JPH07325539A - Image forming device - Google Patents

Abstract

PURPOSE:To easily avoid temperature rise in a device by efficiently discharging heat generated from the heating source of a pair of thermal fixing rollers and the like to the outside even when a fan is not used. CONSTITUTION:An exhaust aperture part 233 is formed by properly opening a point where a paper ejection port 26a provided on a device main body side facing to a paper ejecting tray part 20 is positioned on the tray 20 side from a perpendicular L' passing through the center of the thermal fixing roller 70a, desirably, and the upper wall of the device or/and the neighboring wall thereof positioned on an opposite side to the tray 20 provided successively to the paper ejection port 26a. An exhaust duct 41 is disposed between the aperture part 233 and a thermal fixing unit 7, and air heated by the unit 7 is led to the aperture part 233.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an invention applied as an image forming apparatus incorporating a heat fixing unit for fixing a toner image, such as a copying machine, a printer, a facsimile, or an image forming apparatus combining these. In particular, the present invention relates to an invention capable of taking an apparatus configuration capable of avoiding a temperature rise in the apparatus without using a fan.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus applied as a facsimile, a printer or a copying machine, a photoconductor drum or a belt-shaped photoconductor is used, and a latent image written on the photoconductor by an exposing means is developed. After forming a toner image by means of a toner image, the toner image is transferred onto a recording paper via a photoconductor, for example, an indirect toner image recording system such as an electrophotographic device or an electrostatic recording device, or a toner carrying roller and recording paper are inserted. A matrix-shaped mesh electrode is placed between the back electrode and
A direct recording method is also known in which a toner image is directly flying-adhered from the toner carrying roller side to the recording paper side while controlling the energization of the mesh electrode in correspondence with image information.

All of the recording methods of this type use a heat fixing roller pair consisting of a heat roller and a pressure roller in order to smoothly fix an unfixed toner image carried on a recording material. The temperature rise of the heat fixing roller pair is 1
The temperature reaches 60 to 200 ° C., and the thermal energy to be supplied per hour is also increasing in response to the increase in recording speed. On the other hand, the image forming apparatus is miniaturized as much as possible due to the limitation of the space for installation in the office. Therefore, various process means including the photosensitive drum are laid out in a high density in a narrow space. The heat radiation of the pair not only raises the temperature inside the machine, but also propagates to the various process means and adversely affects the image formation. For example, the temperature rise of the photosensitive drum destabilizes the latent image formation, and the temperature rise of the cleaner and the developing device causes solidification or cross-linking of the toner to make the toner image unstable or cause a mechanical failure. Therefore, conventionally, the periphery of the heat fixing roller pair is surrounded by a heat insulating material, and a fan is arranged on a side wall near the roller pair so that heat generated by the roller pair is discharged to the outside of the machine.

[0004]

However, arranging the fan and the motor for driving the fan increases the number of parts by that much, leads to an increase in cost, and also increases noise and vibration. Further, the heat required for raising the temperature of the heat roller is absorbed by the suction of the fan, and the power consumption of the heat fixing roller pair is unnecessarily increased accordingly. Also, releasing the air inside the machine to the outside means that the floating toner and dust generated inside the machine,
Furthermore, since pollutants such as nitriding products are released indoors (outside the machine), indoor pollution is likely to occur.

In view of the above-mentioned drawbacks of the prior art, the present invention efficiently radiates the heat generated by the heat fixing roller pair and other heat sources to the outside even when a fan is not used,
An object of the present invention is to provide an invention capable of easily avoiding a temperature rise in the device. Another object of the present invention is to prevent radiant heat from the heat fixing roller pair and other heat energy from being transferred to the photosensitive drum and the process means located around the photosensitive drum as much as possible, thereby increasing the temperature of the process means. Another object of the present invention is to provide an invention capable of effectively preventing the instability of latent image formation and toner image formation due to the above, and further mechanical failure.

[0006]

The present invention is applied to an image forming apparatus in which a recording material after passing through a heat fixing roller can be discharged to a reverse discharge tray portion provided on the upper surface of the apparatus while reverse discharging. However, in this case, as long as it has a reverse discharge tray section on the upper surface side of the apparatus, it can be applied not only to the reverse discharge dedicated machine but also to a multi-function machine that selectively performs reverse discharge. In the present invention, as shown in FIG. 5, a sheet discharge port 26a provided on the apparatus main body side facing the sheet discharge tray section 20.
Is located on the discharge tray 20 side with respect to the vertical tangential direction L passing through the peripheral surface on the outlet side of the heat fixing roller 70a, preferably from the vertical line L ′ passing through the center of the heat fixing roller 70a, and the discharge port 26a. The upper wall of the apparatus located on the opposite side of the sheet discharge tray 20 and / or the wall in the vicinity thereof is appropriately opened as an exhaust opening 233, and hot air generated by the heat fixing roller 70a can be exhausted from the exhaust opening 233. Is characterized in that In this case, the opening 233 may be formed in the machine wall in the shape of punching metal, or may be formed in the shape of slit using ribs. Further, the device upper wall and / or the wall in the vicinity thereof means a side wall and the like extending to the upper wall. In order to effectively exhaust the hot air generated from the heat fixing roller 70a from the exhaust opening 233, the exhaust opening 2 is used.
An exhaust duct 41 is provided between the heat exchanger 33 and the heat fixing unit 7,
The air heated by the heat fixing unit 7 is supplied to the opening 2
It is better to lead to 33. Further, it is preferable that the exhaust duct 41 forms a discharge guide 40 for discharging the recording material, which has passed through the fixing unit 7, to the discharge tray 20 side by utilizing the peripheral surface thereof.

[0007]

According to the present invention, since the exhaust opening 233 is provided above the thermal fixing unit 7, the air heated by the unit 7 and the heat generating air discharged from the inlet side and the outlet side of the unit are , Is guided by a duct 41 provided above the heat fixing unit 7 and is discharged from an exhaust opening 233 on the upper wall side of the apparatus to generate an updraft A. Then, the drum unit 60 is provided around the thermal fixing unit 7 where the atmospheric pressure becomes thin due to the release of the upward airflow A on the principle of low pressure.
The cool air flows from the side, and as a result, the air flow from the drum unit 60 → the thermal fixing unit 7 → the ducts 41A and 41B40 → the exhaust opening 233 can be made together, so that even if the exhaust fan is not provided, the heat can be generated. The rising air A of the hot air heated by the fixing unit 7 can be used to exhaust the hot air from the opening 233 via the exhaust duct 41.

The following are two major points for achieving the above-mentioned action. Since the hot air generated in the heat fixing unit 7 has the exhaust opening 233 above it, the upward airflow A can be smoothly generated.

The second point is that the unit 7
The duct 41 is disposed above the. That is, the duct 41 can surely guide the ascending airflow A to the exhaust opening 233, and it is possible to prevent the exhaust opening other than the hot air of the unit 7 from flowing into the duct 41. Exhaust that is not used becomes possible.
Therefore, according to the present invention, the temperature inside the apparatus can be lowered without using a fan while suppressing the heat transfer from the thermal fixing unit 7 to the drum unit including the photosensitive drum 6 and the process means around the photosensitive drum 6.

In this case, as described above, the exhaust duct 41
By forming the paper discharge guide 40 by using the peripheral surface of No. 1, a special duct member is not required, and the number of parts and the space can be saved. Also, the fact that the recording material is ejected from the rear side of the recording material while the airflow is constantly applied allows the recording material to be ejected smoothly without adhering to the surface of the ejection guide 40 or increasing the friction coefficient. Becomes Further, preferably, at least the upper surface side of the heat fixing roller 70a is surrounded by the housing body 71 to form the heat fixing unit 7, and the duct opening of the exhaust duct 41 and the heat fixing unit 7 are formed.
It is better to communicate with the entrance side and exit side respectively. In particular, when the discharge port 26a is located on the vertical line L ′ passing through the center of the thermal fixing roller 70a, the exhaust opening 233 and the inlet side of the thermal fixing unit 7 cannot be directly faced,
As a result, the above-described smooth upward airflow A cannot be generated, and there is a possibility that the heat-generating air at the inlet side of the thermal fixing unit 7 may flow toward the photosensitive drum 6 side. Therefore, according to the present invention, the shielding wall 30 is pulled down from the inner wall of the fixed wall 23 forming the end portion of the paper discharge tray portion 20 toward the recording paper conveyance path 10 to achieve thermal insulation between the photosensitive drum side and The shielding wall 30
It is preferable to form a space 30B between the heat fixing unit 7 and the upper housing 71 of the heat fixing unit 7 so as to form a passage for introducing the heat generating air on the inlet side of the heat fixing unit into the duct 41. As a result, the air generated at the inlet side of the thermal fixing unit can be prevented from flowing toward the drum unit 60 side, and can be smoothly discharged from the exhaust opening 233 via the duct 41 by using the passage 30B. A heat insulating material 30a may be provided on the shielding wall 30 if necessary.

[0011]

Embodiments of the present invention will now be illustratively described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely examples, unless otherwise specified. Not too much. Figure 2
Shows the entire configuration of the image forming apparatus according to the embodiment of the present invention, and is divided into three parts from the lower side through partition walls 1E and 1D, a sheet cassette storage space 1A, a board mounting space 1B, and a process unit mounting space 1C. At the same time, a paper feed opening 2A is provided on the bottom surface of the front end of the paper feed cassette 2, and an optional paper feed unit (not shown) is attached to the paper feed opening 2A.

In the board mounting space 1B, the board 3 can be placed on the leg 3A provided on the partition wall 1E located on the lower surface side, and the board 3 is placed on the right side in the figure along the guide 3B provided on the side wall. It can be pulled out from the rear wall.

The cassette storage space 1A has a paper feed cassette 2
And the cassette storage space 1
A paper feed roller 17 is pivotally supported on the front upper end of A, and the recording paper pulled out from the paper feed cassette 2 is fed to the recording paper conveyance path 10 via a paper feed guide 47 provided on the front wall side of the paper feed cassette 2. The paper can be fed toward the entrance end. Paper cassette 2
Has a front wall 32 that also functions as a cassette drawer portion, and the front wall 32 is erected up to the lower surface position of the display panel mounting portion 16, and a manual paper feed mechanism 34 is provided at the center of the upper surface.

In the process unit mounting space 1C, a recording paper conveying path 10 is formed on the upper surface side of a partition wall 1D that partitions the board mounting space 1B, and a paper feeding guide is formed along the conveying path 10 from the entrance end side 10a of the conveying path 10. Roller 18,
Registration roller pair 4, transfer roller 5 and photosensitive drum 6,
And the heat fixing unit 7 are provided, and the manual paper feeding section 34 integrated with the paper feeding cassette 2 and the paper feeding cassette 2 are provided.
Alternatively, after the recording paper fed from a paper feeding unit (not shown) stands by at the entrance end of the registration roller 4 via the paper feed guide roller 18, the recording paper is registered in synchronization with the start end of the toner image carried on the photosensitive drum 6. After the roller 4 is rotated and the toner image is transferred by the transfer roller 5, the heat fixing roller pair 70 of the heat fixing unit 7 is inserted to fix the image, and then the intermediate discharge roller 8 and the reverse discharge guide 40 And a pair of paper discharge rollers 9 and a paper discharge tray section 20 on the upper surface side of the apparatus.
It is reversed and ejected.

The heat fixing unit 7 has a heat roller 70a on the upper side and a pressure roller 70b on the lower side as shown in FIG.
Fixing roller pair 70, and the heat roller 70a
A rectangular upper housing 71 that surrounds the upper space of
Surrounding the bottom side of the pressure roller 70b, the unit 7
And a lower housing 72 having a rectangular shape for installing at a predetermined position on the partition wall.
At the entrance side communicating with the recording paper conveyance path 10 side of the opening between the two,
An inlet guide 73 for guiding the recording paper to the roller nip position and an outlet guide 74 for guiding the recording paper after image fixing to the nip position of the intermediate paper discharge roller 8 are provided on the outlet side communicating with the intermediate paper discharge roller 8 side. A heat insulating material is attached to the upper housing 71, and a liquid application means 75 for applying the offset prevention liquid to the heat roller 70a is provided on the upper inner wall surface of the heat insulating material.

The reverse sheet ejection guide 40 is the fixing unit 7.
It is arranged in the upper space from to the intermediate paper discharge roller 8, and its detailed configuration will be described later.

On the other hand, around the photosensitive drum 6, the cleaner 11, the particle charging unit 12, the LED unit 13, and the developing unit 1 are arranged along the drum rotating direction (clockwise).
4 is provided, the particle charging unit 12 uniformly charges the photosensitive drum 6 from which the residual toner is removed by the cleaner 11, and then the LED unit 13 writes an exposure latent image corresponding to the image information. Then, the latent image is visualized by the developing unit 14 to form a toner image, and then transferred to the recording paper side by the transfer roller 5. The above operation is repeated thereafter.

Next, the structure of the upper surface of the device will be described with reference to FIGS. The upper surface of the apparatus is connected to a rotating wall 21 that opens and closes around a support shaft 24 provided on the upper side of the display panel mounting portion 16 and a rear wall 19 on the paper ejection guide 40 side, and a slit opening 233 is formed. The fixed wall 23 is provided. The rotary wall 21 extends horizontally from the support shaft, and then is inclined downward at an intermediate position thereof to extend to a cleaner upper space position facing the drum unit 60,
The paper discharge tray portion 20 is formed together with a part of a fixed wall 23 described later.

The fixed wall 23 is inclined downward along the extension line of the inclined end of the rotating wall 21 to form the terminal end portion of the paper discharge tray portion 20, and then a vertical line passing through the center of the heat fixing roller. At the discharge tray 20 side, more specifically, at a position above the inlet side of the thermal fixing unit 7, the printer is substantially vertically raised, and a discharge port 26a is opened in the rising portion 26, and a discharge roller is provided in the discharge port 26a. The pair 9 is axially supported, and is formed continuously from the rising portion 26 along the paper discharge guide 40 so as to have a gentle curved surface and is connected to the rear wall 19. Then, the fixed wall 23 is the discharge guide 4
As shown in FIG. 3, a large number of slit-shaped strip-shaped ribs 2 extending in the paper discharge direction are provided on the curved surface portion 27 facing 0.
31 and 232 are arranged in a pulse-shaped cross section in the axial direction of the photosensitive drum, and slit openings 233 are provided at the step positions.

Therefore, with the above construction, a slit opening is formed in the space above the thermal fixing unit from 7 to the intermediate discharge roller 8, and the ducts 41A and 41B provided in the reverse discharge guide 40 are used. Then, the hot air heated by the heat fixing unit 7 is discharged to the exhaust ducts 41A, 41A.
The air can be exhausted from the opening 233 via B.

However, as shown in FIGS. 1 and 2, on the inlet side of the thermal fixing unit 7, since it does not face the slit opening 233, the heat generated at that portion propagates to the drum unit 60 side, and the photosensitive drum. 6 is likely to cause instability of latent image and toner image formation due to the temperature rise of the process means 6 and its surroundings, and further mechanical failure. Therefore, on the inlet side of the thermal fixing unit 7 that does not face the slit opening 233, the recording paper conveyance path 10 is formed from the inner wall of the fixed wall 23 that forms the terminal end of the paper discharge tray portion 20A.
The shield wall 30 vertically downwards toward the
The lower end and the recording paper conveyance path 10 are opposed to each other with a predetermined gap 30A therebetween, so that thermal cutoff is achieved between the drum unit 60 side and the shield wall 30 and the thermal fixing unit 7.
A passage 3 for introducing the air into the duct 41A.
0B is formed.

A slit groove 301 may be formed in the central portion of the shielding wall 30, and the heat insulating material 30a may be filled in the slit groove 301 if necessary. Also, the shielding wall 30 is
Basically, it is good to hang it down to a position close to the surface of the recording paper conveyance path 10 within a range that does not hinder the recording paper conveyance.
By pulling it down to a position that substantially coincides with the lower end position of the unit upper housing 71, smooth thermal cutoff and easy generation of the heat generation air at the inlet side of the thermal fixing unit 7 can be achieved.
Can lead to 0B.

Further, as shown in FIG.
The sheet discharge port 26a provided on the apparatus main body side facing the sheet discharge tray 20 from the vertical tangential direction L passing through the outer circumferential surface of the heat fixing roller 70a, preferably the vertical line L'passing through the center of the heat fixing roller 70a. When the sheet is positioned (S) on the side, the length of the discharge tray portion is shortened by that amount, and it may not be possible to secure a tray area for a large recording paper size such as B-4 size.
Therefore, as shown in FIG. 2, at the spindle position on the upper surface of the rotating wall 21, there is provided a rectangular mounting plate 15 which rotates to the display panel mounting portion 16 side from the storage position provided in the horizontal portion of the rotating wall 21. It is pivotally supported, and by rotating the mounting plate 15 from the storage position to the panel mounting portion 16 side, it is prevented from falling off when a large-sized recording material is mounted.

Next, the structure of the paper discharge guide 40 will be described with reference to FIGS. The discharge guide 40 connects a large number of vertical guides 401 vertically arranged at predetermined intervals along the axial direction of the photosensitive drum, and connects the adjacent guides 401 to each other, and forms duct-like duct spaces 41A and 41B. A vertical connecting plate 402 to be formed and a reinforcing plate 4 which is formed in a cross shape with respect to the vertical connecting plate 402 to reinforce the vertical guide 401.
03, an installation portion 404 extending from the upper surface of the upper housing 71 of the heat fixing unit 7 to the upper surface of the intermediate paper discharge roller 8, and a frame body 405 arranged on both ends in the longitudinal direction for integrally holding these. The installation site 404 is the shield wall 30 formed on the upper surface of the upper housing 71 of the thermal fixing unit 7.
The position facing the suction air passage and the part facing the outlet opening between the heat fixing unit 7 and the intermediate discharge roller 8 are opened, and the ducts 41A, 41B are opened from the openings 42A, 42B. Through the slit opening 233 of the fixed wall 23. Further, the frame body 405 is provided on the outer side thereof with a mounting plate 4 for fixing the apparatus body 1.
06 and a mounting shaft 407 are provided.

According to this embodiment, the heat roller 70a of the heat fixing unit 7 is used for the upper housing 7
1, the shielding wall 30 can prevent the heated air from flowing toward the drum unit 60 side, and the duct 41A can be opened from the opening 42A located above the upper housing 71. Passing through the slit opening 233 of the fixed wall 23, the air is discharged to the outside of the machine to create an updraft A. In addition, the heat-generating air on the inlet side of the heat fixing unit 7 is also used for the passage 3
It is guided to the duct 41A through 0B and is similarly discharged to the outside of the machine from the slit opening 233 to form an updraft A.

Then, due to the principle of low pressure, the ascending airflow A
The air pressure on the inlet side of the heat fixing unit 7 decreases due to the discharge of the heat, and cool air flows from the drum unit 60 side through the gap 30A between the shield wall 30 and the recording sheet conveying surface, resulting in the periphery of the drum unit 60 → the gap 30A → heat fixing. The air flow from the unit upper surface passages 30B and 42A to the duct passage 41A to the slit opening 233 can be made together. Therefore, by the above two actions, the hot air heated by the heat fixing unit 7 is used to draw in the air inside the machine from the drum unit 60 side, and the hot air heated by the heat fixing unit 7 is exhausted from the exhaust duct 41A. , 41B, the air can be exhausted from the opening 233, and since the opening 42A is only a portion facing the passage 30B, the duct passage 41A guides the upward airflow A to the slit opening 233. In addition to being surely performed, it is possible to prevent the slit openings 233 other than the hot air of the unit 7 from flowing into the duct passage 41A, which makes it easier to exhaust air without using a fan.

Further, since the gap 30A is on the side of the conveying path 10, that is, on the bottom side of the heat roller 70a of the heat fixing unit 7, the air heated by the heat roller 70a does not flow back to the gap 30A and is smooth. Ascend to the duct 41A side. Then, the passage before being introduced into the duct 41A and the gap 30A at the lower end side of the shielding wall 30, that is, the ascending airflow A
By forming the suction side of the air gap 30A in the gap 30A, the suction speed of the air flow can be increased to smoothly generate the upward air flow A, and the floating toner and other dust located around the air flow can be sucked together.

Further, since the duct opening 42B is located above the exit side of the unit, the heat roller 70a.
The hot air that has been heated by the air and has flowed to the outlet side
It is introduced into the duct 41B from B, and the duct passage 41
After passing through B, the air is discharged to the outside from the slit opening 233 of the fixed wall 23, and an ascending airflow A is created.

The rising airflow A on the unit outlet side lowers the air pressure on the unit outlet side, and cool air flows into that portion, so that the recording paper immediately after the image heat fixing is cooled, which is preferable.

Further, in this embodiment, the sheet discharge guide 40 is formed in a lattice shape so as to function as the exhaust ducts 41A and 41B, and the duct openings are provided on the inlet side and the outlet side of the heat fixing unit 7 so that the layout is efficient. Since it is formed, no special duct member is required, and not only the number of parts can be saved but also the space can be saved, and the flow of air and the cooled toner image can be efficiently performed. Also, the fact that the recording material is ejected from the rear side of the recording material while the airflow is constantly applied allows the recording material to be ejected smoothly without adhering to the surface of the ejection guide 40 or increasing the friction coefficient. Becomes

[0031]

As described above, according to the present invention, even when a fan is not used, the heat generated by the heat fixing roller pair and other heat sources is efficiently discharged to the outside to increase the temperature inside the apparatus. It can be easily avoided. For example, in the embodiment shown in FIG. 2, the temperature rise in the machine is about 17 ° C.,
It was able to maintain the same level as the conventional model using a fan.
Further, according to the present invention, the heat around the heat fixing roller can be efficiently guided to the exhaust opening by the duct and the shielding wall, and the radiant heat and other heat energy of the heat fixing unit are located on the photosensitive drum and its surroundings. The heat transfer to the process means is prevented as much as possible, whereby the instability of the latent image or toner image formation due to the temperature rise of the process means, and further mechanical failure can be effectively prevented. It has various remarkable effects.

[Brief description of drawings]

FIG. 1 shows a configuration of a main part around a heat fixing unit shown in FIG.

FIG. 2 shows an overall configuration of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 3 is a plan view showing a configuration of a duct portion of an exhaust guide.

FIG. 4 is a right side plan view showing the configuration of the upper surface side of the device.

FIG. 5 shows the overall configuration of an image forming apparatus according to the basic configuration of the present invention.

[Explanation of symbols]

 6 Photosensitive Drum 7 Thermal Fixing Unit 10 Recording Paper Conveying Path 20 Paper Ejection Tray 23 Upper Machine Wall 30 Shielding Wall 40 Paper Ejection Guide 41, 41A, 41B Exhaust Duct 233 Exhaust Opening

Claims (5)

[Claims] 1. An image forming apparatus configured to discharge a recording material, which has passed through a heat fixing roller, to a reverse discharge tray portion provided on an upper surface side of the apparatus while reversely discharging the paper, and to face the discharge tray portion. The paper discharge port provided on the apparatus main body side is located in a direction of a vertical tangent line passing through the peripheral surface on the outlet side of the heat fixing roller, preferably on the paper discharge tray side with respect to a vertical line passing through the center of the heat fixing roller. A device upper wall located on the opposite side of the paper discharge tray connected to the mouth and / or a wall in the vicinity thereof is appropriately opened as an exhaust opening, and hot air generated from the heat fixing roller can be exhausted from the exhaust opening. Image forming apparatus characterized by 2. Between the exhaust opening and the heat fixing unit,
2. An exhaust duct for guiding the air heated by the heat fixing unit to the opening is provided.
Image forming apparatus described 3. An image forming apparatus according to claim 1, wherein a discharge guide for discharging the recording material, which has passed through the fixing unit, to a discharge tray side is formed by using a peripheral surface of the exhaust duct. apparatus 4. A heat fixing unit is formed by surrounding at least an upper surface side of the heat fixing roller with a housing body, and a duct opening portion of the exhaust duct is communicated with an inlet side and an outlet side of the heat fixing unit, respectively. The image forming apparatus according to claim 1, wherein 5. The thermal fixing unit inlet side, which does not face the exhaust opening, pulls down the shielding wall from the inner wall of the paper discharge tray portion toward the recording paper conveyance path, and thermally shields the photosensitive drum side. And to form a gap between the shielding wall and the upper housing of the heat fixing unit,
2. The image forming apparatus according to claim 1, wherein a passage for introducing heat generating air on the inlet side of the heat fixing unit into the duct is formed.