JPH04104264A - Cooling device - Google Patents

Abstract

PURPOSE:To efficiently cool a cooling roller by providing the cooling roller carrying a sheet ejected from a thermal system fixing device on an image forming device while cooling the sheet, and simultaneously, dipping end part of the cooling roller into a cooling liquid. CONSTITUTION:A gap between a fixing device 1 and a paper ejecting tray 9 serves as the cooling part 16 of the sheet 5, and a carrying roller 17 and the cooling roller 18 formed with a heating pipe are disposed to face each other up and down. The sheet 5 ejected between the ejecting rollers 7 and 8 of the fixing device 1 passes between the carrying roller 17 and the cooling roller 18, and cooled by the cooling roller 18, and simultaneously, heat taken away from the sheet 5 by the cooling roller 18 is radiated from the end part to cool the cooling roller 18 itself. One end part of the cooling roller 18 to cool the cooling roller 18 itself rotatively passes through the side wall of a tank 22 via an oil seal 23, into the tank 22 housed the cooling liquid 21, and dipped into the cooling liquid 21. Thus, the cooling roller 18 is efficiently cooled.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a cooling device used to cool a sheet discharged from a heat fixing type fixing device in an image forming apparatus such as a copying machine, a printer, or a facsimile machine. It is.

[Prior Art] In a copying machine that uses a heat fixing method, the sheets discharged from the heat fixing device usually have a heat of around 120 degrees Celsius, so if the sheets are discharged outside the machine and stacked, the sheets are not stacked. As a result of heat accumulation, the toner on the sheet becomes viscous and may stick to the back side of the next sheet, a so-called blocking phenomenon.

Therefore, conventionally, as a cooling device for cooling a sheet, a heat pipe roller is used as a conveyance roller for conveying the sheet discharged from a fixing device, and heat dissipation fins are provided at the end of the heat pipe roller. It has been proposed that the fins are cooled by wind to dissipate heat (
Utility Model Application No. 60-70847).

[Problems to be Solved by the Invention] However, in the case of the above-mentioned conventional cooling device, the heat pipe roller is cooled by dissipating the heat taken from the sheet by wind, so when the room temperature is high, The disadvantage is that the cooling effect is reduced.

Therefore, the present invention aims to make it possible to efficiently cool a cooling roller that cools a sheet even when the room temperature is high.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a cooling roller that cools and conveys a sheet discharged from a heat fixing type fixing device in an image forming apparatus, and The end of the roller is immersed in cooling liquid.

Further, it is preferable that the cooling roller is made of a heat pipe, and the end portion of the cooling roller is formed into a fin shape.

Furthermore, it is preferable to install a cooler for cooling the coolant above the tank containing the coolant.

[Function] Since the heat taken by the cooling roller from the sheet by contacting the sheet is radiated into the cooling liquid, the cooling roller can be efficiently cooled and the sheet can be effectively cooled. In addition, if the cooling roller is made of a heat pipe and the end of the cooling roller is formed into a fin shape, the heat radiation area of the cooling roller becomes large and the cooling liquid can be stirred by rotation, so that heat radiation can be promoted. If a cooler for cooling the cooling liquid is installed above the tank containing the cooling liquid, the cooling liquid can be forcibly cooled even if the cooling roller is stopped, and the cooling roller can be effectively cooled.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a heat fixing type fixing device l used in a copying machine and a sheet conveyance path downstream thereof.

The fixing device 1 forms a nip between a fixing roller 3 having a built-in heater 2 and a rubber layer with a thickness of 5 mm formed on the surface and rotatably pressed against the fixing roller 3. A sheet (transfer paper) having a pressure roller 4 configured as shown in FIG.
5 is fixed by heating and pressure by passing through the nip between the rollers 3 and 4, and the fixed sheet 5 is separated by a separation claw 6 and discharged onto a paper discharge tray 9 by a paper discharge roller 78. That's how it is. In addition, 111 and 11 respectively detect the fixing entrance guide plate, and I2 detects the surface temperature of the fixing roller 3 and turns on and off the heater 2 according to the detection level.
a thermistor for controlling the temperature of the fixing roller 3 to be constant (usually 185° C.) by sending an OFF command; 13 is a coated felt; 14 is a temperature fuse;
Reference numeral 15 indicates a fixing exit guide plate.

In the above configuration, in the present invention, a cooling section 16 for the sheet 5 is provided between the fixing device 1 and the paper discharge tray 9, and the cooling section 16
A cooling device will be installed in the To be more specific, the cooling unit 16 includes conveyance rollers 17 so as to form a pair of rollers.
and cooling rollers 18 made of heat pipes are disposed vertically facing each other, and upper and lower relay guide plates 19.20 are disposed between 17.18 parts of the rollers and 7.8 parts of the paper ejection roller of the fixing device 1.
The sheet 5 discharged from between the paper discharge rollers 7.8 of the fixing device 1 is guided by the relay guide plate 19.20 and passed between the conveyance roller 17 and the cooling roller 18. The sheet 5 can be cooled by the cooling roller 18, and the heat taken from the sheet 5 by the cooling roller 18 can be radiated from the end to cool the cooling roller 18 itself.

In order to cool the cooling roller 18 itself, as shown in FIG. At the same time, a heat radiation fin 18g is formed in the circumferential direction at one end of the cooling roller 18 as shown in FIG. A Peltier device 24 is installed as a cooler for cooling the cooling liquid 21 inside. The Peltier device 24 has fins 25a on the metal plate 25 on the cooling side.
25a is immersed in the cooling liquid 21, and the fin 261 is also erected on the metal plate 26 on the heat radiation side, and the fin 26M is immersed in the cooling liquid 21.
The configuration is such that the is located in the atmosphere.

In FIG. 2, reference numeral 27 indicates an oil pan for receiving the coolant 21, which is provided in case the coolant 21 leaks from the cooling roller 1B penetrating portion of the side wall of the tank 22. Further, as the cooling liquid 21, a liquid having a viscosity of 100C5 or less is preferably used, and for example, a liquid that is relatively difficult to evaporate, such as water or silicone oil, is used.

The sheet 5 on which the toner has been fixed by passing between the fixing roller 3 and the pressure roller 4 of the fixing device 1 is transferred to the paper ejection roller 7.
．． When ejected to the outside of the fixing device 1 by 8, it is guided by relay guide plates 19 and 20 and transferred to the conveying roller 17 and the cooling roller 1.
The sheet 5 is guided between the rollers 8 and 8, and is conveyed in a pinched manner to be discharged onto the discharge tray 9. At this time, the heat held by the sheet 5 is transferred to the cooling roller 18, and the sheet 5 is cooled. temperature is lowered. The cooling roller 18 is
Since one end penetrates into the tank 22 filled with the coolant 21 and is immersed in the coolant 21, the heat received from the sheet 5 can be radiated from the end to the coolant 21. Therefore, the sheet Even when the sheet 5 is continuously fed, the temperature is maintained at a constant level without impairing the cooling effect on the sheet 5. Also, at this time, a large number of heat radiation fins 18M are formed in the circumferential direction at one end of the cooling roller 18 immersed in the cooling liquid 21, so that the heat radiation area is large and the cooling liquid 21 is stirred as it rotates. From what you can do, the cooling roller! 8 is efficiently cooled. Furthermore, in the above, a Peltier device 24 is installed in the upper part of the tank 22, and a fin 25m erected on the cooling side metal plate 25 is inserted into the cooling liquid 21.
Since the fins 26a erected on the heat radiation side metal plate 26 are located in the atmosphere, when a current is applied, the fins 25a
The heat of the coolant 21 can be absorbed by the fins 261, and the heat can be dissipated to the atmosphere by the fins 261. Therefore, cooling roller 1
Even when the rotation of the cooling roller 8 is stopped, the cooling liquid 21 can be forcibly cooled by natural convection, and the cooling roller 18 can be effectively cooled, thereby further improving the cooling efficiency of the sheet 5 by the cooling roller 18. can.

It should be noted that the present invention is not limited only to the above embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

U Effects of the Invention] As described above, according to the cooling device of the present invention, the end portion of the cooling roller for cooling the sheet discharged from the heat fixing device is immersed in the cooling liquid. The heat transferred from the sheet to the cooling roller can be dissipated into the cooling liquid, and the cooling roller can be efficiently cooled. This allows the sheet to be cooled without being affected by room temperature. By using the above cooling roller as a heat pipe roller and having a fin-shaped end, the heat dissipation area can be increased and the cooling liquid can be stirred by rotation, so the cooling efficiency can be further increased. By installing a cooling device for cooling, the cooling fluid can be forcibly cooled even when the cooling roller is stopped, so the cooling roller can be effectively cooled and the sheet cooling effect can be further improved. Demonstrates excellent effects.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the cooling device of the present invention, and is a schematic diagram showing how it is installed in the conveying rod path downstream of the fixing device of a copying machine, and FIG. 2 is an enlarged view in the direction of the arrow in FIG. Figure 3 is the second
FIG. 2 is an enlarged view taken along line mm in the figure. 1... Fixing device, 5... Sheet, 18... Cooling roller, 18! ... Heat dissipation fin, 21 ... Coolant, 2
2...Tank, 24...Peltier device (cooling machine).

Claims (3)

[Claims] (1) A cooling roller is provided that cools and conveys a sheet discharged from a heat fixing type fixing device in an image forming apparatus, and the end of the cooling roller is immersed in a cooling liquid. Cooling system. (2) The cooling device according to claim (1), wherein the cooling roller is made of a heat pipe, and an end portion of the cooling roller is formed into a fin shape. (3) The cooling device according to claim (1) or (2), further comprising a cooler for cooling the coolant installed above the tank containing the coolant.