JPH0358516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to a recording apparatus configured to transfer a toner image formed on a toner image carrier to a recording medium.

2. Prior Art First, an outline of a recording apparatus using a conventional toner image carrier will be described using a scanning exposure type electrophotographic copying machine as an example. When a copy document is placed on the document table and a copy button is pressed, an exposure lamp illuminates the document and travels in a predetermined direction together with an optical system including a reflecting mirror. Reflected light corresponding to the density of the original is irradiated onto a uniformly charged toner image carrier (for example, a photosensitive drum) via the optical system, and an electrostatic latent image is formed on the toner image carrier. Ru. Furthermore, a toner image corresponding to the density of the original is formed on the photoreceptor drum by the developer.

On the other hand, from the paper feeder to the recording medium (for example, copy paper)
is sent to match the position of the toner image on the toner image carrier and comes into contact with the toner image carrier. and,
The toner image formed on the surface of the toner image carrier is
The image is transferred to copy paper by a transfer electrode. During this time,
The toner image carrier continues to rotate in a predetermined direction, and the toner image is gradually transferred onto the copy paper. after that,
The copy paper onto which the toner image has been transferred is separated from the toner image carrier, and the copy paper is sent to a roller fixing device.
The roller fixing device is composed of two rollers, at least one of which is a heated roller,
The image formed by the developer is heated and fixed on the copy paper. Thereafter, the copy paper is discharged out of the main body of the copying machine.

On the other hand, the toner image carrier is cleaned to remove excess toner powder after the visible toner image is transferred to the copy paper, and this process is repeated every time recording is performed.

However, when a toner image formed on a toner image carrier is electrostatically transferred onto a copy paper using a transfer electrode such as a corona discharger as in the past, charge disturbance occurs and the toner image is Resolution will decrease. Furthermore, when a conductive magnetic toner or the like that can provide a high-quality toner image is used as the toner, a state in which transfer is virtually impossible is caused.

As a method to improve the above-mentioned drawbacks of electrostatic transfer, attempts have been made to press transfer onto a transfer sheet using a pressure roller, but the transfer efficiency is poor and only about half the amount of toner image is transferred. have a disability.

Therefore, for example, in Japanese Patent Publication No. 46-41679, Japanese Patent Publication No. 48-22763, Japanese Unexamined Patent Publication No. 49-78559, and US Pat. A method has been proposed in which an image is transferred by pressure, and the transferred toner image is transferred and fixed (transfer-fixed) onto copy paper while being heated and melted using a heat roller. In such a method, a toner image is transferred by pressure onto the surface layer of a rubber-based transfer layer, such as silicone rubber or fluoro rubber, which has releasability on the one hand and has the property of adhering fine particles when pressed. The toner image on the transfer layer is melted by contact heating with a heating body such as a heat roller, and is transferred under pressure onto copy paper fed at the same time and fixed. That is,
The toner image melted by heating is easily transferred and fixed onto the copy paper based on the above-mentioned releasability of the transfer layer, so there is no reduction in resolution of the toner image due to the transfer process, and transfer is achieved at a high transfer rate. It is said that

Copy paper used in a copying machine using an intermediate transfer member must be heated to a sufficient temperature when it comes into contact with the intermediate transfer member in order to transfer and fix the toner image on the intermediate transfer member. For this reason, the copy paper is designed to be brought into contact with the intermediate transfer member while being preheated by a heat roll or the like.

Now, copy paper generally contains 4 to 7% by weight of water, and when this is heated, the water evaporates and water vapor is generated. When water vapor cools, it condenses and forms water droplets that adhere to nearby objects and wet them.

When the intermediate transfer member is in the form of a roll, for example, a heat roll or the like for preheating the copy paper must be provided near the toner image carrier, and the toner image carrier comes into contact with water vapor generated from the copy paper. It happens a lot. When the surface of the toner image bearing member (i.e., photoreceptor) comes into contact with water vapor, the water vapor condenses and water droplets form because the photoreceptor is kept at a relatively low temperature.

If the toner image carrier gets wet with water droplets, the toner remaining on the toner image carrier may aggregate and become more likely to adhere to the toner image carrier, or the toner may become wet during the next copying process. charging cannot be performed properly. For example, if toner powder adheres to a wet area or toner powder gets wet with water droplets, it is difficult to completely remove it with a cleaning device. In this state, steps such as charging for the next copy will be repeated. When the toner image carrier is exposed to light and a latent image is formed with excess toner powder attached, the areas to which the toner powder has been attached are not exposed, and during the development stage, the toner image carrier is exposed to light and a latent image is formed. Also, toner powder is applied, and this is transferred to copy paper in the transfer stage.

That is, when the toner image carrier gets wet, stains and streaks will appear on the copy paper due to excess toner powder adhering to the copy paper, resulting in a copy that is difficult to read or see. Similarly, the adhesion of water droplets onto the toner image bearing member causes problems in a series of processes such as charging, exposure, and development.

3. Object of the Invention The object of the present invention is to provide a mechanism that can effectively remove the adverse effects of water vapor generated from a heating section of a fixing device for copy paper or the like that generates water vapor near a toner image carrier. An object of the present invention is to provide a recording device having the following features.

4. Structure of the Invention That is, the present invention provides a recording apparatus in which a heating section for heating a recording medium is provided in the vicinity of a toner image carrier, in which water vapor generated from the heating section is applied to the surface of the toner image carrier. A removing means for removing moisture generated by condensation includes a fixed cylinder having a ventilation hole in the side wall, and a removing means rotatably arranged concentrically with the fixed cylinder around the outer periphery of the fixed cylinder, and capable of being ventilated. It is composed of a cylindrical core metal, and a porous elastic layer for moisture absorption, which is coated on the outer periphery of the core metal, rotates together with the core metal, and is provided in contact with the toner image carrier. The present invention relates to a recording device characterized by the following.

5 Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows a pressure transfer type electrophotographic copying machine as an example in which a means for removing moisture adhering to the surface of a toner image bearing member is incorporated according to the present invention.

In this copying machine, an original 4 covered with a platen cover 3 is placed on the glass surface of an original placing table 2 that is movably provided on the upper wall of the main body. Light 6 from 5 is irradiated through a slit 50 provided on the upper wall of the main body, and the reflected light passes through an SLA (self-cleaning lens array) 7, is reflected by a mirror 8, and then enters a photosensitive drum 9. Therefore, the uniformly charged photosensitive layer 10 made of selenium, organic photoconductive material, etc. of the drum 9 is exposed to a pattern corresponding to the original image by moving the original table 2 in the direction of the arrow. is performed to form an electrostatic latent image. Reference numeral 11 in the figure is a corona charger, which charges the entire surface of the photosensitive layer to a predetermined polarity in an unexposed state. Further, 12 is a device consisting of a light emitting diode array or an electroluminescent board for preventing black frames,
It has the function of eliminating the electric charge on the non-image area on the photoreceptor and preventing toner from adhering to the non-image area. A known conductive magnetic toner 14 is supplied from a developing sleeve 13 to the photosensitive drum 9 on which the electrostatic latent image is formed. This toner 14 is conveyed on the sleeve 13 while its thickness is regulated by a magnetic roll 15 for regulating the toner thickness.
3 and the rotation of the magnet roll 16 inside the sleeve 13 provide the conveying force. Since a reverse charge is induced in the toner 14 by the electrostatic latent image on the photoreceptor drum 9, the toner particles are sequentially moved onto the photoreceptor drum 9 and attracted thereto in proportion to the amount of charge of the electrostatic latent image. A toner image of a predetermined pattern is formed thereon, and development is performed.

The toner image thus formed is then applied to the photoreceptor drum 9 under a linear pressure of 1.0 kg/cm or less (for example, 0.4
It is pressed and transferred to the intermediate transfer roll 1 in contact with a pressure of 1 kg/cm). Since this roll 1 has a surface layer mainly composed of a mixture of silicone rubber and fluorosilicone rubber, it sufficiently peels off the toner particles on the photoreceptor drum 9. The peeled toner particles are preheated to a predetermined temperature (that is, a temperature that exhibits sufficient mold releasability) by a heater lamp 17 in the roll 1, and are carried on the roll 1 to the next pressure roll 18. It will be done. The pressure roll 18 is heated to a predetermined temperature by an internal heater lamp 19, and is transferred from the paper feed box 20 to the paper feed roll 21.
The copy paper 24 sent through the guide plates 37, 22 and the conveyance roller 23 is sent between the rolls 1 and 18 while being heated. Therefore, the copy paper 24 has a temperature sufficient to transfer the toner image, and when fed between the rolls 1 and 8, the toner image, which has already been preheated, is separated from or transferred from the roll 1, and At the same time, the toner image can be fixed on the copy paper 24. In the figure, 25 is a cleaning roller for the pressure roll 18, 26 is a cleaning roller for the intermediate transfer roll 1, 27 is a guide plate for sending the fixed copy paper to the paper discharge roller 29 on the paper discharge tray 28 side, and 30
Reference numeral 31 denotes a roller for feeding copy paper from the bottom of the tray 28 during double-sided copying, and a guide plate 31 during double-sided copying.

At the subsequent stage of the intermediate transfer roller 1, the photosensitive drum 9 is irradiated with light from a discharge lamp 32 to erase the residual charge on the drum. Further, a cleaning member 34 made of, for example, a rubber roller is brought into contact with the photoreceptor drum 9, and residual toner particles separated thereby are stored in a cleaning device 35 by a scraping blade (not shown).

What should be noted in the copying machine configured as described above is the removal of moisture condensed on the surface of the photoreceptor drum 9 in contact with the circumferential surface of the photoreceptor drum 9 between the intermediate transfer member 1 and the static elimination lamp 32. The means 36 is provided in the form of a roll. Hereinafter, this effect will be explained in detail.

For example, a paper feed roller 21 is fed from a paper feed box 20, guide plates 37, 22, and a conveyance roller (a roller that restarts the copy paper in order to synchronize with the toner image on the photoreceptor drum 9 and furthermore, the intermediate transfer roll 1) 23. Copy paper 24 sent via
Then, the copy paper 24 is placed on a pressure roll 18 which is internally heated to a predetermined temperature by a heater lamp 19 in order to bring the copy paper 24 to a sufficient temperature so that the toner image on the intermediate transfer roll is transferred and fixed. While being in sufficient contact and being preheated, it is fed between the intermediate transfer roll 1 and the pressure roll 18, which are the transfer/fixing areas.

Since the copy paper 24 originally contains 4 to 7% by weight of water, when it comes into sufficient contact with the pressure roll 18 during transportation and is preheated, the water contained in the copy paper 24 evaporates. do. This water vapor is influenced by the rotation direction of the pressure roll 18 between the pressure roll and the guide plate 22, and the intermediate transfer roll 1
is carried in the direction of the contact area with the pressure roll 18,
At the place B where the guide plate 22 is missing, press the pressure roll 1
It is emitted in the direction away from 8.

As the number of copies increases and the amount of copy paper 24 preheated by the pressure roll 18 increases, the amount of water vapor that evaporates due to moisture contained in the copy paper 24 also increases in proportion to the number of copies, and this water vapor is particularly The cleaning device 35, the static eliminating lamp 32, the photosensitive drum 9, the intermediate transfer roll 1, and the guide plate remain at a location A.

As the water vapor cools, it condenses and adheres to objects nearby. Water vapor is lighter than air, and a large amount of water vapor stays on the circumferential surface of the photoreceptor drum 9, especially at the location A shown in FIG. This caused the problems mentioned above.

Therefore, even if the water vapor staying at the location A comes into contact with the photoreceptor drum 9 and condenses, and moisture adheres to the surface of the photoreceptor drum 9, the provision of the moisture removal means 36 prevents the moisture from leaving the surface of the photoreceptor drum 9. Once the toner powder is removed, the surface of the photoreceptor drum 9 is free from adhering moisture or is in a dry state before reaching the cleaning device 35 in the next step, so excess toner powder is sufficiently removed and the next copy is made in a clean state. The process will now begin.

Next, the moisture removing means 36 will be explained. In the embodiment shown in FIG. 1, the moisture removal means 36 is constructed as shown in FIG.

The water removing means 36 is configured in a roll shape, and when it comes into contact with the photoreceptor drum 9, the rotational force of the photoreceptor drum 9 is transmitted to the water removing means 36, and the water removing means 36 moves counterclockwise as shown by the arrow. Start rotating. When the moisture removal means 36 rotates, the entire surface of the moisture removal means 36 comes into contact with the photoreceptor drum 9, making it possible to sufficiently absorb moisture adhering to the surface of the photoreceptor drum 9. The surface layer 43B of the moisture removing means 36 is
It is made of sponge, etc., and is porous and elastic, so when it is pressed, the entire surface of the photoreceptor drum 9 comes into sufficient contact with these materials, and three functional parts are formed near the contact area (nip area). is configured. The first part is an inlet part of the nip part, and is an exhaust part where air is discharged from voids (pores) in the layer due to compressive deformation of the elastic layer.
The second part is near the center of the nip, where compressive deformation increases and decreases relatively slowly, and is a region where water permeation into the pores is dominated by wettability. The third part is near the exit of the nip, where the elastic layer suddenly recovers to its original state, and the elastic layer becomes under negative pressure transiently, causing pressure to rise at the interface between the roller and the photosensitive surface. , the suction part has a sufficiently large osmotic effect due to the pressure difference. In this way, by applying an external pressing force to the deformed layer with pores and generating a suction force at the outlet, in addition to the penetration effect on the roller due to wetting, the penetration effect due to pressure also works together, making it extremely effective. It is now possible to remove moisture adhering to the photoreceptor drum 9.
There will be no leftover moisture left behind.

As shown in FIG. 2, the water removing means for removing water may be one composed of a roll-shaped aluminum shaft 38 and a covering member 39 of felt or sponge urethane, or a third one. As shown in the figure, the shaft 38 is made of aluminum,
It is also possible to use a laminated structure (36A) using sponge urethane 40 on top and felt as the surface covering material 41 on top of this (36A), but compared to these, the structure according to the present invention shown in FIG. Every single thing is effective.

Now, the surface of the moisture removal means 36 that comes into contact with the photoreceptor drum 9 has hydroxyl groups, amino groups,
It is desirable to perform a hydrophilic treatment such as coating or impregnation with a substance having a hydrophilic group such as a sulfonic acid group. In FIG. 4, the moisture removing means 36 has holes formed above the fixed cylinder 42 (in the nip direction) continuously or intermittently in the axial direction thereof, and a moisture removing roll 43 is rotatably disposed around the holes. This moisture removal roll 43 has a porous elastic layer 43 made of sponge or the like surrounding a porous core metal 43A that can be ventilated.
With the structure covered with B, the rotary movement shown by the black arrow in the figure allows air to flow as shown by the white arrow, and moist air can be drawn into the fixed cylinder 42. A suction duct may be attached to one side of the fixed cylinder 42.

With this configuration, the moist air that has passed through the porous elastic layer 43B can be taken into the fixed cylinder 42 from the core metal 43A through the above-mentioned hole (vent hole in the side wall) of the fixed cylinder 42, so that the porous elastic layer 43B This not only allows moisture on the drum 9 to be absorbed, but also moist air can be sucked into the fixed cylinder 42, which facilitates the above-mentioned air discharge, and also allows some of the moist air to be sucked into the fixed cylinder 42 before being condensed. The moisture removal efficiency can be further increased.

In this embodiment, the moisture removal means 36 is provided between the intermediate transfer body 1 and the static elimination lamp 32.
As shown by the imaginary line in FIG. 1, this may be moved in the rotational direction of the photosensitive drum 9 and provided between the corona charger 11 and the cleaning device 35.

The present invention can be further modified based on its technical idea.

For example, the surface of the cleaning roller 34 in FIG. 1 can be subjected to the above-described hydrophilic treatment to serve both toner removal and moisture removal. In addition, in a general copying machine that does not use an intermediate transfer member, if a heating unit is installed near the photoreceptor drum, such as a fixing device, the water vapor generated from the heating unit is used to remove moisture adhering to the photoreceptor drum. It is also applicable to

6. Effects of the Invention As described above, in the present invention, by providing a means for removing moisture adhering to the toner image carrier, the surface of the toner image carrier is dried before proceeding to the next copying step. Therefore, excess toner powder does not adhere to the toner image carrier due to wetting.
The recording medium will be recorded cleanly and exactly as the original, without any streaks or scratches. In addition, a cylindrical breathable core with a porous elastic layer for moisture absorption is provided around the fixed cylinder with ventilation holes, so air can be discharged smoothly and the porous elastic layer can absorb moisture. Not only can this be done well, but also the efficiency of removing moisture can be further improved by removing moist air within the fixed circle.

[Brief explanation of drawings]

The drawings are for explaining the present invention, and FIG. 1 is an overall schematic diagram of a copying machine using an intermediate transfer member, and FIGS. 2 and 3 are diagrams of a water removal roll shown for reference. Each cross-sectional view, FIG. 4, is a cross-sectional view of a moisture removing roll according to an embodiment of the present invention. Regarding the symbols used in the drawings, 1
... Intermediate transfer roll, 9 ... Photosensitive drum, 13
...Developing sleeve, 18...Crimping roll, 22,
37... Guide plate, 24... Copy paper, 32... Static elimination lamp, 35... Cleaning device, 36...
This is a moisture removal roll.

Claims (1)

[Claims] 1. In a recording device that is provided with a heating section that heats a recording medium near a toner image carrier, for removing moisture generated when water vapor generated from the heating section condenses on the surface of the toner image carrier. The removing means includes a fixed cylinder having a ventilation hole in a side wall, and a cylindrical cored metal rotatably disposed around the outer periphery of the fixed cylinder concentrically with the fixed cylinder and capable of ventilation;
A recording medium comprising: a porous elastic layer for absorbing moisture, which is coated on the outer periphery of the core metal, rotates together with the core metal, and is provided in contact with the toner image carrier. Device.