JPS60142372A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent dew condensation and prevent discharged paper from getting wet by warming a guide plate on which transfer paper passed through a fixing means is guided to a paper discharge roller. CONSTITUTION:The transfer paper S having a toner image on the surface after transfer is guided on the guide plate 2 from the left side and caught by a fixing roller, and an image is transferred thereto while the paper is pressed between both rollers 3 and 4 and also heated. The paper after this fixation is guided by guides plates 8 and 9 and clamped between a couple of rollers 10 and 11, which discharges it to a paper discharge tray 12 as copied paper. End parts of an upper ventilation flue 18-1 and a lower ventilation flue 18-2 are linked mutually to form a continuous ventilation flue; and high-temperature air in the upper ventilation flue 18-1 is guided to the lower ventilation flue 18-2 through the operation of an air discharge fan 17-1 and the temperature of the guide plate 9 is raised by utilizing the warm air to prevent dew condensation, thereby preventing the transfer paper S from getting wet.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a technology for a heat fixing device for transfer paper images in an electrophotographic copying machine.

Prior Art Conventionally, in this type of heat fixing device, a ventilation path is formed between the main body of the device and the fixing device, and outside air is introduced into the ventilation path and is discharged outside the device by natural convection. Transfers the amount of heat released within the image forming device to the outside,
Techniques for preventing heat damage to internal members have been known.

However, in this type of fixing device, dew condensation may occur on the guide member that forms a conveyance path through which the transfer paper with the image fixed thereon passes, resulting in the transfer paper becoming wet and the quality of copying being impaired. This is because the temperature difference between the upper and lower parts of the plate forming the guide portion side becomes large.

Purpose The present invention has been developed in view of the above-mentioned phenomenon, and is designed to prevent dew condensation due to water vapor evaporated from the transfer paper due to heating on the conveyance path through which the transfer paper on which the toner image is fixed is formed by a heated roller. , it is an object of the present invention to provide a fixing device that prevents transfer paper passing through a conveyance path from getting wet.

Configuration The device of the present invention is characterized by the features described above in the claims section, and the following is an explanation of an embodiment thereof with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a cross-sectional view of an embodiment of the fixing device of the present invention installed in an electrophotographic copying machine, and in the figure, Y indicates the fixing device;
2 is a transfer paper guide plate, 3 is a heating roller whose circumferential surface is treated with Teflon and is provided with a heat source 5 such as a halogen lamp inside, and 4 is a pressurizing roller that is pivotally supported in parallel to the heating roller 3. The peripheral surfaces of the rollers 3.4 are made of silicone rubber, etc., and the peripheral surfaces of both rollers 3.4 are in pressure contact with each other.The rollers 3.4 rotate in the directions of the arrows, and the transfer paper is passed between them.
That is, the heating roller 3 and the pressure roller 4 constitute a fixing roller. Further, a cleaning roller 6 and a toner scraping member 7 are in contact with the surface of the pressure roller 4 . A cleaning pad 13 made of felt or the like is in contact with the circumferential surface of the heating roller 3 under a predetermined pressure. cleaning,
Removal takes place.

Further, 20 is a thermistor for temperature control on the surface of the heating roller 3.

8 and 9 are upper and lower kite plates for discharging the transfer paper after image fixation, 10 and 11 are paper discharge rollers, 12 is a paper discharge tray, and 13 is an electrostatic charge installed immediately after the paper discharge rollers 10 and 11. The removal plans 26 and 27 are claw members for peeling off the transfer paper stuck to the circumferential surface of the respective rollers 3 and 4 from the rollers. , 14 is the heating roller 3
Insulating material 15 that efficiently blocks heat radiated from
The cover 16 is a supporting member that supports the roller 3, and is arranged to cover the upper periphery of the roller 3, and constitutes the top part of the fixing device ↓.
An upper ventilation passage 18-1 is formed between the two.

Further, the guide plate 9 and the duct 19 form a lower ventilation passage 18-2. A fan 17-1 is installed at the end of the duct 9 to exhaust air to the outside of the apparatus.

In the figure, the transfer paper S with the toner image on its surface after the transfer is guided from the left side by the gabble plate 2 and held by the fixing roller, where the image is transferred under the pressure and heating action of both rollers 3.4. After fixing, the paper is guided by a guide plate 8.9 and sandwiched between a pair of paper ejection rollers 10, if, and by its ejection action, it becomes a copy paper and is delivered to a paper ejection tray 1.
2.

At this time, the area where the guide plate 9 facing the lower side of the transfer paper is installed is lower in temperature than the upper part of the fixing device, so the temperature is lower than that in the area where the guide plate 9 facing the bottom side of the transfer paper is installed. Condensation occurs on contact with water vapor. In particular, when continuously passing paper,
Since the rise and diffusion of water vapor generated on the underside of the paper is prevented by the paper white body, condensation phenomenon occurs significantly, and wetting of the underside of the paper becomes a major problem.

Therefore, in the present invention, the upper ventilation passage 18-1 and the lower ventilation passage 1
8-2 are communicated with each other to form a series of ventilation passages, and by the action of the exhaust fan 17-1, high-temperature air in the upper ventilation passage 18-1 is guided to the lower ventilation passage 18-2. ,
By raising the temperature of the guide plate 9 using the hot air, consideration is given to preventing the above-mentioned dew condensation and preventing the transfer paper S from getting wet, so that high-quality copies can be obtained.

FIG. 2 shows a rough fragmentation cut along the ventilation path 1-8.

The heat generated from the heating roller 3 is partially transferred to the upper ventilation passage 18 through the heat insulating material 15 and the supporting part 14.
-1 and heats the nearby air. Furthermore, water vapor and heat evaporated from the transfer paper after fixing flow into the ventilation path by convection through the kite plate 8 located on the paper conveyance path. Therefore, in order to prevent heat damage to other devices adjacent to the fixing device↓, it is necessary to exhaust the heat from these devices to the outside of the machine.
In this device, the exhaust fan 17-1 is used to draw outside air into the ventilation path 1-8 to enhance the cooling effect, and the heated air is brought into contact with the lower surface of the guide plate 9 during exhaust. The purpose of preventing dew condensation is achieved by increasing the temperature of the plate 9.

In other words, the upper ventilation passage heated by the heating row 23]
8-1 to the lower ventilation passage 1 by the fan 17-1.
8-2, the discharge guide plate 9 is heated to prevent dew condensation and the discharged paper from getting wet.

Embodiment 2 FIG. 3 is a cross-sectional view of another embodiment of the device of the present invention, most of the structure of which is the same as that described in Embodiment 1. That is, the members designated by the same reference numerals as those shown in the first drawing are the same as those described in connection with the first embodiment, and therefore the description thereof will be omitted.

However, the exhaust fan 17-2 is provided in the center of the upper ventilation passage 18-1 formed between the support member 14 that supports the heat insulating material 15 and the uppermost cover 16. The structure is different from the first embodiment in that the lower plate 9 does not have a duct 19 attached thereto, and a heat generating source 21 such as a surface heater is installed at an appropriate position on the back surface thereof.

FIG. 4 is a schematic perspective view of the guide plate 9 and the surface heater 21. A heat generation source is connected to an electric circuit, and heats the guide plate 9 by a required amount of heat to an extent that no condensation occurs. In FIG. 3, the transfer paper S is guided from the left side to the guide plate 2, passes through the fixing roller, where the toner image is fixed, and is then guided between the guide plates 8 and 90. Inside, the temperature is high at the top, and the temperature at the bottom is low, so the temperature near the guide plate is also low. Therefore, the water vapor that evaporated from the transfer paper S mainly condenses on the surface of the lower guide plate 9, turning the transfer paper S into a pot and copying. The quality of the product was significantly reduced.

Therefore, in this case, by installing a heat source 21 such as a surface heater at the bottom of the kite plate 9, the temperature of the condensation part in the fixing device is increased to prevent condensation and to obtain high-quality copies. This is what I did.

Note that the exhaust fan 17-2 causes the ventilation path 18-+VC air to circulate, and exhausts the heat released through the heat insulating material 15 and the support member 14 to the outside of the device, thereby cooling the vicinity and to prevent heat damage to other equipment being used.

Effects As described above, the apparatus of the present invention warms the guide plate during which the transfer paper that has passed through the fixing means is guided by the paper ejecting roller to prevent dew condensation from forming in this area and prevents the transfer paper from being ejected. This prevents the paper being used from getting wet and allows you to obtain high-quality copied images.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of an embodiment of the fixing device of the present invention installed in an electrophotographic copying machine, and FIG. 2 is a schematic side sectional view taken along a ventilation path. FIG. 3 is a cross-sectional view of another embodiment of the apparatus of the present invention, and FIG. 4 is a schematic perspective view of the lower guide plate and surface heater.
...Guide plate, 3. Heating roller, 4. Pressure roller, 1
0 and 11...Discharge roller, ]4...Insulating material support member, 15...Insulating material, 16...Top cover, 17-
1.17-2 ・Exhaust fan, world, 18-1 and 1
8-2 ・Ventilation duct, 21... Heat source, S... Transfer paper agent Patent attorney Makoto Kon Figure 1 6 Figure 2

Claims (1)

[Scope of Claims] 1. A device for fixing a toner image by heating a transfer paper on which a toner image is placed,
A fixing device comprising: means for heating the surface of the transfer paper that has passed through the fixing means on the discharge kite side side at least to such an extent that no clumps occur due to water vapor evaporated from the transfer paper. 2. A patent claim characterized in that a part of the wall surface in the middle of the duct for exhausting air near the heating roller, which constitutes a part of the fixing means, is also used as a transfer paper guide part or is brought into contact with the same member. The fixing device according to scope 1. 3. The fixing device according to claim 1, characterized in that a heating element is provided adjacent to the transfer paper guide member provided between the fixing means and the paper ejection roller.