JPS60135973A - Copying device - Google Patents

Abstract

PURPOSE:To prevent transfer defects and paper jam by allowing a copy paper, to which a toner image on a photosensitive body should be transferred, to pass between rolls of a drying device before the transfer operation. CONSTITUTION:A core bar roll 17 is coated with a thick elastic layer 18 consisting of a silicone rubber to constitute a pressure roll 16a. The outside circumferential face of a hollow roll 19 consisting of aluminium is coated with a very thin layer consisting of a ''Teflon '' resin which has a heat resisting property and a mold releasing property to constitute a heat roll 16b. The hollow roll 19 incorporates a heat source 21, and power is supplied from another driving source to this hollow roll 19, and the hollow roll 19 is rotated in the same speed as the peripheral speed of a photosensitive drum 1, namely, the speed of an electrophotographic process. Operations are performed in a conventional manner until a toner image is formed on the photosensitive drum 1. Then, a copy paper 8 is carried from a paper supply part 7, and its front end is held between timing rolls 14a, and the holding state is set, and timing rolls 14a are so operated that the toner image coincides with a transfer part, and the copy paper 8 is run. A drying device 16 is provided on the running course, and the copy paper 8 is directly pressurized and dried for a certain time at a certain temperature by a head roll.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a copying apparatus using an electrophotographic process, and more particularly to a copying apparatus equipped with a copy paper drying device.

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 lamp, 4 is a fiber lens, 5 is a document table, 6 is a developer, 7 is a copy paper feed section, 8 is a copy paper, and 9 is a transfer device , 1° is a stripping device, 11 is a fixing device, 12 is a static eliminator, 13 is a cleaning brush, 14a
, 14D is a timing roll, and 15 is a guide plate of the fixing device 11.

The operation of the copying apparatus having the above configuration will be described below. A charge is injected into the surface of the photosensitive drum 1 by a charger 2, and the potential is maintained. A document image is exposed to light through a fiber lens 4 on the photosensitive drum 1 by irradiation with an exposure lamp 3 to form an electrostatic latent image, and the latent image is developed by a developing device 6 to become 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 the dimming roll 14a, and the visualized original image is transferred by the corona discharge of the transfer device 9. The copy paper onto which the toner image has been transferred is peeled off by a peeler 1o, and then guided by a guide plate 15 and led to a fixing device 11, where the toner image is fixed and the sheet is discharged. After the photosensitive drum 1 has been transferred, residual charges are removed by a static eliminator 12, and residual toner is cleaned by a cleaning blanket 13.
One cycle of the electrophotographic process is completed.

Conventionally, copying paper, which is used as a transfer member for electrostatically adhering a toner image to a photoconductor 2 with a transfer charge of opposite polarity to that of the toner image, generally has high hygroscopicity, so it can be easily used in rainy weather, etc. When it is humid, it absorbs moisture and becomes soft and stiff, which can cause paper jams in the device, so-called paper jams, and the resistance value changes and the electric field strength at the transfer section decreases, causing poor transfer and reducing image quality. lower.

In recent years, several proposals have been made as countermeasures against transfer defects in the above process, and these will be described below. 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 changes in humidity inside the copying device using a humidity sensor and the resistance value of the paper, controls the output of the high-voltage power supply accordingly, and if a change in humidity that exceeds the output control range 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, which use the heat of the fixing device indirectly to dry the moisture on the copy paper. There are methods to try to remove it. However, even with these methods, 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 binding section is generally the top paper that is directly exposed to the air. On the other hand, it is the top paper that is used first after the power is turned on, and this paper is not used during the normal warming amplifier time (time for the temperature of the fuser to rise to the desired temperature) of the copying machine. It cannot be dried. Alternatively, it is determined that there is little possibility that manually fed copy paper, which has a short holding time in the paper feed section, can be dried. On the other hand, if the paper is constantly heated and dried, if it is dried without equal control, the paper surface will become deformed and will not lie flat, which may cause paper wrinkles and paper jams.

OBJECTS OF THE INVENTION An object of the present invention is to provide a copying apparatus equipped with a drying device that dries copy paper before a transfer operation, thereby making it possible to prevent the above-mentioned transfer defective paper jam.

Structure of the Invention The copying apparatus of the present invention includes a drying device consisting of a combination of a heating roll that rotates while containing a heat source, and a pressure roll that rotates as a result of contact with the heating roll, and the drying device is equipped with a drying device that includes a combination of a heating roll that rotates while containing a heat source, and a pressure roll that rotates as a result of contact with the heating roll. The copy paper to be transferred is sandwiched and passed between the rolls of the drying device before the transfer operation, and the copy paper is dried to a certain degree directly from a heat source in accordance with the process speed of electrophotography. Therefore, it is possible to prevent transfer defects and paper jams, and to obtain stable images that are not affected by humidity changes.

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

FIG. 2 is a schematic diagram of a copying apparatus in one embodiment of the present invention. The main process parts 1 to 16 are the same as those explained in FIG. Based on the present invention, a drying device 16 is added between the copy paper feeding section 7 and the travel path of the copy paper 8 leading to the transfer device 9.

FIG. 3 shows an outline of the drying device 16 in this embodiment, in which 16a is a pressure roll and 16b is a heat roll containing a heat source. The pressure roll 16a is constructed by covering a core metal roll 17 with a thick elastic layer 18 of silicone rubber. Ushida heat roll 1eb is aluminum hollow roll 1
The outer peripheral surface of 9 is coated with a thin layer 2 of Tecolon resin having heat resistance and mold release properties. The hollow roll 19 contains a heat source 21 and rotates at a peripheral speed of the photosensitive drum 1, that is, the speed of the electrophotographic process, by receiving power from another driving source (not shown). In FIG. 3, a leveling roll 22 can be added to the paper 991+111 of the drying device. This leveling roll 22i'
;i It removes deformation and curling of copy paper after drying, and its addition leads to better results.

Next, the operation of a copying machine incorporating the drying device δ according to the present invention will be explained.

First, the operations up to placing a toner image on the photosensitive drum 1 are the same as those shown in FIG. Here, the copy paper 8 is conveyed from the paper feed section 7, and its leading edge is held by the timing roll 1.
The timing roll 14a is operated so that the copy paper 8 is placed in a standby state while being held between the copy paper 4a and the copy paper 8 is aligned with the toner image relative to the transfer section. A drying device 16 is provided on the traveling route, and the drying device 16 directly pressurizes and dries the material using hot rolls at a certain temperature for a certain period of time. The heating time of the heat roll can be considered to be about the same as that of the fixing device installed in the same copying machine, and the machine can be put into operation immediately after the power is turned on and after a warming-up time. The operation after the toner image on the photoreceptor drum is transferred onto the dried copy paper by the transfer device 9 is the same as that shown in FIG.

An example of data is shown below. The pressure roll 16a has a diameter of 25
The hollow roll 19 of the heated roll 16b is made of aluminum pipe with an outer diameter of 301nll+ and a thickness of 2mm. .4m
It was coated with Teflon resin 2o with a thickness of m, and a 380W halogen lamp was used as the heat source 21.

The surface operating temperature of the heat roll was set at 120° C. by detecting the surface roughness with a thermistor and controlling the electric power applied to the halogen lamp.

The above pressure roll 16a and heat roll 16b were brought into pressure contact as shown in FIG. 3 to construct a drying device, which was incorporated into a copying machine as shown in FIG. 2, and an evaluation test was conducted at a process speed of 70 mm/sec. As a result, the temperature was 35℃.

Even when using copy paper that had been left in an environment of so%RH for 2 hours, paper jams were prevented from occurring and high-quality images were obtained without image omissions due to poor transfer.0 Effects of the Invention From the above explanation As is clear, in the present invention, before the toner image formed on the photoreceptor is transferred, the copy paper is directly dried at a constant temperature for a certain period of time using a hot roll type drying device, thereby taking advantage of changes in humidity. It can be copied without any trouble. Copy paper passes through a pair of rolls that are pressed together, creating a state similar to ironing with heat and pressure, which flattens the copy paper and improves transfer conditions, preventing image loss due to paper jams and poor transfer. It has excellent effects. Furthermore, by applying heat to the copy paper, the transfer rate and fixing properties can be improved and high quality images can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an outline of a copying machine manufactured by Juto, Fig. 2 is a diagram showing an outline of a copying machine in an embodiment of the present invention, and Fig. 3 is a diagram showing an outline of a drying device used in the same embodiment. It is a diagram. 1...Photosensitive drum, 8...Copy paper, 9...
Transfer device, 11... Fixing device, 16... Drying device. Figure 1, da

Claims (1)

[Claims] (1) Equipped with a drying device consisting of a combination of a heat roll that rotates while containing a heat source and a pressure roll that rotates in contact with the heat roll, the copy paper to which the toner image on the photoreceptor is to be transferred is A copying device configured to pass between the rolls of the drying device before a transfer operation. (b)) The copying apparatus according to claim 1, further comprising a leveling roll on the paper discharge side of the drying device.