JP2007233068A - Charge generating device, charging device, image forming apparatus, charge generating method, charging method, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charge generating device, charging device, image forming apparatus, charge generating method, charging method, and image forming method that can reduce the production of discharge products, such as ozone and NOx. <P>SOLUTION: An electron emission element comprising an electrode (substrate electrode) formed on an insulator, an electron-emitting body layer formed on the substrate electrode, and a thin-film electrode constituted of a conductor, including a portion of a metal thin film exposed to space communicating with the atmosphere and filled with a gaseous body, is used; and since a body to be charged is charged with electrons emitted by the electron-emitting element, hardly any discharge products, such as ozone and NOx due to charging, is produced, and the discharge products, such as ozone and NOx can be reduced, as compared with conventional devices. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a charge generating device for generating charges in a space, a charging device for charging an object to be charged using the charge generating device, and electrophotographic recording such as a copying machine, a printer, a facsimile, and a plotter using the charging device. The present invention relates to an apparatus, an image forming apparatus, a charge generation method, a charging method, and an image forming method. In particular, the present invention relates to a charging device for charging an image carrier (charged body) such as a photoconductor, and more particularly to a charging device for charging an image carrier such as a photoconductor without generating harmful products such as ozone. .

Conventionally, charging devices that are used in electrophotographic image forming apparatuses such as copying machines, printers, facsimiles, plotters, and the like and charge a photosensitive member as a charged object include corona chargers, roller chargers, brush chargers, There are solid state chargers.
(Corona charger)
This is the most commonly used charging method for electronic copying machines, electrostatic recording devices, printers, and the like. However, it has the disadvantage of generating a great deal of ozone. Regarding this drawback, for example, Patent Document 1 discloses a means for reducing the amount of ozone generated. For example, the discharge is reduced to 50% or less by discharging using a very thin wire of 40 to 50 μm.

  Also, in Patent Document 2, a metal casing arranged so as to surround three sides of a wire and a metal mesh electrode are arranged in the vicinity of the release portion to confine ozone generated from the wire and release it by increasing the collision probability of ozone molecules. It is disclosed to reduce the amount of ozone produced.

  However, the inventions described in Patent Documents 1 and 2 can only reduce the amount of ozone by about 50%, and it is necessary to take measures such as using a filter containing an ozone adsorbent to discharge the in-machine gas.

(Roller charger)
In the old days, the charging method is disclosed in Patent Document 3 and has been actively studied in recent years. The invention described in Patent Document 3 is considered promising because the generation of ozone can be greatly reduced.
However, the invention described in Patent Document 3 has problems such as high speed processing cannot be performed because of using a contact roller, and charging tends to be non-uniform. Toner contamination on the roller surface, the influence of vibration due to applied bias alternating current, moire, etc. are likely to occur. Further, the roller is a rotating body, and there is a drawback that the number of members increases because the roller surface needs to be cleaned. In addition, the photosensitive layer of the photoreceptor is subject to dielectric breakdown and pinholes are likely to occur, vibration noise, charging roller marks (plasticizer), permanent deformation of the rollers, and the like.

(Brush charger)
In the old days, it is disclosed in Patent Document 4 and the like. In these conventional techniques, streaky charging unevenness is likely to occur, or white spots due to low-temperature streamer discharge are manifested due to environmental fluctuations.
In addition, there are drawbacks such as photoconductor wear, brush slippage, and melting of the brush, which is considered to be abnormal discharge due to scratches on the photoconductor.

(Ozone adsorbent)
Although there are conventional techniques such as oxidizing the generated ozone by a catalytic function such as activated carbon or adsorbing it on the surface, it has been necessary to frequently replace and maintain the ozone filter due to deterioration over time.

(Solid state charger)
In the old days, it is disclosed in Patent Document 5.
Patent Document 6 discloses an apparatus in which a large number of discharge electrodes are provided on an insulating member via a minute interval.

  Patent Document 7 discloses that the distance between the charger and the non-recording member is set to 500 to 3000 μm, thereby shortening the flight distance of ions to suppress the diffusion of ozone and prevent the adhesion of toner and the like. Has been.

  Patent Document 8 discloses a discharge device including a discharge electrode on a plate-like substrate, a creeping glow discharge means disposed on the outer periphery thereof, and a cover covering the entire charger.

  Patent Document 9 discloses a reduction in NOx by using a material having a specific work function as an electrode material of a planar solid-state discharge device.

  Further, as a method using a novel charging method, Patent Document 10 discloses a charge generator in which an electron-emitting device layer made of a PN junction semiconductor device or an electroluminescent material is provided on the surface of a line electrode, and An electrostatic latent image forming apparatus that forms a latent image on a dielectric by independently driving in units of one pixel is disclosed.

  These solid-state chargers are expected to have little deterioration, breakage, contamination, etc. like corona discharge electrodes, and there are advantages such as downsizing of the device, but the area required for discharge is still large and the generated ozone diffuses. It is easy, and as expected, unpleasant substances such as ozone and NOx have not been reduced.

In addition, with increasing environmental awareness, the release of harmful and unpleasant substances outside the aircraft is being regulated. That is, standards for regulating the amount of ozone generated for electrophotographic image forming apparatuses are set by a plurality of organizations in a plurality of countries and regions such as UL standards, TUV standards, BAM standards, etc. Reducing ozone generation in an apparatus or the like is an important issue. Further, in the image forming apparatus, a substance caused by nitrogen oxide (NOx) generated by discharging of the charging device adheres to the photoreceptor and absorbs moisture, so that a defective image is generated by lowering the photoreceptor surface potential. This is a problem.
JP-A-9-114192 JP-A-6-324556 JP 56-91253 A Japanese Patent Publication No.55-29837 JP 54-53537 A JP-A-5-94077 JP-A-6-75457 Japanese Patent Laid-Open No. 9-244350 JP-A-9-115646 JP-A-8-203418

  By the way, among the conventional charging devices (charging methods) described above, the corona charger generates a great amount of ozone and NOx. For this reason, corona chargers that reduce the amount of ozone as described in Patent Documents 1 and 2 can only reduce the amount of ozone by about 50% at the most, and it is necessary to use an ozone adsorbent in combination. It was. Further, when the ozone adsorbent is used in combination, the amount of ozone can be reduced, but the ozone adsorbent has a problem in that it requires replacement of the ozone filter and maintenance because it deteriorates with time, and costs increase.

In addition, the roller charger can reduce the generation of ozone very much due to the contact charging method, but the charging tends to be non-uniform, and when used in an electrophotographic image forming apparatus, toner contamination on the roller surface, There is a problem that vibration due to bias alternating current applied to the roller, moire of images, and the like are likely to occur.
In addition, the roller charger is a rotating body, and since there is a need for cleaning the roller surface, there are many members and the manufacturing cost is high. In addition, the roller charger is insulated from the photosensitive layer of the photosensitive member. There is a problem that pinholes are easily generated due to destruction, charging noise marks due to vibration noise, plasticizer, etc., permanent deformation of the rollers, and the like.

  The brush charger can generate very little ozone due to the contact charging method, but it tends to generate streaky charge unevenness and uneven charge due to environmental fluctuations. There are disadvantages such as body accumulation, occurrence of brush slippage, and melting of the brush due to abnormal discharge with respect to the photoreceptor damage.

Furthermore, although the solid-state charging device has an advantage that the device can be downsized, the discharge area is wide and unpleasant substances such as ozone and NOx cannot be reduced as expected.
In the above-described charge generator and the electrostatic latent image forming apparatus using the same, since the surface has a complicated hole shape, cleaning is impossible when the toner is contaminated. Further, since the local electric field is likely to be concentrated, there is a disadvantage that the charge generating element is easily damaged due to an unexpected discharge.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and is a charge generating device, a charging device, an image forming device, a charge generating device capable of reducing the generation of discharge products such as ozone and NOx. It is a main object to provide a generation method, a charging method, and an image forming method.

  Furthermore, by forming an electrostatic image with the charge generator or the charging device itself, the amount of ions generated per charge forming the image is reduced, and the generation of discharge products such as ozone and NOx is reduced. It is a secondary object to provide an image forming apparatus satisfying standards such as TUV standard and BAM standard.

  In order to achieve the above object, the invention according to claims 1, 2, 11 and 12 includes a substrate electrode formed on an insulator, an electron emitter layer formed on the substrate electrode, and the electron emitter. An electron-emitting device formed on a layer and formed by a thin-film electrode made of a conductor partly including a metal thin film having a thickness of 1 to 50 nm facing a space filled with a gas connected to the atmosphere And a charge generating device characterized in that an object to be charged is charged with electrons emitted from the electron-emitting device.

In the charge generation device according to any one of claims 1 and 2, and the charge generation method according to claims 11 and 12, an object to be charged is charged using electron emission from the surface of the electron-emitting device. In general, the energy of electrons emitted from semiconductor devices is smaller than that generated by conventional corona discharge, and negative ions such as CO ^3- ions and O ^2- ions are generated with little ionization of gas molecules in the atmosphere. Then, this reaches the object to be charged or electrons directly reach the object to be charged.
Therefore, in the charge generation device according to claims 1 and 2, since charging is performed by utilizing this phenomenon, discharge products such as ozone and NOx due to charging are hardly generated, and ozone and NOx are compared with the conventional device. It is possible to reduce the discharge products such as.

  In the inventions according to claims 3, 4, 14, and 15, the boron nitride material, which has been attracting attention as a heat-resistant and wear-resistant material in the past, has remarkably excellent field electron emission characteristics of a specific shape produced under specific conditions. In particular, the sp3-bonded boron nitride film body is used as the electron emitter, and the electron emission characteristics to the space under atmospheric pressure conditions are stable, durable, and a high electron emission current can be obtained. It becomes possible to solve the problem.

  The invention according to claims 5 and 15 is the charge generation device according to any one of claims 1 to 4 or the charge generation method according to any one of claims 11 to 14, wherein Since a positive voltage is applied to the electrode on the metal thin film side of the electron-emitting device and electrons are extracted, charging efficiency can be improved.

  The invention according to claims 6 and 16 is the charge generation device according to any one of claims 1 to 5 or the charge generation method according to any one of claims 11 to 15, wherein When charging an object to be charged with electrons emitted from an electron-emitting device, oxygen gas molecules exist predominately at atmospheric pressure as molecular species that are easy to attach electrons, thereby facilitating negative ion generation. Efficiency can be improved. For this reason, the problem can be solved by using an oxygen-enriched film in the generally closed space where electrons are emitted.

  The invention according to claims 7 and 17 is the charge generating device according to any one of claims 1 to 6 or the charge generating method according to any one of claims 11 to 16, wherein the electron-emitting device is provided. When one of the two electrodes is a scanning electrode, the other electrode is composed of a plurality of signal electrodes, and the plurality of signal electrodes can have different potentials. It becomes possible to form not only a simple charge but also an electrostatic image on the object to be charged. In addition, discharge products such as ozone and NOx can be further reduced.

  The invention according to claims 8 and 18 is the charge generating device according to any one of claims 1 to 7 or the charge generating method according to any one of claims 11 to 17, wherein the electron-emitting device is provided. When charging an object to be charged with electrons emitted from the electron emission element, the maximum energy of the electrons emitted from the electron-emitting device is 24.3 eV or less. Further reduction of discharge products such as the above becomes possible.

  The invention according to claims 9 and 19 is a charging device or a charging method for charging an object to be charged, comprising the charge generation device according to any one of claims 1 to 7, wherein the electrons of the charge generation device Since the gap between the discharge part and the object to be charged is 50 μm or more apart, the generation of discharge products such as ozone and NOx is reduced, and the occurrence of abnormal discharge is prevented. An apparatus or a charging method can be provided.

  According to the tenth and twentieth aspects of the present invention, an electrostatic image is formed on an image carrier that is an object to be charged, the electrostatic image is developed and visualized, and then the visible image is used as a transfer material. In an image forming apparatus or an image forming method for transferring and forming an image, as means for uniformly charging an image carrier as an object to be charged, or means for forming an electrostatic image on the image carrier Since the charge generator according to any one of 1 to 7 or the charging device according to claims 8 and 9 is provided, discharge products such as ozone and NOx are generated. It is possible to provide a reduced image forming apparatus or image forming method.

  According to the present invention, an electrode (substrate electrode) formed on an insulator, an electron emitter layer formed on the substrate electrode, and a gas formed on the electron emitter layer and connected to the atmosphere are filled. An electron-emitting device formed by a thin-film electrode composed of a conductor whose part is a metal thin film facing a formed space is used to charge an object to be charged with electrons emitted from the electron-emitting device. Therefore, discharge products such as ozone and NOx due to charging are hardly generated, and discharge products such as ozone and NOx can be reduced as compared with the conventional apparatus.

Hereinafter, the configuration, operation, and action of an embodiment according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram of a schematic configuration of a charge generator according to an embodiment of the present invention.
In FIG. 1, the charge generation device includes one electrode (substrate electrode) 3 formed on a substrate (for example, quartz glass substrate) 2 made of an insulator, and an electron emitter layer formed on the substrate electrode 3. 4, an electron emitter layer 5, and a metal thin film having a thickness of 1 to 50 nm facing the space 10 formed on the electron emitter layer 5 and filled with a gas connected to the atmosphere. Using the electron-emitting device 1 formed with the other electrode (thin film electrode layer) 6 composed of a body, the object 7 is charged with electrons emitted from the semiconductor cold electron-emitting device 1.

  More specifically, in the electron-emitting device 1 having the structure shown in FIG. 1, an electron emitter layer 5 having a more polymorphic structure is provided on the electron emission side surface of the film-like electron emitter layer 4. In addition, the tip has a sharp structure excellent in field electron emission characteristics, and becomes a dominant surface.

  A thin film electrode layer 6 is formed on the outermost surface of the electron emission side composed of the electron emitter layer 4 and the electron emitter layer 5. Electrons are injected into the electron emitter layers 4 and 5 by applying a positive (+) voltage to the thin film electrode layer 6 from the power source 8.

The outermost surface of the electron emitter layer 5 is a structure having a sharp tip and distributed at nanometer-sized intervals and density, and has a high resistance. Is accelerated, and the thin film electrode layer 6 is tunneled to emit electrons e ⁻ to the outside of the electron-emitting device 1. Due to the emitted electrons e ⁻ , the atmospheric pressure gas in the space 10 between the charged object 7 is ionized. At this time, since a positive (+) bias voltage is applied to the charged object 7 by the bias power source 9, negative ions of the ionized gas maintain a negative charge while changing their shape, and the charged object 7 is charged. It reaches the charged object 7 side, and the object to be charged 7 is negatively charged (−).

  As described above, in the charge generating device according to the present invention, the cold electron-emitting device 1 charges the object to be charged 7 without using discharge, so that generation of a compound due to discharge is performed like scorotron or roller charging that is usually performed. Very few.

<Method for producing electron emitter sp3-bonded boron nitride film>
Next, an outline of a manufacturing method of the electron emitter layer 4 and the electron emitter layer 5 will be described.
Among boron nitrides manufactured under specific conditions, when they are formed in a film shape, those having a surface shape with excellent field electron emission characteristics are generated and have strong electric field strength.
That is, when boron nitride is deposited on a substrate by a gas phase reaction, boron nitride is formed in a film shape on the substrate by irradiating the vicinity of the substrate with high-energy ultraviolet light, and the tip is formed on the film surface. Point-shaped boron nitride is self-organized and grown in the light direction at appropriate intervals, considering the conventional electron-emitting materials, while maintaining a very high level of current density, material deterioration, damage, and loss It was found that a very stable state and performance can be maintained.

The boron nitride film used in the present invention needs to be irradiated with ultraviolet light in order to form a surface shape excellent in field electron emission characteristics in a self-modeling manner by a gas phase reaction. The reason is not necessarily clear at this stage, but it can be considered as follows.
That is, surface morphogenesis by self-organization is grasped as a “Turing structure” pointed out by Ilya Progogin et al. And appears under certain conditions where the surface diffusion of the precursor material and the surface chemical reaction compete. Here, it is considered that ultraviolet light irradiation is related to the photochemical promotion of both, and affects the regular distribution of initial nuclei.

The conditions and the like for the gas phase reaction used in the present invention to obtain the sp3-bonded boron nitride film having excellent field electron emission characteristics will be described.
The reaction vessel used is a CVD reaction vessel having the structure shown in FIG. That is, in FIG. 8, the reaction vessel 1 includes a gas introduction port 2 for introducing a reaction gas and its dilution gas, and a gas outlet 3 for exhausting the introduced reaction gas and the like out of the vessel, It is connected to a vacuum pump and maintained at a reduced pressure below atmospheric pressure. A boron nitride deposition substrate 4 is set in the gas flow path in the container, and an optical window 5 is attached to a part of the wall of the reaction container facing the substrate, and ultraviolet light is transmitted to the substrate through this window. The excimer ultraviolet laser device 6 is set so as to be irradiated.

  The reaction gas introduced into the reaction vessel is excited by ultraviolet light irradiated on the surface of the substrate, and a nitrogen source and a boron source in the reaction gas undergo a gas phase reaction, and are represented by the general formula; BN on the substrate. Sp3-bonded boron nitride having a 5H-type or 6H-type polymorphic structure is generated, precipitated, and grown into a film. In that case, the pressure in the reaction vessel can be implemented in a wide range of 0.001 to 760 Torr, and the temperature of the substrate installed in the reaction space can be implemented in a wide range of room temperature to 1300 ° C. As a result of experiments, the pressure is low, and it is preferable to carry out at a high temperature. In addition, when irradiating the substrate surface or a space region in the vicinity thereof with ultraviolet light and exciting it, an embodiment in which plasma is also irradiated is an embodiment.

FIG. 9 is an explanatory diagram of a method for producing an sp3-bonded boron nitride film body.
In FIG. 9, the plasma torch 91 shows this aspect, and the reaction gas inlet 95 and the plasma torch 91 are directed toward the substrate 94 so that the reaction gas 92 and the plasma 93 are irradiated onto the substrate 94. The reaction vessel 96 is integrally set. Reference numeral 97 denotes an excimer ultraviolet laser, 98 denotes an optical system for irradiating the excimer ultraviolet laser 97 into the reaction vessel 96, and 99 denotes a gas outlet for discharging excess gas 100.

  The boron nitride film body is produced using the reaction vessel 96 described above, and will be described below based on specific examples. However, the following examples are disclosed as an aid for easily understanding the present invention, and the present invention is not limited thereby.

A diborane flow rate of 1.25 × 10 ^{−1 in} a mixed dilution gas flow with an argon flow rate of 2.54 × 10 Torr / s (2 SLM “standard litter par minutes”) and a hydrogen flow rate of 6.35 × 10 ⁻¹ Torrl / s (50 sccm). Torrl / s (10 sccm) and ammonia flow rate 2.54 × 10 ⁻¹ Torr / s (20 sccm) were introduced, and at the same time, the temperature was maintained at 800 ° C. by heating in an atmosphere maintained at a pressure of 30 Torr by exhausting with a pump. Excimer laser ultraviolet light was irradiated on the silicon substrate thus formed (see FIG. 9).

  The target thin film was obtained after a synthesis time of 60 minutes. As a result of identifying the thin film product by the X-ray diffraction method, the crystal system of this sample is a hexagonal system, and it is a 5H type polymorphic structure by sp3 bond, and the lattice constants are a = 2.52Å and c = 10.5Å. Met.

As a result of observation with a scanning electron microscope image, as shown in FIG. 10, this thin film was covered with a conical protrusion structure (having a length of several μm to several tens of μm) with a sharp tip that tends to cause electric field concentration. It was observed that a simple surface shape was formed in a self-modeling manner.
FIG. 10 is an example of an electron micrograph of the surface of the sp3-bonded boron nitride film body.

FIG. 1 is a conceptual diagram showing an embodiment of a charge generating device according to the present invention.
In the charge generating device according to the present invention, as shown in FIG. 1, a positive (+) voltage is applied to a thin film electrode 6 made of a metal thin film of the electron-emitting device 1 by a power source 8 to draw out electrons. When the thin-film electrode 6 on the surface side of the electron-emitting device 1 is set to a positive (+) potential with respect to the potential of the substrate electrode 3 formed on the substrate 2 made of an insulator as described above, a tunnel effect is generated from the inside of the device. Electrons e ⁻ are emitted to the outside and react with gas molecules to form negative ions, so that the charging efficiency of the charged object 7 biased by the power source 9 can be improved.

  However, even if the structure of the charge generation device is the same, if a negative (−) voltage is applied to the thin film electrode 6 contrary to the above structure, electrons are not emitted from the electron-emitting device 1, so that the gas is ionized. The charged object 7 cannot be charged. For this reason, it is necessary to set the thin-film electrode 6 on the surface side of the electron-emitting device 1 to a positive (+) potential.

In the charge generation device of the present invention, when the object 7 is charged with the electrons e ⁻ emitted from the electron-emitting device 1, the maximum energy of the electrons emitted from the electron-emitting device 1 is 24.3 eV or less. ing. The background is as follows.

The generation of NOx starts mainly by the dissociation of nitrogen molecules. That is, a reaction of e ⁻ + N ₂ → e ⁻ + 2N occurs, N + O ₂ → NO + O, and NO + O + M → NO ₂ + M, and nitrogen oxides are created. M is an arbitrary gas molecule.
The dissociation energy of this first ground state nitrogen molecule is 24.3 eV.

  In the present invention, since negative ions are generated mainly using only electron attachment by electrons emitted by energy lower than this, generation of discharge products from the charge generation device can be reduced. Further, the dissociation energy of the oxygen molecule in the ground state is 5.1 eV, and the oxygen molecule is dissociated into oxygen atoms with energy higher than this. Since the oxygen atoms generated here can be combined with oxygen molecules and nitrogen molecules to generate various discharge products such as ozone, the electron energy of the present invention is desirably less than 5.1 eV.

The result of measuring the energy distribution using the retarding electrode for the energy distribution of the electron energy E emitted from the electron-emitting device 1 of the charge generating device of the present invention has a profile as shown in FIG. 5, for example.
FIG. 5 is a diagram illustrating a measurement example of the energy distribution of electrons emitted from the electron-emitting device. In the figure, the vertical axis E indicates the electron energy distribution density N (E) and is compared on an arbitrary scale.
In the figure, the characteristic curve L1 shows the case where the DC voltage VD applied by the power supply 8 is 12V, the characteristic curve L2 shows the case where the DC voltage VD is 15V, and the characteristic curve L3 sets the DC voltage VD to 18V. As shown in this figure, the electron energy can be controlled by the applied DC voltage.

The surface of the metal thin film electrode 6 in the electron emission portion of the electron emission element 1 has a flat shape. In the solid state of the electron-emitting device 1, a voltage of about 100 V at most may be used. However, when the object 7 to be charged is an image carrier such as a photoconductor, an electrostatic image is formed on the image carrier and the toner is attached. For this purpose, a voltage of several hundred volts may be required.
In this case, according to Paschen's law, in the case of a parallel plate, corona discharge or the like does not occur at 330 V or less in the air, but if the surface does not come out flat, an electric field higher than this will cause the metal thin film electrode 6 and charged object 7 on the element surface. There is a possibility that it will take.
That is, when there is a projection on the surface of the metal thin film electrode 6, electric field concentration acts on the projection and the apparent discharge start voltage decreases, and corona discharge or the like may occur. Therefore, the surface portion of the metal thin film electrode 6 in the electron emission portion of the semiconductor cold electron emission device 1 is flat.

  Next, FIG. 2 is a conceptual diagram showing another embodiment of the charge generating device according to the present invention, which uses an electron emission material similar to the material shown in FIG. FIG. 3 is an enlarged plan view showing a part of the surface side of the electron-emitting device 11 of the charge generating device shown in FIG.

  2 and 3, the charge generation device includes a substrate electrode 13 as one electrode formed on a substrate (for example, a quartz glass substrate) 12 made of an insulator, and electrons formed on the substrate electrode 13. The emitter layer 14, the electron emitter layer 15 formed thereon, and a thickness of 1 to 50 nm facing the space 10 formed on the electron emitter layer 15 and filled with a gas connected to the atmospheric pressure. The electron-emitting device 11 formed with the other electrode (thin-film electrode) 16 composed of a conductor having a metal thin film having a part as a material to be charged by electrons emitted from the semiconductor cold electron-emitting device 11 7 is charged.

  However, in this charge generating device, as shown in FIGS. 2 and 3, one of the two electrodes 13 and 16 of the electron-emitting device 11 is used as a scanning electrode, and the other electrode (thin film electrode) 16 is used. Are configured as a plurality of signal electrodes, and the voltages applied to the plurality of signal electrodes 16 via the signal electrode terminals 17 by the power sources 18 and 19 are controlled to make the plurality of signal electrodes 16 have different potentials. .

That is, in the configuration shown in FIGS. 2 and 3, an electrostatic image having gradation can be formed on the object 7 by changing the potential of the signal electrode 16. FIG. 4 shows an example in which the elements shown in FIG. 3 are arranged in an array to form a charge generator, and a charging device is configured using the charge generator.
In FIG. 4, 41 is a photosensitive drum, 42 is an element array, 43 is an element application (drive) power supply, 44 is a common electrode, and 45 is a bias power supply.

  In the case where a charging device included in an image forming apparatus or the like is configured using a charge generation device, the present invention has a configuration in which an interval between an electron emission portion of the charge generation device and an object to be charged is 50 μm or more apart. Yes.

FIG. 6 is a conceptual diagram showing another embodiment of the charge generating device according to the present invention.
As shown in FIG. 6, the object to be charged 7 has a drum-like structure in which a photosensitive layer, a dielectric layer, etc. are laminated on a cylindrical cored bar (electrode) 7a, and the charge generation device is the same as in FIG. In the configuration using the electron-emitting device 1, the lowest voltage point at which discharge of air under atmospheric pressure starts is the distance between the electron-emitting portion (the surface of the metal thin-film electrode 6) of the electron-emitting device 1 and the object 7 to be charged. Is about 400 μm at about 10 μm.

Further, the surface runout due to the rotation of the drum of the object to be charged 7 is about 10 μm at the minimum. Therefore, by providing a space of 50 μm or more between the electron emitting portion (surface of the metal thin film electrode 6) of the semiconductor cold electron emitting device 1 and the object 7 to be charged, a voltage of 400 V is applied to the electrode 6 of the electron emitting device 1. When applied between the electrode 7a of the object 7 to be charged, the object 7 can be charged without causing a discharge phenomenon such as corona discharge even if the charging potential is increased.
As a result, it is possible to realize a charging device in which the generation of discharge products such as ozone and NOx is reduced and the occurrence of abnormal discharge is prevented.

  The charge generation device of the present invention and the charging device using the charge generation device form an electrostatic image on an image carrier that is an object to be charged, and develop the electrostatic image to visualize it. In the image forming apparatus for transferring the visible image to a transfer material and forming an image, a means for uniformly charging the image carrier, which is an object to be charged, or forming an electrostatic image on the image carrier It is possible to provide an image forming apparatus that is optimal for use as a means and has reduced generation of discharge products such as ozone and NOx.

FIG. 7 is a conceptual diagram showing an embodiment of the image forming apparatus according to the present invention. For example, the charge generating device having the configuration shown in FIGS. 1 and 6 is charged uniformly with the image carrier 21 as the object to be charged. In this example, the charging device 22 is used.
In FIG. 7, reference numeral 21 denotes a drum-shaped photoconductive photoconductor as an image carrier. Around the photoconductor 21 is a charging device 22 for uniformly charging the surface of the photoconductor 21 and a charged photoconductor. An optical writing device 23 that forms an electrostatic image by irradiating the body 21 with writing light LB such as a laser beam, a developing device 24 that develops the electrostatic image on the photosensitive member 21 with toner, and visualizes it, and the photosensitive member 21. A transfer device 25 that transfers the toner image on the transfer material such as transfer paper, a cleaning device 26 that removes residual toner and paper dust on the photoconductor 21 after transfer, and a static eliminator that eliminates residual charges on the photoconductor 21 A device 27 and the like are provided.

  The image forming apparatus also includes a paper feeding unit 28 that feeds the transfer material P to a transfer unit between the photoconductor 21 and the transfer device 25, and a fixing device that fixes the toner image transferred to the transfer material P. 29. In the image forming apparatus having the configuration shown in FIG. 7, since the charge generating device having the configuration shown in FIGS. 1 and 6 is used as the charging device 22, the discharge phenomenon such as corona discharge is not involved. The photoreceptor 21 can be uniformly charged, and the generation of discharge products such as ozone and NOx can be reduced.

Next, FIG. 8 is a conceptual diagram showing another embodiment of the image forming apparatus according to the present invention. For example, the charge generating device having the configuration shown in FIGS. This is an example used as means 32 for directly forming an electrostatic image on the top.
In FIG. 8, reference numeral 31 denotes a drum-shaped image carrier. Around the image carrier 31, the surface of the image carrier 31 is selectively charged using a charge generator and an electrostatic image is obtained. The electrostatic image forming means 32 for forming the image, the developing device 33 for developing the electrostatic image on the image carrier 31 with toner, and developing the image, and transferring the toner image on the image carrier 31 to a transfer material such as transfer paper A transfer device 34 that removes residual toner and paper dust on the image carrier 31 after transfer, a static elimination device 36 that eliminates residual charges on the image carrier 31, and the like. The image forming apparatus also includes a paper feeding unit 37 that feeds the transfer material P to a transfer unit between the image carrier 31 and the transfer device 34, and a fixing device that fixes the toner image transferred to the transfer material P. 38.

  In the image forming apparatus having the configuration shown in FIG. 8, the electrostatic image forming means 32 uses a charge generating device having a signal electrode and a scanning electrode as shown in FIGS. Since an electrostatic image can be formed on the image carrier 31 without such a discharge phenomenon, generation of discharge products such as ozone and NOx can be reduced.

  In addition, since the charge carrying device is used to charge the image carrier 31 and form an image at the same time, an image forming apparatus having a simpler configuration than that shown in FIG. 7 can be provided. In the case of the configuration shown in FIG. 8, since an electrostatic image is formed using a charge generating device, the image carrier 31 may be anything that can hold an electrostatic image. For example, a cylindrical cored bar (electrode) ) On which an insulator layer or a dielectric layer is laminated can be used.

Next, the working effects of the present invention will be described in detail by way of examples. However, each example is for explaining the present invention in detail, and it is refused that the present invention is not limited by these examples. Not too long.
In the configuration of the charge generation device (charging device) using the electron-emitting device 1 shown in FIG. 1, the charged object 7 was charged under the following conditions. When the ozone concentration and NOx concentration in the vicinity of the charge generating device at this time were measured, neither ozone nor NOx was detected as a value higher than the background level.

-Substrate (insulator) 2: a quartz glass substrate.
-Substrate electrode 3: Tungsten (W) (formed on a quartz glass substrate).
Electron emitter layers 4 and 5: sp3-bonded boron nitride film bodies. The electron emitter layer 5 mainly contains polymorphic boron nitride such as 5H type or 6H type.
Thin film electrode layer 6: gold (Au) (thickness of about 20 nm).
-Charged object 7: Anodized aluminum alumite coated with insulating hard alumite.
-Power supply 8, 9: DC power supply.
-Distance between thin film electrode and charged object: 1 mm.

  In the configuration of the charge generation device (charging device) using the electron-emitting device 1 shown in FIG. 1, the charged object 7 was charged under the following conditions. When the ozone concentration and NOx concentration around the charging device at this time were measured, neither ozone nor NOx was detected to be a value above the background level.

-Substrate (insulator) 2: a quartz glass substrate.
-Substrate electrode 3: W (sputter deposition on a quartz glass substrate).
Electron emitter layers 4 and 5: sp3-bonded boron nitride film bodies. The electron emitter layer 5 mainly contains polymorphic boron nitride such as 5H type or 6H type.
Thin film electrode layer 6: Au (thickness about 15 nm).
-Charged object 7: Photoconductor (OPC) for a Ricoh printer.
-Power supply 8, 9: DC power supply.
-Distance between thin film electrode and charged object: 0.5 mm.

The object 7 to be charged was charged with the charge generating device having the configuration shown in FIGS. 2 shows an element structure and an example of electrical connection in the case of using scan electrodes and signal electrodes, and FIG. 3 shows an example of an actual electrode layout.
A DC power supply 18 applies a voltage of 20 V between the scanning electrode 13 and the signal electrode terminal 17, and a bias power supply 19 applies a voltage of 400 V between the element 11 and the object 7 to be charged. When a distance of 100 μm was provided between the electrode 16 and the member 7 to be charged, a charging voltage of 300 V could be obtained.

  In addition, an electrostatic image pattern can be obtained by turning on and off the voltage between the signal electrode 16 and the scanning electrode 13, and further, the distribution of the charged potential can be created by controlling the voltage between the electrodes. . In this case, the charged object 7 could be charged when the signal electrode 16 became positive (+). The material conditions of the element configuration are the same as those in Example 2. However, the to-be-charged object 7 is a polymer substrate whose back surface is aluminum coated. When the ozone concentration and NOx concentration around the charging device at this time were measured, neither ozone nor NOx was detected to be a value above the background level.

The object 7 to be charged was charged with the charge generating device having the configuration shown in FIGS.
FIG. 2 shows an example of electrical connection in the case of using an element structure and scan electrodes and signal electrodes, and FIG. 3 shows an example of an actual electrode layout. A space formed on the electron emitter layer shown in FIG. 2 and filled with a gas connected to the atmosphere constitutes a substantially closed space and contains a large amount of oxygen at atmospheric pressure.

In FIG. 2, the configuration in the drawing is omitted, but air is forcibly sent to the above substantially closed space through an oxygen-enriched film using a small diaphragm pump, and an environment in which oxygen components are enriched. It has become.
A DC power supply 18 applies a voltage of 20 V between the scanning electrode 13 and the signal electrode terminal 17, and a bias power supply 19 applies a voltage of 400 V between the element 11 and the object 7 to be charged. Electrode) 16 and the object to be charged 7 are arranged at an interval of 100 μm. Electrons are emitted into the atmosphere by field electron emission from the electron emitter, and attached to oxygen molecules to generate negative ions and radiate into space. Thus, a charging voltage of 370 V could be obtained.

  In addition, an electrostatic image pattern can be obtained by turning on and off the voltage between the signal electrode 16 and the scanning electrode 13, and further, the distribution of the charged potential can be created by controlling the voltage between the electrodes. . In this case, the charged object 7 could be charged when the signal electrode 16 became positive (+). The material conditions of the element configuration are the same as those in the second embodiment. However, the to-be-charged object 7 is a polymer substrate whose back surface is aluminum coated. When the ozone concentration and the NOx concentration around the charging device at this time were measured, neither ozone nor NOx was detected to be higher than the background level.

  In the configuration of the charge generation device using the electron-emitting device 1 shown in FIG. 6, a charge test of the object to be charged 7 was performed under the following conditions. A voltage of 400 V is applied between the element 1 and the object 7 to be charged by the bias power source 9, and the distance between the metal thin film electrode 6 and the object 7 to be charged is 10, 20, 30, 40, 50, 60, 70, 80. , 90 and 100 μm were measured for the occurrence of discharge. The configuration of each part is as follows.

-Substrate (insulator) 2: a quartz glass substrate.
-Substrate electrode 3: Cr (sputter deposition on a quartz glass substrate).
Electron emitter layers 4 and 5: sp3-bonded boron nitride film bodies. The electron emitter layer 5 mainly contains polymorphic boron nitride such as 5H type or 6H type.
Thin film electrode layer 6: Au (thickness about 20 nm).
-Charged object 7: Insulating hard anodized, film thickness 10 μm (inner electrode: aluminum).
-Power supply 8, 9: DC power supply.
As a result of the above charging test, the discharge occurrence frequency (10 minutes) with respect to the interval between the metal thin film electrode 6 and the object 7 to be charged is as follows.
Interval;
10 μm: Discharge occurs immediately and cannot be charged 20 μm: Discharge occurs immediately and cannot be charged 30 μm: Discharge occurs relatively quickly and cannot be charged 40 μm: Discharge occurs twice 50 μm: 0 times 60 μm: 0 times 70 μm: 0 times 80 μm: 0 times 90 μm: 0 times 100 μm: 0 times Measurements at intervals of 50 μm were continued for 50 minutes, but no discharge was observed. The same applies to the cases of 60 μm, 70 μm, 80 μm, 90 μm, and 100 μm.

[Comparative Example 1]
A charged object 1102 was charged by applying a voltage from a power source 1101 under the same conditions as in Example 2 using a conventional corona wire type charge generator (charging device) 1100 shown in FIG. When the ozone concentration and NOx concentration around the charging device at this time were measured, ozone: 4 ppm and NOx: 0.6 ppm were detected.

[Function and effect]
13. The charge generating device according to claim 1, wherein an electrode (substrate electrode) formed on an insulator, an electron emitter layer formed on the substrate electrode, and an electron emitter layer An electron-emitting device formed by a thin-film electrode formed of a conductor partly including a metal thin film having a thickness of 1 to 50 nm and facing a space filled with a gas connected to atmospheric pressure. Since the object to be charged is charged with electrons emitted from the electron-emitting device, discharge products such as ozone and NOx are hardly generated due to charging, and ozone and NOx are not generated as compared with the conventional apparatus. Reduction of discharge products can be achieved.

  The invention according to claims 3, 4, 13, and 14 uses the sp3-bonded boron nitride film body as an electron emitter, and the electron emission characteristics to a space under atmospheric pressure are stable, persistent, and high in electron emission. Since electric current can be obtained, discharge electrons such as ozone and NOx due to charging are not generated by using these emitted electrons for charge generation for charging, and discharge products such as ozone and NOx are generated compared to conventional devices. Can be reduced.

  In the charge generation device according to claim 5 or 15, since a positive voltage is applied to the electrode on the metal thin film side of the electron-emitting device to extract electrons, discharge products such as ozone and NOx Can be reduced, and charging efficiency can be improved.

  In the inventions according to claims 6 and 16, when the charged object is charged by the electrons emitted from the electron-emitting device, oxygen gas molecules are dominantly present at atmospheric pressure as molecular species that are easy to attach electrons, and are negative. Ion generation efficiency can be improved by facilitating ion generation. Since oxygen molecules are dominant over nitrogen in the atmospheric pressure, charge generation is mainly negative ions due to electron attachment, and generation of ozone as an active species and NOx as a nitrogen oxide can be prevented.

  In the charge generation device according to claim 7 or 17, when one of the two electrodes of the electron-emitting device is a scanning electrode, the other electrode is constituted by a plurality of signal electrodes, Since the signal electrodes can be set to different potentials, for example, an electrostatic image composed of fine pixels as well as simple charges can be formed on an object to be charged, and ozone, NOx, and the like can be formed. It is possible to reduce discharge products.

  In the charge generation device according to claim 8 or 18, when charging an object to be charged with electrons emitted from the electron-emitting device, the maximum energy of electrons emitted from the electron-emitting device is 24.3 eV or less. Therefore, discharge products such as ozone and NOx generated from the charge generation device can be reduced to the utmost limit.

   A charging device according to claims 9 and 19 includes the charge generation device according to any one of claims 1 to 7, wherein the charge generation device is provided between an electron emission portion of the charge generation device and an object to be charged. Since it is characterized by having an interval of 50 μm or more, generation of discharge products such as ozone and NOx is reduced, and abnormal discharge is not caused, and gas ionization in the atmospheric environment is generated. Therefore, it is possible to realize a charging device that generates a charge necessary for charging and uses it for charging.

  In the image forming apparatus according to any one of claims 10 and 20, as means for uniformly charging an image carrier that is an object to be charged or means for forming an electrostatic image on the image carrier. Since the charge generating device according to any one of claims 7 or the charging device according to claim 8 or 9 is provided, discharge products such as ozone and NOx are generated. It is possible to meet standards such as UL standard, TUV standard, and BAM standard. Further, when the charge generation device is used as the electrostatic image forming means, the device configuration can be simplified and the cost can be reduced.

  The present invention can be used in an image forming apparatus such as a charge generating device, a charging device, a facsimile machine, a copying machine, a charge generating method, a charging method, and an image forming method.

1 is a schematic configuration explanatory diagram of a charge generation device showing an embodiment of the present invention. It is a conceptual diagram which shows other embodiment of the electric charge generator based on this invention. FIG. 3 is an enlarged plan view showing a part of the surface side of an electron-emitting device 11 of the charge generation device shown in FIG. 2. FIG. 4 shows an example in which the elements shown in FIG. 3 are arranged in an array to form a charge generation device, and a charging device is configured using the charge generation device. It is a figure which shows the example of a measurement of the energy distribution of the electron discharge | released from an electron emission element. It is a conceptual diagram which shows other embodiment of the electric charge generator based on this invention. 1 is a conceptual diagram illustrating an embodiment of an image forming apparatus according to the present invention. It is a conceptual diagram which shows other embodiment of the image forming apparatus which concerns on this invention. It is explanatory drawing of the preparation methods of a sp3-bonding boron nitride film body. It is an example of the electron micrograph of the sp3-bonding boron nitride film body surface. It is a conceptual diagram of a conventional corona wire type charge generator (charging device).

Explanation of symbols

1 Electron-emitting device 2 Substrate 3 Electrode (Substrate electrode)
4 Electron emitter layer composed of sp3-bonded boron nitride film body 5 Electron emitter layer mainly containing 5H-type or 6H-type polymorphic boron nitride among sp3-bonded boron nitride film bodies 6 Thin film electrode layer 7 Charged object DESCRIPTION OF SYMBOLS 8 Power supply 9 Bias power supply 11 Electron emitter 12 Substrate made of insulator 13 Scan electrode terminal 14 Electron emitter layer made of sp3-bonded boron nitride film body 15 5H type or 6H type of sp3-bonded boron nitride film body Electron emitter layer mainly containing polymorphic boron nitride 16 Signal electrode (thin film electrode layer)
17 Signal electrode terminal 18 Power supply 19 Bias power supply 21, 31 Image carrier (charged object)
22 Charging device (charge generator)
23 Optical writing device 24, 33 Developing device 25, 34 Transfer device 26, 35 Cleaning device 27, 36 Static eliminating device 28, 37 Paper feeding unit 29, 38 Fixing device 32 Electrostatic image forming means (charge generating device)

Claims (20)

  A substrate electrode formed on an insulating substrate; an electron emitter layer formed on the substrate electrode; a thin film electrode facing the space formed on the electron emitter layer and filled with a gas connected to the atmosphere; A charge generating device comprising: an electron-emitting device formed by the method described above, wherein electrons are emitted from the electron-emitting device to the space.   1 to 50 nm facing a space filled with a substrate electrode formed on an insulating substrate, an electron emitter layer formed on the substrate electrode, and a gas formed on the electron emitter layer and connected to the atmosphere. And an electron-emitting device formed of a thin-film electrode composed of a conductor that includes a metal thin film having a thickness of 5 mm, and electrons are emitted from the electron-emitting device to the space. Charge generator.   3. The charge generator according to claim 1, wherein an sp3-bonded boron nitride film is used as the electron emitter layer.   4. The charge generating device according to claim 3, wherein the sp3-bonded boron nitride film used as the electron emitter layer includes polymorphic boron nitride such as 5H type or 6H type.   5. The charge generation device according to claim 1, wherein a positive voltage is applied to an electrode on the metal thin film side of the electron-emitting device, and electrons are drawn out to the space. A charge generator.   6. The charge generation device according to claim 1, wherein a positive voltage is applied to an electrode on the metal thin film side of the electron-emitting device, and oxygen is supplied to the space through an oxygen-enriched film. A charge generating device characterized in that it is predominantly included.   7. The charge generation device according to claim 1, wherein one of the two electrodes, the substrate electrode and the thin film electrode, of the electron-emitting device is used as a scanning electrode, and the other electrode is used as the other electrode. A charge generating device, wherein the electrode is a plurality of signal electrodes having different potentials.   8. A charging device for charging an object to be charged with electrons emitted from the electron-emitting device to the space, wherein the electrons emitted from the electron-emitting device according to claim 1. A charging device having a maximum energy of 24.3 eV or less.   A charging device that charges an object to be charged with electrons emitted from the electron-emitting device to the space, comprising the charge generation device according to claim 1, and the charge generation device. A charging device, wherein an interval between the electron emission portion and the object to be charged is 50 μm or more. An image forming apparatus that forms an electrostatic image on an image carrier that is an object to be charged, develops the electrostatic image into a visible image, transfers the visible image to a transfer material, and forms the image In
The charge generation device according to any one of claims 1 to 7, or means for charging the image carrier uniformly or means for forming an electrostatic image on the image carrier. An image forming apparatus comprising the charging device according to claim 9.   An electron-emitting device formed by a substrate electrode, an electron emitter layer formed on the substrate electrode, and a thin-film electrode formed on the electron emitter layer and facing a space filled with a gas connected to the atmosphere A charge generation method characterized in that electrons are discharged from the space into the space.   A metal thin film having a thickness of 1 to 50 nm facing a space filled with a substrate electrode, an electron emitter layer formed on the substrate electrode, and a gas formed on the electron emitter layer and connected to the atmosphere A method for generating charges, comprising: emitting electrons to the space from an electron-emitting device formed of a thin-film electrode formed of a conductor having a portion of   13. The charge generation method according to claim 11 or 12, wherein an sp3-bonded boron nitride film is used as the electron emitter layer.   14. The charge generation method according to claim 13, wherein the sp3-bonded boron nitride film used as the electron emitter layer contains polymorphic boron nitride such as 5H type or 6H type.   The charge generation method according to any one of claims 11 to 14, wherein a positive voltage is applied to the electrode on the metal thin film side of the electron-emitting device to draw electrons into the space. How it occurs.   16. The charge generation method according to claim 11, wherein a positive voltage is applied to the electrode on the metal thin film side of the electron-emitting device, and oxygen is supplied to the space through the oxygen-enriched film. A charge generation method characterized by comprising predominantly.   17. The charge generation method according to claim 11, wherein one of the two electrodes, ie, the substrate electrode and the thin film electrode, of the electron-emitting device is used as a scanning electrode, and the other electrode is used as the other electrode. A charge generation method, wherein the electrode is a plurality of signal electrodes having different potentials.   8. A charging method for charging an object to be charged with electrons emitted from a space filled with a gas connected to the atmosphere from the electron-emitting device, wherein the electrons according to claim 1. A charging method, wherein the maximum energy of electrons emitted from the emitting element is 24.3 eV or less.   A charge method for charging an object to be charged with electrons emitted from the electron-emitting device to the space, comprising the charge generation device according to claim 1, and the charge generation device. A charging method, wherein an interval between the electron emitting portion and the object to be charged is 50 μm or more. An image forming method for forming an electrostatic image on an image carrier that is an object to be charged, developing the electrostatic image to make a visible image, and then transferring the visible image to a transfer material to form an image In
The charge generation device according to any one of claims 1 to 7, or means for charging the image carrier uniformly or means for forming an electrostatic image on the image carrier. An image forming method comprising the charging device according to claim 9.

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