WO2004063818A1 - クリーニング機能を有する電子放出装置 - Google Patents
クリーニング機能を有する電子放出装置 Download PDFInfo
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- WO2004063818A1 WO2004063818A1 PCT/JP2004/000182 JP2004000182W WO2004063818A1 WO 2004063818 A1 WO2004063818 A1 WO 2004063818A1 JP 2004000182 W JP2004000182 W JP 2004000182W WO 2004063818 A1 WO2004063818 A1 WO 2004063818A1
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- electrode
- upper electrode
- electron
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- fine particles
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/02—Apparatus for electrographic processes using a charge pattern for laying down a uniform charge, e.g. for sensitising; Corona discharge devices
Definitions
- the present invention relates to an electron-emitting device for emitting electrons using an electron-emitting device having a semiconductor layer. More specifically, the present invention relates to an electron-emitting device that operates at atmospheric pressure to charge an object to be charged. The present invention relates to an electron-emitting device capable of cleaning attached fine particles.
- the electron emission device can be applied to, for example, an electron emission device used for charging a photosensitive member of a device to which electrophotographic technology is applied, such as a laser printer digital copier.
- Known cold-cathode type electron-emitting devices include a Spindt-type electrode and a carbon nanotube (CNT) -type electrode. Applications to the field of FED (Field Emission Display) are being studied. ing. These devices form a strong electric field of about 1 GV / m by applying a voltage to the sharp part, and emit electrons by tunnel current.
- FED Field Emission Display
- Japanese Patent Application Laid-Open No. Hei 6-255,168 A method is disclosed in which a cold cathode is operated in the atmosphere to emit electrons into the atmosphere, ionize gas molecules to generate ions as charged particles, and form an electrostatic latent image.
- the electrophotographic process after uniformly charging the surface of the photoreceptor, selectively exposing the photoreceptor corresponding to an image to be formed on the surface of the photoreceptor and making the exposed portion of the photoreceptor conductive, the charged charge.
- a charged charge, corresponding to an image, on the surface of the photoreceptor that is, a so-called electrostatic latent image.
- a rotating developing sleeve carrying the charged toner on its surface is passed through a developing section arranged opposite to the surface of the photoreceptor to selectively adhere the toner to the surface of the photoreceptor. Then, the toner adhered in the transfer section is transferred to paper.
- the photoreceptor passes through a static elimination section that removes the charge of the photoreceptor by light irradiation, and further passes through a cleaning section that mechanically removes residual toner and paper dust on the surface of the photoreceptor. Charged again for the image. Therefore, a charger that uniformly charges the photoreceptor is an indispensable device for the electrophotographic process.
- the positive ions generated by the ionization of the gas molecules are accelerated toward the element surface by a strong electric field and collide, and the element is destroyed by sputtering.
- a MIM (Metal Insulator Metal;) type and a MIS (Metal Insulator Semiconductor) type are known.
- Japanese Patent Application Laid-Open No. 8-250706 and Materials Research Society Symposium Proceeding Vol. 638 disclose an electron emission device belonging to the MIS type, which is a porous material formed by anodizing a semiconductor.
- a device that uses the quantum size effect of a porous semiconductor (for example, porous silicon) to accelerate the electrons injected into the porous silicon semiconductor by an electric field, and allows the surface metal thin film to pass through the tunnel effect and be released into vacuum. .
- a porous semiconductor for example, porous silicon
- the cold cathode made of the porous silicon semiconductor has a great advantage that an element can be manufactured by an extremely simple and inexpensive manufacturing method called anodic oxidation.
- the surface of a MIM or MIS type cold cathode that accelerates electrons with the internal electric field of the device also functions as an upper electrode that generates an electric field inside the device.
- the accelerated electrons tunnel through this thin metal film and are emitted to the outer space.
- the thickness of a metal thin film that functions as an upper electrode for generating an internal electric field and at the same time functions as a thin film electrode that emits accelerated electrons is appropriately from several nm to several tens of nm. 8-250766-6 discloses that the thickness of a thin gold film is 15 nm.
- Japanese Unexamined Patent Application Publication No. 2001-313151 describes another measure against dust adhesion when operating MIM-type and MIS-type electron-emitting devices in the air. It is disclosed that a gas introduction means and a 20-particle filter are provided to avoid the adhesion of the particles.
- an object of the present invention is to solve the problem of dust adhesion when operating an electron-emitting device at atmospheric pressure, and furthermore, an electron capable of stably performing charging and forming an electrostatic latent image.
- An object of the present invention is to provide an emission device, an electron emission device cleaning device, or an electron emission device cleaning method. Disclosure of the invention
- An electron emission device made to solve the above-mentioned problem has a lower electrode, an upper electrode made of a thin film, a semiconductor layer formed between the lower electrode and the upper electrode, and a surface of the upper electrode. Is exposed to the external space, an opposing electrode is provided to oppose the upper electrode with an external space therebetween, and a tip in the semiconductor layer is accelerated to pass through the upper electrode.
- a fine particle charging voltage control unit that applies an electron emission voltage for emitting electrons to the external space or a voltage for charging fine particles attached to the surface of the upper electrode between the upper electrode and the lower electrode;
- a flying voltage control unit is provided for applying a voltage for flying from the surface to the counter electrode between the upper electrode and the counter electrode.
- the fine particle charging voltage controller controls the connection between the upper electrode and the lower electrode. By applying a voltage between them, an internal electric field is generated in the semiconductor layer, which accelerates electrons, and the accelerated electrons pass through the upper electrode made of a metal thin film by a tunnel effect and jump out into space ⁇ ). . Thus, a normal function as an electron emitting element is exhibited.
- the flying voltage control unit applies a voltage between the upper electrode and the counter electrode for causing the charged fine particles to fly from the surface of the upper electrode toward the counter electrode. As a result, the charged fine particles are electrostatically attracted to the counter electrode.
- the fine particles are charged and removed from the electrode surface by the fine particle charging voltage control unit and the flying voltage control unit when necessary, so that the metal on the surface of the electron-emitting device can be contactlessly contacted.
- the fine particles on the thin film can be cleaned, and the problem of damage and peeling of the metal thin film due to friction and stress during cleaning is eliminated.
- an n-type silicon substrate having an ohmic electrode (rear electrode) formed on the back surface in this case, the ohmic electrode and the n-type silicon substrate function as the lower electrode
- a glass substrate The electrode formed above can be used.
- the electrode material and the electrode it is preferable to use a group electrode.
- the material is not particularly limited as long as the material has excellent conductivity, and may be a metal oxide.
- Gold is preferable as the material of the upper electrode made of a thin film.
- metals such as aluminum, tungsten, nickel, platinum, chromium, and titanium, and metal oxides such as ITO can be used.
- the thickness of the metal thin film is preferably several nm to several tens nm so that the accelerated electrons can fly out by the tunnel effect.
- an internal electric field In the semiconductor layer formed between the lower electrode and the upper electrode, when a voltage is applied between the lower electrode and the upper electrode, an internal electric field must be formed to accelerate the electrons.
- a non-doped porous polysilicon semiconductor layer is suitable.
- the counter electrode is fixedly arranged so as to face the upper electrode at an interval (external space).
- this electrode is formed of a rigid material such as a metal plate.
- the counter electrode does not necessarily need to be separately provided as a dedicated electrode for the electron-emitting device.
- the counter electrode is opposed to the upper electrode.
- the arranged photosensor may be used as it is as the counter electrode when needed.
- a constant voltage power supply whose output voltage can be set to a desired value can be used for the fine particle charging voltage control unit and the flying voltage control unit.
- the counter electrode may have a semiconductive layer or an insulating layer formed on a surface thereof.
- the particles attached to the electron-emitting device are insulative particles _
- the attached particles that are negatively charged by the operation of the microparticle charging voltage control unit are generated by the operation of the flying voltage control unit. Moved to the opposite electrode by the external electric field. After the movement, it is held on the counter electrode irrespective of the conductivity of the surface of the counter electrode. In this case, no particular problem occurs because the fine particles are retained.
- the attached fine particles are semiconductive or conductive and If the surface of the electrode is conductive, positive charges are injected into the charged fine particles moved to the counter electrode, and the fine particles positively charged by the injected charges are again brought into contact with the surface of the electron-emitting device by the same external electric field. The problem of moving to a location occurs.
- the surface of the counter electrode with a semiconductive or insulating material, it is possible to prevent positive charges from being injected into the conductive or semiconductive fine particles that have moved to the counter electrode.
- the movement of the fine particles to the element surface side can be eliminated.
- the flying voltage control unit may apply a pulse-like voltage at which the counter electrode has a positive potential with respect to the upper electrode.
- the fine particles adhering to the surface of the upper electrode of the electron-emitting device are negatively charged by driving the fine particle charging voltage control unit, and a positive voltage is applied to the counter electrode by driving the flying voltage control unit. Thereby, it is electrostatically attracted to the counter electrode.
- electrostatic attraction is applied so as to impact the charged fine particles, so that the charged fine particles are easily separated from the surface, and the fine particles can be efficiently removed. If a pulsed voltage waveform is repeatedly applied a plurality of times, the impact force is applied a plurality of times, so that the fine particles can be removed more efficiently.
- the flying voltage control unit controls the application of the first voltage value in an external space between the upper electrode and the counter electrode, and the fine particle charging voltage control unit applies a predetermined voltage between the upper electrode and the lower electrode. To charge the fine particles attached to the surface of the upper electrode,
- the flying voltage control unit applies a second voltage value higher than the first voltage value that allows charged fine particles to fly from the upper electrode to the counter electrode and does not generate air discharge.
- the particle charging voltage control unit applies a voltage of the opposite polarity to the electron emission voltage between the upper electrode and the lower electrode, or performs control without applying voltage to charge the charged particles to the upper part. You may make it fly from the surface of an electrode to a counter electrode.
- flying the fine particles from the surface of the upper electrode to the counter electrode means, in other words, removing the fine particles attached to the surface of the upper electrode of the electron-emitting device from the electron-emitting device for cleaning.
- the fine particles attached to the upper electrode include dust such as toner and paper powder.
- the flying voltage control unit is configured to be able to set the polarity of the applied voltage between the upper electrode and the counter electrode to be positive or negative,
- the sho voltage control unit performs control to apply a second voltage value higher than the first voltage value such that the charged fine particles can fly from the upper electrode to the counter electrode and no air discharge occurs,
- the particle charging voltage control unit applies a voltage of the opposite polarity to the electron emission voltage between the upper electrode and the lower electrode, or performs control without applying a voltage to charge the charged particles from the surface of the upper electrode to the opposite electrode. You may make it fly to.
- the fine particles attached to the surface of the electron-emitting device are negatively charged insulating fine particles, the fine particles are removed by electrostatic attraction when a positive voltage is applied to the counter electrode.
- the fine particles adhering to the surface of the electron-emitting device are positively charged insulating fine particles, when a negative voltage is applied to the counter electrode, the fine particles are removed by electrostatic attraction.
- the particles attached to the surface of the electron-emitting device are conductive particles and a positive voltage is applied to the counter electrode, the particles are negatively charged by induction charging and are removed by electrostatic attraction.
- a negative voltage is applied to the opposing electrode when the fine particles adhered to the surface of the electron-emitting device are conductive and are applied with a negative voltage, the fine particles are positively charged by induction charging and are removed by electrostatic attraction.
- the particles are opposed to the fine particles having various electrical characteristics regardless of whether they are insulating or conductive, by effectively applying electrostatic attraction to the fine particles from the upper electrode. Fine particles can be removed by moving to the electrode.
- the conductive or semiconductive fine particles transferred to the counter electrode again have positive or negative charges. Can be prevented from being injected, so that it is possible to prevent the fine particles from moving again to the surface of the electron-emitting device and returning to the original state.
- the semiconductor layer is desirably a porous silicon semiconductor layer in which part or all of polysilicon is made porous.
- An electron-emitting device of a type formed by making a polysilicon film porous has improved thermal stability and can perform stable electron-emitting operation even in a vacuum or in the air.
- the fine particles adhering to the surface of the metal thin film are in a non-uniform charged state, and are momentarily charged by an external electric field. Force acts to improve the cleaning performance.
- the flying voltage control unit may apply a voltage between the upper electrode and the counter electrode so that the surface of the upper electrode of the electron-emitting device is on the negative side.
- the electron emission device may be used in a laser printer or a digital copier.
- the present invention provides a surface-emitting type electron-emitting device that emits electrons from the surface of an upper electrode formed of a thin film, and an electron-emitting device cleaning device that removes fine particles attached to the surface of the upper electrode.
- a counter electrode provided to face the surface of the upper electrode with an external space therebetween, and a voltage for driving the electron-emitting device to charge fine particles attached to the surface of the upper electrode.
- Voltage control unit that applies a voltage to the upper electrode, and a flying voltage control that applies a voltage between the upper electrode and the counter electrode to cause the charged particles to fly in the external space from the surface of the upper electrode to the counter electrode.
- the cleaning device is provided as an electron-emitting device cleaning device including:
- the surface-emitting type electron-emitting device has a lower electrode, an upper electrode made of a thin film, and a semiconductor layer formed between the lower electrode and the upper electrode. During this time, a voltage for charging the fine particles may be applied.
- a surface emitting device that emits electrons from the surface of the upper electrode formed of a metal thin film
- a method of cleaning an electron-emitting device for removing fine particles adhering to a surface of an upper electrode in an emission type electron-emitting device comprising: providing a counter electrode on the surface of the upper electrode so as to face the outer electrode with an external space therebetween. By driving the electron-emitting device, the fine particles adhering to the surface of the upper electrode are charged, and a voltage for causing the charged fine particles to fly from the surface of the upper electrode to the counter electrode is applied between the upper electrode and the counter electrode.
- the present invention is also provided as a method for cleaning the electron-emitting device to be applied.
- FIG. 1 is a diagram showing a configuration of an electron-emitting device used in an electron-emitting device according to one embodiment of the present invention.
- FIG. 2 is a diagram showing a configuration of another electron emitting element used in the electron emitting device according to one embodiment of the present invention.
- FIG. 3 is a diagram showing a configuration of an electron emission device according to one embodiment of the present invention.
- FIG. 4 is a diagram illustrating a driving state of the electron-emitting device of the present invention.
- FIG. 5 is a diagram showing the measurement results of the current-voltage characteristics of the electron-emitting device according to the present invention.
- FIG. 6 is a diagram for explaining a photosensitive charging experiment in an electrophotographic process.
- ⁇ FIG. 7 is a diagram for explaining a result of calculating a relationship between a mirror image force F i and an electrostatic force F e due to an external electric field.
- FIG. 8 is a diagram showing a configuration of an electron-emitting device according to another embodiment of the present invention.
- FIG. 9 is a diagram illustrating induction charging of conductive particles. BEST MODE FOR CARRYING OUT THE INVENTION
- FIG. 1 is a diagram showing a configuration of one embodiment of an electron-emitting device to which the present invention can be applied.
- the electron-emitting device 1 is formed by forming a porous electrode on an n-type silicon substrate 3 on which an ohmic electrode (back electrode) 2a is formed (in this case, the ohmic electrode 2a and the n-type silicon substrate 3 function as the lower electrode 2).
- a porous polysilicon film 4 semiconductor layer
- a gold electrode thin film functioning as an upper electrode 5 is formed on the surface thereof.
- the ohmic electrode 2a and the n-type silicon substrate 3 are joined to form an ohmic contact.
- the n-type silicon substrate 3 has a role not only as an electrode for injecting electrons into the porous polysilicon layer 4 as a semiconductor layer, but also as a support member for the electron-emitting device constituting the present invention. .
- the porous polysilicon layer 4 on the n-type silicon substrate 3 is produced by the following method.
- a non-doped polysilicon layer having a thickness of about 1.5 Aim is formed on the surface of the n-type silicon substrate 3 by LPCVD (Low Pressure CVD).
- LPCVD Low Pressure CVD
- a constant current anodic oxidation treatment was performed using the polysilicon layer as a positive electrode and a separately provided platinum electrode as a negative electrode, Part or all of the polysilicon layer is made porous.
- the surface of the polysilicon layer is irradiated with light using a 500 W tungsten lamp. This is because by irradiating the surface of the silicon substrate with light, an electron-hole pair is generated and the anodic oxidation reaction is promoted.
- porous polysilicon layer is subjected to rapid thermal oxidation (RTO) at approximately 900 ° C to form an oxide film.
- RTO rapid thermal oxidation
- a gold electrode thin film is formed as the upper electrode 5 on the surface of the porous polysilicon layer 4 which has been subjected to the above processing by vapor deposition or a sputtering method, thereby forming the electron-emitting device 1 having the structure 10 in FIG.
- FIG. 2 is a diagram showing a configuration of another embodiment of the electron-emitting device to which the present invention can be applied.
- a lower electrode 13 is formed on the surface of a glass substrate 12
- a porous polysilicon layer 14 is further formed thereon
- an upper electrode 13 is further formed thereon.
- a gold electrode thin film is formed as 15.
- the glass substrate functions as a support for the electron-emitting device.
- a metal such as aluminum, tungsten, gold, nickel, platinum, chromium, or titanium, or a metal oxide of the first group such as IT0 can be used.
- the electrode 13 is formed by steaming or a spa method.
- the porous polysilicon layer 14 formed on the surface of the glass substrate 12 on which the lower electrode 13 is formed is produced by the following method, as in the case of the electron-emitting device of FIG. First, a non-25-doped polysilicon layer (approximately 1.5 zm in thickness) was formed on the surface of the glass substrate 12 on which the lower electrode 13 was formed by LPCVD (Low Pressure CVD). ) You.
- LPCVD Low Pressure CVD
- a constant current anodic oxidation treatment is performed using the polysilicon layer as a positive electrode and a separately provided platinum electrode as a negative electrode, Part or all of the silicon layer is made porous.
- the surface of the polysilicon layer is irradiated with light by a 500 W tungsten lamp during the anodizing process.
- a constant current is applied in about 10% dilute sulfuric acid with the polysilicon layer as the positive electrode and the platinum electrode as the negative electrode, and an electrochemical oxidation (ECO) treatment is performed to form an oxide film.
- ECO electrochemical oxidation
- a gold electrode thin film 15 is formed on the surface of the porous polysilicon layer 14 that has been subjected to the above processing by vapor deposition or sputtering.
- the electrode thin film may be made of a metal such as aluminum, tungsten, nickel, platinum, chromium, titanium, or a metal oxide such as ITO, in addition to gold.
- the process temperature is lower than the manufacturing method using the rapid thermal oxidation (RTO) described above, so that restrictions on usable substrate materials are eased and a glass substrate can be used.
- the porous polysilicon layer 14 can be oxidized by the same jet treatment following the anodizing treatment, so that the process is more complicated than the oxidation using the rapid thermal oxidation (RTO) described above. It can be simplified.
- FIG. 3 is a diagram illustrating a configuration of an electron-emitting device according to an embodiment of the present invention. Specifically, FIG. 3 is a diagram illustrating an electron-emitting device using the electron-emitting device 1 of FIG.
- the electron-emitting device 1 shown in FIG. 1 is used. It is needless to say that the electron-emitting device 11 may be replaced.
- the counter electrode 21 is disposed at a position facing the upper electrode 5 of the electron-emitting device 1 with a space therebetween.
- the distance between the upper electrode 5 and the counter electrode 21 is about 1 mm.
- Some devices that use the electron-emitting device 20 can replace the existing device as the counter electrode 21.
- the photoconductor is arranged so as to face the electron-emitting device. Can also be used.
- the constant voltage power supply 23 is connected to each electrode.
- the constant voltage power supply 22 is for generating an internal electric field in the porous polysilicon layer 4 to accelerate the electrons, and can apply a voltage of several V to several tens V as Vps. .
- the constant voltage power supply 23 is for causing charged fine particles adhered to the upper electrode 5 to fly out to the counter electrode 21, and can apply a voltage of several tens V to several hundred V as V c. .
- the constant voltage power supply 23 is configured so that its voltage polarity can be changed, and the polarity can be switched according to the nature of the attached particles (whether it is positively charged or negatively charged).
- the structure of the electron-emitting device can be regarded as an electron-emitting device cleaning device in which the electron-emitting device 1 is provided with a cleaning device.
- FIG. 4 is a diagram illustrating a driving state of the above-described electron-emitting device 1
- FIG. 5 is a measurement result of a current-voltage characteristic.
- a counter electrode (collector electrode) 21 is arranged at a position opposite to the upper electrode 5 of the electron-emitting device 1, and the upper electrode 5 (which is a positive electrode) and the ohmic electrode 2a (the negative electrode A DC voltage Vps of 100 V is applied between the counter electrode (collector electrode) 21 and the upper electrode 5 to generate an electron-emitting device. Drive one.
- FIG. 5 shows the measurement results of the emission current Ie flowing to the counter electrode 21 due to the ions.
- the horizontal axis represents the value of the DC voltage Vps applied to the electron-emitting device, and the vertical axis represents the current density on a log scale.
- ⁇ indicates the diode current I ps
- the port indicates the emission electron current I e.
- an emission current Ie of 4.5 // A / cm 2 was observed when the device applied voltage Vps was 2 IV, even in the air. Most of this current is accelerated by the porous polysilicon layer 4, and electrons emitted through the tunnel through the upper electrode 5 are attached to gas molecules in the atmosphere, forming negative ions. It is probable that it was transported to 21. 4. Amount of current that 5 ⁇ A / cm 2 is applicable electrodeposition flow to the charging of the photosensitive member of the apparatus which applies the electrophotographic technology, such as, single Zapurin evening or a digital copying machine.
- the charging device as described above has a configuration in which the counter electrode (collector electrode) 21 is replaced with a photoreceptor in FIG.
- the metal thin film forming the upper electrode 5 of the electron-emitting device of the present invention has a thickness of several nm to several tens nm so that electrons generated in the electron-emitting device 1 can be effectively emitted. Therefore, if it is attempted to wipe off fine particles such as dust adhering on the upper electrode 5 with a contact-type cleaning member, the friction at the time of wiping the dust is reduced. There is a possibility that the metal thin film forming the upper electrode 5 may be damaged by the tress, or the metal thin film may be peeled off.
- FIG. 6 is a diagram schematically showing a state when a charging experiment of a photoconductor using the electron-emitting device 1 is performed in an actual electrophotographic process. The results of dust contamination are described below.
- the electron-emitting device 1 has the same shape as that shown in FIG. —Mic electrode 2a, n-type silicon substrate 3), porous polysilicon film 4 (semiconductor layer), and upper electrode (metal thin film) 5.
- an electrode substrate 42 conductive material
- a photoconductor film 43 A photosensitive member 41 composed of a high-resistance material in a dark place
- the space (external space) sandwiched between the upper electrode 5 and the photoconductor 41 will be referred to as a charged space.
- the distance between the upper electrode 5 of the electron-emitting device 1 and the photoconductor 41 is 1 mm, and a DC voltage (collector voltage) Vc applied between the upper electrode 5 and the electrode substrate 42 of the photoconductor 41 is V c. Is set to 800 V, the DC voltage applied between the upper electrode 5 and the phantom electrode 2 a (element applied voltage) V
- the toner has an average specific charge of about -10 to 11 in the current image area and is negatively charged, however, this value is only an average value, and is stochastic. There are a small amount of positively charged toner and uncharged toner in the developing unit, etc.
- the developing unit or the like restrains the toner on the developing sleeve or the photoconductor by electrostatic force.
- Toner with low specific charge or uncharged The toner is liable to be scattered due to the weak electrostatic force, and although slightly, floats on the charged portion and other portions for performing the electrophotographic process.
- the slightly positively charged floating toner enters the charging space during the charging operation and is attracted to the upper electrode 5 by the strong electric field existing in the charging space.
- the surface resistivity of the paper is very sensitively changes with respect to humidity, but because it is generally resistance in.
- the range of 1 0 9 ⁇ 1 0 13 ⁇ lose relatively fast charge. Although it is a reference value, it has been confirmed in a paper powder induction charging experiment that the charge is released in about 1 second.
- the toner has higher resistance (insulating property) than the paper powder, so that it takes more time to lose charge.
- the dust attached to the upper electrode 5 originally has a small charge amount, or loses the charge over time, so that the charge amount is reduced.
- a voltage Vc is applied between the upper electrode 5 of the electron-emitting device 1 and the counter electrode 21.
- the image force F i which is a force acting in the direction of adsorbing on the upper electrode 5 is determined when the charged fine particles adhere to the surface of the conductive electrode. It is understood that charges of opposite polarities are concentrated on the surface, and these are generated by attracting each other.
- the image force F i is expressed by the following equation.
- £ is the dielectric constant
- rt is the particle radius
- Equation 2 From Equation 2, it can be seen that the electrostatic force F e is proportional to the first power of the charge q t of the fine particles.
- the electrostatic force F e due to the external electric field is in the same direction as the mirror image force F i and acts in the direction of the upper electrode 5, so that cleaning becomes impossible.
- cleaning can be enabled by making the charged polarity of the fine particles negative or by reversing the polarity of the external electric field.
- a toner having a diameter of 0.8 zm and insulating particles is attached to the upper electrode 5.
- the specific charge (charge per unit mass) of the toner is a general value—10 CZg and the specific gravity of the toner is 1 g / cm 3
- the charge qt of each toner is —2.68 ⁇ 10 — 15 C.
- Equation 1 Substituting the charge amount qt of this toner into (Equation 1) gives an image force F i of 1.0 nN. If the external electric field strength is 10 6 V / m, the electrostatic force Fe by the external electric field is 2.7 nN. In this example, Fi is smaller than Fe, and the peeling force due to the external electric field is larger than the force adhering to the upper electrode 5 due to the image force, so that the fine particles on the upper electrode 5 can be cleaned.
- the fine particles 32 present on the upper electrode 5 take on a negative charge due to negative ions formed by the electrons adhering to the gas molecules.
- the initial charge polarity of the charged fine particles 32 attached to the upper electrode is considered to be almost positive, but regardless of the initial polarity, the fine particles 32 gradually become negatively charged. It is being done.
- the electron-emitting device 1 is driven, the fine particles 32 are negatively charged, and the force of the electric field formed by the counter electrode 31 causes Fv to Fi or Fe to Fv.
- the fine particles 32 are cleaned by setting the state of ⁇ F e.o
- the increase in the external electric field strength E increases the electrostatic force F e as the removing force while keeping the image force F i as the adhesive force constant. That is, if the external electric field strength E is increased, only F e can be increased from the state of F i, F e, Fv or F e: F i, F v, and F i ⁇ F v ⁇ F Fine particles can be removed from the electron-emitting device 1 in the state of e. However, if the external electric field strength E is too large, an air discharge, which is a dielectric breakdown of air, occurs, and the electron-emitting device 1 may be destroyed.
- the spatial electric field intensity E between the upper electrode 5 and the counter electrode 21 is controlled to be limited to 3 MV / m or less, thereby avoiding a discharge phenomenon.
- the above-mentioned discharge phenomenon due to dielectric breakdown is an avalanche phenomenon (electron 'ions are avalanche amplified) by a strong electric field.
- the number of electrons and negative ions increases, so that discharge is easily generated even at an electric field strength at which a discharge phenomenon does not normally occur.
- the discharge phenomenon starts even with an electric field strength smaller than the electric field strength (3 MV / m) that can avoid the normal discharge phenomenon.
- control is performed as follows.
- the electric field in the external space is set to the minimum necessary.
- the electric field in the external space is made as strong as possible so as not to emit electrons from the electron-emitting device 1.
- the discharge phenomenon due to dielectric breakdown is an avalanche of electrons due to a strong electric field (electrons and ions are avalanchely amplified). Therefore, some time is required for the phenomenon to occur. If the pulse width of the voltage application is set shorter than the time required for the electron avalanche, the discharge phenomenon can be prevented, and destruction of the electron 3 ⁇ 4m element can be avoided.
- FIG. 8 is a diagram showing a configuration of an electron-emitting device according to another embodiment of the present invention. In this embodiment, a case where the conductive fine particles 32 are attached to the upper electrode 5 of the electron-emitting device 1 will be described.
- the electron-emitting device 1 has the same shape as that shown in FIG. 1, and includes the lower electrode 2 (the ohmic electrode 2 a and the n-type silicon substrate 3), the porous polysilicon film 4 (the semiconductor layer), It is composed of an upper electrode (metal thin film) 5.
- a counter electrode 51 is arranged at a position facing the upper electrode 5 of the electron-emitting device 1, and a DC voltage (collector voltage) Vc is applied between the upper electrode 5 and the counter electrode 51.
- This counter electrode 51 is composed of a metal electrode 52 and an insulating layer 53.
- the opposing electrode 51 is formed only of the metal electrode as shown in FIG. 3, if the conductive fine particles 32 away from the upper electrode 5 of the electron-emitting device 1 adhere to the opposing electrode 51, the induced charging causes Positive charges are injected into the fine particles 32, and as a result, an undesirable phenomenon occurs in which the fine particles 32 are pulled by the negative electrode and return to the upper electrode 5 again. +
- the electrostatic force F e satisfies the condition that the electrostatic force F e is larger than the image force F i, which is the adhesive force with the counter electrode, or the van der Waalska F V, it flies toward the upper electrode 5 and returns.
- the conductive fine particles 32 move back and forth between the upper electrode 5 and the counter electrode 31.
- the reciprocating time is determined by the charge injection time to the fine particles 32, that is, the resistance value of the fine particles 32.
- the fine particles are controlled by controlling the timing at which V c is turned off. It is difficult to clean.
- the photoreceptor When applying the electron-emitting device 1 to charging of a photoconductor in an electrophotographic process,
- the photoreceptor is insulative in some places, and therefore, the counter electrode 31 has a two-layer structure of a metal electrode and an insulating layer. Therefore, it is possible to prevent the fine particles 32 from returning to the electron-emitting device 1 as described above, and it is possible to clean the electron-emitting device 1.
- the electron emitting element 1 is driven to negatively charge the fine particles, and a positive voltage is applied to the counter electrode 51. It is necessary to clean the surface by applying electrostatic force F e, but when the adhered fine particles are conductive fine particles as in this embodiment, the charge can be injected by induction charging. The drive of 1 is not always necessary.
- either a positive voltage or a negative voltage may be applied to the counter electrode 51. That is, when the counter electrode 51 is positive, a negative charge is injected into the conductive fine particles and attracted to the positive counter electrode 51 by electrostatic force F e, and when the counter electrode 51 is negative, the conductive fine particles Is injected into the negative electrode and is attracted to the negative counter electrode by the electrostatic force F e.
- an insulating layer 53 is required on the counter electrode 51 so that the conductive fine particles 32 that have moved to the counter electrode 51 do not return.
- the curved surface of the counter electrode 51 is made of a semiconductive or insulating material, it is possible to prevent the conductive fine particles from returning due to induction charging on the counter electrode 51, but if the electron-emitting device 1 is operated, The counter electrode 51 is negatively charged. For this reason, the electric field strength in the external space becomes weak, and it becomes impossible to remove the insulating or conductive fine particles adhered to the surface of the upper electrode 5.
- the voltages Vps and Vc are controlled as follows.
- the fine particles can be negatively charged by operating the electron-emitting device 1, a strong positive charge, a weak positive charge, and no charge can be obtained. i ⁇ Fe and fine particles can be removed.
- the mirror image force F i exceeds the electrostatic force F e for cleaning as shown in FIG. Becomes impossible.
- the electron emission device of the present invention is not limited to the electron emission device using the porous polysilicon layer serving as the electron acceleration layer. It can also be applied to surface-emitting type electron-emitting devices such as MIM type and MIS type.
- the electron emission device of the present invention can be applied to a case where an (n-type) silicon substrate is used and a case where a glass substrate is used. Therefore, which substrate to use may be properly used in consideration of the advantages and disadvantages of the substrate as described below.
- an (n-type) silicon substrate when used, it is superior to a glass substrate in terms of smoothness and material affinity, and a semiconductor film is easily formed on the substrate. Since silicon substrates are excellent in heat resistance, various heat treatments such as thermal oxidation are possible. Instead, the material costs are relatively high, making it difficult to handle large substrates.
- glass-substrate when a glass-substrate is used, the material cost is lower than when a silicon substrate is used, and it is advantageous in that it can be used for large substrates. Instead, glass substrates are inferior to silicon substrates in terms of heat resistance, and are subject to various heat treatments such as thermal oxidation.
- fine particles on the metal thin film on the surface of the upper electrode of the electron-emitting device can be cleaned in a non-contact manner, so that the metal thin film is damaged by friction and stress as in contact cleaning. ⁇ Peel off Problems can be overcome.
- the discharge of air that causes a problem when operating in the atmosphere can be problematic. Dielectric breakdown can be avoided, and destruction of the electron-emitting device due to the discharge can also be avoided. In particular, discharge can be effectively prevented by setting the charging electric field strength to 3 M VZm or less.
- the attached fine particles can be effectively removed.
- the surface of the counter electrode is made of a semiconductive or insulating material, it is possible to prevent positive charges from being injected into the conductive or semiconductive fine particles moved to the counter electrode. The phenomenon can be prevented if the fine particles sucked from the surface to the counter electrode move to the surface of the electron-emitting device again.
- the surface of the counter electrode is made of a semiconductive or insulating material, do not apply a strong voltage between the upper electrode and the counter electrode while the electron-emitting device is operating.
- a strong positive voltage is applied to cause the charged fine particles on the element surface to fly to the positive electrode side, the charge-up of the counter electrode can be prevented by not operating the electron emission element.
- the semiconductor layer is made of porous silicon in which a part of the polysilicon layer is made porous.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- General Physics & Mathematics (AREA)
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
- Cold Cathode And The Manufacture (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US10/541,878 US7317285B2 (en) | 2003-01-14 | 2004-01-14 | Electron emission device having cleaning function |
Applications Claiming Priority (2)
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JP2003006176A JP2004265603A (ja) | 2003-01-14 | 2003-01-14 | 電子放出装置および電子放出素子クリーニング装置および電子放出素子クリーニング方法 |
JP2003-006176 | 2003-01-14 |
Publications (1)
Publication Number | Publication Date |
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WO2004063818A1 true WO2004063818A1 (ja) | 2004-07-29 |
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PCT/JP2004/000182 WO2004063818A1 (ja) | 2003-01-14 | 2004-01-14 | クリーニング機能を有する電子放出装置 |
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Country | Link |
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US (1) | US7317285B2 (ja) |
JP (1) | JP2004265603A (ja) |
CN (1) | CN100474153C (ja) |
WO (1) | WO2004063818A1 (ja) |
Families Citing this family (8)
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JP2004265603A (ja) | 2003-01-14 | 2004-09-24 | Sharp Corp | 電子放出装置および電子放出素子クリーニング装置および電子放出素子クリーニング方法 |
JP4216112B2 (ja) | 2003-04-21 | 2009-01-28 | シャープ株式会社 | 電子放出素子およびそれを用いた画像形成装置 |
JP2005005205A (ja) | 2003-06-13 | 2005-01-06 | Sharp Corp | 電子放出装置、帯電装置および帯電方法 |
JP5133295B2 (ja) * | 2009-04-23 | 2013-01-30 | シャープ株式会社 | 電子放出装置、自発光デバイス、画像表示装置、帯電装置、画像形成装置、電子線硬化装置、および電子放出素子の駆動方法 |
CN102263171B (zh) * | 2011-06-24 | 2013-10-09 | 清华大学 | 外延衬底、外延衬底的制备方法及外延衬底作为生长外延层的应用 |
US8866068B2 (en) | 2012-12-27 | 2014-10-21 | Schlumberger Technology Corporation | Ion source with cathode having an array of nano-sized projections |
JP6106553B2 (ja) * | 2013-07-30 | 2017-04-05 | 住友理工株式会社 | 紙送り用ローラ |
CN105097450B (zh) * | 2015-06-23 | 2019-11-01 | 京东方科技集团股份有限公司 | 多晶硅薄膜及制作方法、tft及制作方法、显示面板 |
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JPH06255168A (ja) | 1993-03-08 | 1994-09-13 | Alps Electric Co Ltd | イオン書き込みヘッドおよび印字装置 |
JP3226745B2 (ja) | 1995-03-09 | 2001-11-05 | 科学技術振興事業団 | 半導体冷電子放出素子及びこれを用いた装置 |
US5990605A (en) * | 1997-03-25 | 1999-11-23 | Pioneer Electronic Corporation | Electron emission device and display device using the same |
JP2987140B2 (ja) | 1997-10-29 | 1999-12-06 | 松下電工株式会社 | 電界放射型電子源およびその製造方法および平面発光装置およびディスプレイ装置および固体真空デバイス |
TW391022B (en) * | 1997-10-29 | 2000-05-21 | Mitsubishi Rayon Co | Field emission electron source, method of producing the same, and use of the same |
TW436837B (en) * | 1998-11-16 | 2001-05-28 | Matsushita Electric Works Ltd | Field emission-type electron source and manufacturing method thereof and display using the electron source |
US6498426B1 (en) * | 1999-04-23 | 2002-12-24 | Matsushita Electric Works, Ltd. | Field emission-type electron source and manufacturing method thereof |
US6765342B1 (en) * | 1999-10-18 | 2004-07-20 | Matsushita Electric Work, Ltd. | Field emission-type electron source and manufacturing method thereof |
JP2002174943A (ja) | 2000-03-17 | 2002-06-21 | Ricoh Co Ltd | 帯電装置及びそれを用いた電子写真装置 |
JP4114842B2 (ja) | 2000-05-02 | 2008-07-09 | 株式会社リコー | 帯電装置 |
JP3658342B2 (ja) * | 2000-05-30 | 2005-06-08 | キヤノン株式会社 | 電子放出素子、電子源及び画像形成装置、並びにテレビジョン放送表示装置 |
JP4616501B2 (ja) | 2001-04-13 | 2011-01-19 | 株式会社リコー | 帯電装置及び帯電装置を用いた画像形成装置 |
CN1216394C (zh) * | 2001-09-25 | 2005-08-24 | 松下电工株式会社 | 场致发射型电子源 |
JP2004265603A (ja) | 2003-01-14 | 2004-09-24 | Sharp Corp | 電子放出装置および電子放出素子クリーニング装置および電子放出素子クリーニング方法 |
JP4133448B2 (ja) | 2003-02-28 | 2008-08-13 | シャープ株式会社 | 清掃装置および清掃方法 |
-
2003
- 2003-01-14 JP JP2003006176A patent/JP2004265603A/ja active Pending
-
2004
- 2004-01-14 WO PCT/JP2004/000182 patent/WO2004063818A1/ja active Application Filing
- 2004-01-14 US US10/541,878 patent/US7317285B2/en not_active Expired - Lifetime
- 2004-01-14 CN CNB2004800020832A patent/CN100474153C/zh not_active Expired - Fee Related
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JP2000019921A (ja) * | 1998-07-06 | 2000-01-21 | Canon Inc | 画像形成装置 |
JP2001357961A (ja) * | 2000-06-14 | 2001-12-26 | Ricoh Co Ltd | 電荷発生装置及び帯電装置及び画像形成装置 |
JP2002258585A (ja) * | 2001-03-02 | 2002-09-11 | Ricoh Co Ltd | 帯電装置のクリーニング方法及び帯電装置 |
Also Published As
Publication number | Publication date |
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US7317285B2 (en) | 2008-01-08 |
JP2004265603A (ja) | 2004-09-24 |
CN1735840A (zh) | 2006-02-15 |
CN100474153C (zh) | 2009-04-01 |
US20060152166A1 (en) | 2006-07-13 |
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