JP3500282B2 - Corona charging method, apparatus and image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona charging method used in electrophotographic copying machines, facsimiles, printers, etc., a corona charging device, and an image forming apparatus equipped with the corona charging device.

[0002]

2. Description of the Related Art In image forming systems such as copying machines, printers, and facsimiles, various methods such as a thermal transfer method, a bubble jet method, and an ink jet method are used when visualizing an image. Of these, the most frequently used method is a method in which a charge carrier called toner is charged to transfer and fix it to a transfer target such as paper. That is, as represented by the Carlson process, a recording medium such as a photoconductor is charged with an electric charge, the charged electric charge of the recording medium is erased by light or the like to form a latent image of an original pattern, and a charge carrier called toner is formed on the original pattern. The image is placed on the paper and transferred to paper or the like.

In this electrophotographic system, there is a phenomenon of charge transfer in each process of charging, development, transfer, and charge removal. In order to cause this phenomenon, charge generation and transfer occur to a photoconductor, a charge carrier or a transfer target. Need to let. That is, an electrical process called charging is performed in order to transfer the charge carrier.

For this purpose, there are methods such as contact triboelectric charging, contact charge injection, and ionization by radiation. The contact friction charging and contact charge injection methods are used as a developing roller and a charging roller.

However, when the charging member comes into contact with the member to be charged, the low-molecular component of the roller is deposited and transferred, so that the member to be charged is contaminated, and as a result, there is a problem in that an image is abnormal. Although ionization due to radiation depends on the type of radiation, it is necessary to prevent exposure to radiation and has not been put to practical use at present.

The corona charging method, which has been most popularly used in the past, applies a high-voltage electric field to the electrodes of fine wires or needles to cause corona discharge between the electrodes and the opposing electrodes, thereby moving the corona ions to the member to be charged. This is a method of loading electric charges.

In this method, the principle and the device are very simple. However, the oxygen content in the air is about 20% by volume.
%, So in a corona discharge in air,
When the oxygen in the air is ionized, ozone O ₃ is generated. This ozone O ₃ is a substance that is a necessary molecule in the air above the air, but is a harmful substance in the office environment, and it is not desirable to generate it.

Further, in corona discharge in a nitrogen atmosphere, there is a problem in that the charging ability of the photoconductor is remarkably deteriorated, for example, the hygroscopicity is increased because the ions generate nox (NOx), and another method is desired. It was rare.

As one method therefor, a method has been started to reduce the generation of ozone by bringing a charging member and a member to be charged into contact with each other and injecting electric charge or using Paschen's law to discharge at a short distance.

However, since the corona discharge is basically used also in this contact charging method, ozone is inevitable as long as it is charged in a gas atmosphere containing oxygen. Therefore, the method of injecting an inert gas such as argon as in JP-A-59-204057 and the generation of ozone by using a gas having an oxygen concentration lower than that of air as in JP-A-60-95459 are used as much as possible. There are suggestions to reduce it.

[0011]

However, although merely reducing the oxygen concentration has the effect of reducing ozone generation, it cannot be sufficiently removed. Further, there is a problem that a complicated mechanism is required such as a gas separation filter as in the conventional example.

As long as the corona discharge phenomenon is used, light emission occurs due to the discharge, and this light emission phenomenon is a phenomenon that can be easily observed by performing corona discharge in a dark room. By the way, the mechanism of forming a latent image forming photoreceptor is to put a charge on the surface in a dielectric state where light is not exposed (so-called charging), and irradiate light according to the original pattern to expose the exposed area. The charge is temporarily made conductive to be released to the ground side, or conversely, a charge of opposite polarity is injected from the ground side to neutralize the charge and form a charge pattern similar to the original pattern. Therefore, the generation of light in the charging process of loading the electric charge deteriorates the charging efficiency. In the past, due to flare inside the machine, weak light emission was not a problem, but as the photoconductor becomes more sensitive due to higher image quality and higher speed, the effect of light emission due to this discharge cannot be ignored. ing.

[0013] Therefore, an object of the present invention is to provide a corona charging method and a device therefor which do not have a complicated mechanism and which generate less ozone than before without contact.

It is another object of the present invention to provide a corona charging device and an image forming apparatus capable of maintaining a discharge atmosphere gas better and performing stable discharge in the corona charging method and the apparatus thereof.

Another object of the present invention is to provide an image forming apparatus capable of obtaining good image contrast without increasing the applied voltage.

Another object of the present invention is to provide an image forming apparatus which can obtain a better image by utilizing the property of light emission due to discharge and which uses a charging method by corona discharge without generation of ozone. is there.

[0017]

In order to achieve the above object, a charging method according to the invention of claim 1 is a charging step, a transfer step, and a discharging step used in an image forming apparatus such as a copying machine, a facsimile, and a printer. In the non-contact charging method using corona discharge in the above steps, carbon dioxide gas is retained and used as a discharge atmosphere gas in at least one of the charging step, the transfer step and the charge eliminating step.

The charging method according to the invention of claim 2 is provided in an image forming apparatus such as a copying machine, a facsimile, a printer, etc., and is a charging device such as a charger, a transfer device or a charge eliminator charged by corona discharge. It is characterized in that carbon dioxide gas is retained and used as a discharge atmosphere gas in at least one of the charger, the transfer device and the static eliminator.

In the structure according to the first or second aspect, since the ozone non-generating gas excluding the inert gas is used as the discharge atmosphere gas, even if the corona discharge is generated in the atmosphere replaced with the gas which does not generate ozone, the ozone is not generated. Not only the generation is suppressed, but also the corona discharge efficiency is high. Further, since the charging device is non-contact charging that does not come into contact with the photosensitive member that is the member to be charged, the photosensitive member is free from contamination and good image quality is maintained.
In addition, in this specification, the inert gas means a rare gas and a nitrogen gas.

An organic photoconductor (hereinafter referred to as OPC)
Is greatly deteriorated by ozone, but since the generation of ozone is suppressed, the life of the photoconductor is extended and the durability is improved.

The corona discharge method has a higher ion generation efficiency than contact charging, and the wire electrode has a simpler structure and is less expensive than the contact charging member.

A gas having a larger specific gravity than air is likely to stay in a low portion and has a long time of diffusive mixing with air. Therefore, the concentration change of the atmospheric gas is small, the discharge condition is stable, and the gas is frequently supplied. You don't have to.

Carbon dioxide is a gas that can be abundantly obtained, is inexpensive, and does not generate new carbon dioxide, so it is also friendly to the global environment (warming).

An image forming apparatus according to a third aspect of the present invention has a charger for charging the latent image carrier by corona discharge, and the discharge atmosphere gas in the charging is an ozone non-generating gas having a specific gravity larger than air. In the forming apparatus, carbon dioxide gas is retained as the ozone non-generated gas and used, and the exposure light source used for forming the latent image on the latent image carrier is a white light source. With this configuration, since the member to be charged is developed at a low potential, it is possible to obtain a good image contrast without increasing the applied voltage, and further, it is possible to reduce power consumption and save energy.
Moreover, since the applied voltage is low, the durability of the charging device and the body to be charged is also improved.

An image forming apparatus according to a fourth aspect is the image forming apparatus according to the third aspect, characterized in that the member to be charged is a photosensitive member containing amorphous silicon as a main component. In this configuration, since the member to be charged is a photosensitive member containing amorphous silicon as a main component, it is possible to easily obtain good image contrast by low-potential development, save energy, and improve durability.

An image forming apparatus according to a fifth aspect is the image forming apparatus according to the third aspect, characterized in that the surface potential of the photoconductor before light irradiation is 400 volts. With this configuration, since the surface potential of the photoconductor is 400 V, good gradation of image quality can be obtained.

An image forming apparatus according to a sixth aspect of the present invention has a charger for charging the latent image carrier by corona discharge, and the discharge atmosphere gas in the charging is an ozone non-generating gas having a specific gravity larger than air. The forming apparatus is characterized in that carbon dioxide gas is retained and used as the ozone non-generating gas. With this configuration, by using carbon dioxide gas, ozone is not generated, and a good image forming apparatus without image blur can be provided. In addition, since the emission intensity of carbon dioxide gas during corona charging is weaker than that of air or argon at the same applied voltage, there is little charge reduction due to exposure of the photoconductor, and image disturbance is reduced.

An image forming apparatus according to a seventh aspect of the present invention has a charger for charging the latent image carrier by corona discharge, and the discharge atmosphere gas in the charging is an ozone non-generating gas having a specific gravity larger than air. In the forming apparatus, carbon dioxide gas is retained as the ozone non-generated gas and used, and the exposure light source used for forming the latent image on the latent image carrier is a white light source. With this configuration, carbon dioxide gas is an easily available gas, the cost is low, and no new carbon dioxide gas is generated. Therefore, not only is there an advantage that it is friendly to the global environment (warming). Since it is an analog system that forms a latent image by using a white light source as an exposure light source, the light emission during corona charging in a carbon dioxide atmosphere is white, so the decrease in charge due to exposure of the photoconductor is panchromatic. The color reproducibility improves.

An image forming apparatus according to an eighth aspect of the present invention is the image forming apparatus according to the sixth aspect, wherein the member to be charged is 0.
It is characterized in that it is a photoreceptor having a sensitivity of 1 m ² / mJ or more. With this structure, the high sensitivity of the photosensitive member, which is the latent image forming member, enables high-speed copying.
It is desirable that the sensitivity of the alloy or the a-Si photoreceptor is 0.1 m ² / mJ or more.

An image forming apparatus according to a ninth aspect of the invention has a charger for charging the latent image carrier by corona discharge, and the discharge atmosphere gas in the charging is an ozone non-generating gas having a specific gravity larger than air. In the forming apparatus, carbon dioxide gas is retained as the ozone non-generating gas, and the exposure light source used for forming the latent image on the latent image carrier is a green or blue monochromatic light source. With this configuration, carbon dioxide gas is an easily available gas, the cost is low, and no new carbon dioxide gas is generated. Therefore, not only is there an advantage that it is friendly to the global environment (warming). Since it is a digital system that forms a latent image by using a monochromatic light source as an exposure light source, when green or blue monochromatic light is used as a light source in the digital system, corona light in a carbon dioxide gas atmosphere is close to white, and air or It is possible to obtain a good image without exposing the photoreceptor to light in an argon atmosphere.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining a Carlson process image forming apparatus including a charging device of the present invention.

This image forming apparatus includes a photosensitive drum 1 on which a photosensitive member such as Se and Se alloy, zinc oxide, cadmium sulfide, OPC is formed in a drum shape, and a charger 2 for uniformly charging the surface of the photosensitive member. , An exposure device 3 for forming an electrostatic latent image
And a developing device 4 for forming a visible image and a toner image on the recording paper 9
Transfer device 5 for transferring the toner image onto the photosensitive drum 1, a fixing device 6 for making the transferred toner image a permanent image, a static eliminator 7 for eliminating the latent image charge on the photosensitive drum 1, and a residual toner on the photosensitive drum 1 is removed. And a cleaner 8 that operates.

In the recording process of this image forming apparatus, first, as a charging step, the surface of the photoreceptor is uniformly charged by the charger 2 in a dark place.

Next, in the exposure step, the exposure device 3 irradiates light to a portion other than the image portion to remove the charged electric charge in the light-exposed portion and form an electrostatic latent image in which the electric charge remains in the image portion. .

Next, as a developing process, the developing device 4
Toner, which is colored fine particles charged in the opposite polarity to the electrostatic latent image, is attached to the latent image to form a visible image.

Next, as a transfer step, the recording paper 9 is superposed on this toner image by the transfer device 5 of the corona charger, and the electric charge having the opposite polarity to the charging polarity of the toner is applied to the recording paper 9 from the back side of the recording paper 9. The toner image is applied and the toner image is transferred to the recording paper by electrostatic force.

Next, as a fixing step, the fixing device 6
Heat or pressure is applied to the transferred toner image to fuse it to the recording paper to form a permanent image.

On the other hand, in the neutralization step, the latent image charges on the photosensitive drum 1 after transfer are neutralized by the neutralizer 7.

In the cleaner step, the residual toner remaining on the photosensitive drum 1 without being transferred is removed by the cleaner 8. Printing is continuously performed by repeating a series of processes from charging to cleaning.

In a printer or a facsimile, the image portion is often irradiated with light by a laser or the like to form an electrostatic latent image in a form in which electric charges in the image portion are removed.

FIG. 2 is a diagram for explaining a corona charging device using the corona charging method of the present invention. The corona charging device of the present invention is used as a charging device such as a charging device, a transfer device, and a static eliminator of the image forming apparatus of FIG. The structure of this corona charging device is, for example, in the case of the charger 2, is arranged in the box-shaped charging house 2b and this charging house 2b, and a high voltage is applied between the photosensitive drum 1. And a charging wire 2a.

The charging house 2b has a side surface and a bottom surface covered with wall surfaces, and has an opening at an upper portion facing the photosensitive drum 1. Further, the ozone non-generating gas source 10 is connected to the charging house 2b so that the ozone non-generating gas can be supplied into the charging house 2b.
As the ozone non-generating gas, carbon dioxide gas (CO ₂ ) was selected as described later. In this way, the charging house 2 with carbon dioxide gas, which has a higher specific gravity than air, opened at the top
Since it is supplied to b, even if it is not continuously supplied,
A carbon dioxide atmosphere can be maintained. Although the case of the charger 2 has been described as the corona charging device,
The transfer device 5 and the static eliminator 7 can be used in the same manner.

Nitrogen gas (N ₂ ) is considered as a gas that can be easily used in our daily lives. Nitrogen is abundant because it is the main component of air, but since it has a close gas density to oxygen, it diffuses into the air immediately. Will be dissipated. Therefore, in order to constantly maintain a pure nitrogen atmosphere, special equipment and nitrogen supply equipment are required.

In the case of nitrogen corona discharge, Japanese Patent Laid-Open No.
It is also known that ions generate knox as described in JP-A-95459, so that the hygroscopicity is increased and the charging ability of the photoconductor is significantly deteriorated.

Other familiar gases include water vapor H ₂
O, hydrogen H ₂ , helium He, neon Ne, propane C
_{Although there are 3} H ₈ and natural gas CH _4, etc., it is not possible to use those that are in danger of fire, and it is impossible to use stably those that are not gases at room temperature.

Further, rare gases such as He, Ne, Ar, and Xe have low corona discharge efficiency and are expensive, so they cannot be used abundantly.

Even if a gas that does not generate ozone is used, if it is lighter than air, it rises to the upper part. Therefore, in order to retain the gas, install an umbrella-shaped container on the upper part so that the gas does not escape, or There was a problem that it had to be washed away and continued to be supplied.

In the present invention, a corona discharge is carried out in a gas which can be easily used in place of these and is charged.
The above problems can be achieved by using carbon dioxide as the gas component.

As the ozone non-generating gas, a gas having a molecular structure containing no oxygen is most suitable, and carbon dioxide gas contains oxygen in its molecular structure, but this molecule is extremely stable, and in the event of a fire. Also used as a digestive agent. Further, at a normal corona discharge level, it does not dissociate to generate oxygen, but is sufficiently ionized and ionized.

Carbon dioxide has a molecular weight of 44, has a specific gravity of gas which is about 1.5 times as heavy as the density of air, and retains downward so as to cause oxygen deficiency in old wells and the like.

Accordingly, unlike the nitrogen gas and the helium gas, the carbon dioxide atmosphere can be maintained for a long time if the box-shaped charging house is provided without gaps on the side surface and the bottom.

If the charging conditions change due to the dissipation or dilution of the gas, the gas may be supplied to the charging house. The method is simply to gently inject gas from a cylinder or the like on which it is mounted and allow it to overflow.

Further, since this method only uses existing carbon dioxide gas and does not generate new carbon dioxide gas, it does not adversely affect global warming.

(Example 1) Using a paper analyzer (SP-428 manufactured by Kawaguchi Electric Co., Ltd.) having a charging potential measuring apparatus having a box-shaped charging house having an upward opening, carbon dioxide gas was used in the air and carbon dioxide gas. The applied voltage and the corona discharge current were measured.

As a result, as shown in FIG. 3, the discharge start does not occur in the carbon dioxide gas unless the applied voltage is a little higher than that in the air, but the discharge can occur stably if the applied voltage is sufficiently high. understood.

On the outside of the fan of the measuring instrument at this time, a strange odor was generated in the air discharge, and the negative discharge was more intense than the positive discharge, but there was no strange odor in the carbon dioxide discharge. 2 pp for air discharge when measured with an ozone concentration meter
m ozone was detected, but it was 0.0 in carbon dioxide discharge.
It was found to be below 05 ppm.

Further, in the carbon dioxide discharge, the discharge current is constant and does not change when the carbon dioxide gas is continuously injected, and the discharge current does not increase for a long time even if the carbon dioxide gas injection is stopped and left to increase. It was confirmed that it takes a longer time to reach the same value as the discharge current in the air even if it starts.

(Embodiment 2) Next, using the same charging potential measuring device, Se photoconductor and SeA
The charge carrier generating layer (CG
Regarding the OPC photoconductor designated as L), the charging potential, sensitivity, and residual potential were measured in air and carbon dioxide. In each case, the applied voltage was set to be the same as the discharge current in air and carbon dioxide in the case of no load on the photoreceptor (about 1.5 times that in air in carbon dioxide). The illuminance for sensitivity measurement is
There is no difference in gas atmosphere, and the same type of photoconductor has the same exposure amount. The measurement conditions are shown in Table 1 below.

[0059]

[Table 1]

As a result, as shown in Table 2 below, it can be seen that there is no difference in the gas atmosphere and the same type of photoconductor shows the same photoconductor characteristics (charging potential, sensitivity, residual potential).

[0061]

[Table 2]

In Table 2, Vm is the potential after charging for 20 sec, RD is the value obtained by dividing the potential after dark decay for 20 sec by the initial potential, and E1 / 10 is 1/10 of the potential after irradiation with light. And Vr represent the residual potential after 30 seconds of light irradiation, respectively.

FIG. 4 is a block diagram showing a third embodiment of the present invention. The image forming apparatus according to the third embodiment of the present invention is a charger 2 that is a charging device that charges the photosensitive drum 1 that is a portion to be charged, and an exposure that is an exposure device that image-exposes the charged photosensitive drum 1. Part rinse 3a, developing device 4 for developing imagewise exposed photoconductor drum 1, transfer device 5 for transferring a toner image which is a developed image of photoconductor drum 1 to paper 9 which is a print medium, and a print start signal And a control unit 11 for stopping the operation after the printing operation is completed. The charger 2 is disposed below the photoconductor drum 1 and has an upper opening 2h (see FIG. 6) that faces the photoconductor drum 1 in close proximity to the ambient gas (a gas that does not generate ozone and has a specific gravity larger than air). , A box-shaped charging house 2b, which is a means for retaining carbon dioxide, for example.

Charging house 2b of the charger 2
As shown in FIG. 6 (A), the bottom plate 2d and the side plate 2c are configured so as to surround the lower side and the lateral side of the charging wire 2a, and as described above, the upper part facing the photosensitive drum 1 faces. The opening 2h is formed. One end of a pipe 2e is connected to approximately the center of the side plate 2c of the charging house 2b, and the other end of the pipe 2e is a discharge atmosphere in which carbon dioxide gas, which is a discharge atmosphere gas, is charged to a high pressure as shown in FIG. A cylinder 2f, which is a gas supply means, is connected. Then, from the cylinder 2f which is the supply source of the discharge atmosphere gas to the pipe 2e.
A discharge atmosphere gas is supplied to the charging house 2b through the charging wire 2a, and a voltage is applied to the charging wire 2a for corona discharge.

At this time, since the corona charger 2 is opened only upward, the residence time of carbon dioxide gas having a gas specific gravity larger than that of air is long, and frequent gas supply is not required. Moreover, since the discharge atmosphere gas supply means 2f is provided,
Even if the discharge atmosphere gas is dissipated, the discharge atmosphere gas can be supplied each time, and stable discharge and charging of the photosensitive drum 1 are possible. In particular, when the discharge atmosphere gas supply source is the cylinder 2f as in this embodiment, the supply source can be easily replaced.

In the charger 2, the charging house 2
After bubbling carbon dioxide gas into the b through the pipe 2e to fill it,
Corona discharge is performed by applying a constant electric field from a high voltage power supply. As a result, the photoconductor drum 1 is charged to a predetermined surface potential, and then an optical signal of the original pattern is guided and irradiated by the exposure unit rinse 3a. Next, the toner is attached to the photoconductor 1 by the developing device 4, and then transferred to the sheet 9. Next, the sheet on which the toner has been transferred is passed through a fixing roller 15 described later to form an image.

As shown in FIG. 6B, the pipe 2e connected to the charging house 12b of the charger 12 is connected to the side plate 12.
The discharge atmosphere gas may be overflowed from the upper opening 2h by connecting to the lower end of c.

As shown in FIG. 6C, the charger 2
The discharge atmosphere gas is charged from the upper opening 2h of the second charging house 22b through the pipe 2e.
It may be filled in b and overflowed from the upper opening 2h.

Further, as shown in FIG. 6D, the charger 3
The discharge atmosphere gas may overflow from the upper opening 2h by connecting the pipe 2e connected to the second charging house 32b to, for example, the central portion of the bottom plate 32d. In the configurations of FIGS. 6B and 6D, since the atmospheric gas supply means is connected to the bottom of the atmospheric gas retention means,
Atmosphere gas can be efficiently supplied.

Further, in the image forming apparatus according to the third embodiment of the present invention, an optical static eliminator 7 for eliminating static electricity from the photosensitive drum 1, which is composed of an LED (light emitting diode), and the photosensitive drum 1 are provided.
A cleaner 8 for cleaning the sheet, a conveyance roller 17 for conveying the sheet 9, a fixing roller 15 for fixing the sheet 9 on which the toner image is transferred while being fed, and a conveyance roller 17 at a standby position from a hopper (not shown) A standby sensor 16a for detecting the discharge of the sheet 9, a discharge sensor 16b for detecting the discharge of the sheet 9, and a motor 14 for rotationally driving the conveying roller 17, the photosensitive drum 1, the developing device 4, the fixing roller 15 and the like. There is. Then, the optical static eliminator 7, the transfer device 5, the motor 14, the developing device 4, the exposure unit rinse 3a, the charger 2 and the fixing roller 15 are driven by the drive unit 13.

Next, the operation of the image forming apparatus of the third embodiment will be described. When the copy operation is started, reading of image data is started by a scanner (not shown), and optical writing and latent image formation by laser light are started from the exposure unit rinse 3a based on the image data. The toner image formed on the photosensitive drum 1 is transferred by the transfer device 5 onto the surface of the sheet 9 conveyed by the conveying roller 17. The transferred sheet 9 is fixed by the fixing roller 15. After the transfer, the photoconductor drum 1 is neutralized by the optical static eliminator 7, and the cleaner 8
To be cleaned.

As Comparative Example 1, an image was formed by using the same charging unit as in Example 3 while the atmospheric gas was not replaced with carbon dioxide gas and air was used. With the same applied voltage as in Example 3, the surface potential of the photoconductor was too high and the image density was too high.
Therefore, the applied voltage was lowered, but the ozone odor outside the machine did not disappear.

As a result of Example 3, the image quality was comparable to that of Comparative Example 1 and was good with no ozone odor. In the third embodiment described above, the case where the pre-charger is used as the charging device has been described, but it can be easily applied to a transfer device, a static eliminator, and the like.

FIG. 7 is a block diagram showing a fourth embodiment of the present invention. The photoconductor drum 1 rotates counterclockwise as shown by the arrow, and the photoconductor cleaning unit 2 is provided around the photoconductor drum 1.
0, static elimination lamp L, charger 2, potential sensor 14, developing device 4c for cyan among the three primary colors (cyan, magenta, yellow) of subtractive color mixing, developing device 4m for magenta, and developing device 4y for yellow, development density pattern detection Equipment for performing the electrophotographic copying process, such as the container 4s and the intermediate transfer belt 21 arranged below the photosensitive drum 1, is arranged.
Each of the developing devices 4c, 4m, and 4y rotates to develop the electrostatic latent image so that the developer faces the photosensitive drum 1, and to rotate the developing sleeve 41 to scoop and agitate the developer. The developing paddle 42 and the toner concentration detection sensor 43 of the developer are included.

A charging house 2b (see FIGS. 5 and 6) of the charger 2 is arranged at a position facing the photosensitive drum 1 inside the intermediate transfer belt 21. By including the charging house 2b, a charging unit for the transfer applied voltage of the intermediate transfer belt 21 is configured. Then, as in the third embodiment, the side wall 2 of the box-shaped charging house 2b is provided.
A hole for supplying the discharge atmosphere gas is provided in c (see FIGS. 5 and 6) to connect the pipe 2e so that the atmosphere gas can be supplied from the cylinder 2f of the supply source. In this configuration, since the atmospheric gas supply means is a cylinder containing the atmospheric gas at a high pressure, it is easy to replace the atmospheric gas supply means. Note that, similarly to the third embodiment, the chargers 12, 22, and 32 of FIGS. 6B, 6C, and 6D can be used instead of the charging house 2b of FIG. 6A.

Next, the case where the order of the developing operations is cyan, magenta and yellow will be described. However, the image forming order is not limited to this.

When the copying operation is started, reading of cyan image data is started at a predetermined timing by a color scanner (not shown), and optical writing and latent image formation by laser light are started based on the cyan image data.
The developing sleeve 41 is started to rotate before the latent image front end reaches the developing position of the cyan developing device 4c so that the cyan latent image can be developed from the front end, and the cyan latent image is developed with cyan toner. After that, the developing operation of the cyan latent image area is continued, but when the rear end portion of the cyan latent image passes the cyan developing position, the developing operation is disabled. This is completed at least before the leading edge of the magenta latent image by the next magenta image data arrives.

The cyan toner image formed on the photoconductor drum 1 is transferred to the surface of the intermediate transfer belt 21 which is driven at the same speed as the photoconductor drum 1 (hereinafter, toner image transfer from the photoconductor to the intermediate transfer belt). Is called the belt transfer). This transfer is performed by the charger 2 which opens upward toward the photosensitive drum 1. On the intermediate transfer belt 21, cyan, magenta, and yellow toner images sequentially formed on the photosensitive drum 1 are sequentially aligned on the same surface to form a three-color belt transfer image, and then the paper 9 is formed. Batch transfer to.

The paper transfer unit 19 is composed of a paper transfer bias roller 19b, a roller cleaning blade 19a, a contact / separation mechanism 19c from the intermediate transfer belt 21, and the like. The paper transfer bias roller 19b is normally separated from the surface of the intermediate transfer belt 21.
When the three-color superimposed images formed on one surface are collectively transferred to the transfer paper 9, the timing is set and the contact / separation mechanism 19c is set.
The toner image is transferred to the paper 9 while being pressed by the paper transfer bias roller 19b while applying a predetermined bias voltage. In addition, 18 is a paper transport unit, 22 is a photoconductor cleaning unit, 20a is a brush roller, and 20 is a brush roller.
b is a rubber blade.

As Comparative Example 2, the same transfer as in Example 4,
In the image forming apparatus having the fixing process, the method of applying the transfer voltage to the conventional conductive roller was used instead of the method of applying the transfer voltage to the intermediate transfer belt of Example 4.

As a result of Example 4, a good image was obtained as in Comparative Example 2. In the fourth embodiment, since the charger is simply used, the rotating mechanism of the roller as in the second comparative example is not required, and the mechanism is simplified, and there is an advantage that unevenness is reduced especially when the speed is increased.

In the above fourth embodiment, the case where the transfer charging device is used as the charging device has been described, but it can be easily applied to a static eliminator or the like.

FIG. 8 is a schematic diagram of the image forming apparatus of the present invention. The image forming apparatus of the present invention includes a photoconductor drum 1 on which a photoconductor such as Se and Se alloy, zinc oxide, cadmium sulfide, and OPC is formed in a drum shape, and a charger 2 that uniformly charges the surface of the photoconductor. Exposure device 3 for forming an electrostatic latent image
And a developing device 4 for forming a visible image and a toner image on the recording paper 9
Transfer device 5 for transferring the toner image onto the photosensitive drum 1, a fixing device 6 for making the transferred toner image a permanent image, a static eliminator 7 for eliminating the latent image charge on the photosensitive drum 1, and a residual toner on the photosensitive drum 1 is removed. And a cleaner 8 that operates.

In the recording process of this image forming apparatus, first, as a charging step, the surface of the photoreceptor is uniformly charged by the charger 2 in a dark place.

Next, in the exposure step, the exposure device 3 irradiates light on a portion other than the image portion to remove the charged electric charge in the light-exposed portion and form an electrostatic latent image in which the electric charge remains in the image portion. .

Next, as a developing step, the developing device 4
Toner, which is colored fine particles charged in the opposite polarity to the electrostatic latent image, is attached to the latent image to form a visible image.

Next, as a transfer step, the recording paper 9 is superposed on this toner image by the transfer device 5 of the corona charger 2, and a charge having a polarity opposite to the charging polarity of the toner is applied from the back side of the recording paper 9 to the recording paper 9. Then, the toner image is transferred to the recording paper by electrostatic force.

Next, as a fixing step, the fixing device 6
Heat or pressure is applied to the transferred toner image to fuse it to the recording paper to form a permanent image.

On the other hand, in the static elimination step, the latent image charges on the photosensitive drum 1 after transfer are eliminated by the static eliminator 7.

In the cleaner step, the residual toner remaining on the photosensitive drum 1 without being transferred is removed by the cleaner 8. Printing is continuously performed by repeating a series of processes from charging to cleaning.

In a printer or a facsimile, the image portion is often irradiated with light by a laser or the like to form an electrostatic latent image in a form in which electric charges in the image portion are removed.

FIG. 9 is a diagram for explaining the discharge atmosphere gas supply device of the corona charging device provided in the image forming apparatus of the present invention. The corona charging device is used as a charging device such as a charging device, a transfer device, and a static eliminator of the image forming apparatus of FIG. The configuration of this corona charging device is, for example, in the case of the charger 2, a box-shaped charging house 2b which is a discharge atmosphere gas retention means, and a charging drum 2b which is disposed in the charging house 2b. And a charging wire 2a to which a high voltage is applied.

The charging house 2b has a side surface and a bottom surface covered with wall surfaces, and an upper portion facing the photosensitive drum 1 is open. Further, a cylinder 13 which is a non-ozone generating gas source is connected to the charging house 2b through a pipe 2e, so that the non-ozone generating gas can be supplied into the charging house 2b. A gas flow rate adjusting valve 32, a pressure gauge or a flowmeter sensor 33, a display panel 34, and a controller 31 are provided in the middle of the pipe 2e.

In this structure, since the atmospheric gas retaining means of the charging device has the upper opening facing the portion to be charged, the residence time of the atmospheric gas having a specific gravity larger than that of air can be lengthened and frequent gas supply is required. There is no.

The gas flow rate adjusting valve 32 is opened and closed to adjust the gas flow rate according to a signal from a gas concentration sensor provided in the charging house 2b. The sensor 33
Detects the gas pressure or the gas flow rate in the pipe 2e and sends a signal corresponding to the replacement time of the cylinder 2f to the control unit 31,
The warning display panel 34 lights up as shown in FIG. Further, the control unit 31 sends out a signal for applying a voltage to the charging wire 2a after replacing the cylinder 2f.

FIG. 10 is a sectional view of the corona charging device. In this corona charging device, the side plate and the bottom plate surround the side surface and the bottom surface of the charging wire 2a, and only the upper part is opened. The pipe 2e is connected to the side plate.

FIG. 11 is a view showing the connection of the cylinder of the image forming apparatus of the present invention. As shown in FIG. 11A, a replacement cylinder 2f is set between the pipe 2e and the holder 23a. At this time, since the elastic body 23b is arranged in the holder 23a, the replacement cylinder 2f is set so as to compress the elastic body 23b.

Next, as shown in FIG. 11 (B), when the force pressing the replacement cylinder 2f against the elastic body 23b is released, the replacement cylinder 2f is opened by the expansion force of the elastic body 23b to connect the pipe 2e. The cylinder 2f is automatically pressed by being pressed against the end. Therefore, by mounting the cylinder 2f by pressing the elastic body 23b, it becomes possible to remove and replace the replacement with one touch, and the replacement work becomes easy. In this configuration, discharge atmosphere gas (carbon dioxide gas)
Since the gas can be supplied each time even if the charge is dissipated, it is possible to stably discharge and charge the charged body.

As the ozone non-generating gas, carbon dioxide gas was selected as described later. In this way, since carbon dioxide gas having a higher specific gravity than air is supplied to the charging house 2b having an upper opening, the carbon dioxide atmosphere can be maintained even if the carbon dioxide gas is not continuously supplied. Although the case of the charger 2 has been described as the corona charging device, the transfer device 5, the static eliminator 7 and the like can be used in the same manner.

Nitrogen gas is conceivable as a gas that can be easily used in our daily lives. Nitrogen is abundant because it is the main component of air, but since it has a gas density close to that of oxygen, it immediately diffuses and diffuses into the air. I will end up. Therefore, in order to constantly maintain a pure nitrogen atmosphere, special equipment and nitrogen supply equipment are required.

Further, in the corona discharge of nitrogen, Japanese Patent Laid-Open No.
It is also known that ions generate knox as described in JP-A-95459, so that the hygroscopicity is increased and the charging ability of the photoconductor is significantly deteriorated.

Other familiar gases include water vapor H ₂
O, hydrogen H ₂ , helium He, neon Ne, propane C
_{Although there are 3} H ₈ and natural gas CH _4, etc., it is not possible to use those that are in danger of fire, and it is impossible to use stably those that are not gases at room temperature.

Further, rare gases such as He, Ne, Ar, and Xe have low corona discharge efficiency and are expensive, so they cannot be used abundantly.

Further, even gas that does not generate ozone rises to the upper part if it is lighter than air. Therefore, in order to make it stay, install an umbrella-shaped container so that the gas does not escape to the upper part, or gas There was a problem that it had to be washed away and continued to be supplied.

According to the present invention, a corona discharge is carried out in a gas which can be easily used in place of these and is charged.
The above problems can be achieved by using carbon dioxide as the gas component.

As the non-ozone-generating gas, a gas having a molecular structure containing no oxygen is most suitable, and carbon dioxide gas contains oxygen in its molecular structure, but this molecule is extremely stable, and in the event of a fire. Also used as a digestive agent. Further, at a normal corona discharge level, it does not dissociate to generate oxygen, but is sufficiently ionized and ionized.

Carbon dioxide has a molecular weight of 44 and has a specific gravity of gas which is about 1.5 times as heavy as the density of air, and retains downward so as to cause oxygen deficiency in old wells and the like.

Accordingly, unlike the nitrogen gas and the helium gas, the box-shaped charging house 2b does not dissipate rapidly.
The carbon dioxide gas atmosphere can be maintained for a long time if the side surface and the bottom portion are provided without a gap.

If the charging conditions change due to the dissipation or dilution of the gas, the gas may be supplied to the charging house 2b. The method is simply to allow the gas to gently flow in from the cylinder 13 or the like mounted and to overflow it.

Further, since this method uses only the existing carbon dioxide gas and does not generate new carbon dioxide gas, it does not adversely affect global warming.

Furthermore, in carbon dioxide discharge, the discharge current is constant and does not change if carbon dioxide gas is continuously injected, and the discharge current does not increase for a long time even if the carbon dioxide gas injection is stopped and left to increase. It was confirmed that it takes a longer time to reach the same value as the discharge current in the air even if it starts.

Example 5 FIG. 13 shows a lighting flow of a display panel, (A) shows a lighting flow of a display panel when a pressure sensor is used, and (B) shows a display when a flow sensor is used. The lighting flow of a panel is shown.

As shown in FIG. 13A, step S1
When the main power source is turned on in step S2, the pressure sensor is automatically turned on in step S2, and detection of the pressure of the discharge atmosphere gas in the cylinder 2f is started.

Next, in step S3, the detected value P of the pressure sensor is compared with the preset pressure value P _{0. If} the detected value P is larger, the process proceeds to step S8, and the charging device is applied. When the voltage is turned on and is equal to or smaller than the pressure value P ₀ , the process proceeds to step S4. By setting the pressure value P ₀ to the atmospheric pressure in advance, it can be detected that the remaining amount in the cylinder 2f becomes zero. Alternatively, the warning display may be turned on before the remaining amount becomes zero by setting the pressure slightly higher than the atmospheric pressure.

Next, in step S4, the warning display is turned on, and the process proceeds to step S5. Next, in step S5, the cylinder 2f is replaced. Next, in step S6, the detected value P of the pressure sensor is compared with the preset pressure value P _0, and if the detected value P is larger, step S7
Then, the warning display is turned off, and if the pressure value is equal to or smaller than P ₀ , the process returns to step S5. Therefore, the cylinder 2f
The warning display is turned on until the gas pressure exceeds the set value P ₀ , and when the cylinder 2f is replaced and the gas pressure exceeds the set value, the warning display is turned off.

Next, the voltage applied to the charging wire of the charging device is turned on. In this way, with a Ricoh copier equipped with a carbon dioxide supply and a charger capable of corona discharge in the atmosphere, a gas pressure gauge is provided between the supply part, the adjusting valve, and the charging part. When the gas pressure becomes lower than the atmospheric pressure, the signal is detected and the display panel 14 is turned on.

In the fifth embodiment, the initial image quality is good,
Since the display panel 34 was turned on at a predetermined number as the sheets were continuously copied, the cylinder 2f was replaced and further copying was continued, but the image quality was good. Even if the display panel 34 was turned on, when copying was continued, the image density suddenly increased and the image quality deteriorated.

(Sixth Embodiment) When a flow sensor is used, as shown in FIG. 13B, when the main power source is turned on in step S1, the flow sensor is automatically turned on in step S2. As soon as the state is reached, the adjusting valve 32 is opened and the flow rate of the discharge atmosphere gas in the pipe 2e is started to be detected.

Next, in step S3, the detected value V of the flow rate sensor is compared with the preset value V _{0 of the} flow rate. If the detected value V is larger, the process proceeds to step S8 and the charging device. When the applied voltage is turned on and is equal to or smaller than the set value V ₀ , the process proceeds to step S4.

Next, in step S4, the warning display is turned on, the adjusting valve 11 is closed, and the process proceeds to step S5. Next, in step S5, the cylinder 2f is replaced.
Next, in step S6, the detection value V of the flow rate sensor is compared with the preset flow rate setting value V _{0. If} the detection value V is larger, the process proceeds to step S7 and the warning display is turned off. If it is equal to or smaller than the set value V ₀ , the process returns to step S5. Therefore, the warning display lights up until the cylinder 2f is replaced and the flow rate exceeds the set value.
If is replaced and the flow rate exceeds the set value, the warning display goes off. Next, in step S8, the applied voltage of the charging wire of the charging device is turned on.

As described above, in a Ricoh-made copying machine equipped with a charging device capable of supplying carbon dioxide gas and performing corona discharge in the atmosphere, a gas flow meter was provided between the supply part, the adjusting valve and the charging part. When the gas flow rate becomes zero, the signal is detected and the display panel 14 is turned on.

The initial image quality was good, and the display panel 14 was lit up in a predetermined number as continuous copying was performed. Therefore, the cylinder 2f was replaced and copying was continued, but the image quality was good. Even if the display panel 14 was turned on, if copying was continued, the image density suddenly increased and the image quality deteriorated.

(Comparative Example 3) A Ricoh copying machine equipped with a charging device capable of supplying a carbon dioxide gas and performing corona discharge in the atmosphere,
No gas pressure gauge or flowmeter was provided between the supply section, the adjusting valve, and the charging section, and no display panel was provided, and images were repeatedly taken.

The initial image quality was good, but when continuous copying was performed, the image density suddenly became higher and the image quality deteriorated at a predetermined number or more.

As described above, the image quality can be kept good by replacing the cylinder 2f when the gas shortage display on the display panel 34 lights up. When I continued without replacing even if it came out, not only did I not get a good image, but I also felt a strange odor of ozone near the device.

By the way, it has been known that the light emission phenomenon associated with the discharge phenomenon is a cause of an image blur phenomenon, a poor color balance reproducibility of a color original document, etc., which have been unknown in the past. That is, it was found that the emission color due to corona discharge in the atmosphere of air or argon was bluish.

Therefore, as a result of earnest studies by the present inventor,
It has been found that carbon dioxide is a gas that causes corona discharge with light emission close to white light. It was also found that the emission intensity in the carbon dioxide gas was smaller than that in the atmosphere of air or argon at the applied voltage for obtaining the same charge amount.

The present invention utilizes these events to provide a good image. That is, when a voltage is applied to cause corona discharge, a part of the corona ions adheres to the surface of the photoconductor and becomes a surface charge, but part of the corona ions is discharged when the electrons or ions of opposite polarities are combined and from the electrode. When the electrons recombine, the extra energy is emitted as light. This is a light emission phenomenon called corona. However, since the photosensitive member, which is the member to be charged, is an optical semiconductor whose electric resistance decreases when exposed to light, extra light should be avoided as much as possible.

It is known that the spectrum of emitted light differs depending on the kind of atmospheric gas, and the emitted light is blue in the atmosphere of air (N ₂ ) or argon Ar. Conventionally, this light emission has not been a serious problem because the light outside the machine of the image forming apparatus, the scattered light from the light source inside the machine, the leakage light, etc. are large and the image quality is at a level corresponding thereto. However, when high image quality is required and a high-sensitivity photoconductor is used for high-speed image formation, even a slight amount of light affects the image quality.

Further, in analog, the spectral sensitivity of the photosensitive member is also important, but since this light emission is superimposed on the reflected light from the original by the light source for exposure, the part of the color tone is PP at a specific wavelength. The density decreases in the (positive-positive) method and increases in the NP (negative-positive) method, and the color tone balance is lost in a color original. Therefore, a panchromatic gas that emits little light and does not have a spectral distribution is desirable. The discharge emission of carbon dioxide gas is white, and the emission intensity is weaker than that of an inert gas such as argon. By doing so, the blurring phenomenon of the image and the color balance reproducibility of the color original are improved.

Example 7 In an analog type image forming apparatus using white light as a light source of Example 3 of FIG. 4, carbon dioxide gas was used as a charging atmosphere gas, and a low potential developing toner was loaded as a toner. Then, an amorphous silicon photoconductor having a film thickness of 20 μm was used as a photoconductor, and an image was formed by setting the charging voltage to 4.5 kV, which is lower than 5 kV used for the Se-based photoconductor. The surface potential (black solid density part) of the photoreceptor before light irradiation is 4
The image was uniform at 00V, and the image was reproduced well in light and shade and color tone by light irradiation. Even after repeated use, no abnormality occurred in the photoreceptor and the image quality.

Example 8 In an analog type image forming apparatus using white light as a light source in Example 3 of FIG. 4, carbon dioxide gas was used as a charging atmosphere gas, and a low potential developing toner was loaded as a toner. using Te, thickness 30μm as photoreceptor Se ₂ as ₃
Using a photoconductor, apply a charging voltage of S with a normal film thickness of 60 μm
An image was printed at 4.5 kV, which was lower than 5 kV for the e-type photoreceptor. The surface potential (black solid density portion) of the photoconductor before light irradiation was uniform at 400 V, and the original was reproduced with good light and shade and color tone of the image by light irradiation. Even after repeated use, no abnormality was found in the photoconductor and the image quality.

Example 9 In a digital type image forming apparatus using a blue diode as a light source of Example 3 of FIG. 4, carbon dioxide gas was used as a charging atmosphere gas, and a low potential developing toner was loaded as a toner. Amorphous silicon photoconductor having a film thickness of 20 μm is used as the photoconductor, and the charging voltage is Se.
Images were printed at 4.5 kV, which was lower than 5 kV for the system photoreceptor. The surface potential (black solid density portion) of the photoconductor before light irradiation was uniform at 400 V, and the light and shade of the image due to the light irradiation reproduced the original satisfactorily. Even after repeated use, no abnormality was found in the photoconductor and the image quality.

Comparative Example 4 In the image forming apparatus of Example 3 shown in FIG. 4, carbon dioxide gas was used as the charging atmosphere gas, toner not used for conventional low potential development was used as the toner, and the film thickness was 20 μm as the photoconductor.
The surface potential of Se is
The applied voltage was increased and adjusted so that the same charge amount (750 V) as that of the system photoconductor was obtained, and images were displayed.

As a result, although the image was good, S
An applied voltage of 6 kV was required in the case of the amorphous silicon photoconductor, whereas it was 5 kV in the case of the e-type photoconductor.
Further, when it was repeatedly used, white pinholes began to appear on the image, and when the photoconductor was observed, a concave portion which was thought to be due to a lightning strike (abnormal discharge) was found at the corresponding position.

Comparative Example 5 In the image forming apparatus of Example 3 of FIG. 4, carbon dioxide gas was used as the charging atmosphere gas, low potential developing toner was used as the toner, and amorphous silicon photosensitive film having a film thickness of 20 μm was used as the photoconductor. Using the body, the applied voltage was increased and adjusted so that the surface potential was the same as that of the Se-based photoreceptor, and the image was displayed. As a result, the image became darker overall, and halftone density could not be reproduced. Then, upon repeated use, the same abnormal phenomenon as in Comparative Example 4 occurred.

(Comparative Example 6) In the analog type image forming apparatus of Example 3 in FIG. 4, the charging atmosphere gas was argon gas, the toner was charged with the toner for low potential development, and the photoconductor was amorphous with a film thickness of 20 μm. An image was printed by replacing the silicon photoconductor with a charging voltage of 4.5 kV, which is lower than 5 kV for the Se-based photoconductor. The surface potential (black solid density part) of the photoconductor before light irradiation is non-uniform from 380 V to 400 V, and light and shade of the image occurs due to light irradiation, and the color tone is slightly emphasized in cyan-based colors with respect to the original. It was

(Comparative Example 7) In a digital type image forming apparatus using a blue diode as a light source of Example 3 in FIG. 4, a charging atmosphere gas was used as an argon gas, and a toner for low potential development was loaded with the toner and exposed. The body was replaced with a photosensitive member of amorphous silicon having a film thickness of 20 μm, and an image was printed with the charging voltage applied to 4.5 kV, which is lower than 5 kV for the Se-based photosensitive member.
The surface potential (black solid density part) of the photoreceptor before irradiation was nonuniform from 370V to 390V, and light and shade of an image was generated by light irradiation.

In carbon dioxide gas, it is necessary to increase the applied voltage in order to obtain the same corona discharge current.
As shown in No. 9, it can be seen that the image forming apparatus using the low potential developing toner can obtain good image quality at the conventional applied voltage level. Further, when a high voltage is applied to a photoreceptor having a low withstand voltage, dielectric breakdown occurs, but since charging is performed at a low applied voltage, durability can be improved.

FIG. 14 shows a main part of an image forming apparatus equipped with the corona charging device of the present invention. Reference numeral 51 is a case-type charging house having an opening 51c at the top and serving as a container and an electrode, and the side surface 51a and the bottom surface 51b of the charging house 51 are sealed. A charging wire 52 as a needle electrode (opposite electrode) is provided in the approximate center of the internal space of the charging house 51. A corona discharge power source (DC) 53 is connected to the charging wire 52. A gas concentration detector 54 is provided on the side surface 51a of the charging house 51 as a gas concentration detecting means for detecting the gas concentration in the charging house 51.

The gas concentration detector 54 is a supply for detecting whether or not the supplied ozone generation suppressing gas is properly kept in the charging house 51, as will be described in detail in the embodiments described later. The gas concentration detector is a generated gas concentration detector that directly detects the concentration of environmentally destructive gases such as ozone and nitrogen oxides generated when air is mixed.
It may be a detection unit that detects the concentration of air flowing into the charging house 51.

Above the opening 51c of the charging house 51, the lower portion of the outer peripheral surface 55a of the drum-shaped photosensitive member 55 is located. The core axis of the photosensitive drum 55 is arranged parallel to the longitudinal direction of the charging house 51. As the photoconductor, organic photoconductor (OPC), Se photoconductor, S
Known photoconductors such as the eAs photoconductor can be used depending on the purpose. Further, as will be described later, according to the present invention, since the generation amount of ozone, knox, etc. is extremely suppressed,
There is a risk of deterioration due to these generated gases, and the photoconductor materials for which adoption has been suspended can also be used.

A gas supply pipe 56 as a gas supply means is connected to one side surface 51a of the charging house 51. The gas supply pipe 56 is for filling the atmospheric gas in the charging house 51 with an ozone generation suppressing gas, and is connected to a gas cylinder 58 filled with carbon dioxide gas, for example, as an ozone generation suppressing gas supply source. There is.

The gas supply pipe 56 is provided with an adjusting valve 57 as a gas supply adjusting means in the middle of the pipe. The adjusting valve 57 is electrically connected to a control circuit 59, which controls the gas concentration detector 54 and the corona discharge power source 53.
Electrically connected to. The control circuit 59 is controlled by receiving a signal corresponding to the gas concentration of the discharge atmosphere from the gas concentration detector 54. The adjusting valve 57 is opened / closed by the signal of the control circuit 59, the ozone generation suppressing gas is intermittently supplied into the charging house 51, the corona discharge power source 53 is operated, and the corona discharge voltage is applied.

The ozone generation-suppressing gas of the present invention means a gas that does not substantially generate ozone under corona discharge conditions (a gas that does not generate ozone), and includes not only gas having a molecular structure containing no oxygen but also carbon dioxide gas. As described above, the oxygen in the molecule is not activated by the gentle discharge at the normal corona discharge level. As such a gas, nitrogen gas is exemplified as an easily available gas. However, since nitrogen gas has a gas density similar to that of oxygen,
It is diffused in the air and easily dissipated. Further, in corona discharge, when oxygen is present, knox is generated. Also, H
Noble gases such as e, Ne, Ar, and Xe are also exemplified, but they are expensive and the corona discharge efficiency is low.

Since carbon dioxide has a specific gravity of about 1.5 and is heavier than air, if it is gently supplied into the charging house 51, the air inside will be exhausted through the opening 51c provided above. The air is replaced with carbon dioxide gas from the bottom. Excess air and carbon dioxide gas are discharged by overflow from the opening 51c. Since the carbon dioxide gas filled in the charging house diffuses slower than the nitrogen gas and the helium gas, the carbon dioxide atmosphere can be maintained for a relatively long time. Thereby, it is not necessary to continuously supply the carbon dioxide gas, and intermittent supply may be performed.

The corona discharge voltage in carbon dioxide is slightly higher than the discharge voltage in air, but if the applied voltage is sufficiently high, the discharge will continue stably and efficiently. Further, the molecules of carbon dioxide gas are stable, and in corona discharge, they are sufficiently ionized to be corona ionized. Further, under this corona discharge condition, carbon dioxide gas is not dissociated and active oxygen is not generated, so that ozone O ₃ is not generated. Further, carbon dioxide is inexpensive, easily available, and safe. In addition, if a carbon dioxide gas cylinder is used, no new gas is generated, so it is friendly to the global environment (warming).

Next, the ozone generation suppressing gas supply system will be described with reference to the block diagram of FIG. 15 and the flowchart of FIG. When the main power source is turned on in S1, the gas concentration detector 54 starts operating in S2. The gas concentration detector 54 detects the gas concentration in the charging house 51 and sends a signal corresponding to the gas concentration N to the control circuit 59.

In S3, the control circuit 59 judges the signal based on the gas concentration N sent from the gas concentration detector 54 and controls the adjusting valve 57 and the corona discharge power source 53. When the gas concentration N is not within the range of the predetermined concentration N ₀ ,
Due to the loop of S2, S3, and S4, the corona discharge power supply 53 is not turned on, the adjustment valve 57 is opened, and the ozone generation suppressing gas is gently supplied from the gas cylinder 58 to the charging house 51. As a result, the gas inside the charging house 51 is replaced with the ozone generation suppressing gas while being discharged from the opening 51c.

When it is determined in S3 that the gas concentration N has reached the predetermined concentration N ₀ , the process proceeds to S5, the adjusting valve 57 is closed, and the supply of ozone generation suppressing gas is stopped. Then,
According to the signal from the control circuit 59, the corona discharge power supply 53 is turned on by S6, and a DC voltage is applied between the charging house 51 and the charging wire 52. As a result, corona discharge is started between the charging house 51 and the charging wire 52, and corona ions are generated.

A charging power supply voltage (not shown) is turned on by a grid power supply, and a direct current voltage is applied between the charging house 51 and the photosensitive member.
Corona charging is started between the photoconductor and the photoconductor. Corona ions generated by the charging device are discharged from the upper opening 51c, and the outer surface 5 of the photoconductor drum 55 is discharged.
5a is uniformly charged.

This corona discharge is caused by the charging house 5
Since the gas atmosphere in 1 is filled with the ozone generation suppressing gas, ozone is not substantially generated.
However, the opening 5 is above the charging house 51.
Since it is 1c, the ozone generation suppressing gas diffuses and dissipates little by little. With the passage of time, the concentration of the ozone generation suppressing gas inside decreased, and instead, the charging house 5
The ambient air in 1 is mixed. In this case, as shown in FIG. 17, S7 to S12 may be added after S6 in FIG.

When it is determined in S8 that the gas concentration in the charging house 51 has fallen outside the range of the predetermined concentration N ₀ due to long-time operation, the adjustment valve 5 is determined in S10.
7 is opened again. When the adjusting valve 57 is opened, the ozone generation suppressing gas is supplied from the gas cylinder 58 to the charging house 51 again. When the gas concentration does not reach the predetermined value, it is determined in S11 whether or not the corona discharge power supply 53 is in the ON state, and in accordance with the loop of S7, S8, S10 and S11, the adjusting valve 57 is kept open and ozone is generated. The suppression gas continues to be supplied.

In S8, when the gas concentration reaches the predetermined concentration (N ₀ ), the process proceeds to S9, the adjustment valve 57 is closed, and the ozone generation suppressing gas is not supplied by the loop of S11, S7, S8 and S9, and the operation is performed. Is continued.

In S11, if the corona discharge power source 53 is off, the process proceeds to S12, the adjusting valve 57 is closed,
The shutdown of the charging device is completed.

In FIG. 17, S2, S3, S
A configuration in which 4 and S5 are omitted may be used. In this case, the discharge is started at the same time when the main power source is turned on. As a result, when the concentration of the ozone generation suppressing gas remaining in the charging house 51 is low and is, for example, air, ozone or the like is generated, but the amount thereof is extremely small. On the other hand, immediately, the adjusting valve 57 is opened by the loop of S7, S8, S10, and S11, and the air in the charging house 51 is replaced with the ozone generation suppressing gas.

Image formation is performed by irradiating the photosensitive drum 55 with light in a pattern to form an electrostatic latent image, transferring the toner, visualizing the toner, and transferring the toner to a transfer target such as paper. If it is used as a device, it is possible to output an image with good image quality.

In the charging device thus constructed, the gas in the charging house 51 is directly detected and kept within a predetermined concentration range. As a result, the discharge current due to corona discharge can be kept stable even after long-term operation. Also,
At this time, the ozone concentration is extremely low.

In the above description, the charging method has been described in the developing step using the photosensitive member as the member to be charged, but in the image forming apparatus, the charging section is used in various steps.

For example, as shown in an example of the Carlson process in FIG. 1, the image forming section A includes a photosensitive drum 1 having a photosensitive member formed in a drum shape and a charging for uniformly charging the surface of the photosensitive drum 1. A portion 2, an exposure portion 3 which irradiates the charged surface of the photoconductor with light to remove a charge in a pattern to form an electrostatic latent image, and an electrostatic latent image to which reversely charged toner is attached. A developing unit 4 for forming a visible image, a transfer unit 5 for transferring a toner image forming a visible image onto a recording paper, a fixing unit 6 for making the transferred toner image a permanent image, and a photosensitive drum 1 2 is composed of a charge eliminating portion 7 for eliminating the electrostatic latent image and a cleaner portion 8 for removing the residual donor on the photosensitive drum 1.

In this image forming apparatus A, the charging device of the present invention is a charger for uniformly charging the photoconductor in the charging section 2 and a charger for reversely charging the recording paper from the back surface of the recording paper in the transfer section 5. Also, it can be used as a static eliminator or the like for neutralizing the surface of the photoconductor that is unnecessarily charged in the static elimination unit 7. In addition, the electric charge applied to the recording paper is removed by performing corona discharge from the back surface of the recording paper, etc. to eliminate the attraction force between the photoconductor drum and the recording paper and separate the recording paper. You may use it as an electric appliance.

An example using carbon dioxide as an ozone generation suppressing gas will be described below. (Embodiment 10) In Embodiment 10, as shown in FIG. 18, a carbon dioxide concentration detector as a supply gas concentration detector is used as the gas concentration detector 54. In this case, the set value Ns ₀ of the carbon dioxide concentration is set to 99% by volume, and the control circuit 59 determines whether or not the carbon dioxide concentration in the charging house 51 has dropped to 99% by volume or less.

When the main power source is turned on in S-S1, the carbon dioxide concentration Ns is detected in S-S2, and S-
At S3, the gas concentration Ns is determined. The carbon dioxide concentration Ns in the charging house 51 is the set value Ns.
If it is determined that the number is greater than ₀ (appropriate), S
The process proceeds to S6, the corona discharge power is turned on, and the corona discharge is started.

When it is determined that the carbon dioxide concentration Ns is below the set value (inappropriate), the process proceeds to S-S4 or S-S10, and S-S2, S-S3, S-S4 or S-. S
According to the loop of 7, S-S8, S-S10, S-S11, the adjusting valve 57 is opened, and carbon dioxide gas is supplied from the gas cylinder 58 into the charging house 51. When the concentration of carbon dioxide in the charging house 51 increases, the generation of ozone is suppressed by the corona discharge.

The gas supply control flow chart may be constructed as shown in FIG. In this case, the carbon dioxide supply limitation after the corona discharge is started is S-S7 to S-S.
11 is performed.

Even after the corona discharge power source 53 is turned on,
The carbon dioxide concentration Ns is detected in S-S7, and S-S
At 8, the gas concentration Ns is determined. When it is determined that the carbon dioxide concentration Ns in the charging house 51 is higher than the set value Ns ₀ , that is, it is appropriately maintained, the process proceeds to S-S9, S-S11, S-S7, S.
According to the loop of -S8 and S-S9, the corona discharge is continued without the supply of carbon dioxide gas.

In S-S8, if it is determined that the carbon dioxide concentration Ns is below the set value, that is, it is determined that the carbon dioxide has been diffused by the long-time operation, the process proceeds to S-S10.
The adjusting valve 57 is opened, and S-S11, S-S7, S-S
Carbon dioxide is supplied from the gas cylinder 58 into the charging house 51 in accordance with the loop of 8 and S-S10. When the carbon dioxide concentration in the charging house 51 increases, S-
After shifting from S8 to S-S9, the adjusting valve 57 is closed again.

In S-S11, the corona discharge power source 53
Is off, the process proceeds to S-S12, the adjustment valve 57 is closed, and the operation stop of the charging device is completed.

In the charging device thus constructed, the carbon dioxide gas in the charging house 51 is directly detected and kept within a predetermined concentration range. For example, the main power supply is turned on, the proper corona discharge power supply 53 is turned on, and corona discharge is started between the charging house 51 and the charging wire 52. The corona discharge voltage at this time is −
The discharge current is set to 5,8 KV and is stable at about -23 μA. As a result, the ozone concentration during corona discharge is always 0.005 ppm or less.

It is understood that if such a charging device is used as a charging device of an image forming apparatus, uniform charging can be performed even if the charging device is operated for a long time, so that an image with good image quality can be obtained.

For comparison, when corona discharge is performed in air without supplying carbon dioxide, the ozone concentration increases to 2 ppm with the passage of time.

(Embodiment 11) As the gas concentration detecting means of Embodiment 10, instead of the carbon dioxide concentration detector 54, a generated gas concentration detector such as an ozone gas concentration detector 54 as shown in FIG. 20 is used. be able to. The ozone concentration detector 54 sends a detection signal to the control circuit 59 when the ozone concentration is about 0.001 ppm. The ozone gas concentration is detected by S-P2 (or S-P7), and the concentration of the generated gas concentration Np is determined at S-P3 (or S-P8).

When the main power source is turned on, the ozone gas concentration detector is activated in S-P2. If ozone gas is not detected, the ozone gas concentration is 0.001 pp
It is judged to be about m or less. Charging house 5
When it is determined that the ozone concentration Np in 1 is smaller than the set value Np _{0, the} corona discharge power is turned on by S-P6 to start the corona discharge.

When ozone is detected (ozone concentration Np exceeds the set value), S-P2, S-P3, S-P4 (or S-P7, S-P8, S-P10, S-P11) is detected. Following the loop, the adjusting valve 57 is opened, and carbon dioxide gas is supplied from the gas cylinder 58 into the charging house 51.
When the concentration of carbon dioxide in the charging house 51 increases,
Generation of ozone due to corona discharge is suppressed, and S-P5
(Or S-P9) and the adjustment valve 57 is closed.

In this eleventh embodiment, the ozone concentration does not increase even after long-term operation. Further, the discharge current due to the corona discharge in this case can be stably maintained at about -23 μA. Therefore, it is understood that if this charging device is used as a charging device for the photoconductor drum 55 of the image forming apparatus, uniform charging can be performed even during long-time operation, so that an image with good image quality can be obtained.

In the case of the eleventh embodiment, ozone which adversely affects the environment can be directly detected, and when the ozone is detected, the concentration of carbon dioxide gas as the ozone generation suppressing gas can be supplied, so that the generation of ozone is suppressed. The charging device can be reliably operated under such conditions.

Since the other structure and operation are the same as those of the tenth embodiment, the description thereof will be omitted.

(Example 12) In corona discharge in air, nitrogen gas and oxygen gas in air react with each other to produce nitrogen oxides (NOx). In this twelfth embodiment, a NOx gas concentration detector is used instead of the means of the eleventh embodiment to determine whether or not air is mixed in the atmospheric gas. In this case, the NOx gas concentration as the generated gas concentration set value Np ₀ is set to 0.001 ppm. The NOx gas concentration is detected by S-P2 (or S-P7), and the concentration of the generated gas concentration Np is determined at S-P3 (or S-P8).

When the main power source is turned on, the gas concentration detector is activated in S-P2, and the gas concentration is determined in S-P3. When it is determined that the NOx concentration Np in the charging house 51 is lower than the set value Np _{0, the} corona discharge power is turned on by S-P6 to start the corona discharge.

When the NOx concentration Np exceeds the set value Np ₀ , S-P2, S-P3, S-P4 or S-P7, S
According to the loop of -P8, S-P10, S-P11, the adjusting valve 57 is opened and carbon dioxide gas is supplied from the gas cylinder 58.

As a result, the concentration of carbon dioxide gas in the charging house 51 is increased, and the generation of ozone due to corona discharge is suppressed. Ozone concentration does not increase even after long-term operation. In addition, the change with time of the discharge current due to corona discharge in this case can be stably maintained at around −23 μA.

In the case of the twelfth embodiment, the concentration of air mixed in the charging house 51 is detected by the concentration of NOx gas generated by corona discharge. When the NOx gas is detected, the supply of carbon dioxide gas as the ozone generation suppressing gas can be controlled by the detected concentration, so that the charging device can be operated under the condition in which the generation of ozone is suppressed. Other configurations and operations are the tenth embodiment and the first embodiment.
The description is omitted because it is the same as 1.

(Embodiment 13) As the gas concentration detecting means of Embodiment 10, as shown in FIG. 21, a carbon dioxide concentration detector and an ozone concentration detector as a generated gas concentration detector can be used together. In this case, the control from S-S1 to SS-6 is the same as that of the tenth embodiment, and the control from S-P7 to SP12 is the same as that of the eleventh embodiment.

When the main power source is turned on, the carbon dioxide concentration detector is activated in S-S2, and the gas concentration Ns is determined in S-S3. When it is determined that the carbon dioxide concentration Ns in the charging house 51 is higher than the set value Ns _{0, the} corona discharge power is turned on by S-S6 to start the corona discharge.

The ozone gas concentration Np is detected by S-P7, and the concentration of the generated gas concentration Np is determined in S-P8. When the ozone concentration Np exceeds the set value,
In accordance with the loop of S-P7, -SP8, S-P10, S-P11, the adjusting valve 57 is opened, and carbon dioxide gas is supplied from the gas cylinder 58 into the charging house 51 again.
When the concentration of carbon dioxide in the charging house 51 increases,
Generation of ozone due to corona discharge is suppressed.

In the thirteenth embodiment, when the main power source is turned on, corona discharge is started after the inside of the charging house is sufficiently replaced with carbon dioxide gas. Further, during long-time operation, the supply of carbon dioxide gas is controlled by the generated ozone concentration Np. Therefore, the generation of ozone is suppressed at the start of the operation, and the ozone concentration Np does not increase even after a long time operation. Other configurations and actions are the same as those of the tenth to twelfth embodiments, and thus the description thereof is omitted.

FIG. 22 shows a main part of an image forming apparatus equipped with the corona charging device of the present invention. Reference numeral 61 is a case-type charging house as an electrode having an opening 61c at the upper side, and the side surface 61a and the bottom surface 61b of the charging house 61 are sealed. A charging wire 62 as a needle electrode (opposite electrode) is provided substantially in the center of the internal space of the charging house 61. A corona discharge power source (DC) 6 is connected to the charging wire 62 via an ammeter 63 for detecting a discharge current.
4 is connected.

Above the opening 61c of the charging house 61, the outer peripheral surface 6 of the photosensitive drum 65 serving as a member to be charged.
The lower part of 5a is located. The core axis of the photosensitive drum 65 is arranged parallel to the longitudinal direction of the charging house 61. As the photoconductor, organic photoconductor (OPC), S
Known photoconductors such as an e photoconductor and a SeAs photoconductor can be used depending on the purpose. Further, as will be described later, according to the present invention, since the generation amount of ozone, knox and the like is extremely suppressed, there is a fear of deterioration due to these generated gases, and the photoconductor material which has been abandoned may also be used. .

A gas supply pipe 66 as a gas supply means is connected to one side surface 61a of the charging house 61. The gas supply pipe 66 is connected to a gas cylinder 68 filled with carbon dioxide as an ozone generation suppressing gas supply source via an adjusting valve 67 as an adjusting means for adjusting the supply amount of gas. The adjusting valve 67 is connected to the control circuit 69, and the control circuit 69 is connected to the ammeter 63 and the corona discharge power source 64. This control circuit 69
Operates by receiving a signal corresponding to the current density of the corona discharge current from the ammeter 63. The adjusting valve 67 is opened / closed by a signal from the control circuit 69, and the ozone generation suppressing gas is intermittently supplied into the charging house 61.

The ozone generation suppressing gas means a gas that does not substantially generate ozone under corona discharge conditions (a gas that does not generate ozone), such as carbon dioxide gas as well as gas having a molecular structure containing no oxygen. It suffices that oxygen in the molecule is not activated by a normal corona discharge level gentle discharge. As such a gas, nitrogen gas is exemplified as an easily available gas. However,
Since nitrogen gas has a gas density similar to that of oxygen, it is easily diffused in air and dissipated. Also, corona discharge is not desirable because it produces knox in the presence of oxygen. Although rare gases such as He, Ne, Ar, and Xe are also exemplified, they are expensive and the corona discharge efficiency is low.

Since carbon dioxide has a specific gravity of about 1.5 and is heavier than air, if it is gently supplied into the charging house 61, the air inside will be exhausted from the opening 61c provided above and the inside of the charging house 61 will be exhausted. The air is replaced with carbon dioxide gas from the bottom. Excess air and carbon dioxide gas are discharged from the opening 61c by overflow. Since the carbon dioxide gas filled in the charging house diffuses slower than the nitrogen gas and the helium gas, the carbon dioxide atmosphere can be maintained for a relatively long time. Thereby, the carbon dioxide gas can be supplied intermittently without continuously supplying it.

The corona discharge voltage in carbon dioxide is slightly higher than the discharge voltage in air, but if the applied voltage is sufficiently high, the discharge will continue stably and efficiently. Further, the molecules of carbon dioxide gas are stable, and in corona discharge, they are sufficiently ionized to be corona ionized. Further, under this corona discharge condition, carbon dioxide gas is not dissociated and active oxygen is not generated, so that ozone O ₃ is not generated.
Furthermore, carbon dioxide is inexpensive, easily available, and
It's safe. In addition, if a carbon dioxide gas cylinder is used, no new gas is generated, so it is friendly to the global environment (warming).

Next, the ozone generation suppressing gas supply system will be described with reference to the block diagram of FIG. 23 and the flowchart of FIG.

When the main power source is turned on in S1,
In S2, a predetermined corona discharge voltage is applied between the charging house 61 and the charging wire 62,
Corona discharge is started. According to this, the ammeter 63 starts to operate. The ammeter 63 detects an increase or decrease in the discharge current and sends a signal based on the discharge current I to the control circuit 69.

In S3, the control circuit 69 determines whether or not the discharge current I is appropriate, based on the signal sent from the ammeter 63. When it is determined that the discharge current I is not appropriate, in S4, the adjusting valve 67 is opened, the carbon dioxide gas is gently supplied from the gas cylinder 68 to the charging house 61, and the inside of the charging house 61 is substantially carbon dioxide gas. Is replaced by. When the discharge current I does not reach the predetermined value, the adjusting valve 67 continues to be opened and the carbon dioxide gas is continuously supplied according to the loop of S3 and S4.

When the inside of the charging house 61 is replaced with carbon dioxide gas, the discharge current I is optimized. When it is determined in S3 that the discharge current I is appropriate, the process proceeds to S5, the adjustment valve 67 is closed, and then the charging application voltage is turned on in S6. As a result, a DC voltage is applied between the charging house 61 and the photosensitive drum 65, and corona charging is started between the charging house 61 and the photosensitive drum 65. The corona ions generated by this charging device are discharged from the upper opening 61c, and the outer surface 65a of the photosensitive drum 65 is uniformly charged.

Image formation is performed by irradiating the photosensitive drum 65 with light in a pattern to form an electrostatic latent image, transferring the toner, visualizing the image, and transferring the image onto a transfer target such as paper. If it is used as a device, it is possible to output an image with good image quality.

In the above description, the charging method is used in the developing process using the photosensitive drum 65 as the member to be charged, but in the image forming apparatus, the charging section is used in various processes.

In the image forming apparatus A of FIG. 1, the charging device of the present invention serves as a charger for uniformly charging the photoconductor in the charging section 2 and a charging section for reversely charging the recording paper from the back surface of the recording paper in the transfer section 5. The device can also be used as a static eliminator for removing static electricity from the surface of the photoconductor that is unnecessarily charged in the static eliminator 7. As a static eliminator that removes the electric charge applied to recording paper etc. by corona discharge from the back side of the recording paper etc. to eliminate the adsorption force between the photoconductor drum and the recording paper etc. and separate the recording paper etc. You may use.

(Embodiment 14) A box-shaped charging house 61 having an upward opening.
A paper analyzer (SP-428 manufactured by Kawaguchi Denki Co., Ltd.) having a charging potential measuring device was used. A gas injection hole was provided on the side surface of the charging house 61, and a gas supply pipe 66 for supplying carbon dioxide gas from a gas cylinder 68 was connected to this hole.

When electric discharge was started after the inside of the charging house 61 was sufficiently replaced with carbon dioxide gas, the applied voltage was -5.8.
The corona discharge current was stable at about -23 μA near KV. This discharge voltage was slightly higher than the corona discharge voltage in air.

In the discharge in the air, an offensive odor is generated due to the generation of ozone O ₃ , and this offensive odor is more remarkable in the negative discharge than the positive discharge in which the positive corona ions are generated. However, when the corona discharge was performed in the state where the carbon dioxide gas was sufficiently supplied, even if the positive and negative of the corona electrode were switched and the positive discharge and the negative discharge were performed, the offensive odor was not substantially confirmed. When the ozone concentration at this time was measured by an ozone densitometer, it was 2 ppm in negative discharge in air, but was 0.005 ppm or less in carbon dioxide gas in all cases.

Therefore, -5.8 KV is set as the predetermined applied voltage in the carbon dioxide gas atmosphere, the initial value of the corona discharge current is set to -23 μA, and if there is a change in current density of ± 5% from the initial value, the adjustment is made. Corona charging was performed by the device shown in FIG. 22 so that the valve 67 was opened. Since the gas atmosphere in the charging house 61 is normally filled with carbon dioxide gas, ozone is not substantially generated. However, an opening 61c is provided above the charging house 61.
Therefore, carbon dioxide diffuses and diffuses little by little. With the lapse of time, the concentration of carbon dioxide gas inside decreases, and instead, ambient air is mixed into the charging house 61. The corona discharge current increases due to the mixing of the air and the generated gas such as ozone and nitrogen oxides slightly generated by the mixing of the air. However, when the current exceeds the set value I ₀ , the control circuit 69 The control valve 67 is operated by the control of. As a result, carbon dioxide gas is supplied, and the mixed air and generated gas are replaced by carbon dioxide gas, so the discharge current is stabilized, and stable discharge can be performed without a gas sensor.

In the charging device constructed as described above, the change with time of the discharge current due to corona discharge can be stably maintained within -23 μA ± 5%, and the carbon dioxide concentration in the charging house 61 can be kept at a predetermined concentration (substantially). 100%). As a result, the ozone concentration is always 0.005 ppm or less even after long-term operation.

(Embodiment 15) FIG. 22 shows the charging section of a Ricoh EP copier (Aficio 200).
It was modified so that carbon dioxide gas could be supplied as shown in. The applied voltage is adjusted so that the initial corona discharge current with which a good image is obtained becomes a constant set value, and if there is a current change of ± 5%, the adjustment valve 67 for supplying carbon dioxide gas is opened. The image was repeatedly displayed. As a result, the image quality was always constant and good.

When corona discharge was carried out in the air without supplying carbon dioxide with the same apparatus, the discharge current increased due to repeated image formation. When the increase in the corona charge current exceeded 10%, the image of intermediate density suddenly became black and became unclear, and the image quality deteriorated.

[0207]

As described above, according to claim 1 or 2,
According to the invention described above, there is an effect that there is no contamination of the photoconductor, good image quality is maintained, the life of the photoconductor is extended and the durability is improved, and the corona discharge efficiency is higher than that of contact charging or rare gas. .

Further, there is an effect that the concentration change of the atmospheric gas is small, the discharge condition is stable, and it is not necessary to supply the gas frequently.

Further, carbon dioxide is a gas that can be abundantly obtained, has a low cost, and does not generate new carbon dioxide, so it has an effect of being friendly to the global environment (warming).

According to the third aspect of the invention, since the charged body of the image forming apparatus is developed at a low potential, good image contrast can be obtained without increasing the applied voltage, and the power consumption is reduced. Therefore, energy saving can be achieved, and since the applied voltage is low, durability can be improved.

Further, according to the invention of claim 4, since the charged body is a photosensitive body containing amorphous silicon as a main component, good image contrast can be obtained by low potential development, energy saving, improvement of durability, etc. Can be easily realized.

According to the fifth aspect of the invention, since the surface potential of the photoconductor is 400 V, good gradation of image quality can be obtained.

According to the invention of claim 6, since the non-ozone-generating gas is carbon dioxide gas, it is easily available and inexpensive, and no carbon dioxide gas is newly generated. It has the effect of being gentle on (warming). By using carbon dioxide gas, ozone is not generated, and a good image forming apparatus without image blur can be provided. In addition, since the emission intensity of carbon dioxide gas during corona charging is weaker than that of air or argon at the same applied voltage, there is little charge reduction due to exposure of the photoconductor, and image disturbance is reduced.

Further, according to the invention of claim 7, since it is an analog system for forming a latent image by using a white light source as an exposure light source, since the light emission during corona charging in a carbon dioxide atmosphere is white, The charge reduction due to the exposure of the photoconductor occurs in panchromatic (pan-color), and the color reproducibility is improved.

According to the invention of claim 8, the charged body is a photoreceptor having a sensitivity of 0.1 m ² / mJ or more. Copying is possible.

Further, according to the invention of claim 9, since it is a digital system in which a latent image is formed by using a monochromatic light source as an exposure light source, when a green or blue monochromatic light is used as a light source in the digital system, carbon dioxide gas is used. Since the corona light in the atmosphere is close to white, it is possible to obtain a good image without exposing the photoconductor to the air or argon atmosphere.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a Carlson process image forming apparatus including a charging device of the present invention.

FIG. 2 is a diagram for explaining a corona charging device using the corona charging method of the present invention.

FIG. 3 is a diagram showing a relationship between a voltage applied by an atmospheric gas and a corona discharge current.

FIG. 4 is a schematic diagram of an image forming apparatus according to a third embodiment.

FIG. 5 is a schematic diagram of supplying gas from a supply source cylinder to a corona charging house through a pipe.

6A and 6B show a charging house of a corona charging device according to the present invention, where FIG. 6A shows the case where the pipe is connected to the center of the side plate, and FIG. 6B shows the case where the pipe is connected to the lower end of the side plate, (C) is when the pipe is supplied from the upper opening,
(D) is the case where the pipe is connected to almost the center of the bottom plate.

FIG. 7 is a schematic diagram of an image forming apparatus using an intermediate transfer belt according to a fourth exemplary embodiment.

FIG. 8 is a schematic configuration diagram of an image forming apparatus of the present invention.

FIG. 9 is a diagram illustrating a discharge atmosphere gas supply device of a corona charging device included in the image forming apparatus of the present invention.

FIG. 10 is a cross-sectional view of a corona charging device included in the image forming apparatus of the present invention.

FIG. 11 is a diagram showing the connection of a cylinder of the image forming apparatus of the present invention.

FIG. 12 is a diagram showing a warning display panel of the image forming apparatus of the present invention.

FIG. 13 shows a lighting flow of a warning display panel according to the fifth embodiment, (A) shows a lighting flow of a display panel when a pressure sensor is used, and (B) shows a display panel when a flow sensor is used. The lighting flow of is shown.

FIG. 14 is a configuration diagram of a main part of an image forming apparatus using the corona charging device according to the present invention.

FIG. 15 is a block diagram illustrating the supply of ozone generation suppressing gas in FIG.

16 is a flowchart illustrating control of gas supply in FIG.

FIG. 17 is a flowchart illustrating control of gas supply in FIG.

FIG. 18 is a flowchart illustrating gas supply control according to the tenth embodiment.

FIG. 19 is a flowchart illustrating gas supply control according to the tenth embodiment.

FIG. 20 is a flowchart illustrating gas supply control according to the eleventh and twelfth embodiments.

FIG. 21 is a flow chart illustrating gas supply control according to a thirteenth embodiment.

FIG. 22 is a configuration diagram of a main part of an image forming apparatus including the corona charging device of the present invention.

FIG. 23 is a block diagram illustrating control of gas supply in FIG. 22.

FIG. 24 is a flowchart illustrating control of gas supply in FIG. 22.

[Explanation of symbols]

1 photoconductor drum 2 charger 2a Charging wire 2b charging house 5 Transfer device 7 Static eliminator

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Claims (9)

(57) [Claims] 1. A non-contact charging method using corona discharge in a process such as a charging process, a transferring process, and a discharging process used in an image forming apparatus such as a copying machine, a facsimile, and a printer, wherein the charging process, the transferring process, and the discharging process are performed. allowed to stay carbon dioxide as a discharge atmosphere gas in at least one step of
Corona charging method characterized by being used. 2. A charging device, such as a charger, a transfer device, or a static eliminator, which is provided in an image forming apparatus such as a copying machine, a facsimile, or a printer, and which is charged by corona discharge. corona charging device according to claim Tei Rukoto used by retained carbon dioxide as a discharge ambient gas in one. 3. A charger for charging by corona discharge, a transfer device has a charging device discharger such as the charger, a discharge atmosphere gas in at least one transfer device and a discharger
In the image forming apparatus, the carbon dioxide gas is retained and used.
Thus , the image forming apparatus is characterized in that the charged body of the image forming apparatus is developed at a low potential. 4. The image forming apparatus according to claim 3 , wherein the member to be charged is a photosensitive member containing amorphous silicon as a main component. 5. The surface potential of the photoreceptor before light irradiation is 400.
The image forming apparatus according to claim 3 , wherein the image forming apparatus is a bolt. 6. have a charger for charging the latent image bearing member by corona discharge, discharge atmospheric gas in the charging, an image forming apparatus comprising a large non-ozone generator gas specific gravity than air, the non-ozone Carbon dioxide gas stays in the generated gas
An image forming apparatus characterized by being used . 7. have charger for charging the latent image bearing member by corona discharge, discharge atmospheric gas in the charging, an image forming apparatus comprising a large non-ozone generator gas specific gravity than air, the non-ozone Carbon dioxide as the generated gas
An image forming apparatus, wherein an exposure light source used for forming a latent image on the latent image carrier is a white light source while being retained . 8. The image forming apparatus according to claim 6 , wherein the member to be charged is a photosensitive member having a sensitivity of 0.1 m ² / mJ or more. 9. have charger for charging the latent image bearing member by corona discharge, discharge atmospheric gas in the charging, an image forming apparatus comprising a large non-ozone generator gas specific gravity than air, the non-ozone the carbon dioxide gas as a generating gas
An image forming apparatus characterized in that the exposure light source used for forming a latent image on the latent image carrier is a monochromatic light source of green or blue while being retained .