JPH0736301A - Heat fixing device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a heating and fixing device that does not cause image blurring by sufficiently preheating transfer paper for image formation and eliminating separation from the fixing roller. A guide device, a guide plate 6 and / or a guide roller 7, or a belt 8 which presses the transfer paper 4 against the fixing roller 2 in front of the fixing roller 2 and the pressure roller 3 each having a halogen lamp 1 are provided. Then, the transfer paper 4 is sufficiently preheated to improve the fixing efficiency and form a low power consumption type fixing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing device for fixing an object to be fixed such as a toner image formed by an electrophotographic device, an electrostatic recording device or a printing machine, a printer or the like.

[0002]

2. Description of the Related Art Conventionally, as a fixing device used in an image forming apparatus such as a copying machine or a printer, 1) a fixing rotating roller which is in contact with an unfixed toner image and a pressure roller which is in pressure contact with the fixing rotating roller. (Japanese Patent Publication 5-2290
No. 8), 2) a heating and fixing roller and a pressure roller capable of coming into contact with and separating from the heating and fixing roller (see Japanese Patent Publication No. 5-22909), 3) a heating roller for fixing, A fixing belt which is brought into contact with the heating roller for fixing and arranged endlessly, and rotates together with the pressure roller (see Japanese Utility Model Laid-Open No. 5-8573), 4) a fixing roller, and an aluminum cored bar. Known are those that use a hard alumite treated paper and press the paper with two emery rollers to fix the toner image (Electrophotographic Society edition), the basics and applications of electrophotographic technology, page 331, Corona Publishing Co., Ltd.). ing.

[0003]

However, in the prior arts 1) and 2) of such a conventional defining device, as shown in FIG. 4, a fixing roller having a halogen lamp 1 for heating therein is provided. Since the nip width for pinching the image forming paper 4 between the pressure roller 2 and the pressure roller 3 was narrow, the heating time was short, and therefore it was necessary to fix with the roller to which high power was supplied. Moreover, there is a problem that this power must be supplied even when the fixing is not performed (when the paper is not passed), which causes a large power consumption of the copying machine. In addition, reference numeral 5 in FIG. 4 is a separation claw.

Further, in the fixing device of the prior art 3), since the belt roller as a pressure roller is small, it is difficult to apply a large pressure.

Further, the fixing device of the prior art 4) has a problem that the image forming paper is separated from the fixing roller because there is no guide member for the image forming paper between the fixing roller and the pressure roller. It was

The present invention has been made to solve the above-mentioned problems, and its purpose is to sufficiently preheat the transfer sheet for image formation and eliminate the separation from the fixing roller to prevent the occurrence of image blur. To provide.

[0007]

SUMMARY OF THE INVENTION The present invention solves the problem that the heating time is short by preliminarily approaching and pressing the image forming paper against the fixing roller before reaching the nip position of the fixing unit, and preheating. At the same time, a sufficient fixing pressure is applied by a large-diameter pressure roller to eliminate separation of the image forming sheet from the fixing roller, thereby providing a heating and fixing device capable of smooth sheet conveyance without image blurring.

That is, the heat fixing device according to the first aspect of the invention is an electrophotographic heat fixing device comprising a fixing roller heated by a heat source and a pressure roller in contact with the fixing roller. It is characterized in that a guide device for pressing or contacting the image forming sheet with the fixing roller is provided at the front position in the rotation direction of the pressure roller,

According to a second aspect of the present invention, in addition to the above configuration, the contact position of the guide roller of the guide device with the fixing roller is at a front position at an angle of 5 to 90 ° from the contact position of the pressure roller. It is characterized by being.

The embodiments of the present invention are as follows. (1) The heat fixing device according to claim 1, wherein the guiding device is composed of a guide plate installed near the fixing roller. (2) The heat fixing device according to claim 1 or 2, wherein the guiding device is composed of a pressure roller having a diameter smaller than that of the pressure roller. (3) The heat fixing device according to claim 1 or 2, further comprising an image forming paper guide plate provided between the guide roller and the pressure roller. (4) The heat fixing device according to claim 1 or 2, wherein a belt having a full width or a partial width is provided on both the guide roller and the pressure roller.

Generally, in an electronic image forming apparatus, such as a copying machine, a fixing roller is made of Teflon coat, a pressure roller is made of silicone rubber, and a fixing roller is always coated with silicone oil for preventing toner offset. After removing the offset toner with a blade, oil is applied with a felt pad, and the amount of application is controlled with a fluororubber blade. Oil is pumped from the oil tank to the oil pan, and excess oil overflows and is returned to the tank.

Besides, there are various combinations of the fixing roller and the pressure roller according to the purpose. For example, the former is a silicone rubber coat, the latter is a Teflon coat, the former is a silicone rubber coat, and the latter is a silicone rubber. A particularly preferred fixing roller used in the present invention is an aluminum core material 2b (aluminum roller) having an inner diameter of 10 to 100 mm coated with a thin Teflon film 2a having a thickness of 0.05 to 2 mm. Further, as the pressure roller, one having a thick silicon rubber layer 3b of 5 to 20 mm coated on an aluminum (or steel) core material 3b having the same inner diameter as described above is particularly preferable.

The belt used in the present invention is preferably made of heat resistant rubber or heat resistant plastic. As the image forming toner, either a dry toner or a wet toner can be used.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of a heat fixing device according to the invention described in claim 1 and the first embodiment.

The transfer paper 4 on which the toner has been transferred is passed through the transfer portion by the electrophotographic image forming method, and the transfer paper 4 is guided by the guide plate 6.
Be led to. The transfer sheet 4 approaches the fixing roller 2 by the guide plate 6 and finally comes into contact with the fixing roller 2. Since the transfer paper 4 is heated until it comes close to the guide plate 6 and goes out of the nip portion of the pressure roller 3, the transfer paper 4 is heated for a longer period of time than the conventional fixing device shown in FIG. It absorbs a lot of heat. Alternatively, if the amount of heat is made equal to that of the conventional example, the heating power can be reduced to a fraction.

Then, the transfer paper 4 is heated and pressed by the fixing roller 2 and the pressure roller 3 similar to those of the conventional fixing device to fix the toner. The separation claw 5 is provided at the rear position of the fixing unit, and the transfer paper 4 is reliably peeled off from the fixing roller 2 by this, and the process is moved to the next step.

When toner that does not require oil application is used, it is not necessary, but when oil application is required, an oil application device is provided. The oil applying device includes an oil pan 9, a fixing oil 10 and an oil pad 11. The oil pad 11 is pressed against the fixing roller 2 to apply the fixing oil 10. Inside the fixing roller 2, a halogen lamp 1 is installed as a heating source.

FIG. 2 is a diagram showing a second embodiment of the heat fixing device according to the invention of claim 2 and the second to third embodiments.
That is, in FIG. 2, instead of the guide plate 6, the guide roller 7
And the guide plate 6 is used. Compared to the case where the guide plate 6 is used alone, the image forming transfer paper 4 is further prevented from moving with respect to the fixing roller 2, and the image is less blurred.
Further, there is an advantage that the degree of adhesion between the transfer paper 4 and the fixing roller 2 is further improved and the heat transfer efficiency is also improved. Therefore, the angle θ (when viewed from the center of the fixing nip portion) of the installation position of the guide roller 7 is preferably 5 to 90 °.

FIG. 3 is a diagram showing a third embodiment according to the invention described in claim 1 and embodiment 4. That is, FIG.
The belt 8 is installed on both the guide roller 7 and the pressure roller 3. The belt 8 is made of heat resistant rubber, heat resistant plastic or the like. The width of the belt 8 may be the full width or a partial width of the roller.

The use of the belt 8 has the advantages that the paper 4 is not separated from the fixing roller 2 at all and the transfer paper 4 can be transported smoothly as compared with the heating and fixing device shown in FIG. Further, Conventional Example 4) (Actual Kaihei 5-857)
3), the belt 8 is installed between the conventional large-diameter fixing roller 2 and the large-diameter pressure roller 3 over the guide roller 7 in front of the roller. In addition to the large diameters of the rollers 2 and 3, higher pressure can be applied to the transfer paper 4.

In all of the above-mentioned embodiments, the lamp 1 serving as the heating source is provided in the fixing roller 2. However, on the contrary, the same applies even if the lamp 1 is inside the pressure roller 3. The effect is obtained.

[0022]

According to the first aspect of the present invention, since the transfer paper is heated for a long time, the fixing rate can be improved and a low power heat fixing device can be obtained. According to the invention described in claim 2, since both the fixing roller and the pressure roller have large diameters, a higher pressure can be applied to the transfer paper.
The fixing efficiency can be improved, and the transfer paper can be smoothly transported.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a first embodiment of the present invention.

FIG. 2 is a sectional view illustrating a second embodiment of the present invention.

FIG. 3 is a sectional view illustrating a third embodiment of the present invention.

FIG. 4 is a sectional view illustrating an example of a conventional fixing device.

[Explanation of symbols]

 1 Heat Source (Halogen Lamp) 2 Fixing Roller 2a Teflon Film 2b Aluminum Core Material 3 Pressure Roller 3a Silicon Rubber 3b Aluminum Core Material 4 Image Forming Paper (Transfer Paper) 6 Guide Plate (Induction Device)

Claims (2)

[Claims] 1. A heat-fixing device for electrophotography comprising a fixing roller heated by a heat source and a pressure roller in contact with the fixing roller, wherein the fixing roller is provided at a position in front of the pressure roller in the rotation direction. A heat-fixing device comprising a guide device for pressing or contacting an image forming sheet. 2. The contact position of the guide roller of the guide device with the fixing roller is 5 to 9 from the contact position of the pressure roller.
A front position at an angle of 0 °.
The heat fixing device described.