JP2004045846A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device in which increase in cost is prevented by reducing required energy for fixing, reduction in fixing performance in a continuous operation is prevented and a fixing device is provided to reduce a fixing warm up time. <P>SOLUTION: The image forming device is provided with a fixing means by which a toner image formed on a transfer material is fused and fixed. The fixing means is provided with an air intake means which takes external air in and blows the air onto a heating roller located in the fixing means, an evacuating means which evacuates air in the fixing means to the outside of the means and a heat transferring means whose one end is connected to the air intake means and the other end is connected to the evacuating means. <P>COPYRIGHT: (C)2004,JPO

Description

【００６１】
〈従来例１〉
２００枚の連続コピーを行った後、加熱ローラの温度分布差が増加する一方で端部温度が２５０℃を越えたため、アラームによる警告が行われ、作像動作が中断され、これ以上のコピーができない状態になった。
【００６２】
〈従来例２〉
アラーム警告はなかった。但し、１５０枚の連続コピーが行われると定着率が８０％を下回り、７５％まで低下してしまった。コピーを軽く手で擦っただけでトナー画像が剥がれてしまい、実用に耐えない。コピー枚数に対する定着率の変化を図５のグラフで示す。
【００６３】
また、ウォームアップ時間が４５秒と長く、端部冷却ファンの電力は１０Ｗと多く必要とした。
【００６４】
〈実施例１〉
アラーム警告はなく、連続コピーでも定着率は８２％以上を維持し、トナー画像が擦れても剥がれずに問題なかった。コピー枚数に対する定着率の変化を図５のグラフで示す。
【００６５】
また、ウォームアップ時間は３１秒で、従来例１，２の約３割分短縮できた。
端部冷却ファンの電力は５Ｗと半減した。
【００６６】
以上の成果は、加熱ローラから放熱した熱をヒートパイプを介して再度加熱ローラに加えたためであり、従来より大幅に省エネルギーになった。
【００６７】
〈実施例２〉
アラーム警告はなく、連続コピーでも定着率は８３％以上を維持し、トナー画像が擦れても剥がれずに問題なかった。
【００６８】
また、ウォームアップ時間は３３秒で、従来例１，２の約３割分短縮できた。
端部冷却ファンの電力は５Ｗと半減した。
【００６９】
以上の成果は、加熱ローラから放熱した熱をヒートパイプを介して再度加熱ローラに加えたためであり、従来より大幅に省エネルギーになった。
【００７０】
なお、実施例２における定着装置の外壁を、樹脂、若しくは樹脂と金属からなる複合材料で厚く形成し、この外壁内にヒートパイプを挿着しても同様の効果が得られることを確認している。
【００７１】
以上の実験により本発明は、多数枚の連続コピーを行った場合に、定着装置の加熱ローラから放散した熱を再度加熱ローラに与えるので、加熱ローラの表面温度が低下して定着性能等が劣化することを防止でき、且つ加熱ローラに与えるエネルギーを削減してコストアップを抑制することができる。また、定着ウォームアップの時間も削減することができる。更に、異配熱２本ハロゲンランプヒータを用いても充分な効果が得られない場合に特に有効である。
【００７２】
なお、通紙する転写材の幅が常に加熱ローラ７１の軸方向の長さと大差なければ、端部冷却ファン１０１及び端部冷却ダクト１０２は不要であって、外気吸引ダクト１０４により加熱ローラ７１の軸方向の全長さに渡って送風するようにすればよい。しかし、幅の狭い転写材（例えばＡ５サイズを縦送り）も幅の広い転写材（例えばＡ４サイズを横送り）も通紙可能に構成して、転写材幅の狭い転写材を通紙して多数の連続コピーをするときには、図２及び図４に示した構成にする必要がある。そして、幅の広い転写材を通紙するときは、端部冷却ファン１０１及び外気吸引ファン１０３の送風を停止する。
【００７３】
また、以上の如く記した二つの実施例はヒートパイプを用いたが、ヒートパイプを用いずに定着装置の中で熱せられた空気を循環させるようにしてもよい。この一例を図６の模式図に示す。
【００７４】
図６において、加熱ローラ７１、端部冷却ファン１０１及び端部冷却ダクト１０２は前述の実施例と同等のものである。
【００７５】
本実施例においては、加熱ローラ７１によって加熱された定着装置７内の空気の熱を循環して加熱ローラ７１に送風する循環ダクト２０２と循環ファン２０１を設けた。これによって、加熱ローラ７１より放出された定着装置７内の熱い空気が循環ダクト２０２を通って、再び熱ローラ７１に吹き付けられる。従って、連続コピーによる加熱ローラ７１の表面温度低下が防止できる。
【００７６】
最後に「特許請求の範囲」で述べた用語と「発明の実施の形態」で述べた用語との対応を説明する。
【００７７】
請求項１及び請求項３における吸気手段は外気吸引ファン１０３及び外気吸引ダクト１０４に相当し、請求項１における排気手段は排気ファン１０５及び排気ダクト１０６に相当する。
【００７８】
請求項４におけるヒートパイプはヒートパイプ１１１，１２１に相当する。
請求項５及び請求項７における端部冷却手段は端部冷却ファン１０１及び端部冷却ダクト１０２に相当する。
【００７９】
請求項６における送風手段は循環ファン２０１及び循環ダクト２０２に相当する。
【００８０】
【発明の効果】
本発明の画像形成装置によれば、多数枚の連続コピーを行った場合に、定着装置の加熱ローラから放散した熱を再度加熱ローラに与えるので、加熱ローラの表面温度が低下して定着性能等が劣化することを防止でき、且つ加熱ローラに与えるエネルギーを削減してコストアップを抑制することができるという効果を奏する。また、定着ウォームアップの時間も削減することもできる。
【図面の簡単な説明】
【図１】画像形成装置の図である。
【図２】実施例１の模式図である。
【図３】ヒートパイプの基本構成図である。
【図４】実施例２の模式図である。
【図５】コピー枚数に対する定着率の変化を示すグラフである。
【図６】熱せられた空気を循環させる構成の模式図である。
【符号の説明】
７　定着装置
７ａ　外壁
７１　加熱ローラ
１０１　端部冷却ファン
１０２　端部冷却ダクト
１０３　外気吸引ファン
１０４　外気吸引ダクト
１０５　排気ファン
１０６　排気ダクト
１０８　装置内気吸引ダクト
１１１，１２１　ヒートパイプ
２０１　循環ファン
２０２　循環ダクト[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus in which a surface temperature of a heating roller of a fixing device is prevented from being lowered due to a large number of continuous copies, so that fixing performance and the like are prevented from being deteriorated.
[0002]
[Prior art]
In recent years, in image forming apparatuses such as electrophotographic copiers, printers, facsimile machines, and multifunction peripherals equipped with these functions, the need for high-quality and high-speed image forming apparatuses based on digital technology due to the advancement of advanced information technology. And the amount of hard copies to be printed on paper is also increasing, and the social demand for an image forming apparatus capable of printing with energy saving and resource saving is increasing.
[0003]
In a fixing device of an image forming apparatus for energy saving, a heat roller is thinned to reduce a heat capacity, and an outer wall of the fixing device is insulated to prevent heat dissipation. .
[0004]
[Problems to be solved by the invention]
When the heating roller is thinned and hundreds of prints are made in order to continuously print a large number of about 1,000 sheets, the surface temperature of the heating roller drops significantly to reduce the heat capacity, and fixing is performed. Insufficient performance. To solve this problem, a fixing alarm is set, and when the surface temperature of the heating roller decreases, the image forming operation is stopped by a warning of the fixing alarm, and the recovery of the heating roller is waited. However, since the image formation during that time is stopped, the operator has to wait extra time unnecessarily, and the entire printing time becomes longer.
[0005]
Further, when a transfer material of a narrow width such as B5 size is continuously passed through the fixing device by longitudinal feeding, the surface temperature of the end portion of the heating roller, which is a non-sheet passing area, excessively increases. To solve this problem, when a narrow transfer material is passed, the end of the heating roller is cooled by a fan. However, energy for operating this fan is required.
[0006]
In the case where the outer wall of the fixing device is heat-insulated, the cost is increased due to an increase in the number of parts for installing a new heat-insulating material, and a space for installing the heat-insulating material is required, which hinders miniaturization of the device. There is.
[0007]
The present invention has been made in view of such a problem, and reduces energy required for fixing, suppresses cost increase, prevents a decrease in fixing performance in continuous work, and further reduces a fixing warm-up time. It is an object of the present invention to propose an image forming apparatus provided with a fixing device that can perform the fixing.
[0008]
[Means for Solving the Problems]
The above object is achieved by any of the following means.
[0009]
(1) In an image forming apparatus provided with a fixing unit for melting and fixing a toner image formed on a transfer material, an intake unit for sucking outside air and blowing air to a heating roller in the fixing unit, and the fixing unit. An exhaust unit for exhausting air inside the unit to the outside of the fixing unit, and a heat transfer unit having one end connected to the intake unit and the other end connected to the exhaust unit, are provided in the fixing unit. Image forming apparatus.
[0010]
(2) In an image forming apparatus provided with a fixing unit for melting and fixing a toner image formed on a transfer material, an intake unit for sucking outside air and blowing air to a heating roller in the fixing unit, and one end thereof. An image forming apparatus, wherein a heat transfer unit connected to the suction unit and the other end connected to an outer wall of the fixing unit is provided in the fixing unit.
[0011]
{Circle around (3)} In an image forming apparatus provided with a fixing unit for melting and fixing a toner image formed on a transfer material, air blown out of the fixing unit is blown and the air is blown to a heating roller. An image forming apparatus, wherein means is provided in the fixing means.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments relating to the image forming apparatus of the present invention will be described in detail with reference to the drawings.
[0013]
First, an example of the image forming apparatus will be described with reference to FIG.
The image forming apparatus main body A includes an image reading device 1, an image processing unit 2, an image writing unit 3, an image forming unit 4, cassette feeding units 5A and 5B, mass feeding units 5C and 5D, manual feeding unit 5E, and conveyance. A re-conveying means (ADU) 9 for automatic duplex copying.
[0014]
On the upper part of the image forming apparatus main body A, a double-sided automatic document feeder RADF is supported so as to be openable and closable.
[0015]
In the automatic duplex document feeder RADF, a is a document feeder, b is a feed roller, c is a separation roller, d is a registration roller, e is a transport drum, f is a flapper, and g is a discharge roller. The automatic duplex document feeder RADF has a single-sided original reading function and a double-sided original reading function.
[0016]
An original platen glass 11, a shading correction plate 12, and a slit exposure glass 13 are arranged above the image reading apparatus 1.
[0017]
The optical system of the image reading apparatus 1 includes an exposure unit 14 including a light source and a first mirror, a V mirror unit 15 including a second mirror and a third mirror, a lens 16, and a CCD image sensor 17.
[0018]
Document reading by the automatic double-sided document feeder RADF is performed at a position where the exposure unit 14 stops at an initial position (home position) below the slit exposure glass 13. The document reading is performed when the document passes the stopped exposure unit 14.
[0019]
Reading of a document on the platen glass 11 is performed while moving the exposure unit 14 and the V mirror unit 15.
[0020]
Image information of the document image read by the image reading device 1 is subjected to image processing by the image processing means 2, converted into a signal as image data, and temporarily stored in a memory.
[0021]
In the image writing unit 3, the output light from the semiconductor laser is applied to the photosensitive drum of the image forming unit 4 to form a latent image. In the image forming unit 4, processes such as charging, exposure, development, transfer, separation, and cleaning are performed, and an image is transferred to the sheet P conveyed from the cassette sheet feeding unit 5 </ b> A. The sheet P carrying the image is conveyed by the conveying unit 6, fixed by the fixing device 7, and discharged onto the discharge tray 61 outside the device by the discharge unit 8.
[0022]
Alternatively, the sheet P on which the image has been formed on the first surface sent to the re-conveying means 9 by the conveying path switching plate 62 is again image-formed on the second surface by the image forming means 4, and then discharged from the apparatus by the paper discharging means 8. The paper is discharged onto the paper discharge tray 61.
[0023]
Alternatively, the sheet P branched from the normal discharge path by the transport path switching plate 62 is switched back and turned upside down in the reverse discharge section 63, and then is discharged onto the discharge tray 61 outside the apparatus by the discharge means 8. Is discharged.
[0024]
The fixing device 7 includes a heating roller 71 having a heater H on the inside for thermally fixing the toner image, a pressure roller 72 for pressing the heating roller 71 from below, and the like. The drive roller 71 is driven to rotate, and the pressure roller 72 is driven to rotate. Although not shown, a temperature sensor such as a thermistor and a thermocouple for detecting the surface temperature of the heating roller 71 is disposed near the heating roller 71.
[0025]
Around the heating roller 71, a fixing cleaning roller 73, an impregnating roller 74, an oil pad 75 and the like are arranged.
[0026]
The pressure roller 72 may be provided with a heater, or a belt may be provided instead of the pressure roller 72.
[0027]
Next, in the fixing device according to the present invention, when the energy required for fixing is reduced, cost increase is suppressed, a decrease in fixing performance in continuous operation is prevented, and a narrow transfer material is passed. Next, a fixing device capable of reducing energy for preventing an excessive rise in the temperature of the end portion of the heating roller and further reducing the fixing warm-up time will be described.
[0028]
In order to achieve the above object, the present inventor conducted comparative experiments on fixing devices having four types of configurations. The implementation conditions, configuration, evaluation method, and experimental results will be described below.
[0029]
First, implementation conditions common to the four types of configurations will be described.
As the developer, a polymerized toner (styrene-acryl, particle diameter 6 μm) and a ferrite carrier (silicone resin coat, particle diameter 60 μm) were used.
[0030]
The CCD image sensor 17 used had a resolution of 600 dpi (the number of dots per 2.54 cm), and the semiconductor laser used had a beam diameter of 55 μm in the main scanning direction and 80 μm in the sub-scanning direction.
[0031]
As the heating roller 71 of the fixing device 7, an iron core having a diameter of 40 mm and a thickness of 0.8 mm was used. Compared to the case where the core metal of the heating roller 71 is made of aluminum, iron can be made thinner while assuring the same strength, which contributes to downsizing of the fixing device 7. However, since iron has a lower thermal conductivity than aluminum, when a large number of transfer materials having a small width such as B5 size are passed through the fixing device 7, the central portion of the heating roller 71 where the transfer material passes is formed. Although the temperature decreases due to the decrease in heat capacity, the end portion where the transfer material does not pass is heated. Thus, as the heater H, a two-halogen lamp heater having a different power distribution of 1200 W was used.
[0032]
It should be noted that the two differently distributed heat halogen lamp heaters are two halogen lamp heaters as the heater H in the heating roller 71, and the heating distribution in the axial direction of the heating roller 71 is controlled by the two halogen lamp heaters. This is to prevent the temperature of the heating roller from being partially increased or decreased in the axial direction during the sheet passing. For example, one heats mainly the central portion of the heating roller 71, and the other heats mainly the end portion of the heating roller 71.
[0033]
As the original, a sheet of B5 size paper having a blackening ratio of 6% and a plurality of black patches was used.
[0034]
As the transfer material, Konica Copy J paper, which is B5 size and plain paper, was used, and one-sided paper was passed vertically. Therefore, the heating roller 71 has a non-sheet passing area at the end.
[0035]
The experimental environment was normal temperature and normal humidity at a temperature of 20 ° C. and a humidity of 50% RH.
Next, four types of fixing devices will be described.
[0036]
<Conventional example 1>
Although the conventional fixing device 7 as described above is used, an end cooling fan for cooling the end of the heating roller 71 is not mounted.
[0037]
<Conventional example 2>
An end cooling fan for cooling the end of the heating roller 71 was mounted on the conventional fixing device 7 as described above.
[0038]
<Example 1>
An end cooling duct for cooling the end of the heating roller 71 is attached to the conventional fixing device 7 as described above, and an outside air suction duct for sucking outside air into the fixing device 7 and a warming inside the fixing device 7 are also provided. An exhaust duct for exhausting air to the outside, and a heat pipe connected to the outside air suction duct and the exhaust duct, respectively, were installed.
[0039]
FIG. 2 shows a schematic diagram of this configuration. FIG. 2 is a view of the fixing device and the like as viewed from above. The left side of FIG. 2 is the front part (the side where the operator is located) of the image forming apparatus, and the lower part is the transfer unit 6 shown in FIG. Is the side transported by
[0040]
In FIG. 2, two end cooling ducts 102 each having an end cooling fan 101 therein and communicating with the outside air are connected to the fixing device 7. When the end of the non-sheet passing area is heated, outside air is blown to the end to cool the end.
[0041]
Further, an outside air suction duct 104 having an outside air suction fan 103 inside and communicating with outside air, and an exhaust duct 106 having an exhaust fan 105 inside and communicating with outside air are connected to the fixing device 7, and the air inside the fixing device 7 is Is exhausted out of the image forming apparatus by the exhaust duct 106. Further, a device internal air suction duct 108 directed to the image forming unit 4 shown in FIG. 1 is connected to the fixing device, and sucks toner powder and ozone which fly into the device and exhausts them through an exhaust duct 106.
[0042]
In addition, a heat pipe 111 is connected between the outside air suction duct 104 and the exhaust duct 106, and the heat of the air in the fixing device 7 heated by the heating roller 71 is transferred by the heat pipe 111, so that the outside air suction duct 104 Dissipates heat inside. Thereby, the air in the outside air suction duct 104 is heated, and the heated air is blown to the central portion of the heating roller 71, that is, the paper passing area. Therefore, a decrease in the surface temperature of the heating roller 71 due to continuous copying can be prevented.
[0043]
Here, the basic configuration of the heat pipe will be described with reference to FIG.
The heat pipe is a pipe-shaped container provided with a porous material called a wick on the inner wall surface, and the inside of the container is evacuated and then filled with a small amount of a highly volatile working fluid. Then, when one end of the container is heated, the internal working fluid evaporates, and the generated steam passes through the central passage through the heat insulating portion and moves to the other end at a low temperature. Then, the steam that has touched the inner wall surface of the condenser condenses and releases latent heat. The condensed working fluid returns to the evaporator due to the capillary force of the wick, and is heated again to evaporate. By repeating this process, a large amount of heat can be transferred.
[0044]
The description of the heat pipe was made with reference to the Dictionary of Mechanical Terms, published by Nikkan Kogyo Shimbun, edited by the Association for the Study of Training, Education and Training.
[0045]
<Example 2>
An end cooling fan for cooling the end of the heating roller 71 is mounted on the conventional fixing device 7 as described above, and an outside air suction duct for sucking outside air into the fixing device 7 and an outside air suction duct and a fixing device A heat pipe connected to each outer wall was attached.
[0046]
FIG. 4 shows a schematic diagram of this configuration. FIG. 4 is a view of the fixing device and the like as viewed from above. The left side of FIG. 2 is the front part (the side where the operator is located) of the image forming apparatus, and the lower part is the transfer unit 6 shown in FIG. Is the side transported by
[0047]
In FIG. 4, similarly to FIG. 2, two end cooling ducts 102 each having an end cooling fan 101 therein and communicating with the outside air are connected to the fixing device 7 so that a narrow transfer material can pass therethrough. When the end of the non-sheet passing area of the heating roller 71 is heated by the paper, the outside air is blown to the end to cool the end.
[0048]
Further, an outside air suction duct 104 having an outside air suction fan 103 therein and communicating with outside air is connected to the fixing device 7.
[0049]
In addition, a heat pipe 121 is connected between the outside air suction duct 104 and the outer wall 7 a covering the internal mechanism of the fixing device 7, and the heat pipe 121 heats the heating roller 71 and transfers the heat to the outer wall 7 a of the fixing device 7. The heat is transferred by the heat pipe 121 and is radiated into the outside air suction duct 104. Thereby, the air in the outside air suction duct 104 is heated, and the heated air is blown to the central portion of the heating roller 71, that is, the paper passing area. Therefore, a decrease in the surface temperature of the heating roller 71 due to continuous copying can be prevented.
[0050]
A portion 121a of the heat pipe 121 that contacts the outer wall 7a of the fixing device 7 is branched into a number of pipes, and transfers heat from a wide area of the outer wall 7a.
[0051]
Next, evaluation methods in the above four examples will be described below.
(1) Fixing rate {circle over (1)} The heater is turned on and warmed up from a state where the fixing device is cooled down to room temperature. When the surface temperature of the heating roller 71 reaches 190 ° C., the display unit of the image forming apparatus is ready to be prepared. Display.
[0052]
{Circle around (2)} Immediately after the display of the completion of preparation, a B5 size sheet is fed vertically, and 1000 continuous copies are performed in one-sided copying.
[0053]
(3) Measure the reflection density of the black patch of the copy to be measured.
{Circle around (4)} A cotton cloth is applied to the measured black patch under a load of 20 g / cm ² , and rubbed back and forth 10 times. After rubbing, the reflection density of the black patch is measured again.
[0054]
{Circle over (5)} The reflection density ratio before and after rubbing is determined to be the fixing rate.
That is, the fixing rate = the reflection density of the black patch after rubbing / the reflection density of the black patch before rubbing. The ideal fixing rate is 100%, but if it is 80% or more, there is no practical problem.
[0055]
(2) Warm-up time This is the time from when the image forming apparatus is cooled down to when the heater is turned on from the room temperature state and when the surface temperature of the heating roller reaches 190 ° C.
[0056]
(3) Heat roller temperature distribution difference During the fixing rate measurement test, temperature measurement was performed at 10 mm intervals in the axial direction of the heating roller at 1 second intervals, and the maximum temperature distribution difference was extracted after 1000 sheets were passed. I do.
[0057]
(4) Heating roller temperature alarm When the surface temperature of the heating roller reaches 250 ° C., a warning is issued by an alarm to prevent destruction due to excessive heating of the fixing device, and the heater of the fixing device is immediately forcibly turned off. Until the temperature reaches a safe temperature (below 190 ° C.).
[0058]
(5) Electric power of the end cooling fan This is the electric power of the end cooling fan required for the temperature distribution difference of the heating roller to be 25 ° C. or less. As the temperature distribution difference increases, the power increases.
[0059]
The air volume was adjusted by switching the voltage applied to the end cooling fan.
Next, Table 1 shows the experimental results in the above-described four examples when the above-described evaluation methods were used, and is annotated below.
[0060]
[Table 1]

[0061]
<Conventional example 1>
After the continuous copying of 200 sheets, while the temperature distribution difference of the heating roller increased and the end temperature exceeded 250 ° C., a warning was issued by an alarm, the image forming operation was interrupted, and further copying was performed. I can not do it.
[0062]
<Conventional example 2>
There were no alarm warnings. However, when 150 sheets were continuously copied, the fixing rate was lower than 80% and decreased to 75%. The toner image peels off when the copy is rubbed lightly with the hand, which is not practical. FIG. 5 is a graph showing a change in the fixing rate with respect to the number of copies.
[0063]
In addition, the warm-up time was as long as 45 seconds, and the power of the end cooling fan was required to be as large as 10 W.
[0064]
<Example 1>
There was no alarm warning, the fixing rate was maintained at 82% or more even in continuous copying, and there was no problem without peeling even if the toner image was rubbed. FIG. 5 is a graph showing a change in the fixing rate with respect to the number of copies.
[0065]
Further, the warm-up time was 31 seconds, which was about 30% shorter than that of Conventional Examples 1 and 2.
The power of the end cooling fan was halved to 5 W.
[0066]
The above result is because the heat radiated from the heating roller was added to the heating roller again through the heat pipe, and the energy was significantly reduced as compared with the related art.
[0067]
<Example 2>
There was no alarm warning, the fixing rate was maintained at 83% or more even in continuous copying, and there was no problem without peeling even if the toner image was rubbed.
[0068]
Further, the warm-up time was 33 seconds, which was about 30% shorter than that of Conventional Examples 1 and 2.
The power of the end cooling fan was halved to 5 W.
[0069]
The above result is because the heat radiated from the heating roller was added to the heating roller again through the heat pipe, and the energy was significantly reduced as compared with the related art.
[0070]
In addition, it was confirmed that the same effect can be obtained even if the outer wall of the fixing device in Example 2 is formed thickly with a resin or a composite material including a resin and a metal, and a heat pipe is inserted into the outer wall. I have.
[0071]
According to the above experiment, the present invention applies heat radiated from the heat roller of the fixing device to the heat roller again when a large number of continuous copies are performed, so that the surface temperature of the heat roller is lowered and the fixing performance is deteriorated. Can be prevented, and the energy given to the heating roller can be reduced, thereby suppressing an increase in cost. Further, the time for fixing warm-up can be reduced. Further, it is particularly effective when a sufficient effect cannot be obtained even when the two halogen lamp heaters with different heat distribution are used.
[0072]
If the width of the transfer material to be passed is not always much different from the axial length of the heating roller 71, the end cooling fan 101 and the end cooling duct 102 are unnecessary, and the heating roller 71 The air may be blown over the entire length in the axial direction. However, a transfer material having a small width (for example, A5 size is vertically fed) and a wide transfer material (for example, A4 size is horizontally fed) are configured to be able to pass, and the transfer material having a narrow transfer material width is passed. When a large number of continuous copies are made, the configuration shown in FIGS. 2 and 4 must be used. Then, when passing a wide transfer material, the blowing of the end cooling fan 101 and the outside air suction fan 103 is stopped.
[0073]
Although the two embodiments described above use a heat pipe, the heated air may be circulated in the fixing device without using the heat pipe. An example of this is shown in the schematic diagram of FIG.
[0074]
In FIG. 6, a heating roller 71, an end cooling fan 101, and an end cooling duct 102 are the same as those in the above-described embodiment.
[0075]
In this embodiment, a circulation duct 202 and a circulation fan 201 for circulating the heat of the air in the fixing device 7 heated by the heating roller 71 and sending the heat to the heating roller 71 are provided. Thus, the hot air in the fixing device 7 released from the heating roller 71 passes through the circulation duct 202 and is blown again to the heating roller 71. Therefore, a decrease in the surface temperature of the heating roller 71 due to continuous copying can be prevented.
[0076]
Finally, the correspondence between the terms described in the claims and the terms described in the embodiments of the invention will be described.
[0077]
The suction means in claims 1 and 3 correspond to the outside air suction fan 103 and the outside air suction duct 104, and the exhaust means in claim 1 corresponds to the exhaust fan 105 and the exhaust duct 106.
[0078]
The heat pipe in claim 4 corresponds to the heat pipes 111 and 121.
The end cooling means in claims 5 and 7 correspond to the end cooling fan 101 and the end cooling duct 102.
[0079]
The blowing means in claim 6 corresponds to the circulation fan 201 and the circulation duct 202.
[0080]
【The invention's effect】
According to the image forming apparatus of the present invention, when a large number of continuous copies are made, the heat radiated from the heating roller of the fixing device is again given to the heating roller. Is prevented from deteriorating, and the energy given to the heating roller can be reduced to suppress an increase in cost. Further, the time for fixing warm-up can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram of an image forming apparatus.
FIG. 2 is a schematic diagram of the first embodiment.
FIG. 3 is a basic configuration diagram of a heat pipe.
FIG. 4 is a schematic diagram of a second embodiment.
FIG. 5 is a graph showing a change in a fixing rate with respect to the number of copies.
FIG. 6 is a schematic diagram of a configuration for circulating heated air.
[Explanation of symbols]
7 Fixing Device 7a Outer Wall 71 Heating Roller 101 End Cooling Fan 102 End Cooling Duct 103 Outside Air Suction Fan 104 Outside Air Suction Duct 105 Exhaust Fan 106 Exhaust Duct 108 Inside Air Suction Duct 111, 121 Heat Pipe 201 Circulation Fan 202 Circulation Duct

Claims (7)

An image forming apparatus including a fixing unit that fuses and fixes a toner image formed on a transfer material,
Suction means for sucking outside air and blowing air to a heating roller in the fixing means;
Exhaust means for exhausting the air in the fixing means to the outside of the fixing means;
An image forming apparatus, wherein a heat transfer unit having one end connected to the suction unit and the other end connected to the exhaust unit is provided in the fixing unit. The image forming apparatus according to claim 1, wherein the exhaust unit also exhausts air in the image forming apparatus other than the fixing unit. An image forming apparatus including a fixing unit that fuses and fixes a toner image formed on a transfer material,
Suction means for sucking outside air and blowing air to a heating roller in the fixing means;
An image forming apparatus, wherein a heat transfer unit having one end connected to the suction unit and the other end connected to an outer wall of the fixing unit is provided in the fixing unit. The image forming apparatus according to claim 1, wherein the heat transfer unit is a heat pipe. End cooling means for sucking outside air and blowing air to both ends of the heating roller and cooling the both ends is provided, and air is blown between the both ends by the suction means. The image forming apparatus according to claim 1, wherein: An image forming apparatus including a fixing unit that fuses and fixes a toner image formed on a transfer material,
An image forming apparatus, wherein a blower for discharging air from the fixing unit and blowing the air to a heating roller is provided in the fixing unit. End cooling means for sucking outside air and blowing air to both ends of the heating roller and cooling the both ends is provided, and air is blown between the two ends by the blowing means. The image forming apparatus according to claim 1, wherein:

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