JP2002365946A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus that prevents slip between paper and a pressure roller in a fixing part and prevents a jam during the carrying of paper and image faults. SOLUTION: Holes for ventilation are arranged on any or all of surfaces in a fixing frame and/or entrance guide and/or lower guide which surround the pressure roller, and a fan and current paths are disposed, so that air flows through the hole or holes.

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 for forming an image on a recording material, such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art FIG. 6 shows a laser beam printer equipped with a process cartridge as a specific example of a conventional image forming apparatus. FIG. 6 is a sectional view of the laser printer A,
The laser printer A mounts the process cartridge 101 to form an image by an electrophotographic method, and records the image on a recording material.

In the process cartridge 101, a photosensitive drum 102 serving as an image carrier is rotatably provided in a frame, and a charging means for uniformly charging the surface of the photosensitive drum 102 is provided around the photosensitive drum 102. Developing means for developing a latent image formed by irradiating the charged photosensitive drum 102 with a light image corresponding to image information with a developer (hereinafter, referred to as toner) to visualize it as a toner image; Cleaning means for removing toner remaining on the surface of the photosensitive drum 102 after transferring the toner image onto the recording material P is provided, and these are integrated by a frame to form a cartridge. The laser printer has a mounting means for mounting the process cartridge 101 in the apparatus main body.

On the other hand, an optical system 103 for irradiating the photosensitive drum 102 with an optical image corresponding to image information is provided at an upper portion in the apparatus main body. Paper cassette 10
The recording material P stored in the paper feed roller 4 is fed by a paper feed roller 10 operated by a print signal from a host computer (not shown).
5 and the separation pad 106 are separated and fed one by one. The recording material P is conveyed while being turned upside down through a paper feeding reversing unit, and is sent to the rear inside the apparatus main body (left side in FIG. 6) through a conveying unit including a conveying roller 107 and a conveying roller 108. Then, the recording material P is guided by a transfer guide 109 and is conveyed to a press nip between the photosensitive drum 102 and the transfer roller 110.

On the other hand, image information from a host computer (not shown) is irradiated as an optical image from an optical system 103 onto a photosensitive drum 102 in a process cartridge 101 to form a latent image on the photosensitive drum 102 in accordance with the image information. The latent image is developed by toner and visualized. Then, the recording material P is conveyed at a timing corresponding to the image information developed as a toner image, and a voltage having a polarity opposite to that of the toner image formed on the photosensitive drum 102 is applied to the transfer roller 110, so that the pressure contact nip portion Photosensitive drum 10
2 is transferred to the recording material P.

The recording material P, to which the toner image has been transferred, passes right above the static elimination needle 111 for removing electric charges after passing through the transfer portion, and travels on a transport path 113 provided on the electrical unit 112. Then, the toner image is conveyed to the fixing unit, and passes through a fixing nip portion between the fixing film 114 and the pressure roller 115 of the fixing unit, thereby receiving the toner image. And
The recording material P that has passed through the fixing unit is turned upside down again through the rear part of the inside of the apparatus main body behind the fixing unit, and is discharged by a discharge roller 116 onto a discharge tray 117 provided at the upper part of the apparatus main body.

[0007]

However, the conventional image forming apparatus has the following disadvantages. FIG. 7 is a sectional view of the fixing unit. As shown in FIG.
In the image forming apparatus, a fixing entrance guide 118 for guiding a sheet to the nip is provided upstream of a nip portion formed by a fixing film 114 as a fixing roller of a fixing unit and a pressure roller 115 with respect to a sheet conveying direction. And a fixing lower guide 119 for guiding the paper from the nip to the paper discharge unit is provided on the downstream side. The fixing inlet guide 118 and the lower fixing guide 119 are attached to the fixing frame 120. Therefore, the pressure roller 115 is arranged so as to be surrounded by a space formed by the fixing entrance guide 118, the lower fixing guide 119, and the fixing frame 120.

In the above configuration, when printing is performed on the paper P that has been left for a long time in a high humidity environment or the like and is sufficiently moist, it is included in the paper P at the nip portion between the pressure roller 115 and the fixing roller 114. Moisture evaporates instantaneously to generate water vapor. In normal printing, the toner T is deposited on the print surface, so that a film of the toner T is formed. Therefore, the water vapor of the paper P is released to the pressure roller 115 side and drifts around, and when continuous printing is performed, Water vapor is applied to the fixing guide 11 surrounding the pressure roller 115.
8 and the area around the lower fixing guide 119 is filled.

As a result, the pressure roller 115 is humid, and the gripping force between the paper P and the pressure roller 115 is reduced by the water vapor released from the paper P in the nip portion, so that the paper P slips. was there.

If the paper P slips, the conveyance of the paper P is delayed, and the paper detection sensor of the image forming apparatus detects the paper P.
There is a problem that it is determined that the sheet has not been conveyed and a jam occurs. Further, in the image transfer section and the nip portion of the fixing roller, the conveyance of the paper
The unfixed toner T transferred above is disturbed by the impact,
As a result, there is a problem that an image is defective.

The present invention has been made in view of the above problems, and an object of a first invention of the present application is to release water vapor around a pressure roller to the outside of a fixing unit to form a sheet and a pressure roller. An object of the present invention is to provide an image forming apparatus which maintains the grip force of the above and eliminates the paper conveyance failure and the accompanying image failure.

Another object of the second invention of the present application is to release the water vapor around the pressure roller to the outside of the fixing unit to maintain the gripping force between the paper and the pressure roller, and to improve the conveyance of the paper. Another object of the present invention is to provide an image forming apparatus which eliminates image defects associated with the image forming apparatus.

Another object of the present invention is to provide an image forming apparatus in which air is efficiently sent to the pressure roller so that the temperature of the pressure roller does not unnecessarily decrease and the fixability does not deteriorate.

[0014]

According to another aspect of the present invention, there is provided an image forming apparatus, comprising: a fixing unit for fixing a recording material onto which an image formed on an image carrier is transferred; In the image forming apparatus having, the fixing unit has a fixing roller and a pressure roller, the pressure roller,
A fixing guide member for guiding a recording material to a nip between the fixing roller and the pressure roller, and a lower fixing guide member for guiding a recording material from a nip between the fixing roller and the pressure roller to a paper discharge side. And a fixing frame member for attaching the lower fixing guide and the lower fixing guide, and the fixing inlet guide member, the lower fixing guide member, and the fixing frame member are provided with ventilation for ventilation on any or all surfaces thereof. A hole is provided, and a fan and its air passage are arranged so that air flows through the hole.

According to a second aspect of the present invention, there is provided an image forming apparatus having a fixing unit for fixing a recording material on which an image formed on an image carrier is transferred, wherein the fixing unit includes a fixing roller and a pressure roller. A fixing roller guide member for guiding a recording material to a nip between the fixing roller and the pressure roller, and discharging a recording material from a nip between the fixing roller and the pressure roller. A fixing lower guide member for guiding to the side, and a fixing frame member for attaching the fixing inlet guide and the fixing lower guide, the fixing inlet guide member, the fixing lower guide member,
A ventilation hole shape is provided only on each end surface of any or all of the fixing frame members in the longitudinal direction, and a fan and its air passage are arranged so that air flows through the hole shape.

Based on the above configuration, a hole shape communicating with the inside or outside of the image forming apparatus is provided on any or all surfaces of the member surrounding the pressure roller. In the hole shape, a fan and its air path are arranged in a direction of sucking or blowing air from one end. This makes it easier for the steam that fills the space surrounding the pressure roller to escape, so that the pressure roller can transport the paper without humidification, improving the paper transportability and preventing jams and image defects.

Alternatively, based on the above configuration, a hole shape communicating with the inside or outside of the image forming apparatus is provided only on one or all of the end surfaces of the member surrounding the pressure roller and only the end surface on the opposite side. In the hole shape, a fan and its air passage are arranged in a direction of sucking or discharging air from one end. This makes it easier for the water vapor filling the space surrounding the pressure roller to escape efficiently, so the pressure roller can transport the paper without moisture, improving the paper transportability and preventing jams and image defects. Become.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIGS. 1 to 3 are views for explaining a laser beam printer which is an image forming apparatus according to a first embodiment of the present invention. 1 is a sectional view of the main body, FIG. 2 is a perspective view of the fixing unit, and FIG. 3 is a sectional view of the fixing unit viewed from the bottom.

1 and 2, reference numeral 1 denotes a fixing unit for fixing and conveying the sheet P on which an image is formed, 2 denotes an entrance guide for guiding the sheet P to the fixing unit 1, 3
Is a fixing roller that forms a fixing nip, 4 is a fixing film that is a fixing roller that is driven and rotated by the rotational force of the pressing roller 3, and 5 is the fixing film 4.
Heater that is provided inside and supplies heat necessary for fixing,
Reference numeral 6 denotes a film guide provided inside the fixing film 4 and guiding the fixing film 4 and the heater 5.
Is a lower guide for guiding the paper P fixed and conveyed by the fixing nip to the discharge section, 8 is an intake hole which is an air intake hole provided in the inlet guide 2, and 9 is provided in the lower guide 7. Exhaust holes, which are air exhaust holes, 1
Numeral 0 denotes a louver for discharging the water vapor discharged from the exhaust hole 9 to the outside of the machine, 11 denotes a fan provided on a side surface of the printer main body A and rotates in a suction direction so as to take outside air outside the machine into the machine, and 12 denotes a fan. An electrical unit 13 is a fixing frame to which the inlet guide 3 and the lower guide 7 are attached and which forms the fixing unit 1 so as to surround the pressure roller 3.

Here, the pressure roller 3 is made of silicone rubber centered on a metal shaft, and its surface is coated with fluorine. The fixing film 4 is also a heat-resistant resin film whose surface is coated with fluorine, and the heat of the heater 5 is transmitted to the paper P through the fixing film 4.

As shown in FIGS. 2 and 3, the intake hole 8 is provided so as to penetrate in the longitudinal direction of the inlet / outlet guide 2 and the fixing frame 13, and the exhaust hole 9 is also provided in the lower guide 7 and the fixing frame 13 similarly. Is provided through. The wind from the fan 11 passes through the intake hole 8 in the direction of the arrow in FIGS.

In the above configuration, the laser beam printer main body A starts printing in response to an image output signal from a host computer (not shown). The sheet P on which an image has been formed in the transfer unit is guided by the inlet / outlet guide 2 and is conveyed to the nip between the fixing film 4 and the pressure roller 3.

At this time, the moisture contained in the paper P evaporates instantaneously due to the fixing heat in the fixing nip, and becomes water vapor. In normal printing, since a film made of the toner T is formed on the image forming surface of the sheet P on which the toner T is placed, most of the water vapor of the sheet P is discharged to the non-image forming side, that is, the pressure roller 3 side. You. For this reason, water vapor drifts around the pressure roller 3 and flows into the fixing frame 13, the inlet guide 2, and the lower guide 7 surrounding the pressure roller 3 depending on the rotation direction.

At this time, since the fixing frame 13, the entrance guide 2, and the lower guide 7 are provided with the intake holes 8 and the exhaust holes 9, the air taken in from the outside by the fan 11 cools the electrical unit 12 after cooling. The air that flows into the intake hole 8 and is sucked from the intake hole 8 discharges water vapor floating around the pressure roller 3 from the exhaust hole 9, thereby performing ventilation around the pressure roller 3. The water vapor discharged from the exhaust hole 9 is discharged from the louver 10 provided at the rear of the printer main body A to the outside of the printer.

For this reason, the sheet P is conveyed by the pressure roller 3 without slipping due to the steam generated in the fixing nip, and the image is fixed. The sheet P is conveyed as it is to the discharge port by the pair of conveying rollers.

In this embodiment, the fan 11 is connected to the apparatus main body A.
However, as described in claim 1, the same operation is performed even when the main unit A is rotated in the discharge direction, and the rotation direction is limited. is not.

By providing the intake hole 8 and the exhaust hole 9 in the member surrounding the pressure roller 3 as described above, the pressure roller 3 transports the paper P without slipping, so that the transportability of the paper is improved. , Jams and image defects are prevented.

Second Embodiment Next, a second embodiment according to the present invention will be described with reference to FIGS. Since the basic configuration of the main body in this example is the same as that of the first embodiment, the same reference numerals are given to the same elements.
A description of them will be omitted.

FIG. 4 is a perspective view of the fixing unit, and FIG. 5 is a sectional view of the fixing unit viewed from the bottom. As shown in FIGS. 4 and 5, the intake hole 8 is provided between the inlet guide 2 and the fixing frame 13.
The exhaust hole 9 is provided at the opposite end through the lower guide 7 and the fixing frame 13. In the above configuration, the wind from the fan 11 passes through the intake hole 8 to the exhaust hole 9 in the direction of the arrow in FIGS. 4 and 5, the laser beam printer main body A prints in response to an image output signal from a host computer (not shown). Start. The sheet P on which an image has been formed in the transfer unit is guided by the inlet / outlet guide 2 and is conveyed to the nip between the fixing film 4 and the pressure roller 3.

At this time, the moisture contained in the paper P evaporates instantaneously due to the fixing heat in the fixing nip, and becomes water vapor. In normal printing, since a film made of the toner T is formed on the image forming surface of the sheet P on which the toner T is placed, most of the water vapor of the sheet P is discharged to the non-image forming side, that is, the pressure roller 3 side. You.

For this reason, water vapor drifts around the pressure roller 3 and flows into the fixing frame 13, the inlet guide 2, and the lower guide 7 surrounding the pressure roller 3 depending on the rotation direction.

At this time, as shown in FIGS. 4 and 5, since the fixing frame 13, the inlet / outlet guide 2, and the lower guide 7 are provided with the intake hole 8 and the exhaust hole 9, the fan 11 sucks in from outside the machine. The wind blows into the intake hole 8 after cooling the electrical unit 12. Inlet guide 2 and fixing frame 13
The air sucked in by the suction hole 8 provided at the end of the pressure roller 3 flows along the longitudinal direction of the pressure roller 3, and the water vapor floating around the pressure roller 3 is dissipated by the lower guide 7 and the suction hole 8 of the fixing frame 13. The air is discharged from an exhaust hole 9 provided at the side end, and ventilation around the pressure roller 3 is performed. The water vapor discharged from the exhaust hole 9 is supplied to a louver 10 provided at the rear of the printer body A.
From the aircraft.

Therefore, the paper P is conveyed by the pressure roller 3 without slipping due to the water vapor generated in the fixing nib, and the image is fixed. The sheet P is conveyed as it is to the discharge port by the pair of conveying rollers. still,
In the present embodiment, the fan 11 rotates in the suction direction with respect to the apparatus main body A, but as described in the claims,
The same operation is performed even if the rotation is performed in the discharge direction with respect to the main body device A, and the rotation direction is not limited.

By providing the intake hole 8 and the exhaust hole 9 at the longitudinal end of the member surrounding the pressure roller 3 and the opposite end thereof as described above, the pressure roller 3 does not slip and the paper P Is transported, so that the transportability of the paper is improved, and jams and image defects are prevented.

[0035]

As described above, the first embodiment according to the present application is described.
According to the invention, since the air around the pressure roller and the recording material can be ventilated, good fixing conveyance properties can be obtained,
This prevents jams and image defects.

According to the second aspect of the present invention,
Since the air around the pressure roller and the recording material can be efficiently ventilated, good fixing and conveying properties can be obtained, and jam and image defects can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a laser beam printer illustrating an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective external view of a fixing unit illustrating the first exemplary embodiment.

FIG. 3 is a cross-sectional view of the fixing unit according to the first exemplary embodiment viewed from a bottom surface.

FIG. 4 is a perspective external view of a fixing unit illustrating a second embodiment.

FIG. 5 is a cross-sectional view of a fixing unit according to a second embodiment as viewed from the bottom.

FIG. 6 is a cross-sectional view illustrating a laser beam printer as an image forming apparatus according to a conventional example.

FIG. 7 is a cross-sectional view illustrating a fixing unit according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing unit 2 Inlet guide 3 Pressure roller 4 Fixing film 5 Heater 6 Film guide 7 Lower guide 8 Intake hole 9 Exhaust hole 10 Louver 11 Fan 12 Electrical unit 13 Fixing frame A Laser beam printer main body P Recording material T Toner 101 Process cartridge Reference Signs List 102 photoconductor drum 103 optical system 104 paper feed cassette 105 paper feed roller 106 separation pad 107 transport roller 108 transport roller 109 transfer guide 110 transfer roller 111 static elimination needle holder 112 electrical unit 113 transport path 114 fixing film 115 pressure roller 116 paper discharge Roller 117 Output tray 118 Fixing entrance guide 119 Lower fixing guide 120 Fixing frame

Claims (2)

[Claims] 1. An image forming apparatus having a fixing unit for fixing a recording material on which an image formed on an image carrier is transferred, wherein the fixing unit has a fixing roller and a pressure roller,
The pressure roller guides the recording material to a nip between the fixing roller and the pressure roller, and guides the recording material from the nip between the fixing roller and the pressure roller to a paper discharge side. And a fixing frame member for attaching the lower fixing guide and the lower fixing guide, and any or all of the lower fixing guide member, the lower fixing guide member, and the fixing frame member. An image forming apparatus comprising: a ventilation hole formed in a surface of a fan; and a fan and an air passage thereof arranged so that air flows through the hole. 2. The image forming apparatus according to claim 1, wherein the hole shape for ventilation is provided in any or all of the fixing guide member, the fixing lower guide member, and the fixing frame member. The image forming apparatus according to claim 1, wherein the hole shape is provided only on a surface near an end in a longitudinal direction of the member and a surface near an opposite end.