JPS60143371A - Belt type fixing device - Google Patents

Abstract

PURPOSE:To prevent a defect in transfer and the occurrence of a jam, etc., even in a high-humidity atmosphere by incorporating a heat source in a device consisting of a belt and a pressure roll in combination, and drying transfer paper before transfer. CONSTITUTION:Belt parts 26 and 28 extended between a couple of support rolls 21 are pressed against the roll part 27 incorporating the heat source 25 with a specific spring, etc. An endless belt 17 uses a silicone rubber sheet 22 containing glass fiber as a base and a thin layer 23 of ''Teflon'' resin, etc., having excellent heat resistance and peeling property is formed on the surface. When copy paper 8 is inserted into the biting part of the contact part of this device, it is dried before transfer and supplied to a transfer position through a leveling roll 19. Consequently, even when copy paper which is humidified for a long time is used, it do not jam and an image of high quality is formed without any defect of transfer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a belt type fixing device used in a copying machine using an electrophotographic process.

Configuration of a conventional example and its problems First, a general copying apparatus using an electrophotographic process will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a copying apparatus. In the figure, 1 is a photosensitive drum, 2 is a charger, 3 is an exposure rung, 4 is a fiber lens, 5 is an original platen, 6 is a developing device, 7 is a copy paper wrapping section,
8 is a copying paper, 9 is a transfer device, 1o is a peeler, 11 is a fixing device, 12 is an AC static eliminator, 13 is a cleaning brush, 14
15 is a timing roll, and 15 is a guide plate of the humidifier 11.

The operation of the copying apparatus having the above configuration will be described below. Charge is injected into the surface of the photosensitive drum by a charger 2, and the potential is maintained.

The photosensitive drum 1 is exposed with an original image through a fiber lens 4 by irradiation with an exposure lamp 3 to form an electrostatic latent image.The latent image is developed by a developing device 6 and becomes a visible image as a toner image.

On the other hand, the copy paper 8 is conveyed in synchronization with the rotation of the photosensitive drum 1 by a timing roll 14, and the visualized original image is transferred by the corona discharge of the transfer device 9. The copy paper on which the toner image has been transferred is peeled off by a peeler 10, and then guided by a guide plate 15 and led to a fixing device 11, where the toner image is fixed, and then the paper is discharged. Also, the photosensitive drum 1 after transfer
The residual charge is removed by the static eliminator 12, and the remaining toner is cleaned by the cleaning brush 13, and one cycle of the electrophotographic process is completed.

Conventionally, copying paper used as a transfer sheet, in which a toner image electrostatically deposited on a photoreceptor is charged with a transfer charge of opposite polarity to that of the toner image, generally has high hygroscopicity. During rainy or humid weather, the paper absorbs moisture and becomes soft and weak, causing the paper to twist inside the machine and cause paper jams.
Furthermore, when the resistance value changes and the electric field strength at the transfer portion decreases, a phenomenon of transfer failure occurs and the image quality is degraded.

In recent years, several proposals have been made as countermeasures against transfer defects in the above-mentioned process, and these will be explained next. The first known method is to control high-voltage power supplied to a copying device such as a transfer charger depending on the environment.

This method detects humidity changes in the copying machine using a total humidity sensor and paper resistance value, controls the output of the high-voltage power supply accordingly, and if a humidity change exceeding the output control limit is detected, the transfer member will jam. To prevent this, a safety measure is provided to control the copying operation to stop. However, the above-mentioned configuration has a drawback that if the detected amount exceeds the allowable control range during a long period of high humidity such as during the rainy season, the copying operation remains stopped. Examples of attempts to improve this point include Utility Model Publication No. 43-23428 and Utility Model Publication No. 58-39464, in which the heat of the fixing device is used indirectly to remove moisture from the copy paper. There is a method to remove it by drying. however,
These methods also have the aspect that it is difficult to obtain satisfactory results. These methods indirectly apply heat to the copy paper, but in the latter case, the paper with the highest moisture absorption in the paper feed section is generally the paper at the top that is directly exposed to the air. On the other hand, the top paper is the first one to be used after power is applied to the copying machine, and this paper is used during the normal warming-up period of the copying machine (the temperature of the humidifier rises to the desired temperature). drying time). Alternatively, it is determined that there is little possibility that manually fed copy paper, which has a short holding time in the extravagant paper feeding section, can be dried. On the other hand, if the paper is constantly heated and dried, the paper surface will become deformed and not flat if it is dried without suppressing the cracks, which may cause paper wrinkles and paper curls.

OBJECTS OF THE INVENTION An object of the present invention is to dry the copy paper before the transfer operation using a drying function built into the fixing device, thereby preventing the above-mentioned transfer defects and paper jam, and obtaining stable images that are not affected by humidity changes. This is what we are trying to do.

Structure of the Invention A belt-type fixing device based on the present invention includes a belt that is supported so as to be wound around at least two support rolls, and a roll that is in pressure contact with the belt, and at least one of which includes a heat source. It consists of a combination of rolls, and has the function of drying the copy paper on which the toner image on the photoreceptor is to be completely transferred by passing it between the belt and the rolls before the transfer operation. By performing constant drying directly from a heat source in accordance with the photographic flossing speed, transfer defects and paper jams can be prevented and stable images unaffected by humidity changes can be obtained.

Description of examples An embodiment of the present invention will be described below.

FIG. 2 is a schematic diagram of a copying apparatus including a fixing device according to a second embodiment of the present invention. 16 is a roll, 1 is an endless belt, 18 is a support roll, and 19 is a leveling roll. Each process equipment is the same as the electrophotographic process described in FIG. Based on the Kinoe 8A, a new copy paper drying function is added to the bell l-' of the fixing device.

The operation of the copying apparatus incorporated in the belt-type fixing device which also serves to dry copy paper according to this embodiment will be described below.

First, the fed copy paper 8 is sandwiched and passed between the roll 16 of the fixing device and the belt section A (support roll 18 and endless belt 17), and is directly dried. Then, the dried copy paper is passed between the leveling rolls 19 to make it flat, and then turned over along the guide plate 15a. The operations up to the point where a toner image is placed on the photosensitive drum 1 are similar to those shown in FIG. The copy paper 8 is conveyed in synchronization with the rotation of the photoreceptor drum 1 by a timing roll 14, a toner image is transferred by a corona discharge of a transfer device 9, and it is peeled off from the photoreceptor drum 1 by a peeler 10. Then, the sheet passes through the fuser roll 16 and the belt section B (support roll 18 and endless belt 17), performs a constant ak operation, and is discharged.

FIG. 3 shows an outline of the first embodiment of the belt type foot restraint device according to this embodiment. Reference numerals 26 and 28 indicate belt portions each containing a pair of support rolls, and 2T indicates a roll portion containing a heat component 25. Support 0)' 18 i'i
The endless belt 17 is made up of a thick elastic layer 21 made of silicone rubber or the like on a core roll 20, and supported by the support roll 18 so as to be freely wound. '
cL, its surface is coated with a very thin layer 23 of Teflon resin or the like having good heat resistance and IIi type properties. Also,
The roll part 27 is a very thin layer 2 of Teflon resin, which has heat resistance and mold release properties, on the outer peripheral surface of the hollow aluminum roll 24.
3 to prevent toner stains on the offset and roll. The roll portion 27 and the belt portions 26 and 28 supported by a pair of support rolls are in contact with each other with a predetermined pressure applied between their axes by a spring or the like. On the other hand, the roll part 27 is driven and rotated at a predetermined angular velocity by an external drive source, and the belt parts 26 and 28 rotate in the opposite rotation direction to the roll part 2 due to the dominant force of the contact part with the roll part. driven by In this state, when the copy paper 8 is inserted into the biting side of the endless belt part 26.28 (!: roll ofi 27 + 7) W contact part, it is directly exposed to pressure and heat while passing through the entire contact part, and is dried. A fixing operation is performed for fakes.

According to the present invention, a leveling roll 19 can be added to the paper discharge side after the copy paper is dried. This leveling roll is for removing deformation and curling of the copy paper during drying, and its addition leads to better results.

Next, an example of the take will be shown.

The support roll 18 is made of a stainless steel core with a diameter of 12 fMl and covered with two elastic layers of noricorn rubber with a thickness of 20K 4 myn, and an endless belt 17id1.
two elastic layers 22 of silicone rubber containing glass fiber;
Furthermore, the Teflon resin layer 231.3) is coated with a thickness of 0.3, and the hollow roll 24 of the roll portion 27 has an outer diameter of 30 m.
0.0 mm on the outer circumferential surface of an aluminum pipe with a thickness of 2 mm.
Covered with 4mm Teflon A fat 23, heat 25
A 900W halogen lamp was used. The surface operating temperature of the roll was set at 100°C.

Then, the belt portion 26, 28 and the roll portion 27 are connected to the third
As shown in the figure, a fixing device was constructed by compressing the belt portions 26 and 28 with the roll portion 27 at the center, and an evaluation test was conducted by incorporating the fixing device into a copying machine as shown in FIG. Result: 35°C, 80
Even when using copy paper that had been left in an environment of %RH for 2 hours, the occurrence of paper smear was prevented and a high quality image without image omission due to poor transfer could be obtained.

As a second embodiment of the present invention, as shown in FIG. 4, the roll parts 29 and 31 are compressed around the belt part 30, and the roll part 29 used on the fixing side is heated with 900 W, and the dry side is heated with 900 W. A 300W halogen lamp is used for the roll section 31, and the surface operating temperature is set to 180°C on the fixing side and 1°C on the drying side.
00'C, as shown in FIG. Two 500W halogen lamps were used for the support roll used on the fixing side, and two 20OW halogen lamps were used for the support roll used on the drying side. 100'C
In the case where the fourth embodiment is set as shown in FIG. Even when two 600 W halogen lamps were used as the heat source 25 and the surface operating temperature was set to 100° C., similar high-quality images could be obtained on the copy paper left under the above environmental conditions. In addition, in the second and fourth embodiments, only a silicone rubber sheet containing glass fiber was used as the belt.
Ita for use.

Effects of the Invention As is clear from the above explanation, the present invention is capable of drying the copy paper directly at a constant temperature for one hour using a belt-type fixing device before transferring the toner image formed on the sensory body. , the condition of the copy paper at the time of transfer is always maintained without being constrained by changes in humidity. The structure of the screener is highly practical as it can apply uniform heat and pressure directly onto the surface of the copy paper by simply adding one roll or belt to the conventional fixing device, allowing sufficient drying even in high humidity conditions. It is. Further, the standby time for drying is the same as the standby time for fixing, and the apparatus can be put into operation immediately after the standby time after turning on the power.

Further, the belt-type fixing method has the advantage that the nip portion can be large, so that the fixing time can be long, and fixing can be performed at low pressure and low fixing temperature.

Deformation and curl of the copy paper due to curling and drying can be removed by passing it between leveling rolls, and adding a leveling roll leads to better results.

Furthermore, the leveling roll can be expected to be effective in preventing paper jams during double-sided copying.

In addition to the above-mentioned effects, the configurations shown in FIGS. 3 to 6 can each provide the following results. In other words, in the configuration shown in Figure 3, in which a belt supported by a pair of support rolls is compressed around a roll containing all heat*, drying and fixing of the copy paper are performed by a single roll. , the desired effect can be obtained with almost the same power consumption as conventional methods. In addition, in a configuration in which a belt supported by a pair of support rolls is sandwiched between a roll containing a heat source at the center as shown in Fig. 4, in order to transfer the heat of each roll through the belt, the set surface of the roll is Warm-up time to reach operating temperature can be significantly reduced. Furthermore, since there is little temperature ripple in the roll and the fixing temperature can be kept at a certain level, images with higher fixability can be obtained. These effects are as shown in Fig. 6) When the heat source is fully contained in the supported support roll and the roll is pressed between the heat belts and the heat belt, the belt support as shown in Fig. 6 is 1. It can also be obtained when the support roll contains the entire heat source and the rolls are pressed together around a heat belt. In particular, when the heat belt is put under pressure around the roll, heating is performed from 4 places, so the fixing temperature is extremely low. High effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 (d) Schematic diagram of a copying device; Fig. 2 is a schematic diagram of a close-up photographing device employing the belt-type fixing device of the present invention; Fig. 3 is a belt fire source in 2 of an embodiment of the present invention) lf cross-sectional view of the device,
Figures 4 and 5 are similar to Figure 6 (This is a sectional view of another embodiment of the present invention. 1...Photosensitive drum, 8. Copying paper, 9.
Transfer device, 10... AC static eliminator, 11...
Fixing device, 14... Timing roll, 15...
... Guide plate, 16 ... Roll, 27, 29,
31.32,34゜36... Roll section 2 that contains a heat source inside and belt section that is supported by the support roll, 26.28゜30,33,35,3a... Contains a heat source A roll part that is in contact with the belt, a roll that is in pressure contact with the belt, and a hel+ part that is supported by the support roll, 19...
・Leveling roll. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (4)

[Claims] (1) It has a belt that is supported so as to be wound around at least two support rolls, and a roll that is in pressure contact with the belt,
It consists of a combination of the belt and the roll, at least one of which contains a heat source, and has a function of drying the copy paper to which the toner image on the sensory body is to be transferred by passing it between the belt and the roll before the transfer operation. Belt 2 fixing device with. (2) The belt type fixing device according to claim 1, wherein the surface of the roll or belt that presses the toner image on the copy paper onto the copy paper is coated with a heat-resistant and releasable thin layer. (3) The belt-type fixing device according to claim 1 or claim 2, further comprising a belt other than the above-mentioned belt that cooperatively presses the belt around the roll without contacting the belt. (4) The belt-type fixing device according to claim 1 or 2, further comprising a roll other than the above-mentioned rolls that cooperatively clamps the rolls at the entire center of the belt without touching each other. (5) After the copy paper to which the toner image on the photoreceptor is to be transferred passes between the belt and the roll, a leveling roll is provided in the conveyance path of the copy paper before the transfer operation. The belt type fixing device according to any one of Item 4.