JP2001194968A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that components existing in air within a device main body adhere to electric discharge wires of an electrifying device and damage the function of the electric discharge wires. SOLUTION: The image forming device has a device main body 11, a photoreceptor drum 12, a corona charge-type electrifying device 13, an exposing device, a developing device, a transfer device, a fixing assembly 19 of a thermal fixing type, a fan 31 disposed in the part facing the clearance S between the photoreceptor drum and the fixing assembly at the side wall of the device main body 11, a first air intake 33 disposed in the part opposed to the fan, on the side wall of the device main body, across a recording paper transporting path between the photoreceptor and the fixing assembly, a second air intake 34 disposed in the part located in the upstream side of the recording paper transportation direction with respect to the photoreceptor on the side wall of the device main body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art An image forming apparatus adopting an electrophotographic method used in a facsimile apparatus, a copying machine, or the like is a front view schematically showing a configuration of an image forming apparatus in one form of the related art, as shown in FIG. A photoconductor drum 2, a charger 3 for charging the surface of the photoconductor drum 2, an exposing device 4 for forming an electrostatic latent image on the surface of the photoconductor drum 2, a photoconductor drum A developing device 5 for developing the electrostatic latent image on the surface of the photosensitive drum 2 to form a toner image;
And a fixing device 7 for fixing the toner image transferred to the recording paper P. After the recording paper P passes between the photosensitive drum and the transfer device, An image is recorded on recording paper through a fixing device.

Generally, in this image forming apparatus, since the charger 3 can perform good charging, the discharging wire 3a
In this case, a corona charging method for performing charging by corona discharge, that is, a scorotron method is used. Further, as the fixing device 7, a heat fixing type of fixing a toner image through a recording sheet between a rotating heating roller 7a and a pressing roller 7b because good fixing can be performed is adopted.

[0004]

When the charger 3 is of the scorotron type using corona discharge by the corona discharge wire 3a, the toner which has lost the electrostatic force by the exposure device floats inside the apparatus main body 1. The toner adheres to the discharge wire 3 a of the charger 3. Further, when the image forming apparatus is used in an environment with a lot of dust, or when the process unit including the photosensitive drum 2 and the developing device is attached to and detached from the apparatus main body 1, dust enters the inside of the apparatus main body 1 from outside. By doing so, dust adheres to the discharge wire 3a. As a result, when the charger 3 performs the corona discharge, the corona discharge by the discharge wire is not properly performed, and the charging on the surface of the photosensitive drum 2 becomes defective, and the image defect is finally recorded on the recording paper. A black streak appears in the raindrop phenomenon (BLCK / MARK), and a good image cannot be obtained. Therefore, when such a situation occurs, it is necessary to stop the operation of the apparatus, remove the charger 3 from the apparatus main body 1, wipe the discharge wire 3a to remove dust.

In a fixing device adopting a heat fixing method, a pressing roller is generally formed by vulcanizing silicone oil as a material having elasticity and heat resistance in order to press recording paper against a heating roller. However, the silicone oil that forms the pressure roller contains siloxane molecules having a low molecular weight, and the siloxane molecules are heated by the heating roller and volatilized, causing ozone generated by air discharge from the discharge wire to ozone. The chemical reaction produces SiO ₂ .
Then, the SiO ₂ in the air adheres to the discharge wire,
Acts to prevent a uniform discharge in the discharge wire,
Finally, black streaks occur in the image as described above.

The low molecular siloxane becomes more volatile when the fixing temperature of the fixing device or the temperature inside the apparatus main body 1 rises.
As a result, the degree of adhesion to the discharge wire increases. The SiO ₂ adhered to the discharge wire is insulative, and the dripping phenomenon easily occurs in a low temperature and low environment. The SiO ₂ once adhered to the discharge wire cannot be easily removed even if it is swabbed.

As a countermeasure against this, it is conceivable to use a pressure roller formed of silicone oil containing a small amount of low molecular siloxane. However, the air inside the apparatus main body 1 still contains siloxane molecules, and 100% of the siloxane could not be removed from the air. This is because a low amount of low molecular siloxane is contained in the pressure roller, and silicon grease is generally used as a lubricant in a rotation drive unit provided inside the apparatus main body. This is because low molecular siloxane is contained.

In the apparatus main body, there is a gap at the joint between the case and the cover which constitutes the apparatus main body, and the air flow generated inside the apparatus main body due to the existence of the gap causes the air inside the apparatus main body to flow. It is conceivable that dust and siloxane (and SiO ₂ generated by a chemical reaction of the siloxane) inside and discharged to the outside of the apparatus main body together with air may be attached to the discharge wire provided in the charger. However, the gap generated in the main body of the apparatus is only a secondary matter, and the air flow generated by this gap is not sufficient in air flow to perform the above-described operation, and is not an effective flow. Can not.

Further, inside the main body of the apparatus, air near the fixing device is heated by the heat generated from the fixing device, and an airflow naturally flows toward the charging device having a lower temperature than the fixing device. Then, the siloxane generated from the pressure roller of the fixing device moves toward the discharge wire, and SiO ₂ is generated and adheres to the discharge wire.

According to the present invention, there is provided an image forming apparatus capable of preventing a component present in the air of the apparatus main body and impairing the function of a discharge wire of a charger from adhering to the discharge wire, thereby obtaining an image of good quality. It is intended to provide a device.

[0011]

An image forming apparatus according to claim 1, wherein a photosensitive member, a charger for charging the surface of the photosensitive member by a corona charging method, and an electrostatic latent image on the surface of the photosensitive member An exposure device that forms an image, a developing device that develops an electrostatic latent image on the surface of the photoconductor to form a toner image, and a toner image on the surface of the photoconductor on recording paper that has been transported to the photoconductor. Transfer device, a fixing device for fixing the toner image transferred to the recording paper conveyed from the photoconductor, a device main body accommodating each of these devices, and a device provided in the device main body. It is characterized by comprising a fan for discharging the air inside the main body to the outside, and an air intake port provided in the main body for taking in the air outside the main body into the inside.

According to the configuration of the present invention, when the fan is rotated, external air is sufficiently taken into the inside of the apparatus main body through the air intake port, and a clear airflow is formed inside the apparatus main body toward the fan. Since it flows, the components present in the air of the apparatus main body and impairing the function of the discharge wire of the charger can be reliably discharged to the outside of the apparatus main body and prevented from adhering to the discharge wire.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the fan is provided at a position facing a gap between the photoconductor and the fixing device on a side wall of the apparatus main body. It is characterized by having.

According to the structure of the present invention, the air near the charger is directly led to the space between the photoreceptor and the fixing device, so that the component that impairs the function of the discharge wire existing in the air near the charger is removed. In addition to being able to reliably discharge to the outside of the device body, it also prevents the air near the charger from flowing near the fuser and chemically reacting with the components contained in the air near the fuser to generate components that impair the function of the discharge wire. In addition, by directing the air near the fixing device to the gap between the photoconductor and the fixing device, the air near the fixing device flows near the charging device and chemically reacts with components contained in the air near the charging device. Therefore, it is possible to prevent the generation of a component that impairs the function of the discharge wire.

According to a third aspect of the present invention, in the image forming apparatus of the second aspect, the air intake port is provided on the side wall of the apparatus main body with a gap between the photoconductor and the fixing device interposed therebetween. And a second air intake port provided at a location on the side wall of the apparatus body located upstream of the photoconductor with respect to the recording paper conveyance direction. It is characterized by having.

According to the structure of the present invention, a clear airflow is formed in which the air taken into the apparatus main body from the first air inlet is directly discharged by the fan in the gap between the charger and the fixing device. The air near the fixing device and the air near the charging device can be guided more reliably and in a sufficient amount directly to the gap between the photoconductor and the fixing device, and can be taken into the inside of the apparatus main body from the second air intake. The charged air reaches the charger and is guided to the gap between the photoconductor and the fixing device together with the air near the charger. The amount of air introduced is increased, and the components contained in the air near the charger can be more reliably discharged.

According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the fixing device has a heat roller and a pressure roller that comes into contact with the heat roller, and the recording paper is driven by both rollers. The fixing is performed by passing through the gap.

According to the structure of the present invention, the siloxane volatilized from the silicone oil forming the pressure roller of the fixing device is prevented from flowing near the discharge wire of the charger, and the siloxane and the ozone released from the discharge wire are prevented. It is possible to prevent a chemical reaction from generating a component that inhibits the function of the discharge wire.

[0019]

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

The image forming apparatus of the present invention is not specified for any use of a facsimile machine, a copying machine or a printer. 1 to 3 do not show a document reading unit in the image forming apparatus. FIG. 1 is a front view schematically showing the configuration of the image forming apparatus, FIG. 2 is a plan view thereof, and FIG. 3 is a perspective view thereof.

As shown in FIG. 1 and FIG.
For example, it has a rectangular box shape, and a mechanism for recording an image on recording paper P is accommodated inside the apparatus main body 11. Reference numeral 12 denotes a horizontally disposed photosensitive drum, which is rotated in a direction indicated by an arrow by a rotation driving mechanism (not shown). A charger 13 is provided above the photosensitive drum 12 and charges the surface of the photosensitive drum 12. The charger 13 employs a corona charging method for performing charging by corona discharge using a discharge wire 13a, that is, a scorotron system. It is. An exposure device 14 is disposed downstream of the charging device 13 in the drum rotation direction and forms an electrostatic latent image on the surface of the photosensitive drum 12. A reference numeral 15 denotes a drum on one side of the photosensitive drum 12 with respect to the exposure device 14. A developing unit 16 disposed downstream of the photosensitive drum 12 to develop an electrostatic latent image on the surface of the photosensitive drum 12 to form a toner image; Is a corona transfer type transfer unit that is disposed on the side of the printer and transfers the toner image on the surface of the photosensitive drum 2 to the recording paper P. A cleaning device 17 is disposed on the other side of the photosensitive drum 12 on the downstream side in the drum rotation direction with respect to the transfer device 16 and removes toner remaining on the surface of the photosensitive drum 12. It is a static eliminator for static elimination. The drum unit U shown in FIG. 3 is configured with these elements.

A fixing unit 19 is provided on the other side of the photosensitive drum 12 at a predetermined distance from the photosensitive drum 12 by a thermal fixing method. The fixing unit 19 is configured to rotate with a rotating heating roller 19a. The toner image is fixed through the recording paper P between the roller 19b and the roller 19b. The pressure roller is formed by molding a silicone oil containing a small amount of low molecular siloxane.

Reference numeral 21 denotes a cassette disposed inside the apparatus main body 11 below the photosensitive drum 12, and stores recording paper P in a stacked state. Then, the recording paper P accommodated in the cassette 21 is fed out and U-turned, and then conveyed along a horizontal conveyance path in the direction of the arrow shown in the drawing, and passes between the photosensitive drum 12 and the transfer device 16. The toner image is transferred from the photosensitive drum 12
And a transfer unit 19 (specifically, a gap between the cleaning unit 17 and the transfer unit 19), and then a fixing unit 19 passes between a heating roller 19a and a pressure rotor 19b. The toner image is fixed by
It is discharged to the outside from the discharge port 20 formed in FIG.

Reference numeral 31 denotes a fan for discharging air from the inside of the apparatus main body 11, and this fan is provided on a side wall of the apparatus main body 11 at a position facing the gap S between the photosensitive drum 12 and the fixing device. The photosensitive drum 12 and the fixing device 19 are arranged with a gap S so that their axes are parallel to each other, and the conveyance path of the recording paper P passes through the gap S between the two. Device body 1
An opening 32 for a fan communicating between the inside and the outside of the main body is formed at the location on the side wall 1, and the fan 31 is mounted in the opening 32. This fan 31 is a motor 31a
And a wing 31b rotated by the motor 31a. When the fan 31 is driven to rotate the blades 31b, the air inside the apparatus main body 11 is discharged to the outside. That is, the components contained in the air inside the apparatus main body 1 and the heat generated by each device can be released to the outside.

A first air intake 33 corresponds to the fan 31 with a gap S between the photosensitive drum 12 and the fixing unit 19 on the side wall of the apparatus main body 11. It is provided in the place. That is, the first
The air intake 33 of the first device takes the air S taken into the apparatus main body 1 from the first air intake 33 into the gap S between the photosensitive drum 12 and the fixing device 19 and the photosensitive drum 12 and the fixing device 1.
9 flows along the axial direction 7 to form an airflow discharged from the fan 31 to the outside. The first air intake 33 is formed, for example, as a plurality of slits arranged in a horizontal direction.

Reference numeral 34 denotes a second air intake port. The second air intake port 34 is located on the side wall of the apparatus main body 11 on the upstream side of the photosensitive drum 12 in the recording paper conveying direction, specifically, The developing unit 15 is provided at a position located on the upstream side in the recording paper conveyance direction with respect to the developing unit 15. In other words, the second air intake 34 is provided with an airflow that flows air introduced into the apparatus main body 1 from the second air intake 34 toward the drum unit U including the charger 13 located above the photosensitive drum 12. Is formed. The second air intake 34 is formed, for example, as a plurality of slits arranged in a horizontal direction.

In the image forming apparatus constructed as described above, when the fan 31 is driven, air outside the apparatus main body 11 is taken into the apparatus main body 11 from the first air intake port 33 as shown in FIG. This air causes the gap S between the photosensitive drum 12 and the fixing device 19 to pass through the photosensitive drum 12
Flows along the axial direction of the fixing device 19 and is discharged from the fan 31 to the outside. Part of the air in the fixing device 19 and the air around the fixing device 19 flows directly to the fan 31 and is discharged to the outside, and the other portion is the photosensitive drum 12.
In the gap S between the first air inlet 33 and the fixing device 19, the air flows to the fan 31 together with the air flowing from the first air inlet 33 toward the fan 31 and is discharged.

The air in the drum unit U including the photosensitive drum 12 and the charger 13 located above the drum and the air surrounding the drum unit U partially flow directly toward the fan 31 and are discharged to the outside. The remaining portion flows to the fan 31 together with the air flowing from the first air intake 33 toward the fan 31 in the gap S between the photosensitive drum 12 and the fixing device 19 and is discharged. Device body 1
The outside air of 1 is taken into the inside of the apparatus main body 11 from the second air intake port 34, and flows to the drum unit U including the photosensitive drum 12 and the charger 13 located above the photosensitive drum 12. This air flows from the drum unit U to the fan 31 and is discharged as described above. The charging wire 13
It is preferable that the wind speed in the portion a is set to be 200 m / min or more.

In this image forming apparatus, a fan 31 provided in the apparatus main body 11 to discharge the air inside the apparatus main body 11 to the outside, and an air provided in the apparatus main body 11 to take the air outside the apparatus main body 11 into the inside. When the fan 31 is rotated, the outside air is sufficiently taken into the inside of the apparatus main body through the air intake ports 33 and 34, and is clearly directed to the fan 31 inside the apparatus main body 11 when the fan 31 is rotated. Siloxane volatilized from the silicone oil forming the pressure roller 19b of the fixing device 19, ozone released by the discharge wire 13a of the charger 13 and the discharge wire 13a generated by a chemical reaction of these components. SiO _2, which is an example of a component that adheres to and inhibits its function
Can be reliably discharged to the outside of the apparatus main body 11. In addition, low-molecular siloxane contained in silicon grease, which is generally used as a lubricant, is also discharged to a rotation drive unit provided inside the apparatus main body 11. As a result, it is possible to finally prevent the occurrence of the raindrop phenomenon in the image recorded on the recording paper P. For example, low molecular siloxanes (D ₄ to
A 10,000-sheet printing test was carried out with a pressure roller (230 ppm) having a large content of D ₁₀ ) and a pressure roller (27 ppm) with a small content, but no raindrop phenomenon occurred on the image.

Further, by providing the fan 31 at a position facing the gap S between the photosensitive drum 12 and the fixing device 19 on the side wall of the apparatus main body 11, air near the charger 19 in the drum unit U can be removed. Drum 12
The ozone emitted from the discharge wire 13a existing in the air near the charger 13 can be reliably discharged to the outside of the apparatus main body 11 while the air near the charger 13 is fixed. Flow to the vicinity of the fixing device 19
Chemical reaction with siloxane volatilized from the silicone oil that forms the pressure roller 19b of the fixing device 19 contained in the surrounding air prevents generation of SiO ₂ that impairs the function of the discharge wire 13a. By directing the air in the vicinity to the gap between the photoreceptor drum 12 and the fixing device 19, the air in the vicinity of the fixing device 19 flows to the vicinity of the charger 13, and the ozone contained in the air in the vicinity of the charger 13 reacts chemically with ozone. It is possible to prevent the generation of SiO ₂ which reacts and impairs the function of the discharge wire 13a.

If the fan 31 is provided at a position facing the end of the fixing device 19 on the side wall of the apparatus main body 11, when the fan 31 is rotated, the fan 3 is attached to the fixing device 19.
Air flows along the axial direction from the end opposite to 1 toward the end facing the fan 31 and is discharged by the fan 31. When such an airflow occurs, the fixing temperature becomes non-uniform at the left and right ends in the axial direction of the fixing device 19, and a situation occurs in which the toner image cannot be fixed satisfactorily. Further, since air near the charger 13 passes through the fixing device 19 and is discharged from the fan 31, the ozone generated by the charging device 13 flows and causes a chemical reaction with the siloxane generated by the fixing device 19 to cause SiO 2.
₂ will be generated. When the fan 31 is provided at a position facing the end of the photosensitive drum 12 on the side wall of the apparatus main body 11, when the fan 31 is rotated, air near the fixing device 19 passes through the charger 13 and passes from the fan 31. Siloxane generated in the fixing device 19 due to discharge is charged in the charging device 1.
This causes a chemical reaction with the ozone generated in step 3 to generate SiO ₂ . Therefore, the gap S between the photosensitive drum 12 and the fixing device 19 on the side wall of the apparatus main body 11 is formed.
These problems can be solved by providing them at a location facing the.

Further, the air inlet is provided with a first air inlet 33 at a position corresponding to the fan 31 with a gap S between the photosensitive drum 12 and the fixing device 19 on the side wall of the apparatus main body 11. Therefore, the first air intake 33 is located in the gap S between the charger 13 and the fixing device 19.
A clear airflow is formed in which the air taken into the apparatus main body 11 is directly discharged by the fan 31, and the air near the fixing device 19 and the air near the charger 13 are more reliably and sufficiently supplied to the photosensitive drum 12. It can be led directly to the gap S between the fixing device 19.

Further, since the second air intake port 34 is provided at a position on the side wall of the apparatus main body 11 located upstream of the photosensitive drum 12 in the recording paper conveying direction, the second air intake port 34 is provided.
The air taken into the apparatus main body 11 from the second air inlet 34 reaches the charger 13 in the drum unit U,
The space between the photosensitive drum 12 and the fixing device 19 is guided together with the air near the charger 13 to the gap S between the photosensitive drum 12 and the fixing device 19. The amount of air guided to the charger 13 increases, and ozone contained in the air near the charger 13 can be more reliably discharged.

The present invention is not limited to the above-described embodiment, but can be implemented with various modifications.

[0035]

According to the image forming apparatus of the first aspect, when the fan is rotated, external air is sufficiently taken into the inside of the apparatus main body through the air intake port and directed to the fan inside the apparatus main body. Since a clear airflow is formed and flows, it is possible to reliably prevent anything that exists in the air of the apparatus main body and impairs the function of the discharge wire of the charger from being discharged to the outside of the apparatus main body and prevented from adhering to the discharge wire.

According to the second aspect of the present invention, the component that impairs the function of the discharge wire existing in the air near the charger by directly guiding the air near the charger to the gap between the photoconductor and the fixing device. Can be reliably discharged to the outside of the device body,
Prevents the air near the charger from flowing near the fuser and chemically reacting with the components contained in the air near the fuser to produce a component that impairs the function of the discharge wire. Directly into the gap between the fuser and the fuser, the air near the fuser flows near the charger and chemically reacts with the components contained in the air near the charger to produce components that impair the function of the discharge wire Can be prevented.

According to the third aspect of the present invention, a clear airflow flowing between the first air intake and the fan is formed in the space between the charging device and the fixing device, and the air near the fixing device and the charging device are charged. The air in the vicinity of the charger can be directly and more reliably and sufficiently introduced into the space between the photoreceptor and the fixing device, and the air taken into the inside of the apparatus main body from the second air intake port can be used. Since the air is guided to the gap between the photoconductor and the fixing device together with the air, the amount of air guided to the gap between the photoconductor and the fixing device together with the air near the charging device increases, and the vicinity of the charging device increases. The components contained in the air can be more reliably discharged.

According to the fourth aspect of the invention, the siloxane volatilized from the silicone oil forming the pressure roller of the fixing device is prevented from flowing near the discharge wire of the charger, and the siloxane and the ozone released by the discharge wire are prevented. Can be prevented from generating a component which inhibits the function of the discharge wire by a chemical reaction.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a configuration of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a front view schematically showing the configuration of the image forming apparatus according to the embodiment.

FIG. 3 is a perspective view schematically showing a configuration of the image forming apparatus according to the embodiment.

FIG. 4 is a front view schematically illustrating a configuration of an image forming apparatus according to a conventional mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Device main body, 12 ... Photoconductor drum, 13 ... Charging device, 13a ... Discharge wire, 19 ... Fixing device, 19a ... Heating roller, 19b ... Pressure roller, 31 ... Fan, 33 ... 1st air intake, 34 ... Second air intake.

Claims (4)

[Claims] 1. A photoreceptor, a charger for charging the surface of the photoreceptor by a corona charging method, an exposing device for forming an electrostatic latent image on the surface of the photoreceptor, A developing device that develops a latent image to form a toner image, a transfer device that transfers a toner image on the surface of the photoconductor to recording paper that has been conveyed to the photoconductor, and a transfer device that is conveyed from the photoconductor A fixing device for fixing the toner image transferred to the recording paper, an apparatus main body accommodating each of these devices, a fan provided in the apparatus main body and discharging air inside the apparatus main body to the outside, An image forming apparatus comprising: an air intake port provided in a main body to take air outside the apparatus main body into the inside. 2. The image forming apparatus according to claim 1, wherein the fan is provided on a side wall of the apparatus main body at a position facing a gap between the photoconductor and the fixing device. . 3. A first air intake provided at a location corresponding to the fan with a gap between the photoreceptor and the fixing device on a side wall of the apparatus main body; 3. The image forming apparatus according to claim 2, further comprising a second air intake port provided at a location on the side wall of the apparatus main body located upstream with respect to the photoconductor in a recording paper conveyance direction. 4. 4. The fixing device according to claim 1, wherein the fixing device includes a heating roller and a pressure roller that is in contact with the heating roller, and performs fixing by passing the recording paper between the two rollers. The image forming apparatus according to claim 1.