JP2933432B2 - Image forming device - Google Patents

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 such as an electrophotographic copying machine, and more particularly, to an unfixed developer image on a transfer material by heating and pressing the image on the transfer material. The present invention relates to an image forming apparatus provided with a fixing device for fixing an image on a sheet.

[0002]

2. Description of the Related Art An image forming apparatus such as an electrophotographic copying apparatus is provided with a fixing device for fixing an unfixed developer image on a transfer material by heating and pressing the unfixed developer image on the transfer material. The fixing device is rotatably pressed against the fixing roller provided with a heating source therein, and the fixing roller,
A pressure roller forming a nip portion for nipping and conveying the transfer material in cooperation with the fixing roller; The fixing roller is heated by a heating source, and the surface temperature of the fixing roller is maintained at a predetermined temperature. The pressing force of the pressure roller against the fixing roller is maintained at a predetermined value.

At the time of fixing, a transfer material on which an unfixed developer image is formed is conveyed toward a nip and inserted into the nip. The transfer material is heated and pressurized while passing through the nip portion, and the unfixed developer image that has received the heat and pressure is fixed as a permanent image on the transfer material.

[0004]

When the image forming apparatus has not been used for a long period of time, the transfer material accommodated in the image forming apparatus absorbs moisture, and the amount of water contained in the transfer material is reduced. May be high.

When an image is formed on a transfer material that has absorbed moisture, the transfer material is conveyed toward a nip portion of a fixing device after an unfixed developer image is formed. When the transfer material receives heat from the fixing roller, the water contained in the transfer material evaporates into the image forming apparatus. The humidity in the surrounding space increases, and moisture in the air condenses on the guide member of the discharge means that is not heated. As a result, water droplets adhering to the guide member may stain the subsequent transfer material.

An object of the present invention is to provide an image forming apparatus capable of preventing water vapor generated from a transfer material from condensing on a guide member of a discharge means.

[0007]

According to the present invention, there is provided a fixing device for heating and fixing an unfixed image on a transfer material.
A guide unit for guiding the transfer of the transfer material passing through the fixing device.
Material and blowing means for blowing air to the guide member.
In the above image forming apparatus, the blower is configured to form a continuous image.
When the main power is turned on.
This is achieved by controlling according to the time from the start to the start of image formation .

[0008]

In the image forming apparatus of the action] according the present invention, the blowing
Prevents dew condensation on the guide member without wasting the drive of the means.
Can be stopped .

When an image is formed on a transfer material that has absorbed moisture, an unfixed developer image is first formed on the transfer material, and the transfer material is sent to a fixing device. In the fixing device, heat and pressure are applied to the transfer material. Moisture contained in the transfer material is evaporated by heat given to the transfer material, and water vapor is released into a space around the fixing device. Water vapor does not condense in the vicinity of the device.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the image forming apparatus of the present invention will be described below with reference to the drawings.

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

As shown in FIG. 1, the image forming apparatus 1 includes a photosensitive drum 3 disposed at a central portion in a housing 2. After the photosensitive drum 3 is charged by the primary charger 4, a light image corresponding to an image on the document placed on the document table 5 is projected via an optical system, and corresponds to the image on the document. A latent image is formed. The optical system includes a document lamp 6 and
It comprises six lenses 7 forming an optical path for guiding an optical image corresponding to an image on the document to the photosensitive drum 3, and a through lens 8 disposed on the optical path of the lens 7.

The latent image formed on the photosensitive drum 3 is visualized as a toner image by the developing device 9. Developing device 9
Is a developer container 10 containing a toner, and a developing sleeve 1 carrying the toner and transporting it toward a photosensitive drum.
1 and a blade 12 for regulating the layer thickness of the toner carried on the developing sleeve 11.

The toner image on the photosensitive drum 3 is transferred to a copy sheet sent from a corresponding cassette 13 through a paper feed roller 14, a guide 15, and a registration roller 16 by a transfer device 17
And an unfixed toner image is formed on the copy sheet.

After the toner image on the photosensitive drum 3 is transferred to the copy paper, the residual toner on the surface of the photosensitive drum 3 is removed by scraping off the blade 19 of the cleaning device 18 to form an unfixed toner image. The copy sheet is transported by the transport belt 20 to the fixing device 21.

The fixing device 21 includes a fixing roller 23 in which a halogen lamp 22 is provided as a heating source.
The fixing roller 10 is rotatably pressed against the fixing roller 10,
And a pressure roller 24 forming a nip portion for nipping and conveying the copy sheet in cooperation with the pressure roller 24. The fixing roller 23 is heated by the halogen lamp 22, and the surface temperature of the fixing roller 23 is maintained at a predetermined temperature. Fixing roller 23
Is maintained at a predetermined value.

The copy sheet transported by the transport belt 20 is inserted into the nip. As the copy sheet passes through the nip, the copy sheet is heated and pressurized, and the unfixed toner image subjected to the heat and pressure is fixed on the copy sheet as a permanent image.

At the downstream side of the fixing device 21, a sheet discharging means 25 is provided.
Is arranged. The paper discharging means 25 includes a paper discharging roller 26 for discharging the copy sheet subjected to the fixing process to the outside,
A discharge guide 27 for guiding the copy sheet from the fixing device 21 to a discharge roller 26;

Above the conveyor belt 20, an exhaust fan 2
8 are arranged. The exhaust fan 28 is positioned between the cleaning device 18 and the fixing device 21. The exhaust fan 28 filters the air around the photosensitive drum 1
The ozone generated when the photosensitive drum 1 is charged by the primary charger 4 and the ozone generated when the toner image on the photosensitive drum 3 is transferred to the copy paper are adsorbed on the filter 29. You. The air from which ozone has been removed is exhausted to the outside. Further, the suction of the exhaust fan 28 raises the temperature of the blade 12 of the developing device 9, the temperature of the blade 19 of the cleaning device 18, and the developer container 10.
The temperature of the toner in the cleaning device 18 and the temperature of the waste toner in the cleaning device 18 are prevented from rising.

Below the fixing device 21, a fan 30 for preventing dew condensation is arranged. The air blowing destination of the dew condensation preventing fan 30 is directed to the vicinity of the fixing device 21 of the paper discharge guide 27.

The copy operation and the related operations are controlled by a control unit (not shown), and an instruction is given to the control unit by a predetermined key operation.

Next, the copying operation will be described. First, after the main power is turned on, the number of copies is set using the operation keys. Next, the start key is pressed, and a copy start command is given to the control unit. The control unit gives an instruction to the corresponding paper feed roller 14, and the paper feed roller 14 is rotated once. Copy paper is fed from the cassette 13 by the rotation of the paper feed roller 14, and the copy paper is
After that, it is guided to the registration rollers 16. The registration roller 16 temporarily stops the copy sheet so as to align the copy sheet.

Next, after the photosensitive drum 3 is charged by the primary charger 4, a light image corresponding to the document image on the document table 5 is projected on the photosensitive drum 3 via the above-described optical system. A latent image is formed on the photosensitive drum 3, and the latent image on the photosensitive drum 3 is visualized as a toner image by the developing device 9.

The toner image on the photosensitive drum 3 is transferred to the copy sheet sent from the registration roller 16 by the transfer unit 17, and an unfixed toner image is formed on the copy sheet. The copy paper on which the unfixed toner image is formed is transported by the transport belt 20.
And the unfixed toner image is fixed on the copy paper by the fixing device 21.

After the fixing, the copy sheet on which the image is formed is guided to a discharge roller 26 via a discharge guide 27, and the discharge roller 26 discharges the copy sheet to the outside of the housing 2.

When the copy sheet absorbs moisture in the cassette 13, the copy sheet receives heat from the fixing roller 23 of the fixing device 21, and the moisture contained in the copy sheet flows downstream of the fixing device 21. Evaporates to the side space.

When the set number of copies is set to three or more, the dew condensation preventing fan is driven almost simultaneously with the pressing operation of the start key. Water vapor generated from the copy sheet while passing through the fixing device 21 is released to a space on the downstream side of the fixing device 21.
7, the water vapor in the space on the downstream side of the fixing device 21 does not condense on the paper discharge guide 27, so that water droplets do not adhere to the paper discharge guide 27. Therefore, the subsequent copy sheet is used as the sheet ejection guide 2
7 is not wetted or soiled by the water droplets.

When the number of copies exceeds 100, or when the number of copies does not reach the set number of copies, the dew condensation preventing fan 30 causes the rear end of the final copy sheet to move to the transfer device 17.
Stop after passing.

The stop time of the dew condensation preventing fan 30 can be determined by a combination of the number of copies and the elapsed time T from the start of turning on the main power supply to the pressing operation of the copy start key. For example, the stop time of the condensation prevention fan 30 is
When the elapsed time T is 60 minutes or more, the number of copies is 5
0, and when the elapsed time T is 120 minutes or less, the copy number reaches 30 sheets,
When the elapsed time T is less than or equal to 180 minutes, it can be the time when the number of copies reaches 20 sheets. When the elapsed time T is 180 minutes or longer, the condensation prevention fan 30
Is not driven by pressing the start key.

Next, another image forming apparatus will be described. FIG. 2 is a block diagram showing another embodiment of the image forming apparatus of the present invention, FIG. 3 is a view showing a switching state in which the wind direction switching plate of the image forming apparatus of FIG. 2 is horizontal, and FIG. FIG. 5 is a perspective view showing a switching state of a wind direction switching plate of the apparatus, and FIG. 5 is a perspective view showing an operation mechanism of the wind direction switching plate of the image forming apparatus of FIG.

As shown in FIG. 2, the other image forming apparatus 31 has a wind direction switch for guiding the air exhausted from the exhaust fan 28 instead of the dew condensation preventing fan 30 to the vicinity of the fixing device 21 of the paper ejection guide 27. A plate 32 is provided.

The wind direction switching plate 32 is formed of a rectangular plate, and one edge thereof is integrally connected with a plate-like support portion 33 rising vertically and a plate-like protrusion 34 projecting in parallel. Reference numeral 33 is disposed at a corner of the edge. Protrusion 34
Is disposed substantially at the center of the edge.

One end of a shaft 35 is attached to the support portion 33 of the wind direction switching plate 32, and the other end of the shaft 35 is attached to a side portion 36 forming the housing 2. A torsion spring 37 is fitted on the shaft 35, and the wind direction switching plate 32 is
Urged in a clockwise manner about the axis 35.

An eccentric cam 38 is in contact with the projection 34 of the wind direction switching plate 32. The eccentric cam 38 is a spring clutch 3
9 are attached to the output shaft 40. Spring clutch 3
Reference numeral 9 denotes a control ring, and a pair of diametrically opposed claws 41 are provided on the outer peripheral surface of the control ring.

One of the claws 41 of the spring clutch 39 is releasably engaged with one end of a lever 42. Lever 42 is rotatably mounted on shaft 43 about it,
The shaft 43 is attached to a support frame 44 fixed to the side portion 36.

The other end of the lever 42 is connected to a solenoid 45
And is connected to one end of a spring member 46. The solenoid 45 is attached to the support frame 44. The other end of the spring member 46 is connected to the support frame 44. The lever 42 is urged clockwise about the shaft 43 by a spring member 46.

The driving force from a main motor (not shown) is transmitted to the spring clutch 39 via a timing belt 47, a pulley gear 48 wound around the timing belt 47, and an idler gear 49 meshed with the pulley gear 48. Is done. The spring clutch 39, the pulley gear 48 and the idler gear 49 are supported by a support frame 50 attached to the side portion 36.

When the image forming apparatus 31 is used, the main power is turned on, and the image forming apparatus 31 enters a standby state.
When the image forming apparatus 31 is in the standby state, the wind direction switching plate 32
Is held horizontally, and the air exhausted from the exhaust fan 28 is exhausted to the outside of the housing 2 through the ventilation holes.

When performing continuous copying (when the number of copies is set to two or more), the wind direction switching plate 32 is angularly rotated with a key operation for setting the number of copies, and the rotation of the wind direction switching plate 32 is performed. Accordingly, the flow direction of the air from the exhaust fan 28 is changed from the horizontal direction to the direction toward the discharge guide 27.

After the number of copies is set, a start key is pressed to instruct the start of copying, and the driving force from the main motor drives the timing belt 47, the pulley gear 48 and the idler gear 49 with the pressing of the start key. The power is transmitted to the spring clutch 39 via the transmission. However, the solenoid 45 is in the OFF state, and the lever 42 and the pawl 41 of the spring clutch 39 are engaged with each other. Therefore, the spring clutch 39 does not transmit the driving force from the main motor to the eccentric cam 38, and the eccentric cam 38
2 is stopped at an angle position where it becomes horizontal.

When the set number of copies is three or more, immediately after the operation of the main motor, the solenoid 45 performs a suction operation of the iron core. The lever 42 is rotated with the above-mentioned operation of sucking the iron core, and the engagement of the end of the lever 42 with the one claw 41 is released for a short time. The output shaft 40 of the spring clutch 39 is rotated, and the eccentric cam 38 is rotated accordingly. After the rotation of the output shaft 40 starts, the solenoid 45 is turned off.
The lever 42 is in a state in which its end is
Is returned to a position where it can be engaged with the other claw 41. Output shaft 4
When 0 is rotated by 180 °, the end of the lever 42 and the other pawl 41 engage with each other, and the rotation of the output shaft 40 is stopped. With the stop of the output shaft 40, the eccentric cam 38 is stopped at a position rotated by an angle of 180 °. You. Therefore, the flow direction of the air from the exhaust fan 28 is directed toward the paper discharge guide 27, and it is possible to prevent the water vapor generated from the copy paper while passing through the fixing device 21 from condensing on the paper discharge guide 27.

When the number of copies exceeds 100, or when the number of copies does not reach the set number, the solenoid 45 is operated after the transfer of the rear end of the last copy sheet is completed, and the spring clutch 39 is driven by the main motor. Is transmitted to the eccentric cam 38. Therefore, the wind direction switching plate 32
Is returned to a horizontal state.

The time when the wind direction switching plate 32 is returned to the horizontal state can be determined by a combination of the number of copies and the elapsed time T from the start of turning on the main power supply to the pressing operation of the copy start key. For example, when the elapsed time T is 60 minutes or less, the time when the wind direction switching plate 32 is returned to the horizontal state is the time when the number of copies reaches 50 sheets, and the elapsed time T is 1
When the number of copies is less than 20 minutes, the time when the number of copies reaches 30 is set. When the elapsed time T is less than 180 minutes, the time when the number of copies reaches 20 is set. When the elapsed time T is 180 minutes or longer, the wind direction switching plate 32 is kept horizontal.

The return timing of the wind direction switching plate 32 can be determined by a combination of the surface temperature of the paper discharge guide 27 and the number of copies.

For example, a temperature sensor is attached to the surface of the paper ejection guide 27, and the temperature sensor detects the temperature of the paper ejection guide 2.
The temperature of 7 is sampled every 5 seconds after the main power is turned on.
The paper ejection guide 27 at the time of pressing the start key
When the temperature TG is 40 ° C. or more, the number of copies is 10
When the number of sheets reaches zero, the wind direction switching plate 32 is returned to the horizontal state. When the temperature TG is equal to or higher than 60 ° C., the wind direction switching plate 32 is returned to the horizontal state when the number of copies reaches 60. When the temperature TG is equal to or higher than 80 ° C., the wind direction switching plate 32 is returned to the horizontal state when the number of copies reaches 30 sheets.

In this embodiment, the wind direction switching plate 32 is of a variable type. However, the wind direction switching plate 32 is fixed at an angular position where air from the exhaust fan 28 can be constantly sent to the discharge guide 27. Can also.

[0047]

As described above, the present invention is unfixed.
Fixing device for heating and fixing an image on a transfer material, and the fixing device
A guide member for guiding the transfer of the transfer material passing through
Image forming apparatus having air blowing means for blowing air to an inner member
Wherein the blowing means is for continuous image formation.
When the main power is turned on.
Is controlled according to the time from start to image formation.
Dew condensation on the guide member can be prevented without wastefully driving the wind means .

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram illustrating another embodiment of the image forming apparatus of the present invention.

FIG. 3 is a diagram illustrating a switching state in which a wind direction switching plate of the image forming apparatus in FIG. 2 is horizontal.

FIG. 4 is a perspective view illustrating a switching state of a wind direction switching plate of the image forming apparatus of FIG. 2;

FIG. 5 is a perspective view showing an operation mechanism of a wind direction switching plate of the image forming apparatus of FIG. 2;

[Explanation of symbols]

 1, 31 Image forming apparatus 2 Casing 21 Fixing device 27 Discharge guide (guide member) 28 Exhaust fan (blowing means) 30 Dew condensation prevention fan (blowing means) 32 Wind direction switching plate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 21/00 370-540 G03G 21/14 G03G 21/20 G03G 15/20-15/20 302

Claims (1)

(57) [Claims] A fixing device for heating and fixing an unfixed image on a transfer material.
Guide the transfer of the transfer material passing through the fixing device.
A guide member, and blowing means for blowing air to the guide member
In the image forming apparatus having:
It is driven at the time of image formation.
An image forming apparatus, which is controlled according to the time from the input to the start of image formation.