A is pressed against the endless belt 4 exposed at the opening 5A by the pressing spring 3B.
Between the endless belt 4 and the endless belt 4 in contact therewith.

FIG. 2 is a vertical cross-sectional view of the structure of the present embodiment when viewed from the direction of arrow A in FIG. The endless belt 4 rotates at a constant speed together with the recording paper P. Then, the recording paper P enters from the right central portion in FIG. For this reason, the positional relationship between the guide case 5 and the endless belt 4 may be such that the guide portions on both sides of the guide case 5 are lower by about 1 to 2 [mm] with respect to the height at which the endless belt 4 contacts the pressure roller 3A. Further, by forming the cover 21 also serving as a guide for recording paper traveling on the side of the pressure roller 3A, it is possible to form a semi-closed state with an aperture ratio of 10% or less.

In FIG. 2, reference numeral 22 denotes an entrance for recording paper, and reference numeral 23 denotes an exit for recording paper. Reference numeral 21A indicates a paper guide surface. The paper guide surface is set on the upper surface in FIG.

Here, regarding the materials used in this embodiment,
As an example, the endless belt 4 is 0.05
A thin stainless steel belt of about [mm] to about 0.1 [mm] (for example, a thin tube of about 25 [mm] in diameter) is used, and the drive roller 6 has a low heat conductive material such as silicon rubber formed on the surface. A roller having a diameter of about 15 [mm] is used. Further, the guide case 5 which forms the first and second spatial air chambers 7 and 8 for the hot air circulation path 2 and has the opening 5A is made of a heat-resistant resin (also a material having a low thermal conductivity).
It is formed with.

With such a configuration, the endless belt 4 is pressed by the pressing roller 3A, pressed against the driving roller 6, and is engaged with the driving roller 6. The space in the endless belt 4 is divided into two by the driving roller 6 and the first and second
The hot air circulation path 2 including the space air chambers 7 and 8 is formed, whereby the heat source for generating heat (the resistance heating element 9) is installed in the substantially closed hot air circulation path 2. ing.

Next, the operation of the above embodiment will be described.

First, the heat generated by the heating resistor 9 as a heat source is turned into hot air by the blower fan 11 in the hot air circulation path 2, and the heat is generated from the first space air chamber 7 having the heating resistor 9. It passes through one hot air circulation path 2 in the endless belt 4 and enters the second space air chamber section 8, and then passes through the other hot air circulation path 2 and returns to the first space air chamber section 7. By repeating this operation, the hot air constantly moves in the endless belt 4, whereby the endless belt 4 is rapidly and uniformly heated.

That is, due to the circulation of the hot air, the endless belt 4 is a thin metal material as described above, and the heat capacity of the drive roller 6 and the guide case 5 is small.
The surface of the endless belt 4 at the fixing opening 5A reaches the fixing temperature in a short time.

For this reason, according to the above embodiment, the first print time, which is one of the performance factors of the recording apparatus, is reduced. On the other hand, before the recording paper enters a portion pressed between the pressure roller 3A and the driving roller 6 as shown in FIG. 2, the recording paper enters in parallel with the endless belt 4 which has already reached the fixing temperature. As a result, the toner image on the recording medium is preheated during this approaching process, and the toner is softened. For this reason, it is not necessary to increase the fixing temperature even when the printing speed is increased.
As a result, the power consumption of the recording apparatus can be reduced.

In the above embodiment, the endless belt 4 is pressed against the driving roller 6 by the pressing roller 3A, thereby forming a hot air circulation path for hot air circulation on both sides of the driving roller 6 in the endless belt 4. Although formed, the structure of the hot air circulation path is not limited to the structure shown in FIG. 2 and may be a structure as shown in FIG.

The embodiment shown in FIG.
Is a hollow roller made of heat-resistant resin, and an endless belt 14 is hung over this hollow
A first hot air circulation path (one hot air circulation path) 14
A, a portion outside the drive roller 16 and surrounded by the endless belt 14 described above is a second hot air circulation path.
(The other hot air circulation path) It may be 14B. Then, the second hot air circulation passage 14B, blowing fan 11A is installed. In this case of the embodiment shown in FIG. 3, the endless belt 14 is equipped with somewhat inclined in the vertical direction, the driving roller 16 on the upper side is disposed.

Further, separately from the above-described FIGS. 1 and 2, an endless belt 14 is placed between the driving roller and the auxiliary roller to form a partition wall or the like inside the endless belt, thereby forming two space chambers. May be formed. Code 21
A indicates a guide cover. Other configurations are described in FIG.
2 to FIG.

In this case, the same operation and effect as in the embodiment shown in FIGS. 1 and 2 can be obtained.

As described above, according to the above-described embodiment, the heat generated from the heat generating resistor 9 as the heat source is converted into a hot air while circulating through the closed air chambers 7 and 8 to form a thin endless air. Since the belt 4 is heated, the temperature of the endless belt 4 rises rapidly and reaches the fixing temperature within, for example, 10 seconds. As a result, the first print time, which is one of the performance factors of the printing apparatus, is much shorter than before, and the printing apparatus completely stops the operation of the heater when print data is not sent. Since the energy saving mode can be used, the heater is turned on only at the time of printing, so that the power consumption of the recording apparatus is much smaller. Further, since the heat generating resistor 9 as a heat source is formed in the first space air chamber 7 in a closed state, the heat generating efficiency is high, and the heat generating resistor 9 is guided by almost all parts other than the pressurized part for fixing. Since the case is semi-sealed, heat leakage into the device is much less. As a result, the printing apparatus does not need a fan motor for exhausting heat, so that the cost of the printing apparatus can be reduced and a low-cost printer can be realized. Further, since the heating element is a resistor heater as described above, no inrush current is generated, and a circuit element for preventing inrush current is not required.

[0045]

Since the present invention is constructed and functions as described above, according to this, the heat generated from the heat generating resistor, which is a heat generating source, is converted into hot air to be in a sealed state. Since the thin endless belt is heated while circulating in the space air chamber, the temperature of the endless belt rises rapidly and reaches the fixing temperature within 10 seconds, for example. As a result, the first print time, which is one of the performance factors of the printing apparatus, is much shorter than before, and the printing apparatus completely stops the operation of the heater when print data is not sent. The power saving mode can be used, and the heater is turned on only during printing, so that the power consumption of the recording apparatus can be greatly reduced.
The heat generation efficiency is good because it is formed in the
Since almost all parts other than the pressurizing part for fixing are in a semi-sealed state by the guide case, heat leakage into the device is much less, so there is no need for a fan motor for exhausting heat. Accordingly, it is possible to provide an unprecedented excellent electrophotographic fixing device that can reduce the cost as a recording device and can improve the reliability of the entire device in this respect.

[Brief description of the drawings]

FIG. 1 is a partially omitted perspective view showing one embodiment of the present invention.

FIG. 2 is a longitudinal sectional view partially viewed from the direction of arrow A in FIG. 1;

FIG. 3 is a partially omitted longitudinal sectional view showing another embodiment.

FIG. 4 is an explanatory diagram showing a main part of a conventional example.

FIG. 5 is a partially omitted cross-sectional view showing an example in which the conventional example of FIG. 4 is incorporated in a main body case.

FIG. 6 is a partially omitted cross-sectional view showing another conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Heating mechanism part 2 Hot air circulation path 3 Pressure mechanism part 3A Pressure roller 4,14 Endless belt 5,15 Guide case 6,16 Drive roller 7 First space air chamber part 8 Second space air chamber part 9 Heat generation Source (heating resistor) 11 Blowing means (blowing fan) 14A First hot air circulation path 14B Second hot air circulation path

Claims (3)

(57) [Claims] 1. An electrophotographic fixing device comprising: a heating mechanism for heating and pressurizing recording paper on which a toner image has been transferred from a photosensitive drum and sequentially fixing the recording paper; and the heating mechanism comprises: An endless belt made of a thin, relatively rigid member having a width equal to or greater than the recording width of the recording paper, and running of the endless belt which are respectively arranged corresponding to the outer surface of the endless belt on the feeding side and the outer surface on the feeding side. A guide case made of a heat insulating member for guiding the endless belt and supporting the endless belt; and a cylindrical drive roller provided in the endless belt for driving the endless belt, and openings on both left and right sides of the endless belt. The drive roller in communication with the part
The first respectively provided on the outer side of both end portions and the second space air chamber section, a structure in which a heat source that is provided on one of the space air chamber portion of this, before Symbol heating mechanism A blower for forming a hot air circulation path by the inside of the endless belt and the first and second space air chambers communicating with the endless belt, and forcibly circulating the air in the hot air circulation path to a predetermined location in the hot air circulation path. A fixing device for electrophotography , wherein a thin tube is used as the endless belt . The method according to claim 2, wherein the cylindrical drive roller, is disposed in a central portion of said endless within belt, across the drive rollers
In the endless belt, part of the hot air circulation path
2. An electrophotographic fixing device according to claim 1, wherein one and another hot air circulation paths are provided. 3. The cylindrical drive roller is a hollow roller.
While, arranged the drive roller on one side of the rotation direction of the endless belt in a first of said driving roller in forming part of the hot air circulation passage
A hot air circulation path and the outside of the drive roller
A second part which forms a part of the hot air circulation path in the endless belt
2. The fixing device for electrophotography according to claim 1 , wherein the hot air circulation path is formed as described above.