JPH09171311A - Image forming device - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To cool the front and back of a transfer paper with a simple structure, to prevent curling and blocking of the transfer paper, and to prevent troubles due to temperature rise of the transfer paper during double-sided copying (photoconductor temperature rise, The purpose is to prevent the occurrence of difference in glossiness between double-sided images. An image forming apparatus including a fixing device that fixes an unfixed toner on a transfer paper onto the transfer paper by the action of heat and pressure, and a cooling device that cools the transfer paper discharged from the fixing device, In the cooling device, an air blowing unit for cooling the transfer paper after fixing and a cooling / heat radiating unit are arranged to face each other with the transfer paper transport path interposed therebetween.

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 having a fixing device for fixing an unfixed toner on a transfer sheet by the action of heat and pressure by cooling the fixed transfer sheet. The present invention relates to an image forming apparatus capable of preventing the occurrence of curling due to an uncured toner on a transfer sheet, and the prevention of problems such as the preceding transfer sheet adhering to the succeeding transfer sheet when printing a large number of sheets.

[0002]

2. Description of the Related Art In an image forming section of an electrophotographic copying machine, printer, facsimile machine or the like, a toner image formed on a photoconductor is transferred onto a transfer paper and then heated and pressed by a fixing device. The image is formed by fixing the image. In such an image forming apparatus, conventionally, a sheet immediately after toner fixing is passed between a pair of cooling rollers, and
A fixing device has been proposed in which the cooling roller is cooled by a fan. (See JP-A-6-75490). FIG. 5 is an explanatory view of a conventional example described in JP-A-6-75490, in which a sheet 1 carries a toner image transferred from a photoconductor of an image forming section located on the left side of the drawing, When passing through the fixing device 5 composed of the heater roller 2 and the pressure roller 3, the toner is heated by the heater roller 2 heated by the heater lamp 4 and the toner is melted.
At the same time, since pressure is applied by the pressure roller 3, the melted toner penetrates into the fibers of the paper 1 and is fixed. The sheet 1 which has been fixed is discharged by the rotation of the heat roller 2 and the pressure roller 3, and is cooled by a fan 6 provided facing each other across the discharge path. Pass between 8. As a result, the temperature difference between the front and back of the sheet 1 is eliminated, and the toner is discharged in a solid state, so that curl is prevented from occurring, and when more sheets are copied and stacked on the sheet discharge tray, the preceding It is possible to prevent the occurrence of a situation in which the succeeding paper adheres to the toner on the existing paper.

[0003]

However, in the above-mentioned conventional fixing device, a cooling roller that nips in a vertical positional relationship is used.
Since it requires a large fan 6 for cooling the rollers 7, 8 and its driving means, and both rollers at the same time, it is difficult to miniaturize and the cooling efficiency is not good. there were. The present invention has been made in order to solve the problems in the above-mentioned conventional fixing device, and can cool the front and back sides of a transfer paper with a simple structure, prevent curling and blocking of the transfer paper, and prevent double-sided copying. The purpose is to prevent problems due to the temperature rise of the transfer paper (photoconductor temperature rise, difference in glossiness of double-sided image).

[0004]

In order to solve the above problems, the invention of claim 1 is a fixing device for fixing an unfixed toner on a transfer paper to the transfer paper by the action of heat and pressure, and a fixing device. In an image forming apparatus including a cooling device that cools the transfer paper discharged from the transfer device, the cooling device includes an air blower that cools the transfer paper after fixing and a cooling / heat radiating device, each of which is a transfer paper transport path. It is characterized in that they are arranged so as to face each other with sandwiching therebetween. For this reason, the transfer paper after fixing is cooled efficiently,
It is possible to prevent curling and blocking of the transfer paper and troubles due to temperature rise of the transfer paper during both sides (photoconductor temperature rise, difference in glossiness of double-sided image). The invention of claim 2 is characterized in that the cooling / heat dissipating means is provided on the upper side and the air blowing means is provided on the lower side of the transfer paper conveyance path. Therefore, the transfer sheet after fixing can be cooled more efficiently, and efficient cooling and heat dissipation including the airflow effect can be performed. According to a third aspect of the present invention, when the transfer paper after fixing is passed through the cooling device, the transfer paper is cooled by the cooling device, and when the space between the paper and the paper non-passage, the cooling / heat dissipating means is the blowing means. It is characterized by being cooled by. For this reason,
It is possible to reliably cool the transfer paper during continuous paper passing, prevent heat from being accumulated in the cooling / heat radiating means, and always perform stable cooling of the transfer paper.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 is a sectional view of a fixing device and a cooling device of an image forming apparatus corresponding to claims 1 and 2 of the invention. An image forming unit including a photoconductor, a charger, a developing unit, a transfer unit, and the like is arranged on the left side of the drawing, and the transfer paper 10 that receives the toner image on the photoconductor and holds the toner image is in the direction of the arrow. Through the entrance 11a of the fixing device 11. The fixing device 11 includes a heating roller 13 having a heater 12 therein.
And a pressure roller 14 that presses the transfer paper 10 passing through the nip portion while being in pressure contact with the outer peripheral surface thereof. At least the outer peripheral surface of the heating roller 13 is coated with a silicon rubber material in order to prevent the adhesion of toner. Cooling device 1
Reference numeral 5 denotes a heat radiation fin 16 made of metal such as aluminum or copper having good heat conductivity, a blower fan 17 disposed on the opposite side of the heat radiation fin 16 with a transfer paper conveyance path interposed therebetween, and a blower fan 17
Drive device 18 of. Reference numeral 19 is a conveying roller.

In the above structure, the transfer paper 10 is subjected to charging, exposure, development and transfer processes in an image forming section (not shown).
The toner is transferred onto the top. The toner on the transfer paper 10 is heated by the heater 12 at 150 to 160 ° C.
At the nip portion between the roller 13 and the pressure roller 14, it is fixed on the transfer paper 10 by heat and pressure from each roller. The transfer paper 10 that has been fixed is discharged from the outlet 11b of the fixing device 11. At this time, the drive device 18 rotates the blower fan (blower means) 17 to bring the transfer paper into contact with the heat radiation fins 16 by the wind pressure from the fan. Let The back surface (lower surface) of the transfer paper 10 is cooled by the wind (air flow) from the blower fan 17, and the front surface (upper surface) having the toner comes into contact with the heat radiation fins 16 at room temperature to remove heat, thereby forming a back surface. Similarly cooled. The heat radiated from the radiating fins 16 (indicated by the upward arrow) is configured to be discharged from an exhaust port (not shown) provided in the casing of the image forming apparatus. Cooling device 1
The transfer paper 10 that has passed through 5 is cooled on the front surface and the back surface in the same manner, and is discharged to the outside of the apparatus by the transport roller 19.

As described above, at the positions facing each other with the discharge path of the fixed transfer paper discharged from the fixing device 11 in between,
Since the blower unit 17 for cooling the transfer sheet after fixing and the cooling / heat radiating unit 16 are provided, the front and back sides of the transfer sheet can be cooled with a simple configuration, and the transfer sheet is heated and It is possible to prevent the occurrence of curling and blocking of the transfer paper due to the discharge of the toner in an uncured state. In addition, in this embodiment, the radiation fin 16 is placed on the upper side,
Although the blower fans 17 are arranged on the lower side, respectively, this is merely an example, and the upper and lower positions may be reversed, or they may be arranged facing each other in the lateral direction. In addition, during double-sided copying, the heated transfer paper is re-fed to the transfer position around the photoconductor, which causes problems due to the temperature rise of the transfer paper, that is, the temperature rise of the photoconductor, the difference in glossiness of double-sided images, etc. However, if the temperature is lowered in advance by the cooling device of the present invention, such a problem disappears. Further, unlike the above-mentioned conventional example, since it is not necessary to provide a large roller pair or a large fan for cooling the same, the cooling means can be downsized while the cooling fins and the fan cooperate to perform efficient cooling. You can [Embodiment 2] FIG. 2 is a sectional view of a fixing device and a cooling device of an image forming apparatus according to a third aspect of the present invention. FIG.
The same parts as those of the above are denoted by the same reference numerals, and the description of the duplicated configuration and operation is omitted. However, in this embodiment, the blower fan (cooling means) 1 is used when the transfer paper 10 is passed through the cooling device 15.
7 and the heat radiation fins (heat radiation means) 16 cool the transfer paper, while the heat radiation fins 16 are cooled by a blower fan 17 between the paper and when no paper is passed. In the above configuration, when the transfer paper does not pass through the cooling device 15 and when the paper does not pass through, the drive controller 18 rotates the blower fan 17 to cool the heat radiation fins 16 in which heat is accumulated during the immediately preceding paper passing. To do. As a result of the bottom surface of the radiation fin 16 being cooled by the wind of the blower fan 17, the entire radiation fin 16 is cooled. In the present embodiment, since the blower fan 17 is controlled so as to cool the radiation fins 16 instead of stopping the driving of the cooling device 15 during the paper interval and the non-paper passage as described above, the radiation fins 16 are controlled. Since heat is not accumulated, stable transfer paper cooling can always be performed. As a result, it is possible to more effectively prevent the occurrence of curling and blocking of the transfer paper and the troubles due to the temperature rise of the transfer paper during double-sided copying (photoconductor temperature rise, difference in glossiness of double-sided image). You can

Next, FIG. 3 is a schematic diagram showing the structure of another embodiment of the present invention. In this embodiment, the cooling fan 15 is a blower fan 17 driven by a drive controller 18.
A characteristic feature is that the belt conveying device 20 facing this is used. The belt conveying device 20 has a structure in which an endless metal belt 21 having good thermal conductivity is stretched by rollers 22 and one of its conveying surfaces faces the discharge path of the transfer paper. The metal belt 21 is driven in the direction of the arrow to transfer the transfer paper 1 in the discharge path.
It has a function of transporting 0 in the direction of the arrow, and a heat dissipation function of removing heat from one surface (upper surface) of the transfer paper which is in a heated state immediately after being discharged from the fixing device 11 like the heat dissipation fin 16 of the above-described embodiment. Since the metal belt 21 travels and comes into contact with each transfer paper on different surfaces, the belt surface immediately after the heat is accumulated by the heat from the transfer paper when the preceding transfer paper is conveyed must be continuously in contact with the transfer paper immediately after. There is no. That is, since the belt surface that has accumulated heat is inverted once to be cooled upward and then cooled, it is inverted to the conveyance path side and then cooled while conveying the next transfer sheet, so that the cooling efficiency is high. In addition, the blower fan 17
Is for removing heat from the lower surface of the transfer paper to cool it, as in the case of the above embodiment.

In this embodiment as well, as in the embodiment of FIG. 2, the metal belt 21 is cooled by driving the blower fan 17 when the paper is not passing, between the paper, and the like. Good. The effect is similar to the case of FIG. Also,
The heat radiated from the upper surface of the metal belt 21 is configured to be discharged from an exhaust port (not shown) provided in the casing of the image forming apparatus. The transfer paper 10 that has passed through the cooling device 15 is similarly cooled on the front surface and the back surface, and is discharged to the outside of the device.

FIG. 4 shows another embodiment of the present invention. In this embodiment, as the cooling device 15, a blower fan 17 driven by a drive controller 18 and a metal roller 25 facing the fan 17 are used. The point that was done is characteristic. At least the outer peripheral surface of the metal roller 25 is made of a metal having a good thermal conductivity, and the outer peripheral surface of the metal roller 25 is in contact with the upper surface of the transfer paper that advances along the transport path. This metal roller 25 is
By being driven in the direction of the arrow, the transfer sheet 10 in the discharge path is conveyed in the direction of the arrow, and the transfer sheet in a heated state immediately after being discharged from the fixing device 11 like the heat dissipation fin 16 of the above-described embodiment. It has a heat dissipation function to remove heat from one side (upper surface). The blower fan 17 is for removing heat from the lower surface of the transfer paper to cool it, as in the above-described embodiment.
Also in this form example, as in the form example of FIG.
The metal roller 25 may be cooled by driving the blower fan 17 between the sheets. The effect is similar to the case of FIG. Also, the metal roller 2
The heat radiated from 5 is discharged from an exhaust port (not shown) provided in the casing of the image forming apparatus. The transfer paper 10 that has passed through the cooling device 15 is similarly cooled on the front surface and the back surface, and is discharged to the outside of the device.

[0011]

The effects of the present invention are as follows. The image forming apparatus according to claim 1, wherein the fixing device fixes the unfixed toner on the transfer paper to the transfer paper by the action of heat and pressure, and blows air downstream of the fixing device to cool the transfer paper after fixing. Means 27 and cooling / radiating means 16, 21, 2
Since the cooling device 15 composed of 5 and 5 is provided, it is possible to cool the front and back surfaces of the transfer paper immediately after being fixed simultaneously and in a short time, while having a small and simple structure, and to sufficiently transfer the transfer paper and the toner image. As a result of being able to cool and harden as a result, defects due to curling and blocking of the transfer paper and temperature rise of the transfer paper during double-sided copying (photoconductor temperature rise, difference in glossiness of double-sided image)
Can be prevented. In the image forming apparatus according to claim 2, the cooling / heat radiating means 16, 21, and 25, which have accumulated heat by removing heat from the transfer paper, are arranged on the upper side of the transfer paper discharge path, and the blower means 17 is on the lower side. By arranging in, the airflow effect can be assisted and cooling and heat dissipation can be efficiently promoted. In the image forming apparatus according to the third aspect of the present invention, since the air blowing means 17 is controlled so as to directly cool the cooling / heat radiating means 16, 21 and 25 during the paper interval and the non-paper passage, heat is radiated to the heat radiation fins 16 and the like. The transfer paper is not accumulated and can always be stably cooled.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an image forming apparatus including a cooling device according to an exemplary embodiment of the present invention.

FIG. 2 is a sectional view of an image forming apparatus according to another embodiment of the present invention.

FIG. 3 is a sectional view of an image forming apparatus according to another embodiment of the present invention.

FIG. 4 is a sectional view of an image forming apparatus according to another embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional cooling device.

[Explanation of symbols]

10 transfer paper, 11 fixing device, 12 heater, 13
Heating roller, 14 pressure roller, 15 cooling device, 16
Heat dissipation fin, 17 blower fan, 18 drive device,
19 Conveyor Roller, 20 Conveyor Belt 25 Conveyor Roll
La.

Claims (3)

[Claims] 1. An image forming apparatus comprising: a fixing device for fixing an unfixed toner on a transfer paper to the transfer paper by the action of heat and pressure; and a cooling device for cooling the transfer paper discharged from the fixing device. In the above cooling device, the cooling device may have a configuration in which an air blowing unit that cools the transfer paper after being fixed by the fixing device and a cooling / heat radiating device are arranged so as to face each other with a transfer paper transport path interposed therebetween. A characteristic image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the cooling / heat dissipating means is provided on the upper side of the transfer sheet conveying path, and the air blowing means is provided on the lower side thereof. 3. When the transfer paper after fixing is passed through the cooling device, the transfer paper is cooled by the cooling device, and the cooling / heat radiating means is cooled by the air blowing means when the paper is not passing or between the paper. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: