JPH07181874A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device by which the temperature rising of a thermal fixing unit is surely prevented, also the ambient temperature rising thereof due to the thermal fixing unit is surely suppressed, other units are surely maintained at appropriate usage temperature and safety is surely secured. CONSTITUTION:This image forming device by which an image is formed by forming an electrostatic latent image by an electrifier unit 8 and an exposure unit 9 on the upper surface of a photoreceptor 7, transferring a toner image sensitized with toner or the like by a developing unit 10 on transfer paper 1 by a transfer unit 11 and then performing thermal fixing by the thermal fixing unit 2 is provided with the thermal fixing unit 2 provided at an upper part on the downstream side in the feeding direction of the transfer paper 1, an air passage 3 surrounding the periphery of the thermal fixing unit 2 with cooling air and a fan 4 allowing the cooling air to flow through the air passage 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a heat fixing apparatus used in an electrophotographic image forming apparatus such as a copying machine, a facsimile, a printer, or a composite machine in which a printer and a scanner are integrated. The present invention relates to improvement of a cooling method of an apparatus.

[0002]

2. Description of the Related Art Conventional electrophotographic copying machines, printers,
In an image forming apparatus such as a facsimile machine, a transfer unit produces a toner image obtained by visualizing an electrostatic latent image formed by a charging unit and an exposure unit on the surface of a photoreceptor with toner or the like from a developing unit. An image is formed by transferring the image onto a transfer paper and then thermally fixing it with a heat fixing unit. Since this heat fixing unit uses a fixing roller with a built-in heater, it tends to be heated to a high temperature, and in order to cool it, a fixing fan that blows air to the conventional heat fixing unit to cool it is provided, or an optical device such as an illuminating device. For example, the wind for cooling the unit is sent to the heat fixing unit to cool the heat fixing unit (see Japanese Utility Model Laid-Open No. 61-206971).

However, it cannot be said that sufficient cooling is performed by such a conventional cooling method by blowing air, and the heat of the heat fixing unit causes the temperature of the photosensitive member to rise and the sensitivity to decrease. There is a high possibility that noise such as squealing noise and fire may occur due to toner adhesion, a change in hardness of the cleaning blade that constitutes the cleaning unit, and fire, and measures to prevent them have been delayed in safety standards.

[0004]

In the conventional image forming apparatus, the heat of the heat fixing unit raises the temperature of the heat fixing unit and its surroundings. For example, the temperature of the photoconductor rises to lower the sensitivity, the developing unit, etc. In this case, there is a possibility that the toner adheres, the noise such as a squeaking noise due to the hardness change of the cleaning blade of the cleaning unit, the occurrence of a fire or the like.

[0005]

SUMMARY OF THE INVENTION Therefore, the present invention is intended to solve such a problem. That is, the image formation that surely prevents the temperature rise of the heat fixing unit and also suppresses the temperature rise of the surroundings by the heat fixing unit, surely keeps other units at an appropriate operating temperature and surely secures safety. The purpose is to provide a device.

[0006]

In order to achieve the above object, the present invention forms an electrostatic latent image on the upper surface of a photoconductor by a charging unit and an exposure unit, and at the same time, a toner is developed by a developing unit on the electrostatic latent image. In an image forming apparatus that transfers a toner image visualized by a transfer unit onto a transfer sheet and then heat-fixes it with a thermal fixing unit to form an image, the heat provided on the downstream upper side in the sheet passing direction of the transfer sheet. It has a fixing unit, a ventilation passage surrounding the thermal fixing unit with cooling ventilation, and a fan for flowing cooling ventilation to the ventilation passage. The blowing direction of the fan can be switched between a suction direction and a discharge direction. That the ventilation operation of the fan is turned on and off according to the fluctuation of the ambient temperature, and the ventilation operation of the fan is turned on according to the number of continuous passing of the transfer paper.
It is characterized by being turned off and on.

[0007]

As described above, in the present invention, the heat fixing unit is surrounded by the ventilation passage by the cooling ventilation by the ventilation operation of the fan so as to be separated from the other units, so that the temperature rise of the heat fixing unit is surely prevented. In addition, it is possible to provide an image forming apparatus in which an ambient temperature rise is surely suppressed by the heat fixing unit and other units are surely kept at an appropriate operating temperature and safety is surely ensured.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. The image forming apparatus of the present invention includes a copying machine, a facsimile, a printer or the like, or a printer and a scanner or the like, such as a facsimile interface (FAX I / F).
The present invention relates to an image forming apparatus using a thermal fixing unit for performing image formation by transferring a toner image onto a transfer sheet by a transfer unit and then thermally fixing the image in a multi-functional machine in which F) is integrated. The main configuration of the mechanical portion of the image forming apparatus includes a paper transport unit that transports paper such as transfer paper and originals, an image forming unit that forms an image and transfers it to the transfer paper, and a transferred toner image of the paper. It is composed of a fixing unit fixed on the transfer paper, a paper discharge unit accommodating the fixed transfer paper, and a structure and an electrical unit for holding and controlling these.

FIG. 1 shows an example of an image forming apparatus to which the present invention is applied. In the image forming apparatus of the present invention, a transfer paper 1 is used.
A heat fixing unit 2 separated from other units is provided on the downstream upper side in the paper passing direction, and the heat fixing unit 2 is surrounded by a ventilation passage 3 for cooling ventilation and separated from other units. A fan 4 for introducing cooling air is arranged in the passage 3. The transfer paper 1 fed in the direction of the registration roller pair 6 from the cassette paper feeding device 5 constituting the transport unit is guided by the guide member at a timing when the leading end portion contacts the registration roller pair 6. Meanwhile, the drum-shaped photoconductor 7 is driven to rotate counterclockwise.
Be transported to the upper part of.

The surface of the drum-shaped photosensitive member 7 is charged by the charging unit 8 and then irradiated with light from the exposure unit 9 to form an electrostatic latent image. This electrostatic latent image is visualized by toner when passing through the developing roller 10 of the image forming unit. This toner image is transferred by the transfer unit 11 to the transfer paper 1 being conveyed to the upper part of the drum-shaped photoconductor 7, and is also heat-fixed to the transfer paper 1 by the heat fixing unit 2 (heat fixing). Be done).

The transfer paper 1 on which the toner image is heat-fixed is discharged to the paper discharge unit 12, while the cleaning unit 13 removes the residual toner from the drum-shaped photoconductor 7 after the toner image is transferred. These operations are performed not only on the transfer paper fed from the cassette paper feeding device 5 but also on the transfer paper 1 fed from the manual paper feeding device 5a.

FIG. 2 is a block diagram showing the configuration of a transmission unit for controlling the image forming apparatus to which the present invention is applied. The electrical unit of the image forming apparatus of the present invention is a host of an information processing apparatus which also serves as a user interface. 14 and a peripheral unit that serves as an input / output unit of the information processing apparatus. On the peripheral side, a simple operation panel 15 such as start and reset, and an IC card 1 for programs, fonts and additional memory
6 is provided.

Next, the operation of the electrical system will be described. At the time of image formation, the information processed by the host 14 for printing for image formation is sent to the controller 17 in the form of text, bitmap, or the like. The controller 17 uses the font information 17a and internal functions to generate control / raster data 17c on the image memory 17b. Control above
The raster data 17c including the input signal from the keyboard 14b and the operation instruction from the controller 17 is sent to the engine control unit 18. The engine control unit 1
Reference numeral 8 controls a printer unit 19 and an optional unit 20 of a mechanism necessary for a printing operation for image formation to carry the transfer paper 1 and the like, and transfers the transfer paper based on the control / raster data 17c from the controller 17. An image is formed on the paper 1.

At the time of image reading, when an image taking request is sent from the host 14 to the engine control unit 18 via the controller 17, the engine control unit 18 is operated.
Controls the scanner unit 21 of the mechanism necessary for the operation of the scanner and a part of the printer unit 19 to carry a document or the like. Read data 21a from the scanner unit 21
Is once buffered by the controller 17 and then sent to the host 14.

During facsimile communication, the telephone number information of the other party is transmitted from the host 14 to the controller 1 during transmission.
It is sent to the FAX I / F 22 via 7. At the same time, with respect to the image information, the controller 17 issues an image acquisition request to the engine control unit 18, and the scanner unit 21
It is further taken in and sent to the FAX I / F 22. The FAX I / F 22 uses the communication line to call the other party, and the image information is MH, MR.
Etc. and send it out. Note that the transmission original is the host 14
In the case of internal information from the upper storage device 23, image information is not fetched.

Upon reception, the procedure is divided into two procedures, that is, the printer section 19 immediately prints an image or the storage section 23 stores the image. When the printer section 19 immediately prints an image, the received information is decompressed by the FAX I / F 22 and sent to the printer section 19 via the controller 17. When the data is stored in the storage device 23, it is sent to the storage device 23 while being compressed. The received information accumulated in the storage device 23 can be confirmed on the display 14a of the host 14 via the controller 17, and the printing of the image formation by the printer unit 19 can be performed at any time as necessary. Has become.

FIG. 3 is an explanatory view of the essential parts of the present invention. A transfer unit 11 such as a transfer charger is provided above the drum-shaped photoreceptor 7, and a charging unit 8 such as a charger is provided below the drum-shaped photoreceptor 7. It is arranged. The thermal fixing unit 2 is provided above the transfer sheet 1 on the downstream side in the sheet passing direction in the direction of arrow A in the figure. Below the heat fixing unit 2, the cleaning unit 13 for cleaning the surface of the drum-shaped photoconductor 7 is provided.

Around the heat fixing unit 2, there is provided a gap for the ventilation passage 3 surrounded by cooling ventilation in the direction indicated by the arrow B, and another unit, for example, the drum-shaped photoreceptor 7,
The cleaning unit 13 and the power supply unit 24
Etc. The fan 4 for generating cooling air in the direction of arrow B shown in the drawing is provided in a part of the air passage 3 together with the ozone filter 25. Ozone contained in the air sucked by the fan 4 is adsorbed and removed when passing through the ozone filter 25. Naturally, a guide plate (not shown) that crosses the ventilation passage 3 is provided with ventilation holes so as not to obstruct ventilation.

FIG. 4 is a detailed view of the main parts. The fan 4 is provided above the power supply unit 24 as shown in the drawing, and the positive and negative electrodes of the power supply of a fan motor (not shown) for driving the fan 4 by the relay 4a and the like are connected. By switching the rotation direction, the fan 4 is switched between normal and reverse directions to switch the direction of cooling and ventilation by the fan 4 between suction in the direction of arrow C and discharge in the direction of arrow D.

FIG. 5 is a diagram showing the operation of each part, the fixing roller, the ambient temperature, etc. When the power supply unit 24 is turned on, the fixing heater 2a of the heat fixing unit 2 is turned on and the roller 2a of the heat fixing unit 2 is turned on. When the temperature reaches 100 ° C,
The fixing heater 2a starts ON / OFF and enters the standby mode (t1). The ventilation operation of the fan 4 at this time is off until the ambient temperature of the thermal fixing unit 2 reaches 40 ° C., and the ambient temperature of the thermal fixing unit 2 is 40 ° C.
When the temperature exceeds ℃ (t2), the temperature of the heat fixing unit 2 is 40 because the cooling air flows through the air passage 3 by rotating occasionally.
Hold at ℃. When image forming printing is started in the printer unit 19 (t3), the temperature of the roller 2a of the heat fixing unit 2 reaches 180 ° C., and the ambient temperature of the heat fixing unit 2 also starts to rise again. In this state, ozone is generated inside, so the ventilation operation of the fan 4 is operated in the suction direction to prevent generation of ozone.

However, since the cooling capacity of the fan 4 is limited, the ambient temperature of the thermal fixing unit 2 continues to rise.
This condition affects other units in the aircraft and safety. In order to avoid this, when the ambient temperature of the thermal fixing unit 2 reaches 70 ° C. or when the ambient temperature of the thermal fixing unit 2 reaches the expected number of continuous passing sheets of the transfer paper 1 reaching 70 ° C. The printing of the image formation in the printer unit 19 is interrupted, the ventilation operation of the fan 4 is reversed to the ejection direction, the heat fixing unit 2 is cooled (t4), and once returned to the safe temperature, the printer is Printing of image formation in the section 19 is continued (t5). The fan starts suctioning with the start of printing. Incidentally, when the printing of the image formation in the printer section 19 is interrupted, ozone is not generated.
After the printing of the image formation in the printer section 19 is completed, the temperature of the roller 2a of the heat fixing unit 2 is 100
However, at the same time, the ventilation operation of the fan 4 is reversed to discharge the heat, and the heat fixing unit 2 is lowered to a safe temperature and then stopped (t).
6).

[0022]

As described above, according to the present invention, since the heat fixing unit is surrounded by the ventilation passage, that is, surrounded by the cooling ventilation by the ventilation operation of the fan and separated from the other units, the temperature rise of the heat fixing unit. Therefore, it is possible to provide an image forming apparatus in which the temperature of the surroundings is reliably suppressed by the heat fixing unit and other units are reliably maintained at an appropriate operating temperature and safety is also ensured. became.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a schematic configuration of an image forming apparatus showing an embodiment of the present invention.

FIG. 2 is a block diagram of an electrical system of an image forming apparatus showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a main part configuration of an embodiment of the present invention.

FIG. 4 is a partial detailed view of FIG.

FIG. 5 is a timing chart illustrating an operation of another main part of the image forming apparatus according to the exemplary embodiment of the present invention.

[Explanation of symbols]

1 ... Transfer paper, 2 ... Thermal fixing unit, 2a ...
Fixing heater, 2b ... Roller, 3 ... Ventilation path, 4 ...
..Fans, 4a ... relays, 5 ... cassette feeders, 5a ... manual feeders, 6 ... registration roller pairs, 7 ... drum-shaped photoreceptors, 8 ... Charging unit, 9 ... Exposure unit, 10 ... Developing roller, 1
1 ... Transfer unit, 12 ... Paper discharge unit, 13
... Cleaning unit, 14 ... Host, 14
a: display, 14b: keyboard, 15
... Operation panel, 16 ... IC card, 17 ...
Controller, 17a ... Font information, 17b ...
・ Image memory, 17c ・ ・ ・ Control / last data, 1
8 ... Engine control unit, 19 ... Printer unit, 20
... Option section, 21 ... Scanner section, 21a
... Read data, 22 ... FAX I / F, 23
... Storage device, 24 ... Power supply unit, 25 ...
Ozone filter.

Claims (4)

[Claims] 1. An electrostatic latent image is formed on the upper surface of a photoconductor by a charging unit and an exposure unit, and the toner image visualized with toner or the like by a developing unit is transferred onto a transfer paper by a transfer unit. Then, in an image forming apparatus that performs heat fixing by a heat fixing unit to form an image, a heat fixing unit provided on the downstream upper side of the transfer paper in the sheet passing direction and ventilation that surrounds the heat fixing unit with cooling air. An image forming apparatus, comprising: an air passage; and a fan for flowing cooling air into the air passage. 2. The blowing direction of the fan can be switched between a suction direction and a discharge direction.
The image forming apparatus described. 3. The ventilation operation of the fan is turned on and off according to a change in ambient temperature.
The image forming apparatus described. 4. The image forming apparatus according to claim 2, wherein the ventilation operation of the fan is turned on and off according to the number of continuous sheets of transfer paper.