JP4083933B2 - Ion generator and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ion generator and an image forming apparatus using the ion generator for charging an image carrier, and more specifically, efficiently and reliably decomposes discharge products generated in an electrophotographic image forming process. The present invention relates to an ion generator and an image forming apparatus.
[0002]
[Prior art]
In an image forming apparatus such as a copying machine, a printer, and a facsimile machine using electrophotography, a charging unit that uniformly charges a photoconductor, a transfer unit that transfers a toner image formed on the photoconductor to an image forming member, and A neutralization unit for neutralizing the residual charge on the photoreceptor and the residual toner charge is provided. These parts often use air discharge, but discharge products are generated by the air discharge. For example, ozone, NO_xThere is. If ozone stays in the image forming apparatus at a high concentration, the surface of the photoconductor is oxidized, causing a reduction in photosensitivity of the photoconductor and a deterioration in charging ability, thereby deteriorating the formed image. Further, there is a problem that deterioration of members other than the photoconductor is promoted and the life of the parts is reduced.
[0003]
When high-concentration ozone is discharged outside the image forming apparatus, there is a concern about adverse effects on the human body such as discomfort to surrounding people due to ozone odor, and some people suffering from allergic symptoms. The ozone concentration discharged outside the image forming apparatus is regulated. For example, in the German Blue Angel Mark Examination Standard (RAL-UZ62), the discharge concentration outside the apparatus is regulated to 0.01 ppm or less.
[0004]
2. Description of the Related Art Conventionally, in an image forming apparatus, ozone around a photoreceptor is sucked by a fan and discharged out of the image forming apparatus through an ozone filter.
[0005]
However, in such a conventional ozone treatment method, there is a problem that the filter is gradually deteriorated due to ozone adsorption, and ozone cannot be properly removed by long-term use. Further, in order to improve the ozone removal rate by the filter, if the filter mesh is made finer or the filter surface area is increased by increasing the filter surface area, the pressure loss in the filter increases and the capacity increases. There is a problem that a fan needs to be attached, which increases the cost of the image forming apparatus, increases power consumption, and increases noise.
[0006]
NO, another major discharge product_xIn this case, although there is currently no restriction on discharge outside the apparatus, it also adversely affects members inside the image forming apparatus. When discharge occurs, NO_xIt is known that nitric acid is formed by reacting with moisture in the air, and metal nitrate is formed by reacting with metal. These products have high resistance in a low humidity environment, and adhere to an ion generating head or the like, thereby causing problems such as unstable discharge and uneven charging. Further, when a thin film of nitric acid or nitrate is formed on the surface of the photoconductor, an abnormal image is generated in which an image flows in a high humidity environment. This is because nitric acid / nitrate absorbs moisture, resulting in low resistance, and the electrostatic latent image on the surface of the photoreceptor is broken.
[0007]
A method is adopted in which deposits on the surface of the photoreceptor are removed by scraping the photoreceptor little by little during cleaning. However, cost increases and deterioration problems with time occur, and this is not an essential solution.
[0008]
In this regard, in the prior art, ozone, NO in the image forming apparatus by utilizing the discharge product decomposition action by the photocatalytic substance._xVarious methods for disassembling are proposed. For example, an electrophotographic developer (in particular, a toner that contains at least a binder resin and a colorant or a semiconductor particle carrying a metal as an external additive to reduce discharge products generated in air discharge (special feature). (See Kaihei 5-134445), semiconductor fine particles carrying a metal are applied to at least one of the eraser lamp, the pre-transfer static elimination lamp or the static elimination lamp provided on the periphery of the image carrier (see FIG. 5). Japanese Patent Laid-Open No. 6-59551) and the like have been proposed (Japanese Patent Laid-Open Nos. 6-124003, 7-92788, etc.).
[0009]
In other words, in each of these proposed examples, ozone can be easily decomposed in the image forming apparatus, so that the ozone concentration flowing out from the charger or the like can be reduced and the load on the ozone filter can be reduced. .
[0010]
Other conventional examples are listed as follows. For example, according to Japanese Patent Laid-Open No. 5-303244, the exhaust heat of the fixing unit is used, and NO._X Is prevented from becoming nitrate. According to Japanese Patent Laid-Open No. 6-167857, deterioration of the photosensitive member is prevented by utilizing the exhaust heat of the fixing unit and decomposing ozone of the discharge member. According to Japanese Patent Laid-Open No. 6-317974, the generation of ozone is suppressed by disposing the catalyst in the vicinity where discharge is generated. According to Japanese Patent Laid-Open No. 7-134473, generation of ozone is suppressed by utilizing a catalyst and heat. According to Japanese Patent Laid-Open No. 9-114191, the surface of the charger is subjected to creeping glow discharge separately from that for charging the photosensitive member._X Is going to be disassembled. According to Japanese Patent Laid-Open No. 9-138619, ozone in an ozone suction duct is decomposed by irradiating light, and the life of the ozone decomposition filter is extended by improving decomposition efficiency. Yes. According to Japanese Patent Laid-Open No. 10-90974, ozone is decomposed by providing a catalyst on a sawtooth electrode. According to Japanese Patent Laid-Open No. 10-301364, generation of ozone is prevented by flowing a non-ozone generating gas through a discharge portion. Furthermore, according to Japanese Patent Publication No. 8-23715, by covering the inside of the discharger with a neutralizing substance, NO_X Is neutralized to prevent deterioration of the photoreceptor.
[0011]
[Problems to be solved by the invention]
However, all of these conventional image forming apparatuses and discharge product reduction methods have been designed to reduce the load on the filter, so there is still room for improvement.
[0012]
That is, since the concentration of the discharge product flowing out from the charger etc. is reduced, the probability that the discharge product flowing out from the charger etc. diffuses into the image forming apparatus and reacts with the catalyst substance is reduced. However, the reduction efficiency of the discharge product concentration is low, and there is a demand for an efficient reduction of the discharge product concentration.
[0013]
In addition, an ion generator that includes an induction electrode and an ion generation electrode formed with a dielectric sandwiched between them and generates an ion in the air by applying an AC voltage between the induction electrode and the ion generation electrode is used. In the conventional charging device, transfer device, and static eliminating device, it is possible to generate a discharge with a smaller voltage than a general corona charger. For this reason, the amount of discharge products is smaller than that of a general corona charger.
[0014]
The problem with using an ion generator that discharges air through such a dielectric layer is that nitrate is produced by the discharge, and the discharge does not occur when this nitrate adheres to the surface of the dielectric layer. There is. In order to prevent this, measures are taken by heating the ion generator itself.
[0015]
The amount of ions generated by the ion generator is also affected by the heating temperature. Since the amount of generated ions is easily affected by temperature fluctuations, a temperature control device is required (US Pat. No. 4,155,093, Japanese Patent Laid-Open No. 5-278258, Japanese Patent Laid-Open No. 5-281835, Japanese Patent Laid-Open No. 75457, JP-A-8-82980, JP-A-10-21395).
[0016]
However, the amount of generated discharge products is not completely eliminated even in an ion generator. There is also a demand for efficient reduction of the concentration of discharge products in ion generators.
[0017]
Therefore, the present invention provides ozone and NO, which are discharge products due to air discharge, even when using an ion generator that generates a relatively small amount of discharge products compared to a corona charging device._XIt is an object of the present invention to provide an ion generating device that can efficiently reduce the concentration before flowing out and suppress adverse effects on the environment, and an image forming apparatus using the same.
[0018]
[Means for Solving the Problems]
  The ion generator according to the first aspect of the present invention comprises at least an induction electrode and an ion generation electrode formed with a dielectric interposed therebetween.Thus, a photocatalytic substance is applied or contained in at least a part of at least one of the dielectric and the ion generating electrode.In an ion generating apparatus that has an ion generating head and generates an ion by generating an air discharge by applying an alternating voltage between the induction electrode and the ion generating electrode,The resistor layer to which the power supply is connected is sandwiched by the dielectricA casing surrounding the periphery of the ion generation head other than the ion generation space was provided, and a photocatalytic substance intended to decompose the discharge product was provided inside the casing.
[0019]
  Therefore, due to the light emission of the discharge,Coated or contained in a part of at least one of the dielectric and the ion generating electrodeSince the photocatalytic substance is activated and reacts with the discharge product, the discharge product generated by the ion generator, particularly ozone and NO._xCan be decomposed efficiently. As a result, the discharge product can be decomposed before flowing out of the ion generator, and adverse effects on surrounding members can be prevented and adverse effects on the environment can be suppressed.
[0024]
  Claim 2According to the present invention, in the ion generation apparatus according to claim 1, the ion generation electrode is coated with a dielectric, and has a photocatalytic substance on at least the surface of the coating layer.
[0025]
Therefore, the discharge product generated at the charging portion can be efficiently decomposed at the generation portion having the highest discharge product concentration. In addition, since the photocatalytic substance is provided on the surface of the coating layer, the function of the coating layer is not impaired. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0026]
  Claim 3According to the present invention, in the ion generating apparatus according to claim 1, the ion generating electrode is coated with a dielectric, and at least the coating layer is made of a material containing a photocatalytic material.
[0027]
Therefore, since the photocatalytic substance is included in the coating layer, it is not necessary to newly provide a coating layer of the photocatalytic substance. This simplifies coating and is advantageous in terms of production and cost. When the photocatalytic substance is only on the surface of the coating layer, the function is lost when the coat layer of the photocatalytic substance is peeled off. On the other hand, when the photocatalytic substance is included in the coating layer, even if the coating layer is somewhat worn due to discharge or the like, it is also included in the coating layer, so that the photocatalytic effect can be maintained. The discharge product generated in the charging unit can be efficiently decomposed in the generation unit having the highest concentration of the discharge product. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0028]
  Claim 4The invention described in claim 1Thru 3In the ion generator according to any one of the above, a light emitter capable of irradiating light including at least ultraviolet rays is provided in the vicinity of the discharge site.
[0029]
Accordingly, since the photocatalytic substance can be more strongly activated by the ultraviolet light of a light emitter such as a lamp, the discharge product can be efficiently decomposed. Further, even when the ion generator is not emitting light, the photocatalytic substance can be activated by the ultraviolet light of the illuminant, so that it can be decomposed even when the discharge product remains. Thereby, the discharge product can be more reliably decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0030]
  Claim 5The described inventionClaim 4In the described ion generator, the light emitter has a photocatalytic substance at least on a light emitting surface thereof.
[0031]
Accordingly, since the photocatalytic substance can be more strongly activated by the ultraviolet light of a light emitter such as a lamp, the discharge product can be efficiently decomposed. Furthermore, since the photocatalytic substance is disposed on the surface of the light emitter, it is possible to prevent the surface of the light emitter from being contaminated by the adhesion of the discharge product. In addition, when a photocatalytic substance is arranged on the surface of the illuminant, it is possible to activate the photocatalytic substance with the ultraviolet light of the illuminant even when the ion generator is not emitting light, so that discharge generation The thing can be decomposed efficiently. Further, since the surface of the light emitter is not contaminated, the light transmittance on the surface of the light emitter is not lowered. Therefore, the photocatalyst can be irradiated with light over a long period of time, and the photocatalyst can be activated. Thereby, the discharge product can be more reliably decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0032]
  Claim 6The described invention is claimed.5 or 6In the described ion generator, light having a wavelength of 300 nm to 400 nm is included in the wavelength of light emitted from the light emitter.
[0033]
The photocatalytic substance is activated rapidly when irradiated with light of a certain energy or more, and the reaction proceeds. For example, in the case of titanium oxide, the wavelength of light serving as the threshold is 380 nm. Therefore, if the wavelength of the ultraviolet light to be irradiated is made appropriate and the photocatalytic substance is more easily activated, the decomposition efficiency of the discharge product becomes very high. Thereby, the discharge product can be more reliably decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0034]
  Claim 7The invention described in claim 16In the ion generating apparatus according to any one of the above, the photocatalytic substance is an n-type semiconductor.
[0035]
Therefore, the discharge product can be efficiently decomposed by using a photocatalytic substance made of an n-type semiconductor having high efficiency as a photocatalytic substance. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0036]
  Claim 8The described inventionClaim 7In the described ion generator, the n-type semiconductor is titanium oxide.
[0037]
Therefore, titanium oxide is an n-type semiconductor photocatalytic substance and is currently said to be the most stable and efficient. By using titanium oxide as a photocatalyst, the discharge product can be efficiently decomposed. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0038]
  Claim 9The described inventionClaim 8In the described ion generator, the titanium oxide includes at least a crystal structure having an anatase structure.
[0039]
Therefore, titanium oxide containing an anatase type structure in the crystal structure has the highest effect as a photocatalyst, so that the discharge product can be efficiently decomposed. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0040]
  Claim 10The image forming apparatus according to the invention is described in claim 1.9The ion generator described in any one of the above is used for charging the image carrier.
[0041]
Accordingly, the photocatalytic substance is activated by the light emission of the discharge and reacts with the discharge product, so that the discharge product generated during charging can be efficiently decomposed. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the image carrier such as the photoconductor can be prevented, and the adverse effect on the environment can be suppressed.
[0042]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description which limits, it is not restricted to these aspects.
[0043]
1 to 7 are diagrams showing an embodiment of an ion generating apparatus and an image forming apparatus of the present invention. FIG. 1 is an image forming apparatus 1 to which an embodiment of the image forming apparatus of the present invention is applied. FIG.
[0044]
In FIG. 1, an image forming apparatus 1 houses a photoreceptor 2 as an image carrier that is driven to rotate clockwise in FIG. 1 in a main body housing (not shown), and a charging unit around the photoreceptor 2. 3, a writing unit 4, a developing unit 5, a transfer unit 6, a paper separating unit 14, a cleaning unit 7, and a photoreceptor charge eliminating unit 8 are sequentially arranged according to an electrophotographic process, and a toner is placed in front of the cleaning unit 7. A static elimination unit 9 is provided.
[0045]
Further, the image forming apparatus 1 of the present embodiment includes a paper feed cassette (not shown) that stores a plurality of recording papers P, and the recording paper P in the paper feed cassette is supplied with a paper feed roller (see FIG. (Not shown) and fed one sheet at a time by the registration roller pair 15 and sent out between the transfer unit 6 and the photosensitive member 2.
[0046]
In the image forming apparatus 1 having such a configuration, first, the photosensitive member 2 is rotationally driven in the clockwise direction in FIG. 1, and the photosensitive member 2 is uniformly charged by the charging unit 3. A laser modulated with data is irradiated to form an electrostatic latent image on the photosensitive member 2, and toner is attached to the photosensitive member 2 on which the electrostatic latent image is formed by the developing unit 5 and developed. Next, the photoreceptor 2 on which the toner image is formed by attaching the toner in the developing unit 5 is transferred to the recording paper P conveyed between the photoreceptor 2 and the transfer unit 6 by the transfer unit 6, and the toner image The transferred recording paper P is conveyed to the fixing unit 10.
[0047]
Here, the fixing unit 10 includes a fixing roller 11 heated to a predetermined fixing temperature by a built-in heater, and a pressure roller 12 pressed against the fixing roller 11 with a predetermined pressure, and has been conveyed from the transfer unit 6. The recording paper P is heated and pressurized to fix the toner image on the recording paper P onto the recording paper P, and then discharged onto a paper discharge tray (not shown).
[0048]
On the other hand, the photosensitive member 2 on which the toner image is transferred onto the recording paper P by the transfer unit 6 is further rotated, and the toner charge removal unit 9 removes the residual toner charge remaining on the photosensitive member 2. The toner remaining on the surface of the photosensitive member is scraped off and removed by the blade 13, and then neutralized by the photosensitive member neutralizing unit 8. Then, after the photosensitive member 2 discharged by the photosensitive member discharging unit 8 is uniformly charged by the charging unit 3, the next image formation is performed in the same manner as described above. The cleaning unit 7 is not limited to the one that scrapes off the residual toner on the photoconductor 2 with the blade 13, but may be one that scrapes off the residual toner on the photoconductor 2 with a fur brush, for example.
[0049]
In such an image forming apparatus 1, in the present embodiment, for example, an ion generator as shown in FIG. 2 is used for the charging unit 3 for uniformly charging the photoreceptor 2. An ion generator may also be used for the transfer unit 6, the paper separation unit 14, the toner neutralization unit 9, and the photoreceptor neutralization unit 8.
[0050]
Here, the ion generator will be described with reference to FIG. 2A is a cross-sectional structural view, and FIG. 2B is a plan view seen from the ion generating electrode side.
[0051]
In this ion generator (ion generation head 20), an induction electrode 22 is formed on a substrate 21 made of ceramic or the like, and a dielectric layer 23 made of glass or the like is formed so as to cover the induction electrode 22. The ion generation electrode 24 is formed on the dielectric layer 23. The induction electrode 22, the dielectric layer 23, and the ion generation electrode 24 can be formed by thick film printing. For example, the induction electrode 22 is preferably formed to have a thickness of 1 to 5 μm, the dielectric layer 23 to have a thickness of 20 to 50 μm, and the ion generating electrode 24 to have a thickness of 1 to 30 μm. The dielectric layer 23 should have a dielectric constant as high as possible. This is because the higher the dielectric constant, the larger the capacitance of the dielectric layer and the greater the electric field distortion.
[0052]
  A high frequency high voltage having a frequency of several hundred Hz to several tens of kHz and a peak value of 1 to 4 kV is applied between the induction electrode 22 and the ion generation electrode 24 of the ion generation head 20 having such a structure by the power source 26 and ions. Generating electrode24When a bias voltage is applied to the bias power source 27, air in the vicinity of the ion generation electrode 24 (hereinafter referred to as ion generation space 29) is ionized to generate positive and negative ions. Here, as shown in the figure, when a negative voltage is applied as a bias voltage by the bias power source 27, only negative ions are extracted from the ion portion. If the bias voltage is positive, positive ions are extracted. The ion generating head 20 can generate a discharge with a smaller voltage than a general corona charger.
[0053]
The surface of the ion generating electrode 24 is SiO.₂The coating layer 30 may be applied. This can prevent deterioration of the ion generation electrode 24 due to sputtering or oxidation by ions, and can prevent creeping discharge at the ion generation electrode 24. For example, the coating layer 30 is formed to have a thickness of 1 to 5 μm. If the coating layer 30 is too thick, the ion generation efficiency decreases. The coating may be nitride, silicon nitride, magnesium oxide, titanium oxide, glass or the like.
[0054]
The dielectric layer 23 may be formed in a form in which the resistor layer 25 is sandwiched.
[0055]
A power source 28 is connected to the resistor layer 25, and Joule heat can be generated by a current flowing through the resistor layer 25. The voltage from the power supply 28 is a direct current or an alternating voltage. This Joule heat heats the dielectric layer 23 and the ion generation space 29. Thereby, the decomposition effect of the discharge product by the photocatalyst substance mentioned later can be made still higher.
[0056]
The conductive film for forming the resistor layer 25 may be formed by forming chromium, copper, tungsten, aluminum, platinum, titanium, or the like by a technique such as sputtering, and patterning them by photolithography etching.
[0057]
For example, a temperature sensor such as a thermistor 31 may be installed in the ion generating head 20 at an appropriate location as shown in FIG. 3A or 3B, for example, so that the heating temperature can be constantly monitored. By feeding back the value of this sensor to the temperature control device, correction can be made even if environmental fluctuations or abnormalities occur in the heating element and the heating temperature deviates from a normal range (for example, 50 to 70 ° C.).
[0058]
The resistor layer 25 may be a heating resistor having self-heating controllability.
[0059]
Even when such an ion generation head 20 is used, ozone or NO_XIn this embodiment, the photocatalyst material 40 is added in the vicinity of the discharge site because the generation of such a discharge product is not completely eliminated. The location where the photocatalytic substance 40 is disposed is appropriate, and several examples will be described with reference to FIGS.
[0060]
First, when the coating layer 30 is not provided in the ion generation head 20, the photocatalytic substance 40 is applied to or contained in at least a part of the dielectric layer 23 and the ion generation electrode 24. 4A shows an example in which the photocatalytic substance 40 is applied to a part of the dielectric layer 23, and FIG. 4B shows an example in which the photocatalytic substance 40 is contained in a part of the dielectric layer 23. 4 (c) shows an example in which the photocatalytic substance 40 is contained in the entire dielectric layer 23, and FIG. 4 (d) shows an example in which the photocatalytic substance 40 is applied to a part of the ion generating electrode 24.
[0061]
When the coating layer 30 is provided in the ion generating head 20, the photocatalytic substance 40 is applied to the surface of the coating layer 30 as shown in FIG. Alternatively, as shown in FIG. 5B, the photocatalytic substance 40 is contained in the coating layer 30, or the coating layer 30 itself is made of the photocatalytic substance 40.
[0062]
  Further, as shown in FIG. 6, at least the housing 32 of the ion generating head 20 is used.(Sometimes called a casing)The photocatalytic substance 40 may be disposed on the portion of the ion generating head 20 that faces the ion generating portion.
[0063]
Of course, these methods may be combined so that the most effective decomposition of the discharge product appears.
[0064]
For such a photocatalytic material 40, an n-type semiconductor such as titanium oxide is used. An n-type semiconductor has an action of decomposing ozone when it is exposed to light and contacted with a discharge product, for example, ozone. That is, when an n-type semiconductor such as titanium oxide is irradiated with light having a wavelength corresponding to the band gap, electrons are excited to the conduction band and holes are generated in the valence band. The excited electrons of the n-type semiconductor exert a reducing action, and when a metal is supported, the electrons flow from the valence band to the metal and exert a reducing action there. In this way, by irradiating the n-type semiconductor with light of an appropriate wavelength, the discharge product is reduced and decomposed by the reducing action of the excited electrons.
[0065]
As a substance used as the photocatalytic substance 40, in addition to the above-described titanium oxide, tungsten oxide, zinc oxide, cadmium oxide, tin oxide, indium oxide, silver oxide, manganese oxide, copper oxide, iron oxide, vanadium oxide, niobium oxide, Cadmium oxide, titanium hydroxide, zinc hydroxide, and the like can be used. In particular, titanium oxide is preferable in terms of reaction efficiency, durability, safety, and usable wavelength range. Furthermore, titanium oxide is classified into three types of rutile type, anatase type, and brookite type depending on the crystal structure, but the anatase type structure is optimal because it has a high effect as a photocatalyst.
[0066]
These photocatalytic substances 40 may be a mixture of two or more of the above-mentioned substances, and when Pt, Pd, Rh, Nb and the like are mixed, the photocatalytic action can be further promoted.
[0067]
The photocatalytic substance 40 can be attached by being directly formed on the coating layer by a chemical vapor deposition method, neutralization or hydrolysis of an inorganic metal salt, hydrolysis of a metal alkoxide, a sol-gel method, or the like. Commercially available photocatalyst fine powder can also be attached by adhering onto the coating layer. Furthermore, each member itself can have a photocatalytic action by mixing the photocatalytic substance 40 with the material constituting the coating layer to form each member.
[0068]
Air discharge is accompanied by light emission close to purple. It is known that ultraviolet light is contained in the wavelength range of the purple emission, and the photocatalytic substance 40 is excited by the ultraviolet light, and the discharge product can be decomposed by the photocatalytic substance 40.
[0069]
Next, the operation of the present embodiment will be described. The image forming apparatus 1 has a photocatalyst material 40 in the charging unit 3 using the ion generating head 20, and the photocatalyst material 40 decomposes the discharge product in the vicinity of the discharge portion of the charging unit 3. There is.
[0070]
That is, the photosensitive member 2 that is driven to rotate in the clockwise direction in FIG. 1 is uniformly charged by air discharge in the charging unit 3, and then the photosensitive member 2 is irradiated with a laser modulated with image data by the writing unit 4. An electrostatic latent image is formed, and development is performed by attaching toner to the photosensitive member 2 on which the electrostatic latent image is formed by the developing unit 5. Then, the photosensitive member 2 on which the toner is attached by the developing unit 5 to form a toner image is transferred to the recording paper P conveyed between the photosensitive member 2 and the transfer unit 6 by the air discharge in the transfer unit 6. Since the recording sheet P is charged with a charge opposite to that of the toner at the transfer unit 6, an electrostatic attractive force acts on the photosensitive member 2. After the transfer, the paper separation unit 14 removes the charge on the back surface of the recording paper P to separate the paper from the photoreceptor 2.
[0071]
The recording paper P to which the toner image has been transferred is conveyed to the fixing unit 10, and the toner image on the recording paper P is fixed on the recording paper P by the fixing unit 10, and then discharged onto the paper discharge tray. Then, the photosensitive member 2 on which the toner image is transferred to the recording paper by the transfer unit 6 is further rotated, and the charge of the residual toner remaining on the photosensitive member 2 is removed by air discharge in the toner discharging unit 9. The toner remaining on the surface of the photoreceptor 2 is scraped off and removed by the blade 13 in the cleaning unit 7, and then the charge is eliminated by the photoreceptor neutralization unit 8.
[0072]
In such an image formation process, when using air discharge, ozone, NO_xSuch a discharge product is generated.
[0073]
The photocatalytic substance 40 is activated and exerts a reducing action when irradiated with light emitted by air discharge as described above, and thus ozone or NO._xDecompose discharge products such as
[0074]
Therefore, the discharge product generated in the ion generating head 20 by the air discharge is efficiently decomposed by the photocatalytic substance 40 in the vicinity of the ion generating head 20. As a result, it is possible to prevent, for example, ozone from oxidizing the surface of the photoreceptor 2 and deteriorating the image, and preventing ozone from flowing out of the image forming apparatus 1 and deteriorating the environment. be able to. NO_xAs a result, it is possible to prevent the nitric acid and nitrate from adhering to the surface of the photoconductor 2 and to prevent image flow in a high humidity environment. Furthermore, it becomes difficult for nitric acid and nitrate to adhere to each other over time, and discharge unevenness in a low humidity environment can be prevented.
[0075]
  Thus, according to the present embodiment, by arranging the photocatalytic substance 40 in the ion generating head 20, ozone, NO_xSince decomposition takes place very close to the production site, it is very efficient. Moreover, since the ultraviolet rays are also generated from the ion generation head 20, the decomposition efficiency is improved. As a result, the discharge product can be decomposed before flowing out of the casing 32, and adverse effects on the photoreceptor 2 and the like can be prevented and adverse effects on the environment can be suppressed. Further, contamination of the ion generating head 20 due to nitric acid and nitrate as one of the discharge products and adhesion to the surface of the photoconductor 2 are suppressed, thereby preventing uneven charging and image flow on the photoconductor 2. Furthermore, a cleaning device for the ion generating head 20 is not required, and it is possible to significantly reduce costs and maintenance. The number of parts is reduced. Further, it is not necessary to scrape the surface of the photosensitive member by the photosensitive member cleaning blade, the blade life is prolonged by reducing the pressing pressure, the deterioration is prevented, and the toner is not fixed to the photosensitive member 2 due to the strong pressing pressure. As a result, the thickness of the photosensitive member 2 does not decrease with time, and the process control load can be reduced and the life of the photosensitive member 2 can be extended. Furthermore, on the ion generation head 20Nitric acid, nitrateWhen the ion generating head 20 is used for a long time, the discharge becomes uneven and the charge becomes nonuniform, but the photocatalytic substance 40 should be disposed. Is formed on the ion generating head 20Nitrate compoundsThe generation of ions can be suppressed, and thereby the life of the ion generating head 20 can be extended.
[0076]
In the present embodiment, the photocatalytic substance 40 is activated using light generated in the discharge part to decompose the discharge product. However, the decomposition efficiency of the discharge product by the photocatalytic substance 40 is improved. In order to achieve this, a lamp 50 as a light emitter that emits light including a wavelength that excites the photocatalytic substance 40 may be provided (see FIG. 7).
[0077]
As this lamp 50, for example, an n-type semiconductor as the photocatalytic substance 40 is TiO 2.₂In this case, it is only necessary to include a wavelength of 400 nm or less, and a normal fluorescent lamp, a halogen lamp, or the like can be used. If an ultraviolet lamp is used, the effect can be further improved.
[0078]
In addition, when the n-type semiconductor photocatalytic substance 40 is coated on the surface of the lamp 50, the photocatalytic substance 40 coated on the lamp 50 is excited, and the discharge products that have come into contact with the lamp 50 can be decomposed.
[0079]
When the lamp 50 is provided in this manner, even when there is no light emission due to discharge, the photocatalytic substance 40 attached to the member can be activated by the light of the lamp 50 to decompose the discharge product. Decomposition efficiency can be improved.
[0080]
When the lamp 50 is provided in the charging unit 3 as in the present embodiment, it is conceivable that the photosensitive member 2 is not charged by the light irradiation of the lamp 50. For this reason, the lamp 50 of the charging unit 3 is lit, irradiated with light, and ozone is decomposed only during standby when image forming processing is not performed.
[0081]
However, the lamp may be turned on at any timing as long as the light emitted from the lamp 50 does not reach the photoreceptor 2. During the image forming process, that is, when a discharge occurs in the charging unit 3, most discharge products are generated. Therefore, it is preferable that the lamp 50 of the charging unit 3 is lit to perform light irradiation even during the image forming process. FIG. 7 shows a configuration example of the lamp 50 arranged with directivity in this way.
[0082]
Here, in order to verify the effect of the photocatalytic substance 40 as described above, the following comparative experiment was performed. First, an ion generator coated with titanium oxide and an uncoated one were prepared. The device alone was set in a laboratory environment, an alternating voltage (3.0 kV, 5 kHz) was applied between the induction electrode and the ion generation electrode, and discharge was caused at the ion generation electrode. Then, air 5 mm ahead was sucked from the ion generating electrode where the discharge product was most present. Ozone and NO in the sucked air_x(Ozone measuring device: DY1500 manufactured by Direc Co., NO._xMeasuring instrument: HORIBA, APNA300). The measurement was performed continuously for 10 minutes after the discharge became stable, and the average value was obtained.
[0083]
First, ozone and NO in a single ion generator that is not coated with titanium oxide_xWhen the density | concentration of was measured, they were 6.8 ppm and 0.43 ppm.
[0084]
In contrast, in an ion generator coated with titanium oxide, ozone and NO_xThe concentration of was measured. Titanium oxide was applied to the dielectric layer of the ion generator and the inside of the housing. Then, the voltage was applied and the concentration was measured as before. As a result of the measurement, the ozone concentration was 0.75 ppm, NO_xWas 0.080 ppm.
[0085]
Furthermore, ozone and NO can also be applied to the case where an ion generating head coated with titanium oxide is irradiated with an ion generating head with an ultraviolet lamp._xThe concentration of was measured. At this time, the ozone concentration is 0.40 ppm, NO_xWas 0.019 ppm.
[0086]
The verification experiment about the image flow phenomenon was also conducted. First, our copier (imagio MF-4550 modified machine) using an ion generator that does not use the photocatalytic substance according to the present invention as a charger was installed in a high-temperature, high-humidity environment. And about 10,000 copies were made. After the production, the copying machine was stopped, and it was rested overnight in a high temperature and high humidity environment. When the operation was resumed the next morning, a phenomenon called image flow was observed in the copy image. This is the in-flight NO_xReacts with moisture in the air to form nitric acid or nitrate compounds (HNO_Three, NH_FourNO_ThreeThis is probably due to the fact that it has fallen on the photoconductor. This nitric acid / nitrate compound is an insulator at low humidity, but at high humidity it reduces the resistance of the photoreceptor surface. That is, even if an electric charge is applied to the surface of the photoconductor, the surface of the photoconductor cannot maintain the electric charge in its place, so that the electrostatic latent image is destroyed. For this reason, it is considered that image flow occurs.
[0087]
On the other hand, when the ion generator using the photocatalyst material according to the present invention is used in the above-mentioned copying machine manufactured by our company using the charger, the image flow phenomenon does not appear even if the same experiment is performed.
[0088]
【The invention's effect】
  According to the first aspect of the present invention, the photocatalytic substance is activated by the light emission of the discharge and reacts with the discharge product. Therefore, the discharge product generated by the ion generator, particularly ozone and NO._xThus, the discharge product can be decomposed before it flows out of the ion generator, and adverse effects on surrounding members can be prevented and adverse effects on the environment can be suppressed.Moreover, the Joule heat generated by the current flowing through the resistor layer 25 heats the dielectric layer and the ion generation space, further increasing the decomposition effect of the discharge product by the photocatalytic substance.
[0091]
  Claim 2According to the described invention, the discharge product generated in the charging portion can be efficiently decomposed in the generation portion having the highest concentration of the discharge product, and the photocatalytic substance is provided on the surface of the coating layer. Without impairing the function of the layer, the discharge product can be decomposed before flowing out of the casing, thereby preventing adverse effects on the photoreceptor and the like, and suppressing adverse effects on the environment.
[0092]
  Claim 3According to the described invention, in addition to the effect of the invention described in claim 1, since the photocatalyst substance is included in the coating layer, it is not necessary to newly provide a coat layer of the photocatalyst substance. This is advantageous in terms of cost. In addition, when the photocatalytic substance is only on the surface of the coating layer, the function is lost when the coating layer of the photocatalytic substance is peeled off. Even so, the photocatalytic effect can be maintained because it is also contained inside the coating layer.
[0093]
  Claim 4According to the described invention, since the photocatalytic substance can be more strongly activated by the ultraviolet light of a light emitter such as a lamp, the discharge product can be decomposed efficiently, and even when the ion generator does not emit light. Since the photocatalytic substance can be activated by the ultraviolet light of the illuminant, it can be decomposed even when the discharge product remains, thereby more reliably decomposing the discharge product before flowing out of the casing. It is possible to prevent adverse effects on the photoreceptor and the like, and to suppress adverse effects on the environment.
[0094]
  Claim 5According to the described invention, the photocatalytic substance can be more strongly activated by the ultraviolet light of the light emitter such as a lamp, so that the discharge product can be efficiently decomposed, and the photocatalytic substance is disposed on the surface of the light emitter. Therefore, it can prevent that the surface of a light-emitting body gets dirty by adhesion of a discharge product. In addition, when a photocatalytic substance is arranged on the surface of the illuminant, it is possible to activate the photocatalytic substance with the ultraviolet light of the illuminant even when the ion generator is not emitting light, so that discharge generation The thing can be decomposed efficiently. Further, since the surface of the light emitter is not contaminated, the light transmittance on the surface of the light emitter is not lowered. Therefore, the photocatalyst can be irradiated with light over a long period of time, and the photocatalyst can be activated. Thereby, the discharge product can be more reliably decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0095]
  Claim 6According to the described invention, the photocatalytic substance is activated rapidly when irradiated with light of a certain energy or more, and the reaction proceeds. For example, in the case of titanium oxide, the wavelength of light serving as the threshold is 380 nm. If the wavelength of the ultraviolet light to be irradiated is made appropriate and the photocatalytic substance is more easily activated, the decomposition efficiency of the discharge product becomes very high. Thereby, the discharge product can be more reliably decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0096]
  Claim 7According to the described invention, the discharge product can be efficiently decomposed by using the photocatalytic substance made of an n-type semiconductor having high efficiency as the photocatalytic substance. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0097]
  Claim 8According to the described invention, titanium oxide is an n-type semiconductor photocatalytic substance, and is currently said to be the most stable and efficient. Therefore, by using this titanium oxide as a photocatalyst, it is possible to discharge efficiently. The product can be decomposed. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0098]
  Claim 9According to the described invention, titanium oxide containing an anatase type structure in the crystal structure has the highest effect as a photocatalyst, and therefore the discharge product can be efficiently decomposed. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the photoconductor and the like can be prevented, and the adverse effect on the environment can be suppressed.
[0099]
  Claim 10According to the image forming apparatus of the invention described in claim 1,9By using the ion generator according to any one of the above for charging the image carrier, the photocatalytic substance is activated by the light emission of the discharge and reacts with the discharge product. Can be decomposed. As a result, the discharge product can be decomposed before flowing out of the casing, the adverse effect on the image carrier such as the photoconductor can be prevented, and the adverse effect on the environment can be suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention.
2A and 2B show a configuration example of an ion generating head, in which FIG. 2A is a cross-sectional structure diagram, and FIG. 2B is a plan view thereof.
FIG. 3 is a cross-sectional structure diagram of an ion generating head showing an example of addition of a thermistor.
FIG. 4 is a cross-sectional structure diagram of an ion generation head showing an example of addition of a photocatalytic substance when there is no coating layer.
FIG. 5 is a cross-sectional structure diagram of an ion generating head showing an example of addition of a photocatalytic substance when a coating layer is present.
FIG. 6 is a sectional structural view of an ion generating head showing an example of adding a photocatalytic substance to a casing.
FIG. 7 is a configuration diagram showing a case where a lamp is provided.
[Explanation of symbols]
2 Image carrier
3 Charging part
22 Induction electrode
23 Dielectric
24 Ion generating electrode
30 Coating layer
40 Photocatalytic substance
50 illuminant

Claims (10)

At least a dielectric Ri Do induction electrode and the ion generating electrode formed across the, one of the dielectric and the ion generating electrode, an ion generation head photocatalytic material is applied or contained in a portion of at least one In an ion generator that generates an ion by generating an air discharge by applying an AC voltage between the induction electrode and the ion generation electrode, a resistor layer to which a power source is connected is the dielectric. Ion generation characterized by having a casing surrounding the area other than the ion generation space of the ion generation head sandwiched by, and providing a photocatalytic substance for the purpose of decomposing discharge products inside the housing apparatus. 2. The ion generating apparatus according to claim 1, wherein the ion generating electrode is coated with a dielectric and has a photocatalytic substance on at least the surface of the coating layer . 2. The ion generating apparatus according to claim 1, wherein the ion generating electrode is coated with a dielectric, and at least the coating layer is made of a material containing a photocatalytic material . The ion generator according to any one of claims 1 to 3, wherein a light emitter capable of emitting light including at least ultraviolet rays is provided inside the housing . The ion generator according to claim 4, wherein the light emitter has a photocatalytic substance on at least a light emitting surface thereof . 6. The ion generator according to claim 4, wherein light having a wavelength of 300 nm to 400 nm is included in a wavelength of light emitted from the light emitter . The ion generator according to claim 1, wherein the photocatalytic substance is an n-type semiconductor . The ion generator according to claim 7, wherein the n-type semiconductor is titanium oxide . 9. The ion generator according to claim 8 , wherein the titanium oxide includes at least an anatase type crystal structure . An image forming apparatus using the ion generating apparatus according to claim 1 for charging an image carrier.

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