JP2015079182A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply outside air to water vapor which reaches the vicinity of a guide plate or a conveyance roller after passing through a fixing apparatus, without installing a fan which supplies the outside air, to prevent dew condensation.SOLUTION: An image forming apparatus includes: a fixing apparatus for fixing an image on a sheet; an outlet which discharges the sheet to the outside at a downstream side in a sheet-conveyance direction of the fixing apparatus; a reverse sheet conveyance unit which reverses the sheet during duplex printing; a reverse outlet which temporarily discharges the reversed sheet to the outside; and a blowing mechanism 9 which sucks the outside air through the outlet during single-sided printing in the reverse sheet conveyance unit. Water vapor which reaches the vicinity of a guide plate 4 or a reverse conveyance roller 5 is mixed with the outside air, to prevent dew condensation in the guide plate 4 or the reverse conveyance roller 5. An exhaust duct is arranged around the blowing mechanism 9, to reduce internal pressure in the body of the image forming apparatus, while facilitating receiving the outside air through the reverse outlet and discharging the water vapor mixed with the outside air to the outside.

Description

  The present invention relates to an image forming apparatus having a fixing device.

  In an image forming apparatus having a fixing device, when the paper passes through the fixing device, water contained in the paper is evaporated and water vapor is generated. The generated water vapor condenses on the paper discharge guide plate and the conveyance roller, and water droplets due to the dew condensation adhere to the paper, resulting in an abnormal image. In order to suppress the occurrence of dew condensation on the paper discharge guide plate and the conveyance roller, a method for suppressing dew condensation by blowing and mixing outside air having low humidity to a location where water vapor is generated is already known.

  For example, Patent Document 1 discloses a configuration in which outside air is blown by a fan to a sheet immediately after the fixing device for the purpose of preventing abnormal images such as condensation.

  However, in the method for suppressing condensation as described above, a fan is used to blow outside air, which is not only costly but also requires a space for installing an air flow path such as a duct. .

  SUMMARY OF THE INVENTION An object of the present invention is to suppress dew condensation by blowing outside air to water vapor that reaches the vicinity of a guide plate and a conveyance roller after a fixing device without installing a fan that blows outside air.

  An image apparatus according to the present invention includes a fixing device that fixes an image on a sheet, a discharge unit that is downstream of the fixing device in a sheet conveyance direction and discharges the sheet to the outside, and a reversing sheet that reverses the sheet during duplex printing. A conveyance unit, a reversal discharge port for temporarily discharging the reversal paper to the outside of the apparatus, and an airflow generating means for sucking outside air from the reversal discharge port during single-sided printing in the reversal paper conveyance unit, It is characterized by that.

  According to the present invention, the low-humidity outside air is blown from the reverse discharge port to the water vapor reaching the discharge guide plate and the conveyance roller by the blades rotating in synchronization with the reverse conveyance roller shaft. Without installing a fan for blowing air, outside air can be blown to water vapor that reaches the vicinity of the guide plate and the conveyance roller after the fixing device, and condensation can be suppressed.

FIG. 2 is a diagram schematically illustrating a configuration of a fixing paper discharge unit of the image forming apparatus. FIG. 5 is a diagram specifically illustrating the behavior of the fixing paper discharge unit during single-sided printing. It is the figure shown about the reverse conveyance roller provided with the ventilation mechanism. It is a figure which shows the crossflow fan which is an example of a means employable as a ventilation mechanism.

An embodiment of the present invention will be described.
In the image forming apparatus according to the present embodiment, low-humidity outside air is blown from the reverse discharge port to the water vapor reaching the discharge guide plate and the vicinity of the conveyance roller by the blade rotating in synchronization with the reverse conveyance roller shaft. It is a feature.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically illustrating a configuration of a fixing paper discharge unit of the image forming apparatus. In the figure, reference numeral 1 denotes an image forming apparatus main body, and 2 denotes a fixing device. When the paper 3 on which the toner image is formed passes through the fixing device 2 that fixes the image by heating and pressurization, the water contained in the paper 3 evaporates and the water vapor w is generated.

  The water vapor w rises due to the rising air flow generated by the heat of the fixing device 2. When the temperature inside the image forming apparatus main body 1 is low, dew is generated on the guide plate 4 and the reverse conveying roller 5 provided at the portion where the sheet 3 is conveyed in the process of rising, and the remaining water vapor without dew condensation. w is discharged from the exhaust duct 6 to the outside of the machine.

  The illustrated example includes a reversing paper transport unit that reverses the paper 3 during duplex printing. In the illustrated example, in order to reverse the sheet 3 during duplex printing, on the upstream side in the drawing of the discharge unit (discharge port 7 in the figure) for discharging the sheet 3 to the outside of the apparatus, downstream in the sheet conveyance direction to the fixing device 2. A reverse discharge port 8 is provided for temporarily discharging to the outside of the machine. Around the reverse discharge port 8, a reverse conveyance roller 5 for conveying the paper 3 at the time of reverse is located.

  FIG. 2 is a diagram specifically illustrating the behavior of the fixing paper discharge unit during single-sided printing. FIG. 3 is a view showing a reverse conveyance roller provided with a blowing mechanism. During single-sided printing, the sheet 3 passes through the fixing device 2 and is discharged out of the apparatus from the discharge port 7. In the meantime, the reverse conveying roller shaft 5a provided with the air blowing mechanism 9 rotates. As a result, outside air f having low humidity is taken in from the reverse discharge port 8 and is blown to the vicinity of the guide plate 4 and the reverse conveyance roller 5.

  That is, the water vapor w reaching the vicinity of the guide plate 4 and the reverse conveying roller 5 and the outside air f are mixed, which leads to suppression of dew condensation on the guide plate 4 and the reverse conveying roller 5. Further, by arranging an exhaust duct around the blower mechanism 9, the internal pressure of the image forming apparatus main body 1 decreases, it becomes easy to take outside air f from the reverse discharge port 8, and water vapor w mixed with the outside air f is exhausted outside the apparatus. It can be done easily.

  As shown in FIG. 3, a plurality (three in the figure) of reverse conveying rollers 5 are integrally provided on a common reverse conveying roller shaft 5a. A blower mechanism 9 having a diameter smaller than that of the reverse conveyance roller 5 is disposed between the reverse conveyance rollers 5, and the blower mechanism 9 also rotates in synchronization with the rotation of the reverse conveyance roller shaft 5a. By providing the air blowing mechanism 9 integrally with the reverse conveying roller shaft 5a, it is easy to control and space saving can be achieved. Since the blower mechanism 9 is smaller than the roller diameter of the reverse conveying roller 5, it can be configured not to interfere with the conveyance of the paper 3. Further, the air blowing efficiency can be improved by installing a plurality of air blowing mechanisms 9 between the reverse conveying rollers 5.

  The blower mechanism 9 blows the low-humidity outside air f taken from the reverse discharge port 8 to the guide plate 4 and the like around the reverse transfer roller 5 and the reverse transfer roller shaft 5a. By rotating the blower mechanism 9 in synchronization with the reverse conveyance roller shaft 5a, the external air f can be supplied to the guide plate 4 and the reverse conveyance roller 5 in a space-saving manner without installing a fan for taking in the external air f.

  FIG. 4 is a diagram illustrating a cross flow fan that is an example of means that can be employed as the blower mechanism 9. A cross flow fan 10 (or a blade 11 used for the cross flow fan) is attached to the reverse conveying roller shaft 5a as a blowing mechanism. By using the blade shape of the cross flow fan 10 as the air blowing mechanism 9, the generated air current is sucked from the direction perpendicular to the reverse conveying roller shaft 5a, and a wide film-like air current is obtained. Therefore, the outside air f can be blown over the entire width of the wide guide plate 4.

  Although illustration is omitted, an exhaust duct may be provided around the air blowing mechanism 9.

  The present invention is not limited to the embodiments described above, and many variations are possible by those having ordinary knowledge in the art within the technical idea of the present invention.

1: Image forming apparatus main body 2: Fixing device 3: Paper 4: Guide plate 5: Reverse conveying roller 5a: Reverse conveying roller shaft 6: Exhaust duct 7: Discharge port 8: Reverse discharge port 9: Blower mechanism 10: Cross flow fan 11: Cross flow fan blade f: Outside air w: Water vapor

JP 2011-191706 A

Claims (6)

A fixing device for fixing an image on paper;
A discharge unit that is on the downstream side of the fixing device in the paper conveyance direction to the fixing device and discharges the paper outside the apparatus;
A reversing paper transport section that reverses the paper during duplex printing;
A reverse discharge port for temporarily discharging the reverse paper outside the machine;
In the reversing paper transport unit, air flow generating means for sucking outside air from the reversing discharge port during single-side printing,
An image forming apparatus comprising: The airflow generation means is a blower mechanism that rotates in synchronization with a reverse conveyance roller shaft in the reverse paper conveyance unit.
The image forming apparatus according to claim 1. The diameter of the air blowing mechanism is smaller than the roller diameter of the reverse conveying roller shaft,
The image forming apparatus according to claim 2. The reversing paper transport unit has a plurality of the reversing transport rollers,
A plurality of the air blowing mechanisms are installed between the reverse conveying rollers on the reverse conveying roller shaft,
The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus. The air blowing mechanism has a blade having a blade shape of a cross flow fan.
The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus. An exhaust duct is provided around the air blowing mechanism.
The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.