JP3589545B2 - Corona charging device and image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to corona charging used in electrophotographic copying machines, printers, facsimile machines, etc.Device and image forming apparatus using the sameAbout.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile, a recording medium such as a photoreceptor is uniformly charged, as represented by the Carlson process, and the charged recording medium is erased in a pattern. To form a pattern-like electrostatic latent image, attach a charge carrier called toner to it, form a visible image consisting of toner, and further apply this visible toner to a transfer target such as paper. Transcribed. In these processes, it is necessary to cause generation and movement of electric charge in steps such as charging and discharging of the photoconductor, a developing step, and a transfer step.
[0003]
It is known to use contact-type frictional charging, contact charge injection, ionization by radiation, corona discharge, and the like as a charging device for generating and moving the charge.
[0004]
[Problems to be solved by the invention]
However, the charging device that causes the generation and transfer of electric charge by contacting the members is such that a low-molecular substance or the like added to impart functionality to one member is transferred to the other member, Contamination of the other member occurs. If a charging device using the contaminated member is used as an image forming apparatus, abnormalities such as poor charging and white spots on an image occur, and finally, a defect such as an abnormality occurs in a visible image.
[0005]
Further, ionization due to radiation depends on the type of radiation, but requires prevention of exposure to radiation, and is difficult to put into practical use due to the complexity of the apparatus and increase in price.
[0006]
The charging device using corona discharge applies so-called corona discharge by applying a high voltage of several KV between a needle electrode such as a thin conductive wire or a needle and a box-shaped metal shield case electrode called a charge. The corona ions are attached to the member to be charged by an electric field or the like. This device is simple in principle and device, and is often used as an effective method.
[0007]
However, in corona discharge, oxygen in the air reacts due to energy at the time of discharge, and ozone O with an unpleasant smell is generated.₃Occurs. In addition, when ozone is generated, the corona discharge current increases, which causes a problem that the stability of corona discharge is lacking. For these reasons, it is desired to minimize the generation of ozone.
[0008]
One approach is to use a contact-type charging method in which the charging member is brought into direct contact with the photoreceptor to inject electric charge, or a contact is made using Paschen's law, followed by a discharge at a close non-contact distance. Methods to reduce the occurrence of phenomena have begun to be used.
[0009]
The present inventor has proposed a corona charging method and an apparatus thereof in an oxygen-free gas atmosphere in which ozone is not generated. Specific conditions such as gas supply means are described in, for example, Japanese Patent Application No. 8-304377. It is disclosed in the specification and the like.
[0010]
These charging devices include a box-shaped charging house having an upward opening, and a charging wire located in a space inside the box-shaped charging house. The charging house acts as a shield case electrode, and the charging wire acts as a needle electrode. This charging house is provided with gas introduction holes as gas supply means. The gas introduction hole is connected to a carbon dioxide gas cylinder for generating no ozone and having a higher specific gravity than air, for example, carbon dioxide gas. This charging device is used together with a member to be charged such as a photosensitive drum or paper. In this case, the opening of the charging device is directed to the photosensitive drum.
[0011]
In such a charging device, if carbon dioxide gas is introduced from the gas introduction hole, the specific gravity of carbon dioxide gas is about 1.5, which is heavier than air. While being replaced from below by the carbon dioxide gas, the replaced carbon dioxide gas stays in the charging house for a relatively long time. By applying a high voltage between the charging wire and the charging house, corona discharge is started and corona ions are generated. At this time, no ozone is generated because oxygen does not exist in the atmosphere. Therefore, this charging device is characterized in that, although it is corona discharge, ozone, which is a problem of corona discharge, is not generated.
[0012]
However, even when carbon dioxide gas having a higher specific gravity than air is used, since the charging house is open at the top, the carbon dioxide gas diffuses and dissipates little by little, and instead, ambient air is mixed into the charging house. It becomes. Then, the corona discharge current changes, and the amount of corona ions generated changes. At the same time, ozone and nitrogen oxides (NOx) are generated under the influence of oxygen and nitrogen in the mixed air, and the generation of these gases is not desirable for the environment.
[0013]
An object of the present invention is to provide a corona charge proposed by the inventor.apparatusTo improve the discharge current stability and suppress the increase of ozone generation and knock generation.apparatusIs to provide.
It is another object of the present invention to provide an image forming apparatus capable of performing uniform charging even after long-time operation and achieving high-quality image output.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 comprises a container having one open side, a pair of electrodes held inside the container, and a high-voltage power supply for applying a corona discharge voltage between the electrodes. In a corona charging device for applying a high voltage under an ozone generation suppressing gas atmosphere for suppressing ozone generation between the electrodes to generate corona ions by corona discharge in the container to charge a member to be charged, Is a gas that is directed upward in the direction of gravity and has a specific gravity greater than air as the ozone generation suppressing gas, and a gas that supplies the ozone generation suppressing gas to make the discharge atmosphere in the container an ozone generation suppressing gas atmosphere. Supply means, gas supply adjustment means for adjusting a gas supply amount of the gas supply means, and gas concentration detection means for detecting an atmosphere gas concentration in the discharge atmosphere. The vessel by controlling the gas supply adjustment means receiving a detection signal by the gas concentration detection meansAppropriate prescribed concentrationAnd a control means for maintaining the gas atmosphere in an ozone generation suppressing gas atmosphere.
[0017]
According to this structure, the ozone generation suppressing gas, which is heavier than air, is supplied into a container (a case electrode) holding a pair of electrodes each having an opening above the direction of gravity. The air inside is exhausted from the upper opening of the case electrode by overflow, and the inside of the case electrode is replaced with an ozone generation suppressing gas. Since this ozone generation suppressing gas is heavier than air, it stays in the case electrode for a relatively long time.
Since the upper part of the container is open, the ozone generation suppressing gas diffuses and dissipates little by little, but the concentration of the discharge atmosphere gas in the container is detected by the gas concentration detecting means, and the signal detected by the gas concentration detecting means is received. The control means is operated to control the gas supply adjusting means, and the supply amount of the ozone generation suppressing gas is adjusted. As a result, the detected discharge gas concentration becomesAppropriate prescribed concentrationIf not, the discharge atmosphere is maintained in the ozone generation suppressing gas atmosphere by supplying the ozone generation suppressing gas to the discharge atmosphere.
As described above, the concentration of the ozone generation suppressing gas in the container is not limited even when the operation is started, and even when the operation is performed for a long time.ProperCorona discharge can be performed in a discharge atmosphere maintained at a predetermined concentration and substantially free of ozone.
[0018]
ContractRequest 2In the invention, the ozone generation suppressing gas is carbon dioxide gas.
[0019]
With this configuration, the carbon dioxide gas can stably and efficiently perform corona discharge without generating ozone. Further, since the carbon dioxide gas diffuses slowly, it can stay in the discharge atmosphere for a relatively long time, and the ozone generation suppressing gas does not need to be continuously supplied.
[0022]
Claim 3The described invention is characterized in that the gas concentration detector is a supply gas concentration detector that detects whether or not the ozone generation suppression gas supplied by the gas supply unit is maintained at an appropriate concentration in the container. To beClaim 12. The corona charging device according to item 1.
With this configuration, the concentration of the discharge atmosphere gas such as carbon dioxide is directly detected, so that it is possible to reliably control whether or not the discharge atmosphere gas is appropriate.
Claim 4The described invention is characterized in that the gas concentration detecting means is a generated gas concentration detector for detecting a generated gas concentration generated by the presence of air.Claim 1It is a corona charging device of the description.
With this configuration, the generated gas generated due to the presence of air is detected, and the supply of the ozone generation suppressing gas can be controlled based on the detected generated gas concentration. Operation control can be performed reliably.
Further, if the generated gas concentration detector is an ozone gas concentration detector, ozone which has a bad influence on the environment can be directly detected, and the supply of the ozone generation suppressing gas can be controlled by the detected ozone gas concentration. The operation control of the charging device under the suppressed condition can be reliably performed.
In addition, if the gas generating gas concentration detector is a NOx gas concentration detector, the concentration of NOx that has an adverse effect on the environment can be directly detected, and the supply of the ozone generation suppressing gas can be controlled based on the detected NOx concentration. The operation control of the charging device under the condition in which the generation of NOx is suppressed can be reliably performed.
Further, if the gas concentration detecting means is an air concentration detector that detects the concentration of air mixed into the container, the concentration of the ozone generation suppressing gas is controlled by detecting the concentration of the mixed air. The operation control of the charging device can be reliably performed under the condition that substantially no air exists.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 shows a main part of an image forming apparatus provided with a corona charging device of the present invention. Reference numeral 1 denotes a case-shaped charging house having an opening 1c at the upper side as a case / electrode. The side surface 1a and the bottom surface 1b of the charging house 1 are sealed. A charging wire 2 as a needle electrode (counter electrode) is provided substantially at the center of the inner space of the charging house 1. A corona discharge power supply (DC) 3 is connected to the charging wire 2. Further, a gas concentration detector 4 as gas concentration detecting means for detecting a gas concentration in the charging house 1 is provided on a side surface 1a of the charging house 1.
[0025]
The gas concentration detector 4 detects whether or not the supplied ozone generation suppressing gas is properly maintained in the charging house 1 as will be described in detail in an embodiment described later. And a generated gas concentration detector for directly detecting the concentration of environmentally destructive gases such as ozone and nitrogen oxides generated when air is mixed in. A detecting means for detecting the concentration of the air flowing into the charging house 1 may be used.
[0026]
Above the opening 1c of the charging house 1, the lower part of the outer peripheral surface 5a of the drum-shaped photoconductor 5 is located. The core axis of the photosensitive drum 5 is arranged parallel to the longitudinal direction of the charging house 1. As the photoconductor, a known photoconductor such as an organic photoconductor (OPC), a Se photoconductor, or a SeAs photoconductor can be used according to the purpose. Further, as described later, according to the present invention, since the amount of generation of ozone, knock, and the like is extremely suppressed, there is a fear of deterioration due to these generated gases, and a photoreceptor material whose use has been withdrawn can be used. .
[0027]
A gas supply pipe 6 as gas supply means is connected to one side surface 1a of the charging house 1. The gas supply pipe 6 is for filling the atmosphere gas in the charging house 1 with the ozone generation suppressing gas, and is connected to a gas cylinder 8 filled with, for example, carbon dioxide as an ozone generation suppressing gas supply source. I have.
[0028]
The gas supply pipe 6 is provided with an adjusting valve 7 as gas supply adjusting means in the middle of the pipe. The regulating valve 7 is electrically connected to a control circuit 9, and the control circuit 9 is electrically connected to the gas concentration detector 4 and the corona discharge power supply 3. The control circuit 9 is controlled by receiving a signal from the gas concentration detector 4 corresponding to the gas concentration in the discharge atmosphere. The regulating valve 7 is opened and closed by the signal of the control circuit 9, the ozone generation suppressing gas is intermittently supplied into the charging house 1, the corona discharge power supply 3 is operated, and the corona discharge voltage is applied.
[0029]
The ozone generation suppressing gas of the present invention means a gas which does not substantially generate ozone under corona discharge conditions (non-ozone generating gas), and includes not only a gas having a molecular structure containing no oxygen but also a carbon dioxide gas. Some slow discharges at normal corona discharge levels include those in which oxygen in the molecule is not activated. As such a gas, a 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. In the corona discharge, the presence of oxygen generates knock. In addition, rare gases such as He, Ne, Ar, and Xe are also exemplified, but they are expensive and have low corona discharge efficiency.
[0030]
Since carbon dioxide gas has a specific gravity of about 1.5 and is heavier than air, if it is gently supplied into the charging house 1, the internal air is exhausted from the opening 1c provided above and the internal air is discharged downward. Are sequentially replaced by carbon dioxide gas. Excess air and carbon dioxide gas are discharged from the opening 1c by overflow. The carbon dioxide gas filled in the charging house has a slower diffusion time than the nitrogen gas or the helium gas, so that the carbon dioxide gas atmosphere can be maintained for a relatively long time. Thus, the carbon dioxide gas does not need to be continuously supplied, but may be supplied intermittently.
[0031]
The corona discharge voltage in carbon dioxide gas is slightly higher than the discharge voltage in air, but if the applied voltage is sufficiently high, the discharge is stably and efficiently continued. The molecules of the carbon dioxide gas are stable, and in corona discharge, they are sufficiently ionized to become corona ions. Under the corona discharge conditions, the carbon dioxide gas does not dissociate and does not generate active oxygen.₃Is not generated. Further, carbon dioxide gas is inexpensive, easily available, and safe. In addition, if a carbon dioxide gas cylinder is used, no new gas is generated, so that it is friendly to the global environment (warming).
[0032]
Next, the supply system of the ozone generation suppressing gas will be described with reference to the block diagram of FIG. 2 and the flowchart of FIG. When the main power is turned on in S1, the gas concentration detector 4 starts operating in S2. The gas concentration detector 4 detects the gas concentration in the charging house 1 and sends a signal corresponding to the gas concentration N to the control circuit 9.
[0033]
In S3, the control circuit 9 determines the signal based on the gas concentration N sent from the gas concentration detector 4 and controls the regulating valve 7 and the corona discharge power supply 3. The gas concentration N is equal to the predetermined concentration N₀Is not within the range, the corona discharge power supply 3 is not turned on by the loop of S2, S3, and S4, the regulating valve 7 is opened, and the ozone generation suppressing gas is quietly supplied from the gas cylinder 8 to the charging house 1. . Thereby, the gas inside the charging house 1 is replaced with the ozone generation suppressing gas while being discharged from the opening 1c.
[0034]
At S3, the gas concentration N becomes the predetermined concentration N₀Is reached, the process proceeds to S5, the regulating valve 7 is closed, and the supply of the ozone generation suppressing gas is stopped. Then, in response to a signal from the control circuit 9, the corona discharge power supply 3 is turned on in S6, and a DC voltage is applied between the charging house 1 and the charging wire 2. Thereby, corona discharge is started between the charging house 1 and the charging wire 2, and corona ions are generated.
[0035]
A charging power supply is turned on by a grid power supply (not shown), a DC voltage is applied between the charging house 1 and the photoconductor, and corona charging between the charging house 1 and the photoconductor starts. Corona ions generated by the charging device are discharged from the upper opening 1c, and the outer surface 5a of the photosensitive drum 5 is uniformly charged.
[0036]
This corona discharge does not substantially generate ozone since the gas atmosphere in the charging house 1 is filled with the ozone generation suppressing gas. However, since the upper part of the charging house 1 has the opening 1c, the ozone generation suppressing gas diffuses and dissipates little by little. As the time elapses, the concentration of the inside ozone generation suppressing gas decreases, and the surrounding air is mixed into the charging house 1 instead. In this case, as shown in FIG. 4, S7 to S12 may be added after S6 in FIG.
[0037]
By the operation for a long time, the gas concentration in the charging house 1 is reduced to a predetermined concentration N in S8.₀Is determined to have fallen outside the range, the regulating valve 7 is opened again in S10. When the regulating valve 7 is opened, the gas cylinder 8 supplies the ozone generation suppressing gas to the charging house 1 again. If the gas concentration does not reach the predetermined value, it is determined in S11 whether or not the corona discharge power supply 3 is in the ON state, and the control valve 7 is kept open according to the loop of S7, S8, S10, and the ozone generation suppressing gas is Will continue to be supplied.
[0038]
In S8, the gas concentration reaches a predetermined concentration (N₀), The process proceeds to S9, where the regulating valve 7 is closed, and the operation is continued without supplying the ozone generation suppressing gas by the loop of S11, S7, S8, and S9.
[0039]
In S11, when the corona discharge power supply 3 is off, the process proceeds to S12, the adjustment valve 7 is closed, and the operation stop of the charging device is completed.
[0040]
In FIG. 4, S2, S3, S4, and S5 may be omitted. In this case, corona discharge is started at the same time when the main power is turned on. Thus, when the concentration of the ozone generation suppressing gas remaining in the charging house 1 is low and is, for example, air, ozone or the like is generated, but the amount is very small. On the other hand, the regulating valve 7 is opened immediately by the loop of S7, S8, S10, and S11, and the air in the charging house 1 is replaced with the ozone generation suppressing gas.
[0041]
The photosensitive drum 5 is irradiated with light in a pattern to form an electrostatic latent image, and then the toner is transferred. Then, an image with good image quality can be obtained.
[0042]
In the charging device configured as described above, the gas in the charging house 1 is directly detected and is kept within a predetermined concentration range. As a result, even if the operation is performed for a long time, the discharge current due to corona discharge can be kept stable. At this time, the generation of the ozone concentration is extremely small.
[0043]
In the above description, the charging method in the developing step using the photosensitive member as the member to be charged has been described. However, in the image forming apparatus, the charging section is used in various steps.
[0044]
For example, as shown in FIG. 5 showing an example of the Carlson process, the image forming unit 10 includes a photoconductor drum 11 having a photoconductor formed in a drum shape, and a charging unit 12 for uniformly charging the surface of the photoconductor drum 11. An exposure unit 13 for irradiating the charged photoreceptor surface with light to remove the charged charges in a pattern and form an electrostatic latent image; and applying an oppositely charged toner to the electrostatic latent image to form a visible image. , A transfer unit 15 for transferring a toner image for forming a visible image onto recording paper, a fixing unit 16 for making the transferred toner image a permanent image, and an electrostatic device on the photosensitive drum 11. The image forming apparatus includes a charge removing section 17 for removing a latent image and a cleaner section 18 for removing residual toner on the photosensitive drum 11.
[0045]
In the image forming apparatus 10, the charging device of the present invention is a charging unit that uniformly charges the photoconductor in the charging unit 12, and a charging unit that reversely charges the recording paper from the back side of the recording paper in the transfer unit 15, It can also be used as a static eliminator or the like for eliminating the surface of the photosensitive member that is unnecessarily charged in 17. In addition, the charge applied to the recording paper or the like is removed by performing corona discharge from the back surface of the recording paper or the like, thereby removing the adsorbing force between the photosensitive drum and the recording paper or the like to separate the recording paper or the like. It may be used as an electric appliance.
[0046]
Hereinafter, an embodiment using carbon dioxide gas as the ozone generation suppressing gas will be described.
[0047]
(Example 1)
In the first embodiment, as shown in FIG. 6, a carbon dioxide concentration detector as a supply gas concentration detector is used as the gas concentration detector 4. In this case, the set value Ns of the carbon dioxide concentration₀Is set to 99% by volume, and the control circuit 9 determines whether or not the carbon dioxide concentration in the charging house 1 has decreased to 99% by volume or less.
[0048]
When the main power supply is turned on, the carbon dioxide gas concentration Ns is detected in SS2, and the gas concentration Ns is determined in SS3. The concentration Ns of carbon dioxide in the charging house 1 is equal to the set value Ns₀If it is determined that the number is more than appropriate (appropriate), the flow shifts to S-S6, where the power of the corona discharge is turned on to start the corona discharge.
[0049]
If it is determined that the carbon dioxide concentration Ns is lower than the set value (inappropriate), the process proceeds to S-S4 or S-S10, and S-S2, S-S3, S-S4 or S-S7, S According to the loop of -S8, S-S10, S-S11, the regulating valve 7 is opened, and the carbon dioxide gas is supplied from the gas cylinder 8 into the charging house 1. When the concentration of carbon dioxide in the charging house 1 increases, the generation of ozone due to corona discharge is suppressed.
[0050]
The control flowchart of this gas supply may be configured as shown in FIG. In this case, the supply control of the carbon dioxide gas after the start of the corona discharge is performed by S-S7 to S-S11.
[0051]
Even after the corona discharge power supply 3 is turned on, the carbon dioxide gas concentration Ns is detected in S-S7, and the gas concentration Ns is determined in S-S8. The concentration Ns of carbon dioxide in the charging house 1 is equal to the set value Ns₀If it is determined that the corona discharge is maintained properly, the process proceeds to S-S9 and follows the loop of S-11, S-S7, S-S8, and S-S9, and the corona discharge is caused by carbon dioxide gas. Will continue without supply.
[0052]
In S-S8, when it is determined that the carbon dioxide concentration Ns is lower than the set value, that is, it is determined that the carbon dioxide has been diffused by the operation for a long time, the process proceeds to S-S10, in which the regulating valve 7 is opened, and S-S10 is opened. According to the loop of S11, S-S7, S-S8, and S-S10, carbon dioxide gas is supplied from the gas cylinder 8 into the charging house 1. When the concentration of carbon dioxide in the charging house 1 increases, the process moves from S-S8 to S-S9, and the regulating valve 7 is closed again.
[0053]
In S11, when the corona discharge power supply 3 is off, the process proceeds to S12, the adjustment valve 7 is closed, and the operation stop of the charging device is completed.
[0054]
In the charging device configured as described above, the carbon dioxide gas in the charging house 1 is directly detected, and is kept within a predetermined concentration range. For example, when the main power supply is turned on, the corona discharge power supply 3 is turned on soon, and corona discharge starts between the charging house 1 and the charging wire 2. At this time, the corona discharge voltage is set to -5.8 KV, and the discharge current is stable at about -23 μA. Thereby, the ozone concentration during corona discharge is always 0.005 ppm or less.
[0055]
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 when the charging device is operated for a long time, so that an image with high image quality can be obtained.
[0056]
For comparison, when corona discharge is performed in air without supplying carbon dioxide, the ozone concentration increases to 2 ppm over time.
[0057]
(Example 2)
As the gas concentration detecting means in the first embodiment, a generated gas concentration detector such as an ozone gas concentration detector 4 can be used as shown in FIG. The ozone concentration detector 4 sends a detection signal to the control circuit 9 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 in S-P3 (or S-P8).
[0058]
When the main power supply is turned on, the ozone gas concentration detector is activated in SP2. If no ozone gas is detected, the ozone gas concentration is determined to be about 0.001 ppm or less. The ozone concentration Np in the charging house 1 is equal to the set value Np₀When it is determined that the number is less than the power, the power of the corona discharge is turned on by S-P6, and the corona discharge is started.
[0059]
When the ozone is detected (the ozone concentration Np exceeds the set value), according to a loop of SP2, SP3, SP4 (or SP7, SP8, SP10, SP11), The regulating valve 7 is opened, and carbon dioxide gas is supplied from the gas cylinder 8 into the charging house 1. When the concentration of carbon dioxide in the charging house 1 increases, the generation of ozone due to corona discharge is suppressed, and the process shifts to S-P5 (or S-P9), where the regulating valve 7 is closed.
[0060]
In the second embodiment, even if the operation is performed for a long time, the ozone concentration does not increase. In this case, the discharge current due to the corona discharge can be stably maintained at about -23 μA. Accordingly, it can be understood that if this charging device is used as a charging device for the photosensitive drum 5 of the image forming apparatus, uniform charging can be performed even when the charging device is operated for a long time, so that an image with good image quality can be obtained.
[0061]
In the case of the second embodiment, ozone which adversely affects the environment can be directly detected, and when the ozone is detected, the concentration of carbon dioxide as an ozone generation suppressing gas can be supplied. The operation of the charging device can be reliably performed.
[0062]
The other configuration and operation are the same as those of the first embodiment, and the description is omitted.
[0063]
(Example 3)
In the corona discharge in air, nitrogen gas and oxygen gas in air react with each other to generate nitrogen oxides (NOx). In the third embodiment, a NOx gas concentration detector is used in place of the means of the second embodiment to determine whether or not air is mixed in the atmospheric gas. In this case, the generated gas concentration set value Np₀NOx gas concentration 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 in S-P3 (or S-P8).
[0064]
When the main power supply is turned on, the gas concentration detector is activated in SP2, and the gas concentration is determined in SP3. The NOx concentration Np in the charging house 1 is equal to the set value Np₀When it is determined that the number is less than the power, the power of the corona discharge is turned on by S-P6, and the corona discharge is started.
[0065]
NOx concentration Np is equal to set value Np₀Is exceeded, the regulating valve 7 is opened according to the loop of SP2, SP3, SP4 or SP7, SP8, SP10, SP11, and carbon dioxide gas is supplied from the gas cylinder 8. You.
[0066]
Thereby, the concentration of carbon dioxide in the charging house 1 increases, and the generation of ozone due to corona discharge is suppressed. Ozone concentration does not increase even after long-time operation. In this case, the temporal change of the discharge current due to the corona discharge can be stably maintained at around -23 μA.
[0067]
In the case of the third embodiment, the concentration of air mixed into the charging house 1 is detected based on the concentration of NOx gas generated by corona discharge. When the NOx gas is detected, the supply of the carbon dioxide gas as the ozone generation suppressing gas can be controlled based on the detected concentration, so that the charging device can be operated under conditions where the generation of ozone is suppressed. Other configurations and operations are the same as those of the first and second embodiments, and therefore, description thereof will be omitted.
[0068]
(Example 4)
As shown in FIG. 9, the gas concentration detecting means of the first embodiment may use a carbon dioxide gas concentration detector and an ozone concentration detector as a generated gas concentration detector in combination. In this case, the control of S-S1 to SS-6 is the same as that of the first embodiment, and the control of S-P7 to SP12 is the same as that of the second embodiment.
[0069]
When the main power supply is turned on, the carbon dioxide concentration detector is activated in SS2, and the gas concentration Ns is determined in SS3. The concentration Ns of carbon dioxide in the charging house 1 is equal to the set value Ns₀When it is determined that the number is larger than the number, the power of the corona discharge is turned on by S-S6, and the corona discharge is started.
[0070]
The ozone gas concentration Np is detected by S-P7, and the concentration of the generated gas concentration Np is determined at S-P8. When the ozone concentration Np exceeds the set value, the regulating valve 7 is opened according to the loop of S-P7, -PS8, S-P10, S-P11, and the carbon dioxide gas is supplied from the gas cylinder 8 into the charging house 1 again. You. When the concentration of carbon dioxide in the charging house 1 increases, the generation of ozone due to corona discharge is suppressed.
[0071]
In the fourth embodiment, when the main power is turned on, corona discharge is started after the inside of the charging house is sufficiently replaced with carbon dioxide. Further, in long-time operation, the supply of carbon dioxide gas is controlled by the generated ozone concentration Np. Therefore, generation of ozone is suppressed at the start of the operation, and the ozone concentration Np does not increase even if the operation is performed for a long time. The other configuration and operation are the same as those of the first to third embodiments, and thus the description is omitted.
[0072]
【The invention's effect】
As explained above,According to the present invention, it is possible to provide a corona charging device capable of stabilizing a discharge current and suppressing an increase in generation of ozone and knock.
Further, according to the present invention, by using such a corona charging device as a charging device of an image forming apparatus, uniform charging can be performed even when the image forming apparatus is operated for a long time, and image formation with good image quality can be performed. An apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a main part configuration diagram of an image forming apparatus using a corona charging device according to the present invention.
FIG. 2 is a block diagram illustrating supply of an ozone generation suppressing gas of FIG.
FIG. 3 is a flowchart illustrating control of gas supply in FIG. 1;
FIG. 4 is a flowchart illustrating control of gas supply in FIG. 1;
FIG. 5 is a main configuration diagram illustrating an image forming apparatus including a charging device.
FIG. 6 is a flowchart illustrating control of gas supply according to the first embodiment.
FIG. 7 is a flowchart illustrating control of gas supply according to the first embodiment.
FIG. 8 is a flowchart illustrating control of gas supply according to the second and third embodiments.
FIG. 9 is a flowchart illustrating control of gas supply according to a fourth embodiment.
[Explanation of symbols]
1 Charging house (case electrode and container)
1c opening
2 Charging wire (needle electrode)
4 Gas concentration detector (gas concentration detection means)
6 Supply piping (gas supply means)
7 Adjusting valve (gas supply adjusting means)
8 gas cylinders (supply source gas for suppressing ozone generation)
9 control circuit (control means)

Claims (5)

An ozone generation suppressing gas which is composed of a container having one open side, a pair of electrodes held inside the container, and a high-voltage power supply for applying a corona discharge voltage between the electrodes, wherein ozone generation is suppressed between the electrodes. In a corona charging device for applying a high voltage under an atmosphere to generate corona ions by corona discharge in the container to charge a member to be charged,
The opening is directed upward in the direction of gravity, and a gas having a higher specific gravity than air is used as the ozone generation suppressing gas,
Gas supply means for supplying an ozone generation suppressing gas to make the discharge atmosphere in the container an ozone generation suppressing gas atmosphere; gas supply adjusting means for adjusting a gas supply amount of the gas supply means; and an atmosphere in the discharge atmosphere Gas concentration detecting means for detecting gas concentration, and control means for controlling the gas supply adjusting means in response to a signal detected by the gas concentration detecting means to maintain the inside of the container at an ozone generation suppressing gas atmosphere of an appropriate predetermined concentration. And a corona charging device. The corona charging device according to claim 1 , wherein the ozone generation suppressing gas is carbon dioxide gas. 2. The gas concentration detector according to claim 1, wherein the gas concentration detector is a supply gas concentration detector that detects whether or not the ozone generation suppressing gas supplied by the gas supply unit is maintained at an appropriate concentration in the container. 3. The corona charging device according to claim 1. The corona charging device according to claim 1 , wherein the gas concentration detecting means is a generated gas concentration detector that detects a generated gas concentration generated by the presence of air.   A corona charging device according to any one of claims 1 to 4,
  An image forming apparatus, wherein an outer peripheral surface of a photoreceptor is located above the opening.

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