JPH07160179A - Image forming device - Google Patents

Abstract

PURPOSE:To provide a very reliable image forming device capable of reducing or vanishing the dew condensation generated on a device surrounding a transporting path, and preventing water content from sticking to a paper sheet, the paper from jamming, the paper sheet from causing irregularity and the paper sheet from generating the stain, by causing air flow between the fixing means and the transporting means and removing the water content generated from the paper sheet. CONSTITUTION:When a power is supplied, the heater 33a is turned on for starting to warm up the fixing roller 33 and the fun 41 is driven. Thus, the air flow arises between the paper sheet P severally in the direction of the arrow s and the direction of the arrow t at the time of the fixing. Namely, as for the fixing side duct 42a, the warm air generated by heating of the fixing roller 33 is ventilated to the fun 41 side, while, as for exhaust duct 42b, the dry air from the outside is ventilated to the fun 41 side. Therefore, the water content generated from the paper sheet P is exhausted out side the device main body together with the air flow in the direction of the arrow s and the direction of the arrow t, hence the dew condensation is not generated onto the duct 42 so much as waterdrop fall down, even at the time of performing much consecutive copying.

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 apparatus which performs fixing by a pair of fixing rollers having a heating roller.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as a copying machine, a sheet of paper is guided to the conveying roller and the sheet discharging roller in a sheet conveying path from a fixing roller to a sheet discharging section, and an operator heats the sheet at a high temperature during maintenance. An upper sheet discharge guide is provided to prevent the sheet from being heated by the transport roller, and a fan is provided to cool the sheet passing through the sheet transport path. Conventionally, in the upper paper ejection guide, in order to enhance the guide property of the paper, the distance from the paper conveyance path is set as low as 1.5 to 2 mm, and the distance between the upper paper ejection guide and the paper conveyance path is narrow. The air flow generated by the fan was difficult to ventilate. On the other hand, in the fixing roller, water is generated from the paper heated at the time of fixing, but if the surrounding devices are cooled, such as in cold regions or early morning in winter, the generated water is discharged upward. Condensation was generated on the surrounding devices such as the paper guide, and water droplets were formed.

[0003]

Conventionally, in order to improve the guideability of the paper, the upper paper ejection guide is provided low in the paper conveyance path from the fixing roller to the paper ejection section. For this reason, the paper passing through the upper paper ejection guide easily comes into contact with the paper ejection guide, and the ventilation between the upper paper ejection guide and the paper conveyance path is poor. Condensation is likely to occur on the discharge guide because it is not discharged, and condensed moisture adheres to the paper that passes through the paper transport path, which causes paper jams in the transport path or uneven discharge of paper. Problems such as paper stains and waviness have occurred.

When continuous copying is performed especially in a high-speed image forming apparatus, the amount of water generated increases in proportion to the number of copies, so that the water condensed on the upper paper ejection guide also increases. Even if the paper does not come into contact with the conveyance guide, it becomes a water drop and is dropped onto the paper or the paper conveyance path, causing paper jams, uneven discharge of paper, and stains on the paper.

Therefore, the present invention eliminates the above-mentioned problems. By removing the moisture generated from the paper, the dew condensation that occurs in the apparatus around the transport path is reduced or eliminated, and the adhesion of the moisture to the paper is prevented. However, it is an object of the present invention to provide a highly reliable image forming apparatus that does not cause paper jams, paper irregularities, and paper stains.

[0006]

In order to solve the above problems, the present invention provides an image forming means for forming a developer image on a sheet in a main body of an apparatus, and a developing device formed on the sheet by the image forming means. Fixing means for heating and fixing the agent image on the sheet, and the sheet for discharging the developer image by the fixing means provided between the fixing means and the sheet discharging section of the apparatus main body for discharging the sheet. And a blower provided above the conveyer, and a blower provided between the fixing unit and the sheet discharge unit, and an air flow between the fixing unit and the conveyer by the blower is inserted. And a ventilation means for allowing it to be provided.

[0007]

According to the present invention, by the above means, an air flow is generated between the fixing means and the conveying means to remove the water content generated from the paper, and to reduce or eliminate the dew condensation of the water content on the apparatus around the fixing means. This prevents moisture from adhering to the paper. This prevents paper jams and misalignment at the time of paper discharge, and also prevents paper stains and stains due to undulations.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic explanatory view of the image forming apparatus. In the apparatus main body 1 having a high copy speed of 420 mm / sec, charging, exposure, development, transfer, peeling,
The image forming means 2 for performing cleaning, charge removal, fixing, etc. is built in,
A document table 3 that supports a document D is provided on the upper surface of the apparatus body 1. Reference numeral 4 denotes a document table cover that covers the document table 3.

A front loading type sheet feeding cassette device 10 for accommodating the sheets to be supplied to the image forming means 2 is detachably attached to the lower part of the apparatus body 1 on the right side of the apparatus body 1. A paper feed tray 11 for manually feeding the paper P is provided. 37a, 37b
Are first and second pick-up rollers for taking out the paper P from the paper feed cassette device 10 or the paper feed tray 11.

The image forming means 2 has the following structure. That is, the photoconductor drum 20 is arranged substantially in the center of the apparatus main body 1, and around the photoconductor drum 20,
The charging charger 21, the exposure unit 22a of the exposure device 22, the developing device 23, the transfer charger 25, the peeling charger 26, and the cleaning device 2 which are well known in the related art along the rotation direction thereof.
7 and the static eliminator 28 are sequentially arranged.

Further, the photosensitive drum 20 in the apparatus main body 1
On the upstream side, a first sheet-feeding cassette device 10 or a sheet-feeding tray 11 is provided to prevent the double picking of the sheets P from being fed.
Further, the second separation / conveyance rollers 38a and 38b, the guide roller 35, and the registration roller 32 that conveys the sheet while aligning the leading ends of the sheet P and synchronizing the developer image formed on the photosensitive drum 20 are arranged. On the downstream side, a conveyor belt 36, a pair of fixing rollers 33 that are fixing means, and a transmission means that conveys the paper P from the fixing rollers 33 to the discharge tray 12 via the discharge port 1a that is a discharge portion. Laura 3
4a and the paper discharge roller 34b are arranged.

Then, the transmission roller 34a and the paper discharge roller 3
A fan 41, which is a blower for sucking the paper P on the paper transport path 37 and the heat and moisture around the fixing roller 33, is provided above the paper transport path 37 that supports the paper P between the sheet 4 and 4b. There is.

Further, 42 is a transmission roller 34a whose temperature is raised by an operator during maintenance such as paper jam removal.
It is a duct that serves as a guard that prevents the touching of the sheet P, and is a ventilation unit that efficiently sucks heat and moisture around the sheet P and the fixing roller 33 by the fan 41. The duct 42 is a fixing-side duct 42a that generates an airflow from the fixing roller 33 toward the transmission roller 34a.
And a discharge side duct 42b for generating an airflow from the discharge port 1a in the direction of the discharge roller 34b. Each of the ducts 42a and 42b is sufficiently separated from the center of a roller provided on the upper side of the paper discharge roller 34a to be 5 mm above the paper transport path 37 so that the paper being transported may not come into contact with each other. Has been done.

The fixing roller 33 has a heater 33a.
And a pressure roller 33c that is pressed against the heat roller 33b by a pressure spring (not shown). The heating roller 33b is rotated by a drive motor (not shown), and the pressure roller 33c is rotated.
Is pressed against this and is driven to rotate. Furthermore,
Reference numeral 63 is a peeling claw, and 64 is a cleaning device having a cleaning felt 64a that is in sliding contact with the heating roller 33b.

Next, the copy operation of the apparatus main body 1 will be described. When a power source (not shown) is turned on, in the apparatus main body 1, the heater 33a is turned on to start warming up the fixing roller 33, and the fan 41 is driven.

After the warm-up is completed and the ready state is established, the document D is set on the document table 3 and further copied.
Copy conditions such as the number of sheets and paper size are set by a numeric keypad or the like on an operation panel (not shown), and a copy key (not shown) is turned on to start the copy operation. By the start of this copy operation, the photosensitive drum 20 is rotated at a high speed of 420 mm / sec, and in accordance with the rotation, the image forming means 2 sequentially executes the steps of charging, exposing, and developing to form a developer image. .

On the other hand, in the paper feed cassette device 10 or the paper feed tray 11, the paper P taken out by any one of the pickup rollers 37a and 37b is separated one by one by the separating and conveying means 38a and 38b, and the registrar. To the transfer charger 25 of the photoconductor drum 20 in synchronism with the developer image on the photoconductor drum 20 by the image forming means 2 and the developer on the photoconductor drum 20. The image is transferred.

Further, the sheet on which the developer image is transferred is peeled from the photosensitive drum 20 by the peeling charger 26, is conveyed by the conveying belt 36, is conveyed to the fixing roller 33, and is between the heating roller 33b and the pressure roller 33c. The image is heated and pressurized and fixed, and is ejected toward the paper ejection tray 12. On the other hand, after the transfer is completed, the cleaning device 27 removes the residual toner according to the rotation of the photoconductor drum 20, and the charge removing device 28 removes the charge so that the next copy can be performed. Then, the above copy operation is repeated to obtain the required number of copies.

During this time, the fixing roller 33 repeats heating and fixing of the toner image on the sheet.
Moisture contained in the paper P is generated from the heated paper P, and when the ambient temperature is low, the generated water is
Condensation will form on the duct 42 and other peripheral devices.

However, in the duct 42, since the power is turned on, the air flow in the arrow s direction and the arrow t direction are generated between the sheet P and the sheet P by the drive of the fan 41.
That is, in the fixing duct 42a, the fixing roller 33
While the warm air generated by the above heating is ventilated to the fan 41 side, in the paper discharge side duct 42b, the dry air from the outside is ventilated to the fan 41 side. Therefore, the water generated from the paper P is discharged to the outside of the apparatus main body 1 together with the air flow in the arrow S direction and the arrow t direction.
Even if a large amount of continuous copying is performed, the duct 42 will not be condensed with water to the extent that it drops into water drops. In particular,
A large amount of water is generated on the fixing side duct 42a side, but since the fixing side duct 42a is warmed by the ventilation of warm air from the heating roller 33b, even if continuous copying is performed, dew condensation of water is particularly large. Of course, it is discharged to the outside of the apparatus main body 1 by the fan 41 together with the warm air.

Even if water droplets adhere to the fixing-side duct 42a and the discharge-side duct 42b due to a large amount of continuous copying, since the conveying speed of the sheet P is high, the sheet P peeled off from the heating roller 33b. As shown by the dotted line in FIG. 2, the leading edge passes through the transmission roller 34a and the paper discharge roller 34b before floating up, and the paper P is less likely to come into contact with the duct 42, and the paper transport path 37 is smaller than the conventional one. The height from the duct 42 to the duct 42 is set to be twice or more, so that the paper P does not come into contact with the duct 42, and there is no possibility that moisture adheres to the leading end of the paper P.

Further, even after the copying of a predetermined number of sheets is completed, since air currents in the directions of the arrows s and t are constantly generated in the duct 42, it is assumed that water droplets are attached to the duct 42 immediately after the copying is completed. Even dried immediately.

Incidentally, when continuous copying is performed using A.3 size paper in the apparatus main body 1 of the present embodiment, the conventional copying is as follows.
Water was wet on the paper after continuous printing of 50 sheets, and then water droplets were found to be adhered to about 20 papers up to 250 sheets. Very good results were obtained, that is, none occurred.

According to this structure, the moisture generated at the time of fixing is efficiently discharged to the outside of the apparatus main body 1 by the fan 41 and the airflow generated between the duct 42 and the sheet P or the sheet conveying path 37 and dried. Therefore, continuous copying is performed with a high-speed model, and even if the amount of water generated is large, there is no risk that water drops will drop from the duct 42 and wet the paper or the paper transport path 37. Further, during continuous copying at high speed, water droplets will adhere to the duct 42 even if the water droplets do not fall, but since the space between the duct 42 and the paper conveyance path 37 is wider than before and the paper conveyance speed is high. , The paper P is in the upper duct 4
There is no risk of contact with 2, and there is no possibility of wetting due to contact.

Therefore, it is possible to prevent paper jamming due to poor conveyance caused by water wetting and unevenness at the time of paper discharge, and to improve the reliability of the apparatus without causing stains or distortion of the paper P due to water wetting. I can.

The present invention is not limited to the above-mentioned embodiment, and changes can be made within the scope of the invention. For example, the copy speed is arbitrary, but the amount of water generated is particularly high. It is effective when there are many. Further, the shape of the ventilation means and the distance between the sheet or the sheet conveying path are arbitrary, and if the airflow is generated in the ventilation means, the first and second ducts 47a and 47b shown in FIG. In addition, it may not be integrally attached to the fan 48, and the direction of air blown by the fan may be such that air outside the apparatus body is blown onto the paper.

[0027]

As described above, according to the present invention,
Moisture generated during fixing is discharged and dried by the air flow in the ventilation means generated by the blowing means, so even if a large amount of water is generated during continuous copying at high speed,
It is possible to prevent the water condensed in the ventilation means from being dropped as water drops as in the conventional case, and to prevent the paper or the paper transport path from getting wet due to the drop of the water drops. Further, since the ventilation means is separated from the paper conveying path as compared with the conventional paper discharge guide so that the airflow can be passed, there is no possibility that the paper comes into contact with the ventilation means at the time of conveyance, and the paper due to contact with the ventilation means. It can also prevent water from getting wet. Therefore, it is possible to reliably prevent paper jamming and paper misalignment caused by water wetting of the paper, improve the reliability of the apparatus, and prevent soiling of the paper due to water wetting.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a device body of an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a fixing roller and a sheet discharging unit according to an embodiment of the present invention.

FIG. 3 is a schematic sectional view showing another modification of the present invention.

[Explanation of symbols]

 1 ... Device main body 33 ... Fixing roller 41 ... Fan 42 ... Duct

Claims (3)

[Claims] 1. An image forming means for forming a developer image on a sheet in a main body of the apparatus, a fixing means for heating and fixing the developer image formed on the sheet by the image forming means on the sheet, and Conveying means that is provided between the fixing means and the discharge section of the apparatus main body, and that conveys the sheet, on which the developer image is heat-fixed by the fixing section, to the discharge section,
The air blower is provided above the conveying unit, and the air blowing unit is provided between the fixing unit and the sheet discharge unit, and the air blowing unit allows the air flow between the fixing unit and the conveying unit by the air blowing unit to pass therethrough. An image forming apparatus characterized by. 2. An image forming means for forming a developer image on a sheet in a main body of the apparatus, a fixing means for heating and fixing the developer image formed on the sheet by the image forming means, and a fixing means. A transmission roller provided downstream of the fixing unit for transmitting the conveyance of the sheet, a sheet ejection roller provided downstream of the transmission roller for conveying the sheet to the sheet ejection unit of the apparatus main body, and the sheet ejection roller for ejecting the sheet. An air blower provided above the paper conveying path reaching the paper roller and an air flow between the fixing unit and the transmission roller by the air blower are inserted, and an air flow between the paper ejection roller and the paper ejection unit by the air blower is inserted. An image forming apparatus comprising: a ventilation unit for controlling the image forming apparatus. 3. The air blowing direction by the air blowing means is between the fixing means and the transmission roller to generate an airflow from the fixing means toward the transmission roller, and between the paper discharge section and the paper discharge roller, the paper discharge section The image forming apparatus according to claim 2, wherein an air current is generated in the direction of the discharge roller.