JP2001313151A - Static charging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of ozone and NOx or irregular charging and make the life of the charging device long. SOLUTION: The charging device comprises an anion forming space portion that is formed of the electron emitting surface of the electron emission element 101 which emits electron given energy by means of the electric field inside the element, and guide means 105, 106 that guide the gas for making anion in the anion forming space portion. The anion and electron formed in the anion forming space portion are emitted together with the gas guided in the anion forming space portion, and the charge an object with the anion and electron.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device used for a copying machine, a printer, a facsimile, etc., for charging an object to be charged by electron emission.

[0002]

2. Description of the Related Art Standards such as UL standards, TUV standards, and BAM standards have been set by a plurality of organizations in a plurality of countries and regions to regulate the amount of ozone generated in electrophotographic image forming apparatuses. I have. Further, in the image forming apparatus, there is a problem that a substance caused by NOx generated by discharge of the charging device adheres to the photoconductor and absorbs moisture, thereby lowering the surface potential of the photoconductor, thereby generating a defective image. It has become.

Conventionally, charging devices used in image forming apparatuses such as copying machines, printers, and facsimile machines include a corona charger, a roller charger, a brush charger, and a solid charger.
The corona charger is the most widely used charging method. However, the corona charger generates a large number of ozone and NO _x. Therefore, for example, a corona charger configured to reduce the amount of generated ozone is described in JP-A-9-114192. In this corona charger, the amount of ozone generated is reduced to 50% or less by performing discharge using a very thin wire of 40 to 50 microns.

Japanese Patent Application Laid-Open No. Hei 6-324556 has a metal housing arranged so as to surround three sides of a wire, and a metal mesh electrode arranged in the vicinity of an open portion thereof. A corona charger is disclosed that traps ozone and increases the probability of collision of ozone molecules to reduce the amount of ozone released. The roller charger is a charging system which has been described in Japanese Patent Application Laid-Open No. 56-91253 and has been actively studied in recent years. Roller chargers are very promising because they can generate very little ozone. The brush charger is described in Japanese Patent Publication No. 55-29837.

An ozone adsorbent is used to oxidize ozone generated by a charging device by a catalytic function such as activated carbon or to adsorb it on the surface. As the solid-state charger, there is an old one described in JP-A-54-53537. Japanese Patent Application Laid-Open No. 5-94077 describes an apparatus in which a large number of discharge electrodes are provided on an insulating member at minute intervals. Japanese Patent Application Laid-Open No. 6-75457 discloses that, by setting the distance between a charger and a recording medium to 500 to 3000 μm, the flight distance of ions is shortened to suppress the diffusion of ozone and prevent the adhesion of toner and the like. Is described.

Japanese Patent Application Laid-Open No. 9-244350 describes a discharge device including a discharge electrode on a plate-like substrate, a creeping glow discharge means disposed on the outer periphery of the discharge electrode, and a cover for covering the entire charger. . Japanese Patent Application Laid-Open No. Hei 9-115646 describes a flat solid-state discharge device in which NO _x is reduced by using a material having a specific work function as an electrode material.

Japanese Patent Application Laid-Open No. 8-203418 discloses a charge generator in which a PN junction semiconductor element or an electron emission element layer made of an electroluminescent material is provided on a line electrode surface.
Further, an electrostatic latent image forming apparatus that forms a latent image on a dielectric by independently driving the latent image on a pixel basis is disclosed. JP
JP-A-8-137215 discloses that in a charge generator formed by arranging charge generation control elements one-dimensionally or two-dimensionally, a charge generation part having a charge emission member of the charge generation control element is provided on the outermost surface of the element. A charge generator is described, wherein the charge generation control element is formed below the element.

Japanese Patent Application Laid-Open No. 8-92130 discloses a charge generator formed by arranging charge generation control elements in a one-dimensional or two-dimensional manner. The charge emission part of the generation control element is P
A charge generator is described, which is constituted by a diode having an -N junction and configured to emit electrons or charges by applying a reverse bias to the diode.

[0009]

Corona charger [SUMMARY OF THE INVENTION] generates a large number of ozone and NO _x. JP-A-9-11419
In the corona charger described in Japanese Patent Publication No. 2 and JP-A-6-324556, which reduces the amount of ozone, the amount of ozone can be reduced by only about 50% at most. Was needed. Since the ozone adsorbent deteriorates with time, replacement and maintenance of the ozone filter are required.

[0010] The roller charger tends to have non-uniform charging, and is liable to cause toner contamination on the roller surface, vibration due to bias AC applied to the roller, and image moire. Further, the roller charger is a rotating body, and requires many cleaning members because the roller surface needs to be cleaned. In addition, in the roller charger, the photosensitive layer of the photoconductor is dielectrically damaged, so that a pinhole is easily generated, a vibration noise, a charging roller mark (plasticizer), and a permanent deformation of the roller are easily generated.

[0011] The brush charger has uneven streaks, environmental fluctuations, low-temperature streamer discharge, white spots, abrasion of the photoreceptor, accumulation of abrasion photoreceptor, removal of the brush, melting of the brush due to abnormal discharge to the photoreceptor flaw, etc. There are disadvantages. The solid chargers above, although there are advantages such as the apparatus can be downsized, wide discharge area, can not reduce the unpleasant substances such as ozone and NO _x as expected. In the above-described electrostatic latent image forming apparatus, since it is an element configured to be driven in units of one pixel, it is difficult to apply to an electrophotographic process by uniform charging, and the entire device configuration such as a driving device is complicated. It has disadvantages such as becoming.

Further, since it is necessary to operate the device to face the member to be charged, if the bias voltage applied to the member to be charged is higher than the discharge threshold value according to Paschen's rule, the distance between the charge generator and the member to be charged is increased. There is also a disadvantage that discharge breakdown occurs in the space, and ozone and NOx are eventually generated. In addition, since particles and ions from the charged body and the surrounding atmosphere adhere to the electron emission surface, there is a problem that stable operation cannot be performed. In particular, in the case of an electron-emitting device layer made of an electroluminescent material, there is a problem that a simultaneous decrease in the charged potential occurs when the electrophotographic photosensitive member is charged due to simultaneous emission of light incident on the charged member. .

It is an object of the present invention to provide a charging device capable of preventing generation of ozone and NOx and prolonging its life, and capable of performing uniform charging. Another object of the present invention is to provide a charging device capable of preventing generation of ozone and NOx, prolonging the life and improving charging efficiency, and performing uniform charging.

A third object of the present invention is to provide a charging device capable of preventing generation of ozone and NOx, prolonging life and improving charging efficiency, and performing uniform charging. . A fourth object of the present invention is to provide a charging device capable of preventing generation of ozone and NOx, prolonging the service life, and improving uniform chargeability.

A fifth object of the present invention is to provide a charging device capable of preventing generation of ozone and NOx, prolonging the service life and further improving the uniform charging property. An object of the invention according to claim 6 is to provide a charging device capable of preventing generation of ozone and NOx, extending the life and improving charging efficiency, and performing uniform charging.

An object of the present invention is to provide a charging device capable of preventing generation of ozone and NOx, prolonging the service life and further improving charging efficiency, and performing uniform charging. And It is an object of the present invention to provide a charging device capable of preventing generation of ozone and NOx, prolonging the life and further improving charging efficiency, and performing uniform charging.

A ninth aspect of the present invention is to provide a charging device capable of preventing generation of ozone and NOx, prolonging the life and preventing emission of toxic gas components, and performing uniform charging. I do. The invention according to claim 10 provides a charging device capable of preventing generation of ozone and NOx, extending the life, improving the productivity of the device, and improving the stability of the charging capability, and performing uniform charging. The purpose is to:

According to the eleventh aspect of the present invention, it is possible to prevent the generation of ozone and NOx, extend the life, improve the productivity of the apparatus, reduce the cost and improve the stability of the charging ability, and perform uniform charging. It is an object of the present invention to provide a charging device that can perform charging. The invention according to claim 12 can prevent the generation of ozone and NOx, extend the life, improve the productivity of the device, reduce the cost and improve the stability of the charging ability, and perform the charging that can perform uniform charging. It is intended to provide a device. The invention according to claim 13 can prevent the generation of ozone and NOx, prolong the life, improve the productivity of the device, reduce the cost and improve the stability of the charging ability, and perform the charging that can perform uniform charging. It is intended to provide a device.

[0019]

In order to achieve the above object, the invention according to claim 1 is directed to a negative ion formed by an electron emitting surface of an electron emitting element for emitting electrons energized by an electric field inside the element. A generating space portion, and means for introducing a gas for negative ionization into the negative ion generating space portion, and introducing negative ions and electrons generated in the negative ion generating space portion into the negative ion generating space portion. The charge is discharged together with the discharged gas, and the charged object is charged by the negative ions and electrons.

According to a second aspect of the present invention, in the charging device according to the first aspect, the charging device is provided at a predetermined position in a path of the introduced gas before reaching the negative ion generation space, and emits particles mixed in the gas. It is provided with a particle filter that removes so as not to adhere to the surface.

The invention according to claim 3 is the invention according to claim 1 or 2
The charging device according to claim 1, further comprising: a positive ion filter electrode having a negative potential with respect to the surroundings, which is provided at a predetermined position in a path of the introduced gas before reaching the negative ion generation space, and removes a positive charge from air. Things.

According to a fourth aspect of the present invention, in the charging device according to any one of the first to third aspects, negative ions can be passed between the gas discharge portion and the charged body in parallel with the surface of the charged body. It has an electrode having a shape, and applies a voltage between the electrode and the gas discharge portion to extract negative ions toward the member to be charged.

According to a fifth aspect of the present invention, in the charging device according to any one of the first to third aspects, the charging device is provided between the gas discharging portion and the member to be charged and is parallel to the surface of the member to be charged and passes negative ions. A first electrode having a shape capable of passing through the first electrode; and a second electrode having a shape parallel to the first electrode and capable of passing negative ions and divided into a plurality of sections. A voltage is applied to each section independently of each other to control the distribution of negative ions, and a voltage is applied between the first electrode and the gas discharge portion to extract negative ions toward the member to be charged. .

According to a sixth aspect of the present invention, there is provided the charging device according to any one of the first to fifth aspects, further comprising means for heating the gas introduced into the negative ion generation space.

According to a seventh aspect of the present invention, in the charging device according to any one of the first to sixth aspects, compressed air supply means as means for introducing gas into the negative ion generation space, Gas separation means for separating the compressed air supplied by the air supply means into a high-oxygen component and a low-oxygen component and discharging the separated oxygen gas; and separating the high-oxygen component separated by the gas separation means into the negative ion generation space. Means for introducing the

According to an eighth aspect of the present invention, in the charging device according to the seventh aspect, the gas separation means is constituted by a hollow fiber-shaped gas separation membrane.

According to a ninth aspect of the present invention, in the charging device according to the eighth aspect, the gas to be charged is irradiated with the low-oxygen component separated by the gas separating means. It has a means for guiding it to the vicinity of the route that passes later.

According to a tenth aspect, in the charging device according to any one of the first to ninth aspects, the electron-emitting device has a MIS structure.

According to an eleventh aspect of the present invention, in the charging device according to any one of the first to ninth aspects, the electron-emitting device has an MIM structure.

According to a twelfth aspect of the present invention, in the charging device according to the tenth aspect, the electron-emitting device has a porous semiconductor layer and a thin-film electrode capable of passing electrons on a surface side of the porous semiconductor layer. Further, an electrode capable of injecting electrons into the porous semiconductor layer is provided on the back side of the porous semiconductor layer.

According to a thirteenth aspect of the present invention, in the charging device according to any one of the first to tenth aspects, the electron-emitting device includes a lower electrode and a tantalum oxide) film formed on the lower electrode. And a ZnS film formed on the tantalum oxide) film, and an upper electrode formed on the ZnS film.

[0032]

1 and 2 show a first embodiment of the present invention.
An example will be described. The first embodiment is an embodiment of the invention according to claim 1, and is an example of a charging device used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile. In the charging device of the first embodiment, the negative ion generation space 107 is formed by the electron emission surface of the electron emission element 101 supported by the holder 102 also serving as an electrode. The electron-emitting device 101 operates when a voltage is applied from a power supply 109. At this time, the negative ion generation space 1
The electron-emitting surface of the electron-emitting device 101 forming the element 07 is an equipotential surface, and the negative ion generation space 107 is in an electric field-free state.

The negative ion generation space 107 is connected to an introduction passage 105 into which gas is introduced, and gas feeding means 106 such as a blower fan or a compressed gas supply unit supplies gas into the negative ion generation space 107 through the introduction passage 105. It is designed to be sent. The opening of the negative ion generating space 107 forms an outlet 108 for discharging the gas and the negative ions introduced into the negative ion generating space 107, and the negative ion generating space 107 is connected to the outlet 108 and the inlet 108. Road 10
A closed space is formed except for a connection portion with No. 5. If the substrate constituting the electron-emitting device 101 is rigid such as a thick metal plate, the structure of the negative ion generation space 107 can be maintained by the electron-emitting device 101 itself.
It is not always necessary to support the electron-emitting device 101 with the holder 102.

FIG. 3 shows an electron-emitting device 101 of the first embodiment. The electron-emitting device 101 is configured by stacking a lower electrode 211, an upper electrode 213 having an opening, and an electron-emitting member 212. The electron emission member 212 includes a P-type semiconductor layer 212-1, a P ⁺ -type semiconductor layer 212-2 formed thereon, and an N ⁺⁺ -type semiconductor layer 212-3 further formed thereon. Have been. Examples of a material for the P-type semiconductor layers 212-1, P ⁺ -type semiconductor layers 212-2, and N ^++- type semiconductor layers 212-3 include single-crystal silicon, polycrystalline silicon, and amorphous silicon. The thickness and the carrier concentration of each of the semiconductor layers 212-1 to 212-3 are set so that the P-type semiconductor layer 212-1 has a thickness of several hundred nm to several μm.
In ^{10 14 ~10 16 cm -3, 10} 16 ~10 18 cm -3, N ++ type semiconductor layer 212-3 is several nm~ several tens nm P ⁺ -type semiconductor layer 212-2 is several tens nm in m It is set to about 10 ¹⁹ to 10 ²⁰ cm ^-3 .

In the first embodiment, the lower electrode 211
Is a negative potential of several V to several tens V with respect to the DC potential applied to the upper electrode 213. In such a bias state, the P-type semiconductor layer 212-1 and the N ^++- type semiconductor layer 212-3 are in a reverse bias state, and avalanche breakdown occurs due to a strong electric field in the vicinity of the P ⁺ -type semiconductor layer 212-2.

This avalanche breakdown occurs as follows. Assuming that one electron is accelerated (increased in energy) by the high electric field of the PN junction in the electron-emitting member 212, this electron has a high energy and cuts off a covalent bond to generate an electron-hole pair. The generated high energy electrons generate yet another electron-hole pair. This phenomenon occurs at a high electric field of 10 ⁵ to 10 ⁶ V · cm ⁻¹ or more. Avalanche breakdown is a junction breakdown phenomenon that occurs when the number of electron-hole pairs increases like an avalanche.

High-energy electrons (hot electrons) generated by the avalanche breakdown are converted into N ⁺⁺ type semiconductor layers.
Since electrons are more efficiently emitted from the surface of 212-3 into the opening of the upper electrode 213, electron emission that can significantly reduce the electron emission start voltage can be realized.

FIG. 4 shows an electron-emitting device according to a second embodiment of the present invention. This second embodiment is another embodiment of the invention according to claim 1, wherein an electron-emitting device as shown in FIG. 4 is used instead of the electron-emitting device 101 in the first embodiment. . This electron-emitting device includes a P ⁺ type semiconductor substrate 301 and a P type semiconductor region 3 formed thereon.
03, an N ⁺ -type semiconductor guard ring 302 surrounded by the P-type semiconductor region 303, a P ^{+ -type} semiconductor region 304 causing avalanche breakdown, an ohmic electrode 306 for the P ^{+ -type} semiconductor 301, and a metal electrode serving as a Schottky barrier junction. 307, the power supply 309 and the electrode 3
A voltage is applied between 06 and 307. A region 310 surrounded by a dotted line of the electron-emitting device is a depletion layer at the time of electron emission.

In this electron-emitting device, in principle, semiconductor materials such as Si, Ge, GaAs, Ga
P, AlAs, GaAsP, AlGaAs, SiC, B
P, AlN, diamond, and the like can be applied. In particular, an indirect transition type material having a large band gap is suitable.
The material of the metal electrode 307 serving as a Schottky barrier junction, in addition to Al of W, Au, or as long as it forms a Schottky barrier junction with the P-type semiconductor, known in the LaB _6, etc. In general.

Here, the operating principle of the electron-emitting device of the second embodiment will be described with reference to FIG. A power supply 30 is connected to a Schottky diode forming a Schottky barrier junction with the P-type semiconductor.
By applying a reverse bias voltage from FIG. 9, the bottom E _c of the conduction band of the P-type semiconductor can be set to an energy level higher than the vacuum level E _vac of the electrode 307 forming the Schottky barrier φBP. By causing avalanche breakdown, a large number of electrons, which were minority carriers in the P-type semiconductor, can be generated, and the electron emission efficiency can be increased. Further, since the electric field in the depletion layer 310 gives energy to the electrons, the electrons become hot electrons, the kinetic energy becomes larger than the temperature of the lattice system, and the electrode 30 forming a Schottky barrier junction is formed.
7 is injected. Electrons having energy higher than the work function φWK on the surface of the electrode 307 forming the Schottky barrier junction are emitted into vacuum.

In the case where the charging member 116 is charged by using the charging device of the first embodiment or the second embodiment having the above-described structure, as shown in FIG.
Are arranged opposite to the member to be charged 116 at a predetermined interval. This charging device operates as follows. Here, for example, the gas introduced into the negative ion generation space 107 is air. Power supply 1 for electron-emitting device 101
When a voltage is applied from 09 and a voltage is applied from a power supply 309 to the electron-emitting device as shown in FIG. 4, electrons are emitted in the negative ion generation space 107.

The air is introduced into the introduction path 10 according to the air flow generated by the gas feeding means (here, a blowing fan) 106.
5 is introduced into the negative ion generation space 107 and negative ions are generated by electron attachment to molecules and atoms that take an energetically stable negative ion state such as oxygen molecules existing in the air. On the other hand, molecules and atoms in which negative ions are energetically unstable, such as nitrogen molecules, are dissociated from electrons again even if negative ions are generated, resulting in an energetically stable negative ion state. Until electrons are attached to the molecules to be taken, the negative charges move through the gas in the form of electrons.

Here, electrons are not accelerated due to the absence of an electric field in the negative ion generation space 107, and even if the electrons emitted from the electron-emitting device can cause ionization of gas molecules, Each time the electrons lose energy, they eventually become energy that cannot be ionized. Also, electrons emitted from gas molecules due to ionization are not accelerated. Since an avalanche does not occur as a result, self-sustained discharge such as corona discharge does not proceed.

The negative ions generated as described above move toward the discharge port 108 together with the airflow, thereby generating a negative ion flow. Further, the discharge port 108 and the charged object 1
A bias power supply is provided on the side of the charged body 116 so that an electric field is formed between the charged body 116 and the negative ion generation space 107 so that negative ions and electrons generated in the negative ion generation space 107 accelerate and flow toward the charged body 116. A bias voltage is applied from 120.

The negative ion flow moving toward the discharge port 108 is transferred onto the member 116 by the electric current generated by the air flow from the discharge port 108 to the outside and the potential difference between the discharge port 108 and the member 116. Is charged, the charged body 116 is charged.

Since this charging device uses an electron-emitting device that emits electrons that are energized by an electric field inside the device, unlike a field emission cathode having a needle-like electron-emitting end, an electron emission operation is performed. In addition, no strong electric field is required outside the electron-emitting device. Therefore, negative ions can be generated in a space without an electric field formed on the electron emission surface, and no discharge occurs.

The object to be charged 116 and the electron emitting portion 108
Need not be opposed to each other, even if a bias voltage is applied to the member 116 to be charged, it is possible to prevent the electric field outside the electron-emitting device from being affected. Further, since electrons are emitted from the entire wall surface forming the negative ion generation space 107, it is possible to generate negative ions with extremely high efficiency.

As described above, in the first embodiment and the second embodiment, the negative ions are generated only by the electron attachment to the molecules and atoms by the electrons emitted from the electron-emitting device. Since there is no place where reactive radicals are generated unlike the discharge method, generation of ozone and NOx, which are well known as discharge products, hardly occurs.

Further, the field emission cathode having the above-mentioned needle-like electron emission end has other problems such as local temperature rise at the tip due to concentration of emission current and damage to the tip due to ion bombardment. Eliminates long-life and stable operation. Further, since the distribution of the amount of negative ions can be adjusted by the shape and position of the emission port 108, uniform charging can be performed without depending on the position of the electron-emitting device in the shield.

The entire surface of the member to be charged 116 (for example, Ricoh photoconductor unit type 800) is charged to -700 V by the charging devices of the first and second embodiments using the electron-emitting devices of FIGS. is allowed, was subjected to measurement of the ozone concentration and the concentration of NO _x in the charging apparatus around at this time, any ozone background level or higher values with NO _x was detected.

As described above, according to the first embodiment and the second embodiment, the negative ion generation space 107 formed by the electron emission surface of the electron emission element that emits electrons energized by the electric field inside the element. And a gas feeding means 106 and an introduction path 105 as means for introducing a gas for negative ionization into the negative ion generation space 107, and the negative ions and electrons generated in the negative ion generation space 107 are Since it is discharged together with the gas introduced into the negative ion generation space 107 and the charged body 116 is charged by the negative ions and electrons, the generation of ozone and NOx can be prevented and the life can be extended, and uniform charging can be achieved. It can be carried out.

That is, since negative ions are generated only by using the electron attachment of gas by the electrons emitted from the electron-emitting device, there is no place where reactive radicals are generated as in the ordinary corona discharge method. Almost no generation of ozone or NOx well-known as a discharge product occurs. Further, the electron-emitting device does not have a problem such as a local temperature rise due to a concentration of the emission current and a damage to the tip due to ion bombardment. Furthermore, since the distribution of the amount of negative ions can be adjusted by the shape and position of the emission port, uniform charging can be performed without depending on the position of the electron-emitting device in the shield.

Next, a third embodiment of the present invention will be described. This third embodiment is an embodiment of the invention according to claim 2, and in the first embodiment, as shown in FIG.
A particle filter 130 is provided in front of the gas feeding means 106. In this charging device, the gas is introduced into the negative ion generation space 107 from the introduction path 105 in accordance with the air flow generated by the gas feeding means (here, the blowing fan) 106. The particles (toner, dust, tobacco smoke, etc.) mixed in the gas are removed by the particle filter 130 disposed in the, and a clean gas is sent into the negative ion generation space 107. Therefore, it is possible to prevent the amount of electron emission from becoming unstable due to the attachment of particles in the gas to the electron emission surface.

As the particle filter 130, a nonwoven fabric filter can be used, but if it is necessary to prevent smaller particles from entering, a HEPA filter can also be used. In the third embodiment, the particle filter 130 is provided before the gas feeding means 106. However, the same effect can be obtained by providing the particle filter 130 in the introduction path 105.

In the charging device of the third embodiment, the member to be charged 116 (for example, Ricoh photoreceptor unit type 80) is used.
0) the whole was charged to -700V surface was measured for the ozone concentration and the concentration of NO _x in the charging apparatus around at this time, any ozone background level or higher values with NO _x were detected . In addition, comparing the time required for charging the charged member 116 before and after the provision of the particle filter 130,
The time required for charging the member to be charged 116 is shorter after the device is provided.

As described above, according to the third embodiment, in the first embodiment, the particles introduced into the gas path before reaching the negative ion generation space 107 are disposed at predetermined positions, and The provision of the particle filter 130 for removing so as not to adhere to the emission surface enables prevention of generation of ozone and NOx, extension of life and improvement of charging efficiency, and uniform charging.

That is, the same effect as that of the first embodiment is obtained, and the particles (toner, dust, tobacco smoke, etc.) mixed in the gas are removed by the particle filter, and the negative ion generation space is removed. Since the clean gas is supplied, it is possible to prevent the amount of electron emission from becoming unstable due to the attachment of particles in the gas to the electron emission surface. In the second embodiment, a particle filter 130 may be provided in front of the gas feeding means 106 as in the third embodiment.

Next, a fourth embodiment of the present invention will be described. The fourth embodiment is an embodiment of the third aspect of the present invention. In the first embodiment, as shown in FIG. Electrode 131 is provided.
, A negative voltage is applied from the power supply 132.

The Journal of the Electrostatics Society of Japan, 23 (1), p. 37-4
3 (1999) states that H ₃ O ⁺ (H
The presence of positive ions such as ₂ O) _n , NH ₄ ⁺ (H ₂ O) _n , a positive ion of a homolog of pyridine, and an ion of a homo homolog of amine has been confirmed. When introduced into the cell, the neutralization of the negative charge occurs, which causes a reduction in charging efficiency.

In the charging device of the fourth embodiment, the gas is introduced from the introduction path 105 into the negative ion generating space 107 in accordance with the air flow generated by the gas feeding means (here, the blowing fan) 106. At this time, the positive ions mixed into the gas are removed by a positive ion filter electrode 131 (here, a metal mesh) having a negative potential with respect to the surrounding disposed in front of the blower fan 106, and the negative ion generation space 107 Is supplied with a gas from which positive charges have been almost removed. For this reason, it is possible to prevent the negative charge from being neutralized by the positive ions, which leads to an improvement in charging efficiency. In particular, in an environment where a positively charged toner is used, the introduction of the floating toner into the negative ion generation space can be prevented, which is more effective.

In the charging device of the fourth embodiment, the member to be charged 116 (for example, Ricoh photoreceptor unit type 800)
The entire surface of is charged to -700 V, was measured for the ozone concentration and the concentration of NO _x in the charging apparatus around at this time, any ozone background level or higher values with NO _x was detected. The charged member 11 before and after the positive ion filter electrode 131 is provided.
Comparing the time required for charging of No. 6, the time required for charging the charged body 116 was shorter after the positive ion filter electrode 131 was provided. In the fourth embodiment, a metal mesh electrode is used as the positive ion filter electrode 131. However, the positive ion filter electrode 131 can of course be applied in other shapes such as a lattice shape.

As described above, according to the fourth embodiment, in the first embodiment, it is disposed at a predetermined position in the path of the introduced gas before reaching the negative ion generation space 107 to remove positive charges from the air. Since the electrode 131 for the positive ion filter having a negative potential with respect to the surroundings is provided, ozone and NOx can be prevented from being generated, the life can be extended, and charging efficiency can be improved, and uniform charging can be performed.

That is, the same effect as that of the first embodiment can be obtained, and the positive ions contained in the gas are removed by the positive ion filter electrode 131. A gas whose charge has been substantially removed is sent. For this reason, neutralization of negative charges can be prevented,
This leads to improvement in charging efficiency. In the above-described second and third embodiments, a positive ion filter electrode 131 having a negative potential with respect to the surroundings is provided in front of the gas feeding means 106 in the same manner as in the fourth embodiment, and a power supply is provided to the electrode 131. A negative voltage may be applied from 132.

Next, a fifth embodiment of the present invention will be described. This fifth embodiment is an embodiment of the invention according to claim 4, and is different from the first embodiment in that the charging member 116 is disposed between the discharge port 108 and the charging member 116 as shown in FIG.
Electrode 140 that is parallel to the surface of
(In this case, a metal mesh). Here, the shape of the electrode 140 is not particularly limited as long as it does not prevent the negative ions from reaching the charged body 116, such as a lattice shape.

A voltage is applied to the electrode 140 by a power supply 141 so that the potential of the gas discharge unit 108 becomes positive. Further, a bias power supply 120 is provided on the side of the charged body 116 such that an electric field is formed such that negative ions and electrons passing through the electrode 140 flow toward the side of the charged body 116.
Is applied. Since the shape of the electrode 140 is parallel to the surface of the charged body 116, the electric field between the electrode 140 and the charged body 116 does not depend on the shape of the gas emission unit 108, and negative ions fly in a uniform electric field. In addition, the charging of the charged body 116 is made uniform. In the charging device of the fifth embodiment, the entire surface of the member to be charged 116 (for example, Ricoh photoconductor unit type 800) is charged to -700 V, and the ozone concentration and N around the charging device at this time are charged.
When the measurement of the O _x concentration was performed, it was found that both of the ozone and NO _x
No value above the background level was detected. Further, the distribution of the charged potential of the charged body 116 is
Comparing before and after disposing 0, the distribution of the charged potential of the charged body 116 was smaller when the electrode 140 (here, metal mesh) was disposed.

According to the fifth embodiment, in the first embodiment, the electrode 1 having a shape parallel to the surface of the charged body 116 and capable of passing negative ions is provided between the gas releasing portion 108 and the charged body 116.
Since a voltage is applied between the electrode 140 and the gas releasing portion 108 to extract negative ions toward the member 116, generation of ozone and NOx is prevented, the life is extended, and the uniform chargeability is obtained. Improvement can be achieved.

That is, the same effect as that of the first embodiment can be obtained, and the electric field between the electrode 140 and the member to be charged 116 does not depend on the shape of the gas discharge portion 108, and the negative ions fly in a uniform electric field. Charging is made uniform. In the second to fourth embodiments, similarly to the fifth embodiment, the charging member 1 is disposed between the discharge port 108 and the charging member 116.
An electrode 1 parallel to the surface of 16 and capable of passing negative ions
A voltage may be applied to the electrode 140 by the power supply 141 so that the electrode 140 has a positive potential with respect to the gas discharge unit 108.

Next, a sixth embodiment of the present invention will be described. This sixth embodiment is an embodiment of the invention according to claim 5, and is different from the fifth embodiment in that it has a shape parallel to the surface of the charged body 116 and capable of passing negative ions as shown in FIG. The electrodes are composed of an electrode group 142 divided into a plurality of sections, and a voltage can be applied to each section of the electrode group 142 independently of each other. In the sixth embodiment, a voltage is applied independently to each section of the electrode group 142 by the power supply group 143.

Here, the shape of each section of the electrode group 142 is
Although it has a lattice shape, it is not particularly limited as long as it does not prevent negative ions from reaching the charged body 116, such as a mesh shape. A voltage is applied to each section of the electrode group 142 independently by the power supply group 143 so that the gas discharge unit 108 has a positive potential. Thereby, the gas release unit 108
Even if the distribution of the negative ions is non-uniform at the time when the negative ions are released from, the distribution of the negative ions can be made uniform by adjusting the potential distribution of the electrode group 142.

The electrode 140 is connected to the electrode group 1 by the power source 141.
A voltage is applied so as to be positive with respect to.
Further, a bias power supply 120 is provided on the side of the charged body 116 so that an electric field is formed such that negative ions and electrons passing through the electrode 140 flow toward the side of the charged body 116.
Is applied. Since the shape of the electrode 140 is parallel to the surface of the charged body 116, the electric field between the electrode 140 and the charged body 116 does not depend on the potential distribution of the electrode group 142, and negative ions fly in a uniform electric field. Charged object 1
16 are made uniform. In the charging device of the sixth embodiment, the entire surface of the member to be charged 116 (for example, Ricoh photoconductor unit type 800) is charged to -700 V, and the ozone concentration and N
When the measurement of the O _x concentration was performed, it was found that both of the ozone and NO _x
No value above the background level was detected. In addition, the distribution of the charging potential of the member 116 to be charged
As compared with the embodiment, the distribution of the charging potential of the member to be charged 116 was further reduced and improved in the sixth embodiment.

According to the sixth embodiment, in the fifth embodiment described above, it is provided between the gas releasing portion 108 and the charged member 116 and has a shape parallel to the surface of the charged member 116 and capable of passing negative ions. The first electrode 140 and the first electrode 14
A second electrode 142 having a shape parallel to zero and capable of passing negative ions, and divided into a plurality of sections, and applying a voltage to each section of the second electrode 142 independently of each other to form negative ions. Is controlled, and a voltage is applied between the first electrode 140 and the gas discharge unit 108 to generate negative ions.
6, the ozone and NOx can be prevented from being generated, the life can be extended, and the uniform chargeability can be further improved.

That is, the same effect as that of the fifth embodiment is obtained, and the power supply group 143 is provided for each section of the electrode group 142.
Independently, by applying a voltage to the gas discharge unit 108 so as to have a positive potential, even if the distribution of the negative ions is not uniform when the negative ions are released, the potential distribution of the electrode group 142 Is adjusted, the distribution of negative ions can be made uniform.

In the second to fourth embodiments, similarly to the sixth embodiment, negative ions pass between the gas discharging portion 108 and the charged member 116 in parallel with the surface of the charged member 116. A first electrode 140 having a different shape and a second electrode 142 parallel to the first electrode 140 and having a shape capable of passing negative ions and divided into a plurality of sections. A voltage is applied to each section of the electrode 142 independently of each other to control the distribution of the negative ions, and a voltage is applied between the first electrode 140 and the gas discharge unit 108 to move the negative ions toward the member 116 to be charged. May be pulled out.

Next, a seventh embodiment of the present invention will be described. The seventh embodiment is an embodiment of the present invention. In the above embodiment, the negative ion generation space 10
When the gas introduced into 7 is air, gas condensed at a low temperature in the living temperature range, such as water vapor, is mixed in the air. During the operation of the electron-emitting device, the electron-emitting surface can be higher than room temperature due to the current flowing through the electron-emitting device. Operation will be significantly impaired.

In the seventh embodiment, a means 150 (here, a heating wire) for heating the electron emission surface of the electron emission element 101 is provided in the introduction path 105 as shown in FIG. are doing. Due to the heat transfer from the gas heated by the heating means 150, the temperature of the electron emission surface of the electron emission element 101 becomes higher than the gas outside the charging device even when not in use. Accordingly, it is possible to prevent water vapor and the like from condensing on the electron emission surface of the electron emission element 101 and reducing the electron emission efficiency when not in use, thereby improving the charging efficiency.

Further, since the decomposition of ozone is promoted by heat, even a very small amount of ozone generated by the ionization of a small number of gas molecules as described in the first and second embodiments can generate gas at a high temperature. Will be decomposed. In the charging device of the seventh embodiment, the member to be charged 116
(E.g. Ricoh photoconductor unit type 800) charges the entire surface -700V of was measured for the ozone concentration and the concentration of NO _x in the charging apparatus around at this time, any ozone, or background level with NO _x Was not detected.

The object to be charged 11 is heated when the heater 150 is heated when not in use and when the heater 150 is not heated.
6, the time required for charging was compared.
Was heated, the time required for charging the member to be charged 116 was shortened. In the seventh embodiment, the heating means 1
Although a heating wire is used as 50, a lamp or a means for heating the introduction path 105 itself may be used as the heating means 150.

As described above, according to the seventh embodiment, in the first embodiment, since the means 150 for heating the gas introduced into the negative ion generation space 107 is provided, the generation of ozone and NOx can be prevented and the length can be reduced. The service life can be extended and the charging efficiency can be improved, and uniform charging can be performed.

That is, the same effect as that of the first embodiment can be obtained, and the temperature of the electron emission surface is lower than that of the gas outside the charging device even when not in use due to the radiant heat from the heater 150 and the heat transfer from the heated gas. As a result, it is possible to prevent water vapor and the like from condensing on the electron emission surface when not in use and to reduce the electron emission efficiency, and to improve the charging efficiency. Furthermore, even if a small amount of ozone is generated, it can be thermally decomposed. It should be noted that the second to sixth embodiments described above.
In the embodiment, a means 150 for heating the gas introduced into the negative ion generation space 107 may be provided similarly to the seventh embodiment.

Next, an eighth embodiment of the present invention will be described. The eighth embodiment is an embodiment of the present invention. In the eighth embodiment, the oxygen separating means 180 is provided in the middle of the introduction path 105 as shown in FIG. 11 in the first embodiment. As means 180 for separating oxygen from the compressed air and separating the compressed air into a component having a high oxygen concentration and a component having a low oxygen concentration, a silicone-based oxygen-enriched membrane ( An oxygen-enriched film made of Nagayanagi Industry Co., Ltd.) or polyimide can be used.

The air pressurized by the gas feeding means 106 (compressed air supply device such as a compressor) is sent to the oxygen separating means 180 through the introduction path 105 and is supplied to the air separating means 180 shown in FIG.
The high oxygen concentration gas after passing through the oxygen-enriched film 180 as shown in 2 is introduced into the negative ion generation space 107 through the introduction path 105. As a result, more oxygen molecules that can easily obtain the negative ion state are supplied into the negative ion generation space 107, and the negative ion generation efficiency is improved.

In the charging device of the eighth embodiment, the member to be charged 116 (for example, Ricoh photoreceptor unit type 800)
The entire surface of is charged to -700 V, was measured for the ozone concentration and the concentration of NO _x in the charging apparatus around at this time, any ozone background level or higher values with NO _x was detected. In addition, comparing the time required for charging the charged body 116 before and after the provision of the oxygen separating means 180, the time required for charging the charged body 116 was shorter after the provision of the oxygen separating means 180. .

According to the eighth embodiment, in the first embodiment, compressed air supply means (gas feeding means 106 and introduction path 105) as means for introducing gas into the negative ion generation space 107, Oxygen separation means 1 as gas separation means for separating compressed air supplied by the air supply means into a high oxygen concentration component and a low oxygen concentration component and discharging the same
80 and the introduction path 105 as a means for introducing the high-oxygen-concentration component separated by the gas separation means into the negative ion generation space 107, thereby preventing ozone and NOx from being generated, extending the life, and improving the charging efficiency. Further improvement can be achieved, and uniform charging can be performed.

That is, the same effect as that of the first embodiment can be obtained, and the high oxygen concentration gas after passing through the oxygen-enriched film is introduced into the negative ion generating section 107, so that it is easy to obtain the negative ion state. More molecules are supplied into the negative ion generation unit 107, so that the negative ion generation efficiency is improved and the charging efficiency can be improved.

In the second to seventh embodiments, similarly to the eighth embodiment, the compressed air supply means (the gas supply means 106 and the introduction path) serve as a means for introducing gas into the negative ion generation space 107. 105), oxygen separating means 180 as gas separating means for separating and discharging compressed air supplied by the compressed air supply means into a high oxygen concentration component and a low oxygen concentration component, and separated by the gas separation means. An introduction path 105 may be provided as a means for introducing the high oxygen concentration component into the negative ion generation space 107.

Next, a ninth embodiment of the present invention will be described. The ninth embodiment is an embodiment of the present invention. In the ninth embodiment, as shown in FIG. 13, a bundle of a large number of hollow fiber membranes made of an oxygen-enriched membrane is provided as oxygen separation means 181 in the gas introduction passage 105 as shown in FIG. ing. This oxygen separation means 18
Reference numeral 1 denotes a polyimide hollow fiber membrane formed by bundling a large number of polyimide nitrogen-enriched membranes manufactured by Ube Industries, Ltd., for example.

As shown in FIG. 14, the side surface of this hollow fiber membrane has a property that oxygen is more easily permeable than nitrogen in the air, and when compressed air using air is introduced, the hollow fiber membrane passes through the hollow fiber membrane. , The nitrogen concentration inside the hollow fiber membrane increases,
Oxygen permeates from the side. The high oxygen concentration gas released from the side surface of the hollow fiber membrane is introduced into the negative ion generation space 107. The oxygen separating means 181 has a structure in which the gas inside the hollow fiber membrane is released to the outside through another path so that the hollow fiber membrane does not burst due to pressure.

By forming the oxygen separating means 181 into a shape in which a large number of hollow fiber membranes are bundled, even if the flow path diameter is the same, the oxygen separating means 181 can be formed as shown in FIG.
Thus, the cross-sectional area of the film through which oxygen can pass can be greatly increased as compared with the case where the film is simply passed through a flat film.
Therefore, more air with a high oxygen concentration can be supplied into the negative ion generation space 107. This allows
Oxygen molecules that are more likely to obtain negative ions are supplied into the negative ion generation space 107, and the negative ion generation efficiency is further improved.

The gas separation membrane has a relationship in which the compressed air pressure is proportional to the flow rate of the separated gas. However, since the compressed air has viscosity and the hollow fiber membrane is a very thin tube (with an inner diameter of about 20 μm), the compressed air Even if the air pressure changes to some extent, the amount of separated gas does not fluctuate suddenly in response to the change. That is, if the hollow fiber gas separation membrane is used, the oxygen concentration of the compressed air supplied to the negative ion generation space 107 can be increased, and even if the air supply of the compressed air supply source slightly varies. In addition, the gas separation membrane acts as a buffer material to absorb fluctuations in air supply. Further, even when the fluctuation has a certain magnitude, the flow rate of the separation gas gradually changes, so that the change has a reduced effect on the negative ion flow, and a change on the charging of the charged body 116. It can be prevented at a minimum. In this case, by setting the length of the gas separation membrane to 70 cm or more, the buffer function can be sufficiently functioned, and the charged member 116 can be uniformly charged even when the compressed air supply source fluctuates. .

In the charging device of the ninth embodiment, the member to be charged 116 (for example, Ricoh photoreceptor unit type 80) is used.
0) the whole was charged to -700V surface was measured for the ozone concentration and the concentration of NO _x in the charging apparatus around at this time, any ozone background level or higher values with NO _x were detected . Further, when the time required for charging the member to be charged 116 was compared with that in the eighth embodiment, the time required for charging the member to be charged 116 was further shortened in the ninth embodiment.

According to the ninth embodiment, in the first embodiment, the oxygen separation means 181 as the gas separation means is constituted by a hollow fiber gas separation membrane, so that ozone and NOx
Can be prevented, the service life can be extended, and the charging efficiency can be further improved, and uniform charging can be performed.

That is, the same effect as that of the eighth embodiment can be obtained, and the oxygen separating means 181 is formed by bundling a large number of hollow fiber membranes. Since the cross-sectional area through which oxygen can pass can be greatly increased as compared with the case where a flat membrane is passed through the air, a larger amount of air having a high oxygen concentration can be supplied to the negative ion generation space 107.
Can be supplied to As a result, more oxygen molecules that can easily obtain negative ions are supplied to the negative ion generation space 107, and the negative ion generation efficiency is further improved, and the charging efficiency can be further improved.

In the second to seventh embodiments, a large number of hollow fiber membranes made of an oxygen-enriched membrane are bundled in the middle of the introduction path 105 in the same manner as in the ninth embodiment. May be provided as gas separation means.

Next, a tenth embodiment of the present invention will be described. The tenth embodiment is an embodiment of the ninth aspect of the present invention. In the tenth embodiment, as shown in FIG. 15, a large number of hollow fiber membranes made of an oxygen-enriched membrane are bundled in the middle of the introduction passage 105 as shown in FIG. A flow path 182 is provided so as to guide the low oxygen concentration gas separated by the oxygen separating means 181 to the vicinity of a path through which the gas discharged from the discharge port 108 passes after the charged body 116 is irradiated with the gas. The flow path 182 is specifically a pipe that guides the low-oxygen-concentration gas separated by the oxygen separating means 181 to the vicinity of a path through which the gas to be charged passes after being irradiated.

Since the air flow out of the discharge port 108 is in a so-called high oxygen concentration state, if it is discharged out of the apparatus as it is, there is a risk that abnormal combustion may occur. On the other hand,
Since the air in the pipe 182 is in an oxygen-deficient state, if it is discharged outside the machine as it is, there is a possibility that it may harm the human body. Therefore, in the tenth embodiment, the above-mentioned problem can be solved by combining the air flowing out from the discharge port 108 and the air from the pipe 182 before the discharge outside the apparatus.

In the charging device of the tenth embodiment,
Charged member 116 (for example, Ricoh photoreceptor unit type
The entire surface of the 800) is charged to -700 V, was measured for the ozone concentration and the concentration of NO _x in the charging apparatus around at this time, any ozone background level or higher values with NO _x were detected .

According to the tenth embodiment, in the ninth embodiment, the oxygen separating means 181 as the gas separating means is used.
Means 182 for guiding the low-concentration oxygen component separated by the gas to the vicinity of a path through which the gas discharged from the charging device passes after being irradiated on the charged body 116, so that generation of ozone and NOx can be prevented and long life can be achieved. Therefore, it is possible to achieve uniform charging.
That is, the same effect as that of the ninth embodiment can be obtained, and the high oxygen concentration gas and the low oxygen concentration gas are combined before being discharged outside the apparatus, so that the emission of the harmful gas component can be prevented.

Next, an eleventh embodiment of the present invention will be described. The eleventh embodiment is an embodiment of the tenth aspect of the present invention. In the eleventh embodiment, in each of the first to tenth embodiments, a MIS (metal-insulator-type) as shown in FIG.
This is an embodiment using an electron-emitting device having a (semiconductor) structure. In this MIS structure electron-emitting device, an n-type Si substrate is used as a lower electrode 513, and the surface thereof is oxidized by a method such as thermal oxidation to form an insulating layer 512 to a thickness of 5 nm. On the insulating layer 512, Au is formed to a thickness of 6 nm as the upper electrode 518 by a method such as sputtering.

In this case, as shown in FIG. 17, electrons near the Fermi level in the n-type Si substrate 513 pass through the barrier due to the tunnel phenomenon and are injected into the conduction band of the insulating layer 512,
There, it is accelerated and injected into the conduction band of the upper electrode 518 to become hot electrons. Among these hot electrons, those having energy equal to or higher than the work function φ of the upper electrode 518 are emitted to the outside of the electron-emitting device.

The electron-emitting device having the MIS structure has various advantages. First, since the element has a simple structure in the form of a thin film, the area can be easily increased, and a planar electron-emitting element can be easily formed. Further, since the upper electrode 518 is flat and has a large area, the state of the interface with the outside of the element is more stable than that of a field emission cathode array having a needle-like electron emission end, and the surface of the upper electrode 518 has an atmosphere gas. Even if the work function φ changes due to contamination due to the adhesion of the particles, the electron emission characteristics are not significantly affected, and therefore, are not easily affected by the environmental gas. In addition, the power supply 517 supplies a voltage between the upper electrode 518 and the lower electrode 513.
The electron emission operation is possible even when a low voltage of about 0 V is applied, and there is a great advantage that a high-voltage power supply or the like is not required.

The eleventh embodiment in which the electron emission element having the MIS structure described above is used for the charging device of each configuration of the first to tenth embodiments.
In the embodiment, the surface of the charged member 116 (for example, Ricoh photoreceptor unit type 800) is charged to −700 V, and the ozone concentration and N around the charging device at this time are charged.
When the measurement of the O _x concentration was performed, it was found that both of the ozone and NO _x
No value above the background level was detected.

According to the eleventh embodiment, since the electron-emitting device has the MIM structure, the generation of ozone and NOx can be prevented, the life can be extended, the productivity of the device can be improved, and the stability of the charging ability can be improved. And uniform charging can be performed. That is, the same effects as those of the first to tenth embodiments can be obtained, and since the electron-emitting device has a simple structure in the form of a thin film, it is easy to increase the area. It is easy to do and productivity is improved. Furthermore, the state of the interface with the outside of the electron-emitting device is stable, and even if the surface of the upper electrode is contaminated by the adhesion of atmospheric gas and the work function φ changes, the electron-emitting characteristics are not significantly affected, and Since it is hardly affected, the charging ability is stabilized.

Next, a twelfth embodiment of the present invention will be described. The twelfth embodiment is an embodiment of the present invention. In the twelfth embodiment, in each of the first to tenth embodiments, an MIM (metal-insulator-type) as shown in FIG.
This is an embodiment using an electron-emitting device having a (metal) structure. In the electron emission element having the MIM structure, an insulating layer 412 is formed on a lower electrode 413, and an upper electrode 411 is formed on the insulating layer 412.

The operating principle of the electron-emitting device having the MIM structure will be described. As shown in FIG. 19, a voltage (several volts to 10) is applied between the upper electrode 411 and the lower electrode 413 from the power supply 417.
When V) is applied, due to the electric field in the insulating film 412, electrons near the Fermi level in the lower electrode 413 pass through the barrier due to the tunnel phenomenon and are injected into the conduction band of the insulating film 412, where they are accelerated and accelerated. The electrons are injected into the conduction band of the electrode 411 and become hot electrons. Among these hot electrons, those having energy equal to or higher than the work function φ of the upper electrode 411 are emitted to the outside 410 of the element.
For example, electron emission based on this principle has been observed in an Au—Al ₂ O ₃ —Al structure or the like (applied physics, Vol. 32, Vol.
No. 8, (1963) p568).

An electron emission device having an MIM structure, for example, Au-
Fabrication of an electron-emitting device having an Al ₂ O ₃ —Al structure can be performed, for example, by the following method. 20 nm of Al is deposited as a lower electrode 413 on the substrate 414 whose surface has been cleaned. Subsequently, the Al is oxidized by an anodic oxidation method. The anodic oxidation is performed with a 3% ammonium tartrate aqueous solution at a formation voltage of 4V. Since the film thickness of Al that can be oxidized by anodic oxidation depends on the formation voltage with high accuracy, 4 n
Only m of Al can be selectively oxidized. Thus, the insulating film 412 made of Al ₂ O ₃ can be formed on the lower electrode 413. When the film thickness of Al is set to a value other than 20 nm, it goes without saying that the formation voltage is set to a voltage corresponding thereto. Next, an upper electrode 411 is formed over the insulating film 412. As the upper electrode 411, for example, Au may be formed to a thickness of 10 nm by vapor deposition in an ultrahigh vacuum.

In the twelfth embodiment, it is possible to use a vapor phase oxidation method instead of the anodic oxidation method in the Al oxidation process. That is, the Al film is put in a vacuum chamber,
By heating the substrate by introducing oxygen at about 10 Torr, Al is oxidized, and an insulating film 412 made of Al ₂ O ₃ can be formed.

The electron emission device having the MIM structure has various advantages as follows. First, since the element has a simple structure in the form of a thin film, the area can be easily increased, and a planar electron-emitting element can be easily formed. Further, since the upper electrode 411 is flat and has a large area, the state of the interface with the outside 410 of the element is more stable than that of a field emission cathode array having a needle-like electron emission end, and the surface of the upper electrode 411 is formed of an atmospheric gas. Even if the work function φ changes due to contamination due to adhesion, there is no significant effect on the electron emission characteristics, so that it is hardly affected by the environmental gas. Also, 1
The electron emission operation can be performed even when a low voltage of about 0 V is applied, which is a great advantage in that a high-voltage power supply or the like is not required. Further, unlike the electron-emitting device having the MIS structure described above, the substrate does not need to be made of a semiconductor material, and can be formed on glass, so that the length and the area can be reduced.

In the twelfth embodiment in which the above-described MIM structure electron-emitting device is used in the charging device of each configuration of the first to tenth embodiments, the member to be charged 116 (for example, Ricoh photoreceptor unit type 800 ) Was charged to −700 V, and the ozone concentration and NO _x concentration around the charging device were measured at this time.
Background level or higher values with NO _x was detected.

According to the twelfth embodiment, in the first to tenth embodiments, since the electron-emitting device has the MIM structure, the generation of ozone and NOx can be prevented, and the life can be extended.
It is possible to improve the productivity of the apparatus, reduce the cost and improve the stability of the charging ability, and perform uniform charging.

That is, the same effects as those of the eleventh embodiment can be obtained, and the electron-emitting device can be formed on glass without using the substrate as a semiconductor material. Can be.

Next, a thirteenth embodiment of the present invention will be described. The thirteenth embodiment is an embodiment of the twelfth aspect of the present invention. In the electron-emitting device having a thin insulating film according to the eleventh and twelfth embodiments, if the emission efficiency of electrons is to be further increased (if more electrons are to be emitted), the thickness of the insulating film is reduced. Although it is necessary to further reduce the thickness, if the thickness of the insulating film is too thin,
When a voltage is applied between the upper and lower electrodes of the laminated structure, dielectric breakdown may occur, and in order to prevent such dielectric breakdown, there is a restriction in reducing the thickness of the insulating film or the oxide film. Therefore, there is a problem that the electron emission efficiency (drawing efficiency) cannot be increased so much.

In order to solve this problem, the electron-emitting device in the thirteenth embodiment is basically a device using a porous semiconductor as a high-resistance layer.
The semiconductor substrate is a constituent element. Such an electron-emitting device and an electron-emitting operation are described in detail in IEICE Technical Report, Technical Report of IEICE, ED96-141, (1996-12).

FIG. 20 shows the structure of an electron-emitting device according to the thirteenth embodiment. The thirteenth embodiment is an embodiment using the electron-emitting device shown in FIG. 20 as the electron-emitting device in each of the first to tenth embodiments. This electron-emitting device can be manufactured, for example, by the following method.

A plane orientation (1) with an ohmic electrode on the back
00) on the surface of an n-type silicon substrate (n-type silicon wafer) 601 (specific resistance 0.01 to 0.03 Ωcm)
A constant current anodic oxidation treatment is performed in a mixed solution of 5 wt% HF aqueous solution and ethanol (mixing ratio is 1: 1) to form a porous silicon layer (hereinafter, referred to as a PS layer) 602. During the anodic oxidation, the sample surface is irradiated with light by a 500 W tungsten lamp. The thickness of the PS layer 602 is about 3 μm. An Au thin film is vacuum-deposited (thickness: 100 °) on the surface of the produced PS layer 602, and this is deposited on the Au thin film electrode 6 on the surface side.
As 03, a diode is formed with the ohmic electrode 604 on the back surface.

A positive voltage V _PS is applied to the Au thin film electrode 603 of this diode by the power supply 605, and electrons are injected from the n-type silicon substrate 601 to the PS layer 602. The current at that time is I _PS . In that case, since the PS layer 602 has high resistance, most of the applied electric field is applied to the PS layer 602, but since an oxide layer exists on the surface of the PS layer 602,
As shown in the energy band diagram of FIG. 21, the electric field intensity is higher on the surface of the PS layer 602.

Further, the electrons injected from the n-type silicon substrate 601 are directed toward the Au thin film electrode 603 side by the PS layer 60.
2 toward the Au thin film electrode 603. PS layer 6
The electrons that have reached the vicinity of the surface of 02 are partially emitted through the Au thin film to the outside of the device due to the strong electric field there.

In the electron-emitting device of the thirteenth embodiment, the substrate is made of silicon. However, in the twelfth embodiment, the substrate of the electron-emitting device is not limited to silicon, and anodic oxidation can be applied. All semiconductors can be used for the substrate of the electron-emitting device. That is, germanium (Ge), silicon carbide (SiC), gallium arsenide (G
aAs), indium phosphide (InP), cadmium selenide (CdSe), and the like, and many elemental and compound semiconductors of the IV group, III-V group, II-VI group, and the like fall under this category.

According to the electron-emitting device of the thirteenth embodiment, the step of forming a thin insulating film is unnecessary, the possibility of dielectric breakdown is small, no complicated steps are required, and the element configuration is simple and large. The advantage that the area can be easily obtained is obtained, and the above-described problem can be solved. However, IEICE Technical Report, TECHNICAL R
According to EPORT OF IEICE., ED96-141, (1996-12),
Since the electron-emitting device of the embodiment can also function as a light-emitting device, when the device is opposed to the charged member 116, for example, a photoconductor of electrophotography, light emission directly irradiates the photoconductor, thereby inhibiting charging of the photoconductor. However, in the thirteenth embodiment,
Since the negative ions are generated in the shield, it is not necessary for the electron-emitting device to face the photoconductor, so that the above problem can be avoided.

Also, IEICE Technical Report, Technical Report
According to OF IEICE., ED96-141, (1996-12), the formed PS
The layer 602 is subjected to rapid thermal oxidation (RTO: Ra
After the pidThermal Oxidation) treatment, the PS layer 602
It has also been reported that the amount of emitted electrons increased when a thin Au film was vacuum-deposited on the surface of. It is considered that this is because the leakage current was reduced due to the oxidation of the surface of the PS layer 602, and the electric field effect inside the element was increased. Of course, it goes without saying that an electron-emitting device that has been subjected to such processing can also be applied to the present invention.

Further, the display antenna image 199
According to 9, Vol8, pp77-82, it is reported that by applying anodized polycrystalline silicon film as a porous semiconductor layer, scattering loss of electrons can be reduced and stable electron emission can be obtained. Have been. This is very effective for stable operation of the charging device.

The thirteenth embodiment in which the above-described electron-emitting device is used in each of the charging devices of the first to tenth embodiments.
In the embodiment, the surface of the member to be charged 116 (for example, Ricoh photoreceptor unit type 800) is charged to −700 V, and the ozone concentration and N around the charging device at this time are charged.
When the measurement of the O _x concentration was performed, it was found that both of the ozone and NO _x
No value above the background level was detected. In addition, as compared with the electron-emitting devices of the eleventh embodiment and the twelfth embodiment, the frequency of occurrence of dielectric breakdown of the electron-emitting device was significantly lower.

According to the thirteenth embodiment, the electron-emitting member of the electron-emitting device includes a semiconductor substrate 601 and a porous semiconductor layer 602 having a porous surface on the semiconductor substrate 601.
Metal thin film electrode 6 formed on porous semiconductor layer 602
03 and an ohmic electrode formed on the back surface of the semiconductor substrate, it is possible to prevent ozone and NOx from being generated, extend the life, improve the productivity of the device, reduce the cost, and improve the stability of the charging ability. And uniform charging can be performed.

That is, the same effects as those of the eleventh embodiment can be obtained, and the electron-emitting device does not require a step of forming a thin insulating film, has a small possibility of dielectric breakdown, and does not require a complicated step. This has the advantage that the element configuration is simple and the area can be easily increased, and further, the productivity of the charging device, the cost can be reduced, and the stability of the charging capability can be improved.

Next, a fourteenth embodiment of the present invention will be described. The fourteenth embodiment is an embodiment of the present invention. In the fourteenth embodiment, in each of the first to tenth embodiments, an electron-emitting device including an electroluminescent device as shown in FIG. 22 is used instead of the electron-emitting device. . FIG.
In 2, reference numeral 911 denotes a lower electrode, and 913 denotes an upper electrode. The electron emission member 912 is formed of a tantalum oxide (Ta ₂ O ₅ ) film 912-having a thickness of 300 to 500 nm.
1, a ZnS film 912-2 having a thickness of about 500 nm formed thereon,
An upper electrode film 912-3 made of gold (Au) and having a thickness of about 10 nm is formed on the upper portion of the upper electrode film 912-3. Such an E
Regarding the material of the L thin film and the electron emission operation, see Applied Physics
63, No. 6, pp. 592-595 (1994).

Next, in the fourteenth embodiment, the drive voltage waveform applied to the lower electrode 911 in the ON state of the switching transistor of the electron-emitting device is shown in FIG.
3 will be described. In FIG. 23, DC potential applied to the upper electrode 913, that is, the upper electrode film 912-3 made of gold. Is a potential applied to the lower electrode 911 in the electron emission state. In a bias state in which a negative potential is applied as the lower electrode potential with respect to the DC potential, hot electrons are generated in the ZnS film 912-2, and the hot electrons are converted to the upper electrode film 912-3 made of gold. Is released to the outside through tunneling. The publication (applied physics) shows that the waveform of the driving potential applied to the lower electrode 911 shown in FIG. 23 may be a pulse waveform as shown in FIG.

In the fourteenth embodiment, since the charging operation can be performed without causing the electron emission surface that emits light to face the member 116, even if the member 116 is an electrophotographic photosensitive member. Does not lower the charged potential. This eliminates the need for a step of forming a thin insulating film,
There is little risk of dielectric breakdown, no complicated process is required,
An electron-emitting device having an advantage that the element configuration is simple and the area can be easily increased can be used without any problem.

The fourteenth embodiment in which the above-described electron-emitting device is used in each of the charging devices of the first to tenth embodiments.
In the embodiment, the surface of the charged member 116 (for example, Ricoh photoreceptor unit type 800) is charged to −700 V, and the ozone concentration and N around the charging device at this time are charged.
When the measurement of the O _x concentration was performed, it was found that both of the ozone and NO _x
No value above the background level was detected. In addition, as compared with the electron-emitting devices of the twelfth embodiment and the thirteenth embodiment, the frequency of dielectric breakdown of the electron-emitting device was significantly lower.

As described above, according to the fourteenth embodiment, the electron-emitting device includes the lower electrode 911, the tantalum oxide film 912-1 formed on the lower electrode 911, and the tantalum oxide film 912-1 on the lower electrode 911. Formed in ZnS
Since it is an electroluminescent element composed of the film 912-2 and the upper electrode 913 formed on the ZnS film 912-2, the generation of ozone and NOx is prevented.
It is possible to extend the life, improve the productivity of the apparatus, reduce the cost and improve the stability of the charging ability, and perform uniform charging.

That is, the same effects as those of the first and second embodiments can be obtained. Further, the electron-emitting device does not require a step of forming a thin insulating film, is less likely to cause dielectric breakdown, and is more complicated. This eliminates the need for a simple process, provides a simple element configuration, and facilitates an increase in the area. It is possible to improve the productivity of the charging device, reduce the cost, and improve the stability of the charging capability.

Next, a comparative example with respect to the first to fourteenth embodiments will be described. Using the conventional corona wire charging device 100 shown in FIG. 25, the surface of the member to be charged 116 was −
It was charged to 700V. It was subjected to measurement of ozone concentration and NO _x concentrations in the charging device near at this time, ozone: 4ppmNO _x: 0.6ppm was detected. In contrast, in the first embodiment to the fourteenth embodiment, the value of ozone, than background levels with NO _x as described above was detected.

The present invention is not limited to the above-described embodiment, but can be applied to, for example, a transfer charging device and a separation charging device.

[0132]

As described above, according to the first aspect of the present invention, the generation of ozone and NOx can be prevented, the life can be extended, and uniform charging can be performed. According to the second aspect of the present invention, it is possible to prevent the generation of ozone and NOx, prolong the life and improve the charging efficiency, and perform uniform charging. According to the third aspect of the present invention, the generation of ozone and NOx can be prevented, the service life can be extended, and the charging efficiency can be improved, and uniform charging can be performed.

According to the fourth aspect of the present invention, it is possible to prevent the generation of ozone and NOx, extend the life, and improve the uniform chargeability. According to the fifth aspect of the invention, it is possible to prevent the generation of ozone and NOx, prolong the service life, and further improve the uniform charging property. According to the invention according to claim 6,
The generation of ozone and NOx can be prevented, the service life can be increased, and the charging efficiency can be improved, and uniform charging can be performed.

According to the seventh aspect of the present invention, the generation of ozone and NOx can be prevented, the life can be extended, and the charging efficiency can be further improved, and uniform charging can be performed. According to the invention of claim 8, prevention of generation of ozone and NOx,
Longer life and higher charging efficiency can be achieved,
Uniform charging can be performed. According to the ninth aspect of the invention, it is possible to prevent the generation of ozone and NOx, prolong the service life, and prevent the emission of toxic gas components, and perform uniform charging.

According to the tenth aspect, it is possible to prevent the generation of ozone and NOx, extend the life, improve the productivity of the apparatus, and improve the stability of the charging ability, and perform uniform charging. . According to the invention of claim 11, prevention of generation of ozone and NOx, extension of service life, improvement of device productivity,
Cost reduction and stability improvement of charging ability can be achieved, and uniform charging can be performed.

According to the twelfth aspect of the invention, it is possible to prevent the generation of ozone and NOx, prolong the life, improve the productivity of the apparatus, reduce the cost, and improve the stability of the charging ability. It can be carried out. According to the thirteenth aspect, it is possible to prevent the generation of ozone and NOx, extend the life, improve the productivity of the apparatus, reduce the cost and improve the stability of the charging ability, and perform uniform charging. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing the first embodiment.

FIG. 3 is a sectional view showing the electron-emitting device of the first embodiment.

FIG. 4 is a sectional view showing an electron-emitting device according to a second embodiment of the present invention.

FIG. 5 is a diagram showing an energy band of the electron-emitting device according to the second embodiment.

FIG. 6 is a sectional view showing a third embodiment of the present invention.

FIG. 7 is a sectional view showing a fourth embodiment of the present invention.

FIG. 8 is a sectional view showing a fifth embodiment of the present invention.

FIG. 9 is a sectional view showing a sixth embodiment of the present invention.

FIG. 10 is a sectional view showing a seventh embodiment of the present invention.

FIG. 11 is a sectional view showing an eighth embodiment of the present invention.

FIG. 12 is a perspective view showing an oxygen-enriched film of the eighth embodiment.

FIG. 13 is a sectional view showing a ninth embodiment of the present invention.

FIG. 14 is a perspective view showing a hollow fiber membrane of the ninth embodiment.

FIG. 15 is a sectional view showing a tenth embodiment of the present invention.

FIG. 16 is a sectional view showing an electron-emitting device having a MIS structure according to an eleventh embodiment of the present invention.

FIG. 17 is a view for explaining the operation of the electron-emitting device.

FIG. 18 is a sectional view showing an electron emitting device having an MIM structure according to a twelfth embodiment of the present invention.

FIG. 19 is a view for explaining the operation of the electron-emitting device.

FIG. 20 is a sectional view showing a configuration of an electron-emitting device according to a thirteenth embodiment of the present invention.

FIG. 21 is a view showing an energy band of the electron-emitting device.

FIG. 22 is a sectional view showing an electron-emitting device according to a fourteenth embodiment of the present invention.

FIG. 23 is a waveform chart showing a lower electrode drive voltage waveform of the electron-emitting device in the fourteenth embodiment.

FIG. 24 is a waveform chart showing another example of the lower electrode drive voltage waveform of the electron-emitting device in the fourteenth embodiment.

FIG. 25 is a cross-sectional view showing a conventional corona wire charging device.

[Explanation of symbols]

 Reference Signs List 101 electron emitting element 102 holder also serving as electrode 105 introduction path 106 gas feeding means 107 negative ion generation space 108 emission port 109, 120 power supply 116 charged body 130 particle filter 131 positive ion filter electrode 140, 142 electrode 150 heating means 180, 181 Oxygen separation means 182 Pipe 601 Semiconductor substrate 602 Porous semiconductor layer 603 Metal thin film electrode 911 Lower electrode 912-1 Tantalum oxide film 912-2 ZnS film 913 Upper electrode

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tomoaki Sugawara 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Inventor Masaharu Tanaka 1-3-6 Nakamagome, Ota-ku, Tokyo・ F-term in Ricoh Co., Ltd. (reference) 2H003 AA12 AA18 BB11 BB16 CC01 DD01 EE00 EE01 EE03 EE08 EE12

Claims (13)

[Claims] A negative ion generating space formed by an electron emitting surface of an electron emitting element for emitting electrons energized by an electric field inside a device, and a gas for negative ionization in the negative ion generating space. Means for introducing the negative ions and electrons generated in the negative ion generation space together with the gas introduced into the negative ion generation space to charge the member to be charged with the negative ions and electrons. A charging device characterized in that: 2. The charging device according to claim 1, wherein the charging device is provided at a predetermined position in a path of the introduced gas before reaching the negative ion generation space so that particles mixed in the gas do not adhere to the electron emission surface. A charging device comprising a particle filter for removing. 3. The charging device according to claim 1, wherein the charging device is disposed at a predetermined position in a path of the introduced gas before reaching the negative ion generation space, and removes a positive charge from air. A charging device comprising a positive ion filter electrode having a potential. 4. The charging device according to claim 1, further comprising an electrode between the gas discharging portion and the charged member, the electrode having a shape parallel to the surface of the charged member and capable of passing negative ions. A charging device, wherein a voltage is applied between the electrode and the gas releasing portion to extract negative ions toward the member to be charged. 5. The charging device according to claim 1, wherein the charging device is provided between the gas discharge portion and the member to be charged and has a shape parallel to the surface of the member to be charged and capable of passing negative ions. A first electrode and a second electrode which is parallel to the first electrode and has a shape capable of passing negative ions and is divided into a plurality of sections, and each section of the second electrode is independent of each other. A charging device, characterized in that a voltage is applied to control the distribution of negative ions, and a voltage is applied between the first electrode and the gas releasing portion to extract the negative ions toward the member to be charged. 6. The charging device according to claim 1, further comprising means for heating a gas introduced into said negative ion generation space. 7. The charging device according to claim 1, wherein compressed air is supplied by said compressed air supply means as means for introducing gas into said negative ion generation space. Gas separation means for separating compressed air into high oxygen concentration components and low oxygen concentration components and discharging the same, and means for introducing the high oxygen concentration components separated by the gas separation means into the negative ion generation space. A charging device comprising: 8. The charging device according to claim 7, wherein said gas separating means is constituted by a hollow fiber-shaped gas separation membrane. 9. The charging device according to claim 8, wherein the low-concentration oxygen component separated by said gas separating means is placed in the vicinity of a path through which the gas discharged from said charging device passes after being irradiated on a member to be charged. A charging device having a guiding means. 10. The charging device according to claim 1, wherein said electron-emitting device has a MIS structure. 11. The charging device according to claim 1, wherein said electron-emitting device has an MIM structure. 12. The charging device according to claim 10, wherein the electron-emitting device has a porous semiconductor layer and a thin-film electrode capable of passing electrons on a surface side of the porous semiconductor layer. A charging device comprising: an electrode capable of injecting electrons into the porous semiconductor layer on the back side of the layer. 13. The charging device according to claim 1, wherein said electron-emitting device comprises: a lower electrode;
A tantalum oxide film formed on the lower electrode,
A ZnS film formed on the tantalum oxide film,
A charging device characterized by being an electroluminescent element composed of an upper electrode formed on the ZnS film.