JP2009031607A - Ion generating element, manufacturing method for ion generating element, charging device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion generating element that has a long life, a manufacturing method for the ion generating element, a charging device that has a long life, and an image forming apparatus that has the charging device. <P>SOLUTION: In the ion generating element 21, a discharge electrode 1 is disposed so as to be embedded in a dielectric 4, and the surface of the discharge electrode 1, except for a surface that is in contact with the dielectric 4, is covered with a coating layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is used in an image forming process that is used in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, and that develops an electrostatic latent image formed on an image carrier with toner and transfers and fixes the image onto a print medium. The present invention relates to an ion generating element used, a method for manufacturing the ion generating element, a charging device including the ion generating element, and an image forming apparatus including the charging device.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic method, a charging unit that charges a photosensitive member that is an image bearing member that carries an electrostatic latent image, and a toner image formed on the photosensitive member is a transfer material and an intermediate transfer Charging using a corona discharge system for transfer means for transferring to a recording paper that is a recording medium and recording medium via a transfer belt that is a body, and for peeling means for peeling the recording paper that is electrostatically in contact with the photoreceptor The device is used.

  A charging device disclosed in Patent Document 1 which is such a corona discharge charging device includes a shield case having an opening facing a charged body such as a photoconductor and a transfer belt, a linear discharge surface, and a sawtooth. And a discharge electrode which is in the shape of a needle or is stretched inside the shield case. The charging device disclosed in Patent Document 1 generates a corona discharge by applying a high voltage to a discharge electrode, so as to uniformly charge an object to be charged, so-called corotron, between the discharge electrode and the object to be charged. This is a so-called scorotron in which a grid electrode is provided and a target voltage is applied to the grid electrode to uniformly charge an object to be charged.

  FIG. 10 is a diagram illustrating a charging mechanism in a corona discharge charging device. By applying a high voltage between the discharge electrode 71 having a small curvature radius and the grid electrode 72, an unequal electric field is formed between the two electrodes. As a result, a local ionization effect due to a strong electric field is generated in the vicinity of the discharge electrode 71, electrons are emitted in the direction D toward the charged body 11 (discharge due to electron avalanche), and the charged body 11 is charged. The grid electrode 72 is for controlling the amount of electrons traveling toward the charged body 11, and the grid electrode 72 is also discharged with electrons.

  For example, Patent Documents 2 and 3 disclose that the above-described corona discharge charging device is used as a pre-transfer charging device for charging a toner image before being transferred to a transfer medium such as an intermediate transfer member or recording paper. Has been. According to the techniques disclosed in Patent Documents 2 and 3, even if there is a variation in the charge amount in the toner image formed on the image carrier, the charge amount of the toner image is made uniform before transfer. The toner image can be stably transferred to a transfer medium by suppressing a decrease in transfer margin when transferring the toner.

  However, the above-described conventional charging device has a plurality of problems. The first problem relates to the space where the charging device is arranged. A corona discharge charging device requires not only the discharge electrode 71 but also a shield case, a grid electrode 72, and the like. Further, it is necessary to ensure a relatively large distance between the discharge electrode 71 and the member 11 to be charged (for example, about 10 mm). For this reason, a large space is required for installing the charging device. In an image forming apparatus, around a charging device, a developing unit that supplies toner to an electrostatic latent image formed on the photosensitive member to form a toner image on the photosensitive member, and a toner image formed on the photosensitive member. A primary transfer means for transferring the toner image onto the transfer belt, a recording transfer means for transferring the toner image formed on the transfer belt onto the recording paper, and the like. For this reason, a corona discharge type charging device that requires a relatively large space with a small space for arranging the charging device is difficult to layout.

The second problem relates to a discharge product generated when the charging device charges the member 11 to be charged. In the corona discharge charging device, as shown in FIG. 10, a large amount of discharge products such as ozone (O ₃ ) and nitrogen oxide (NOx) are generated. Specifically, due to the energy accompanying the discharge of electrons emitted from the charging device, nitrogen molecules (N ₂ ) present in the atmosphere dissociate into nitrogen atoms (N), which bind to oxygen molecules (O ₂ ). Thus, nitrogen oxides (nitrogen dioxide: NO ₂ ) are generated. Similarly, oxygen molecules (O ₂ ) present in the atmosphere are dissociated into oxygen atoms (O), which are combined with oxygen molecules (O ₂ ) to generate ozone (O ₃ ). When ozone is produced in a large amount in this way, problems such as generation of ozone odor, harmful effects on the human body, and deterioration of parts due to strong oxidizing power are caused. Further, when nitrogen oxide is generated, the nitrogen oxide adheres to the photoreceptor as an ammonium salt (ammonium nitrate), which causes an abnormal image. In particular, when an organic photoreceptor (OPC) is used as the photoreceptor, image defects such as white spots and image flow are likely to occur due to ozone and nitrogen oxides.

  The third problem relates to the corona wind that is generated when the charging device charges the member 11 to be charged. The corona wind is generated from the discharge electrode 71 toward the charged body 11 by the flow of electrons by corona discharge. When a corona discharge charging device is used as a pre-transfer charging device, the toner image formed on the member 11 to be charged is disturbed by the corona wind.

  Here, as a charging device capable of reducing the generation of discharge products, a contact charging type charging device has been proposed in which a conductive roller or a conductive brush is brought into contact with an object to be charged for charging. However, in this contact charging type charging device, since the conductive roller or conductive brush is brought into contact with the member to be charged, it is difficult to charge the toner image formed on the member to be charged without disturbing it. . Therefore, it is inappropriate to use a contact charging type charging device as a pre-transfer charging device.

  Patent Document 4 discloses a corona discharge charging device that can reduce the generation of discharge products. The charging device disclosed in Patent Document 4 includes a plurality of discharge electrodes arranged in a predetermined axial direction at a substantially constant pitch, a high-voltage power supply for applying a voltage higher than a predetermined discharge start voltage to the discharge electrodes, A resistor installed between the output electrode and the discharge electrode of the high-voltage power supply, a grid electrode installed near the discharge electrode and between the discharge electrode and the charged object, and a predetermined grid voltage on the grid electrode And a gap between the discharge electrode and the grid electrode is set to 4 mm or less. Thus, by reducing the gap between the discharge electrode and the grid electrode, the discharge current is reduced, and the generation of discharge products can be reduced.

  However, in the charging device disclosed in Patent Document 4, it cannot be said that the effect of reducing the generation of discharge products is sufficient, and ozone of about 0.3 ppm is generated. Further, in the charging device disclosed in Patent Document 4, since the gap between the discharge electrode and the grid electrode is small, foreign matters such as discharge products, toner, and paper dust derived from recording paper as a transfer material adhere to the discharge electrode. It's easy to do. The foreign matter adhering to the discharge electrode is difficult to remove (clean) because the discharge surface of the corona discharge type discharge electrode has a complicated shape such as a needle shape. In addition, the tip of the discharge electrode is easily worn and deteriorated by the discharge energy, so that the discharge by the discharge electrode becomes unstable. Further, in the charging device disclosed in Patent Document 4, since the object to be charged is arranged in a state where the distance from the discharge electrode is small, the longitudinal direction (a plurality of discharge electrodes are arranged due to the pitch of the plurality of discharge electrodes). Variation in the charging direction). Although it is conceivable to reduce the pitch of the discharge electrodes in order to eliminate the charging variation, in that case, the number of discharge electrodes increases and the manufacturing cost increases.

Therefore, Patent Documents 5, 6, and 7 disclose a creeping discharge type ion generating device and a charging device. In a creeping discharge type ion generator or charging device, a discharge electrode and an induction electrode are arranged to face each other through a dielectric, and an ion generating element that generates ions by applying a pulse waveform voltage between the two electrodes (Creeping discharge element). In a creeping discharge type ion generator or charging device, a charged body is disposed opposite to the induction electrode so as to face the discharge electrode, and the charged body is charged by the generated ions.
Japanese Patent Laid-Open No. 6-11946 (Publication date: January 21, 1994) JP 10-274892 A (publication date: October 13, 1998) JP 2004-69860 A (publication date: March 4, 2004) JP-A-8-160711 (publication date: June 21, 1996) JP 2000-173744 A (publication date: June 23, 2000) JP 2003-327416 A (publication date: November 19, 2003) JP 2005-50590 A (publication date: February 24, 2005)

  The creeping discharge charging device does not require the shield case, grid electrode, or the like of the corona discharging charging device. Therefore, the space for arranging the charging device can be set relatively small. Further, in the creeping discharge type charging device, the discharge electrode is formed in a plate shape, and the discharge surface is flat. Therefore, when a foreign substance adheres to the discharge electrode, the foreign substance can be easily cleaned. Further, in the creeping discharge type charging device, since a discharge is generated between the discharge electrode and the induction electrode, no corona wind is generated. Therefore, the toner image formed on the member to be charged can be prevented from being disturbed by the corona wind.

  However, in the above-described conventional creeping discharge type charging device, defects such as uneven thickness, pinholes, voids, cracks, etc. are likely to occur in the coating layer covering the discharge electrode, and the coating layer is thin or defective. There is a problem that the life is short (durability is low), such as excessive discharge of the metal, and deterioration of this portion is promoted, and the discharge current is rapidly lowered or the discharge electrode is disconnected.

  In view of the above problems, an object of the present invention is to provide an ion generating element having a long life (durable), a method for manufacturing the ion generating element, a charging device having a long life, and an image forming apparatus including the charging device. That is.

  In the ion generating element of the present invention, in order to solve the above problems, the discharge electrode and the induction electrode are provided to face each other with a dielectric interposed therebetween, and a potential difference is provided between the discharge electrode and the induction electrode. An ion generating element that generates ions in accordance with creeping discharge when a voltage is applied, wherein the discharge electrode is embedded in the dielectric and disposed on a surface other than the surface in contact with the dielectric Is covered with a coat layer.

  According to the above configuration, since the discharge electrode is buried in the dielectric, the coat layer on the discharge electrode is formed more uniformly and thicker than when the discharge electrode is exposed on the dielectric. be able to. Therefore, the discharge electrode can be appropriately coated, discharge unevenness can be reduced, and ions can be generated uniformly and stably. In addition, a decrease in discharge current, disconnection of the discharge electrode, and the like can be suppressed, and the life of the ion generating element can be lengthened.

  Moreover, in the ion generating element of this invention, in addition to the said structure, the said coating layer may be formed from the several layer. Thus, a more uniform coat layer can be formed because the coat layer is formed of a plurality of layers.

  In the method of manufacturing an ion generating element of the present invention, the discharge electrode and the induction electrode are provided to face each other with a dielectric interposed therebetween, and a voltage is applied so as to give a potential difference between the discharge electrode and the induction electrode. A method of manufacturing an ion generating element that generates ions in accordance with creeping discharge, wherein the discharge electrode is buried in the dielectric and disposed, and the discharge electrode is disposed after the buried step. And a coating treatment step of covering a surface other than the surface in contact with the dielectric with a coat layer.

  According to the above method, since the discharge electrode is buried and disposed inside the dielectric, the coat layer on the discharge electrode is formed more uniformly and thicker than when the discharge electrode is exposed on the dielectric. Can do. Therefore, the discharge electrode can be appropriately coated, discharge unevenness can be reduced, and ions can be generated uniformly and stably. In addition, a decrease in discharge current, disconnection of the discharge electrode, and the like can be suppressed, and the life of the ion generating element can be lengthened.

  Moreover, in addition to the said method, the manufacturing method of an ion generating element may perform a coating process in multiple times in the said coating process process. Thus, a more uniform coat layer can be formed by performing the coating treatment a plurality of times under different conditions.

  In the coating process, a plurality of types of coating processes may be performed. Thus, a more uniform coat layer can be formed by performing a plurality of types of coating processes.

  The charging device of the present invention includes any one of the ion generating elements described above, and a voltage applying unit that applies a voltage so as to give a potential difference between the discharge electrode and the induction electrode.

  According to the above configuration, since any one of the ion generating elements of the present invention is provided, the object to be charged can be charged stably and efficiently, the generation of discharge products is small, and the life is long. A charging device can be provided.

  The image forming apparatus of the present invention is characterized in that the charging device is provided as a charging device for charging the electrostatic latent image carrier.

  By using the charging device of the present invention as a device for charging the electrostatic latent image carrier, the electrostatic latent image carrier can be appropriately charged, the generation of discharge products is small, and the life is long. Can be provided.

  The image forming apparatus of the present invention is characterized in that the charging device is provided as a charging device for pre-transfer charging that applies a charge to the toner carried on the carrier.

  By using the charging device of the present invention, it is possible to appropriately and appropriately charge the toner before transfer, and it is possible to improve transfer efficiency and transfer uniformity.

  In the ion generating element of the present invention, as described above, the discharge electrode is arranged so as to be buried in the dielectric, and the surface other than the surface in contact with the dielectric is covered with the coat layer.

  According to the above configuration, since the discharge electrode is buried in the dielectric, the coat layer on the discharge electrode is formed more uniformly and thicker than when the discharge electrode is exposed on the dielectric. be able to. Therefore, the discharge electrode can be appropriately coated, discharge unevenness can be reduced, and ions can be generated uniformly and stably. In addition, a decrease in discharge current, disconnection of the discharge electrode, and the like can be suppressed, and the life of the ion generating element can be lengthened.

Embodiment
Hereinafter, an embodiment of an ion generating element, a charging device, and an image forming apparatus including the same according to the present invention will be specifically described with reference to FIGS. The following embodiments are examples embodying the present invention, and do not limit the technical scope of the present invention.

  First, the ion generating element and the charging device in the present embodiment will be described. FIG. 2 is a diagram illustrating a configuration of the charging device 100 according to the embodiment of the present invention. 3 is a diagram showing the configuration of the ion generating means 20 having the ion generating element 21, FIG. 3 (a) is a side view of the ion generating means 20, and FIG. 3 (b) is a front view of the ion generating means 20. It is.

  The charging device 100 charges the object to be charged 11 which is an object to be charged. When a toner image is formed on the member 11 to be charged, the toner 12 on the member 11 is charged. As shown in FIG. 2, the charging device 100 includes an ion generating unit 20, a counter electrode 3, and a voltage control unit 10.

  The ion generating means 20 applies a voltage to the ion generating element 21 including the dielectric 4, the discharge electrode 1, the induction electrode 2, and the coat layer (protective layer) 6, and the discharge electrode 1 or (and) the induction electrode 2. Discharge voltage application means 7 is provided. The ion generating means 20 gives a potential difference between the discharge electrode 1 and the induction electrode 2 by the discharge voltage applying means 7, and generates a corona (corona generated in the creeping direction of the dielectric 4 near the discharge electrode 1). Ions are generated by discharge.

  The dielectric 4 is formed in a flat plate shape by bonding a substantially rectangular upper dielectric 4a and a lower dielectric 4b. As a material constituting the dielectric 4, a material excellent in oxidation resistance is suitable as long as it is organic. For example, a resin such as polyimide or glass epoxy can be used. When an inorganic material is selected as the material constituting the dielectric 4, mica, high-purity alumina, crystallized glass, forsterite and steatite, low-temperature co-sintered ceramics that is a composite material of glass and alumina (Low Temperature Co) Ceramics such as -fired Ceramic (LTCC) can be used. In view of corrosion resistance, the material constituting the dielectric 4 is preferably an inorganic material, and ceramic is used in consideration of formability, ease of electrode formation described later, low moisture resistance, and the like. It is preferable to mold. In addition, since it is desirable that the insulation resistance between the discharge electrode 1 and the induction electrode 2 is uniform, the density variation inside the material of the dielectric 4 is small, and the insulation rate of the dielectric 4 is more uniform. It is.

  The discharge electrode 1 is formed integrally with the upper dielectric 4a on the surface of the upper dielectric 4a. Any material can be used for the discharge electrode 1 as long as it has conductivity, such as tungsten, silver, silver palladium, and stainless steel. However, it is a condition that it does not cause deformation such as melting or scattering by electric discharge. In this embodiment, the discharge electrode 1 is disposed so as to be buried in the dielectric 4 (upper dielectric 4a). Thus, when the discharge electrode 1 is arrange | positioned inside the top dielectric 4a, it is preferable to arrange | position so that the depth of the discharge electrode 1 from the surface of the top dielectric 4a may become uniform. In this embodiment, the discharge electrode 1 is comprised with the material which consists of silver palladium. As long as the shape of the discharge electrode 1 extends in a direction perpendicular to the moving direction of the charged body 11 moving between the ion generating element 21 and the counter electrode 3 and is along the surface of the charged body 11, The shape may also be However, if the discharge electrode 1 has a shape in which electric field concentration with the induction electrode 2 is likely to occur, for example, in a comb shape, even if the voltage applied between the discharge electrode 1 and the induction electrode 2 is low, the above-mentioned Such a shape is desirable because it is discharged between both electrodes. In the present embodiment, as shown in FIG. 3B, the periphery of the discharge electrode 1 has a comb shape having a plurality of tip portions, and discharge is likely to occur.

  The induction electrode 2 is formed inside the dielectric 4 (between the upper dielectric 4a and the lower dielectric 4b), and is disposed to face the discharge electrode 1 with the dielectric 4 interposed therebetween. The induction electrode 2 is arranged in this way, since the insulation resistance between the discharge electrode 1 and the induction electrode 2 is preferably uniform, and therefore it is desirable that the discharge electrode 1 and the induction electrode 2 be parallel. Because. By disposing the discharge electrode 1 and the induction electrode 2 in this way, the distance between the discharge electrode 1 and the induction electrode 2 (distance between the electrodes) becomes constant, so that the discharge between the discharge electrode 1 and the induction electrode 2 is performed. The state is stable and ions can be suitably generated. Here, the discharge electrode 1 and the induction electrode 2 are provided to face each other with the upper dielectric 4a interposed therebetween.

  The induction electrode 2 can be provided on the back surface of the dielectric 4 (surface opposite to the surface on which the discharge electrode 1 is disposed) with the dielectric 4 as one layer. In other words, in this case, the discharge electrode 1 and the induction electrode 2 are provided to face each other with a single-layer dielectric interposed therebetween. In this case, a sufficient creepage distance with respect to the voltage applied to the discharge electrode 1 is prevented in order to prevent the current flowing through the discharge electrode 1 when the voltage is applied from flowing through the dielectric 4 to the induction electrode 2. It is necessary to ensure or to cover the discharge electrode 1 or the induction electrode 2 with an insulating coat layer 6 described later.

  As the material of the induction electrode 2, as in the case of the discharge electrode 1, any material having conductivity such as tungsten, silver, silver palladium, and stainless steel can be used without particular limitation. In the present embodiment, the induction electrode 2 is made of a material made of silver palladium. When the shape of the induction electrode 2 is formed so that the edge of the discharge electrode 1 has a sawtooth shape having a plurality of sharpened portions as shown in FIG. 3B, the portion facing the sharpened portion of the discharge electrode 1 In this case, the shape of the induction electrode 2 is such that the top surface of the induction electrode 2 is U-shaped.

  The discharge voltage applying means 7 includes an AC high voltage power source that applies a voltage to the discharge electrode 1 and / or the induction electrode 2, and a voltage application circuit that becomes a circuit through which a current flows when a voltage is applied by the AC high voltage power source. Consists of. For example, when both the discharge electrode 1 and the induction electrode 2 are connected to a voltage application circuit, the AC high-voltage power supply applies a voltage to both the discharge electrode 1 and the induction electrode 2. In addition, when the induction electrode 2 is connected to the ground to have a ground potential and the discharge electrode 1 is connected to the voltage application circuit, the AC high-voltage power supply applies a voltage only to the discharge electrode 1. In addition, when the discharge electrode 1 is connected to the ground to have a ground potential and the induction electrode 2 is connected to the voltage application circuit, the AC high-voltage power supply applies a voltage only to the induction electrode 2. In the present embodiment, the discharge voltage applying means 7 applies a voltage only to the discharge electrode 1. When the discharge voltage applying means 7 applies a voltage to the discharge electrode 1 while the induction electrode 2 is grounded, creeping discharge occurs in the vicinity of the discharge electrode 1 based on the potential difference between the discharge electrode 1 and the induction electrode 2. . By this creeping discharge, air existing around the discharge electrode 1 is ionized, and negative ions are generated.

  The ion generating means 20 is preferably provided with a heating means for heating the dielectric 4, and the induction electrode 2 may also serve as the heating means. In the present embodiment, the induction electrode 2 is formed such that the shape of the top surface of the induction electrode 2 is U-shaped. One end of the induction electrode 2 is connected to the heater power source 9 and the other end is grounded. When a predetermined voltage (for example, 10 V) is applied to the induction electrode 2 by the heater power source 9, the induction electrode 2 generates heat due to Joule heat. As the induction electrode 2 generates heat in this way, the dielectric 4 is heated (for example, 60 ° C.). As the temperature of the dielectric 4 rises, moisture absorption of the dielectric 4 can be suppressed. Therefore, ions can be stably generated even in a high humidity environment. When the dielectric 4 is ceramic, the dielectric 4 itself does not absorb moisture. However, if the surface of the dielectric 4 is condensed, the discharge characteristics are deteriorated. Therefore, the heat generated by the heater prevents condensation or eliminates condensation. Is valid.

  The coat layer (protective layer) 6 is formed on the dielectric 4 so as to cover the discharge electrode 1. Coat layer 6 is formed of, for example, alumina (aluminum oxide), glass, silicon, or the like. By providing such a coat layer 6, it is possible to prevent a current flowing through the discharge electrode 1 to which a voltage has been applied from flowing through the dielectric 4 to the induction electrode 2, and the discharge electrode 1 and the induction electrode 2. And insulation can be maintained. Further, since the coat layer 6 is formed so as to cover the discharge electrode 1, it is possible to prevent the discharge electrode 1 from being worn or deteriorated by the discharge energy when a voltage is applied to the discharge electrode 1.

  In the present embodiment, the discharge electrode 1 is arranged buried in the dielectric 4 (upper dielectric 4 a), and the surface other than the surface in contact with the dielectric 4 is covered with the coat layer 6. As described above, since the discharge electrode 1 is disposed so as to be buried in the dielectric 4, the coat layer 6 on the discharge electrode 1 is more uniform than when the discharge electrode 1 is exposed on the dielectric 4. In addition, it can be formed thick. Therefore, the discharge electrode 1 can be appropriately coated, discharge unevenness can be reduced, and ions can be generated uniformly and stably. Moreover, the fall of discharge current, the disconnection of the discharge electrode 1, etc. can be suppressed, and the life of the ion generating element 21 can be lengthened.

  Below, the manufacturing method of the ion generating element 21 in this embodiment is demonstrated. However, the manufacturing method of the ion generating element 21 is not limited to the following methods and numerical values. First, a green sheet made of LTCC having a thickness of 0.2 mm and a thickness of 0.7 mm is cut into, for example, a width of 400 mm × a length of 400 mm, and an upper dielectric 4a having a thickness of 0.2 mm and a lower portion having a thickness of 0.7 mm. The dielectric 4b is created. Next, the discharge electrode 1 made of silver palladium is formed by screen printing on the upper surface of the upper dielectric 4a, and the discharge electrode 1 is integrated with the upper dielectric 4a. Similarly, the induction electrode 2 made of silver palladium is formed by screen printing on the upper surface of the lower dielectric 4b, and the induction electrode 2 is integrated with the lower dielectric 4b. The final size of the ion generating element 21 is 8 mm × 356 mm, and a plurality of ion generating elements 21 are formed in one green sheet (in this embodiment, 14 from one green sheet). The ion generating element 21 is obtained.

  Next, the lower surface of the upper dielectric 4a and the upper surface of the lower dielectric 4b are overlapped so that the discharge electrode 1 and the induction electrode 2 face each other via the upper dielectric 4a, and then crimped using a press jig ( Hot water isostatic pressing (WIP) is performed. Then, a coat layer 6 is formed on the surface of the upper dielectric 4 a on which the discharge electrode 1 is formed so as to cover the discharge electrode 1. Next, the cut | interruption half-cut is formed with respect to the laminated | stacked green sheet with the metal mold | die match | combined with the external shape of several ion generating element. Then, these are put into a heating furnace and baked at 800 to 900 ° C. in a non-oxidizing atmosphere. Finally, the plurality of ion generating elements 21 are separated along the half cut.

  As described above, the ion generating element 21 in which the discharge electrode 1 and the induction electrode 2 are arranged to be opposed to each other via the upper dielectric 4a and integrated can be produced.

  Thereafter, the ion generating means 20 can be manufactured by connecting the discharge voltage applying means 7 to the discharge electrode 1 and connecting the heater power source 9 to the induction electrode 2 as the ion generating means 20.

  The counter electrode 3 is disposed to face the discharge electrode 1 of the ion generating means 20 and controls the flow of ions generated by the ion generating means 20. As the material constituting the counter electrode 3, any material can be used without particular limitation as long as it has conductivity, such as carbon steel plate, aluminum, and stainless steel. In the present embodiment, the counter electrode 3 is made of a material made of stainless steel and is formed in a plate shape. A counter voltage applying means 8 is connected to the counter electrode 3. The counter voltage application means 8 includes a counter electrode power source for applying a voltage to the counter electrode 3. The counter electrode 3 is connected to the ground via a counter electrode power source, and is configured such that a predetermined voltage is applied from the counter electrode power source. The counter voltage applying unit 8 applies a voltage having a polarity opposite to the voltage applied to the discharge electrode 1 by the discharge voltage applying unit 7 to the counter electrode 3. By configuring the counter electrode 3 in this way, ions generated in the vicinity of the discharge electrode 1 of the ion generating means 20 flow toward the counter electrode 3. Such a counter voltage applying means 8 is arranged to make ions generated in the vicinity of the discharge electrode 1 more easily directed in the direction of the charged body, and is not necessarily required and may be omitted. it can.

  When charging the charged body 11 in the charging device 100, the charged body 11 is disposed between the discharge electrode 1 and the counter electrode 3 of the ion generating means 20, and is in close contact with the counter electrode 3. Opposed to each other. When the discharge voltage applying means 7 applies a voltage to the discharge electrode 1 with the charged body 11 arranged as described above, a discharge occurs between the discharge electrode 1 and the induction electrode 2, and the discharge electrode 1 is near the discharge electrode 1. Creeping discharge occurs. As described above, since the discharge is generated between the discharge electrode 1 and the induction electrode 2, it is possible to prevent the generation of corona wind as in the conventional corona discharge charging device.

  Ions generated by ionizing the air around the discharge electrode 1 by creeping discharge flow in a direction toward the counter electrode 3 (in the direction of arrow A in FIG. 2), and charge the charged object 11. The ions generated by the ion generating means 20 flow toward the counter electrode 3 to charge the object 11 to be charged, so that the ions can be prevented from staying in the vicinity of the discharge electrode 1. Therefore, it is possible to prevent the amount of ions used for charging the charged body 11 from being reduced with respect to the amount of ions generated by the ion generating means 20, and to improve the use efficiency of ions. Therefore, as will be described in detail later, the ion generating means 20 can generate an amount of ions necessary for charging the charged body 11 while the applied voltage applied to the discharge electrode 1 is relatively small. As a result, the amount of discharge products such as ozone can be reduced.

  The voltage control means 10 includes a counter electrode ammeter 22 that measures the amount of current flowing through the counter electrode 3. The counter electrode ammeter 22 is connected to the counter electrode 3. As will be described in detail later, the voltage control means 10 discharges the discharge voltage so that the amount of current flowing through the counter electrode 3 is equal to or greater than the amount of current flowing through the counter electrode 3 when the charge amount of the charged body 11 reaches the saturation amount. The magnitude of the voltage applied by the applying means 7 or (and) the counter voltage applying means 8 is feedback-controlled. The amount of ions generated by the ion generating means 20 varies depending on the adhesion of foreign matter to the discharge electrode 1, environmental conditions for generating ions, and the like. In addition, the rate at which the generated ions reach the charged body 11 varies due to changes in the flow of wind in the vicinity of the discharge electrode 1 and the charged body 11. For this reason, the charged amount of the charged body 11 may not always be the same even if the voltage applied to the discharge electrode 1 is kept constant. Therefore, since there is a correlation between the amount of charge of the body 11 to be charged and the amount of current flowing through the counter electrode 3, the amount of current flowing through the counter electrode 3 is used as an index for controlling the amount of charge of the body 11 to be charged. Based on the above, the magnitude of the voltage applied to the discharge electrode 1 is feedback controlled. As a result, the optimum ion amount can always be imparted to the charged body 11.

  Next, an image forming apparatus having the charging device 100 will be described. FIG. 4 is a cross-sectional view illustrating a schematic configuration of the image forming apparatus 200 of the present embodiment. The image forming apparatus 200 is a so-called tandem and intermediate transfer type printer, and can form a full-color image.

  As shown in FIG. 4, the image forming apparatus 200 includes visible image forming units 30 a to 30 d, a transfer unit 40, and a fixing unit 50.

  Four visible image forming units 30a to 30d are provided to correspond to image information of each color of cyan (C), magenta (M), yellow (Y), and black (K) included in the color image information. The four visible image forming units 30a, 30b, 30c, and 30d have the same configuration except that the color of the toner used is different, and cyan (C), magenta (M), yellow (Y), and black ( K) toner is used. Hereinafter, only the visible image forming unit 30a will be described, and description of the other visible image forming units 30b to 30d will be omitted. Accordingly, only members in the visible image forming unit 30a are shown in FIG. 4, but the other visible image forming units 30b to 30d also have the same members as the visible image forming unit 30a. The visible image forming unit 30 a includes a photoconductor (electrostatic latent image carrier) 31, a latent image pre-charging unit 110, a developing unit 32, a pre-intermediate transfer charging unit 120, and a photoconductor cleaning unit 33.

  The photoconductor 31 is an image carrier that carries an electrostatic latent image corresponding to image information transmitted from the outside. The photoconductor 31 is supported by a driving unit (not shown) so as to be rotatable around an axis, and has a cylindrical shape (not shown). And a photosensitive layer formed on the surface of the conductive substrate. The photoconductor 31 rotates at a predetermined peripheral speed (for example, 167 to 225 mm / s) during image formation. The electrostatic latent image formed on the photoconductor 31 is formed by irradiating (exposing) laser light by laser writing means (not shown) in accordance with image information transmitted from the outside. As the photoreceptor 31, those commonly used in this field can be used. For example, a photoreceptor drum including an aluminum base tube which is a conductive substrate and an organic photosensitive layer formed on the surface of the aluminum base tube is used. . The organic photosensitive layer is formed by laminating a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. The organic photosensitive layer may include a charge generation material and a charge transport material in one layer.

  The latent image pre-charging unit 110 is for charging the surface of the photoconductor 31 before being irradiated with laser light by the laser writing unit to a predetermined potential. In this embodiment, the charging device 100 described above is used as the charging unit 110 before forming a latent image, and the photosensitive member 31 is charged by emitted ions, as will be described in detail later.

  The developing means 32 supplies toner to the electrostatic latent image formed on the photoconductor 31 and visualizes the electrostatic latent image to form a toner image. The developing means 32 includes a developing roller that supplies toner to the photoreceptor 31, a layer thickness regulating member that regulates the thickness of the toner layer formed on the outer peripheral surface of the developing roller, an agitation supply roller that supplies toner to the developing roller, and the like It is comprised including.

  The pre-intermediate transfer charging unit 120 is a unit that charges the toner image formed on the surface of the photoreceptor 31 before transfer. In the present embodiment, the charging device 100 described above is used as the pre-intermediate transfer charging unit 120. As will be described in detail later, the toner image is charged by the released ions.

  The photoconductor cleaning means 33 removes and collects from the surface of the photoconductor 31 toner that has not been transferred from the photoconductor 31 to the transfer belt 41 by the transfer operation, that is, residual toner.

  A latent image pre-charging unit 110, a laser writing unit, a developing unit 32, and an intermediate pre-transfer charging unit 120 are provided around the photoconductor 31 from the upstream in the rotation direction of the photoconductor 31 (the direction of arrow B in FIG. 4). The devices are arranged in the order of the photoconductor cleaning means 33. Four visible image forming units 30 a to 30 d corresponding to the respective colors are arranged along the transfer belt 41.

  The transfer means 40 superimposes and transfers the toner image of each color formed by being developed on the photoreceptor 31 onto the transfer belt 41, and the toner image transferred to the transfer belt 41 is a recording paper 60 as a recording medium. Is to be retransferred. The transfer unit 40 includes a transfer belt 41, four intermediate transfer units 42 a to 42 d arranged around the transfer belt 41, a pre-recording charging unit 130, a recording transfer unit 43, and a transfer cleaning unit 44. Yes.

  The transfer belt 41 is an intermediate transfer body onto which toner images of respective colors visualized by the visible image forming units 30a to 30d are transferred in a superimposed manner. Specifically, the transfer belt 41 is an endless belt, is stretched by a pair of driving rollers and idling rollers, and has a predetermined peripheral speed (for example, 167 to 225 mm / s) during image formation. It is controlled and transported.

  The intermediate transfer means 42a to 42d are provided for each of the visible image forming means 30a to 30d, and a toner image is applied by applying a bias voltage having a polarity opposite to that of the toner image formed on the surface of the photoreceptor 31. Is transferred to the transfer belt 41. Each of the intermediate transfer units 42 a to 42 d includes an intermediate transfer roller that is driven to rotate about an axis, and the intermediate transfer roller is disposed to face the photoreceptor 31 with the transfer belt 41 interposed therebetween.

  The pre-recording transfer charging unit 130 recharges the toner image superimposed and transferred on the transfer belt 41. The charging device 100 described above is used, and the details will be described later. Charge the image.

  The recording transfer unit 43 is a unit that retransfers the toner image transferred to the transfer belt 41 to the recording paper 60. The recording transfer means 43 includes two recording transfer rollers that are driven to rotate around an axis, and is configured to sandwich the transfer belt 41 between the two recording transfer rollers. The recording paper 60 fed onto the transfer belt 41 from a paper feeding means (not shown) passes through the pressure contact portions of the two recording transfer rollers, whereby the toner image is transferred to the recording paper 60. The transfer cleaning unit 44 is for cleaning the surface of the transfer belt 41 after the toner image is transferred to the recording paper 60. Around the transfer belt 41, from the upstream with respect to the rotation direction of the transfer belt 41 (in the direction of arrow C in FIG. 4), intermediate transfer means 42a to 42d, pre-recording transfer charging means 130, recording transfer means 43, transfer Each device is arranged in the order of the cleaning means 44.

  The fixing unit 50 is a unit that fixes the toner image transferred to the recording paper 60 to the recording paper 60. The fixing unit 50 is disposed downstream of the recording transfer unit 43 in the conveyance direction in which the recording paper 60 is conveyed. The fixing unit 50 includes a heating roller and a pressure roller that are rotationally driven around an axis. A heat source for heating the surface of the heating roller to a fixing temperature is disposed inside the heating roller. At both ends of the pressure roller, a pressure member that presses the pressure roller against the heating roller with a predetermined pressure is disposed. The fixing unit 50 passes the recording paper 60 onto which the toner image has been transferred through the pressure contact portion between the heating roller and the pressure roller, and heats and melts the toner image with the heating roller, and the recording paper with the toner image with the pressure roller. The toner image is fixed on the recording paper 60 by the throwing action on the recording paper 60. The recording paper 60 on which the recording image is formed in this way is discharged to a paper discharge means (not shown).

  Here, the image forming apparatus 200 includes a latent image pre-charging unit 110, a pre-intermediate transfer charging unit 120, and a pre-recording transfer charging unit 130 configured by the above-described charging device 100. In the latent image pre-charging unit 110, the member to be charged is the photosensitive member 31, and the discharge electrode 1 of the ion generating unit 20 is disposed so as to face the photosensitive member 31. The latent image pre-charging unit 110 is configured such that the photoconductor 31 also serves as a counter electrode. In the latent image pre-charging unit 110, ions generated from the ion generating unit 20 flow in the direction of the photoconductor 31 that also serves as a counter electrode, and charge the surface of the photoconductor 31 rotating around the axis.

  In the pre-intermediate transfer charging unit 120, the charged object that is the object to be charged is a toner image formed on the photoconductor 31, so that the discharge electrode 1 of the ion generating unit 20 faces the photoconductor 31. Be placed. The pre-intermediate transfer charging unit 120 is configured such that the photoconductor 31 also serves as a counter electrode. In the pre-intermediate transfer charging unit 120, ions generated from the ion generation unit 20 flow in the direction of the photoconductor 31 that also serves as a counter electrode, and charge the toner image formed on the photoconductor 31 rotating around the axis. Let

  In the pre-recording transfer charging unit 130, the object to be charged is a toner image formed on the transfer belt 41, and the transfer belt 41 is connected to the discharge electrode 1 and the counter electrode 3 of the ion generating unit 20. And arranged so as to face the discharge electrode 1 in close contact with the counter electrode 3. In the pre-recording transfer charging unit 130, ions generated from the ion generation unit 20 flow in the direction of the counter electrode 3 to charge the toner image formed on the transfer belt 41 moving at a predetermined peripheral speed.

  As described above, in the image forming apparatus 200, the charging unit for charging the toner image formed on the photoconductor 31 as the image carrier and the transfer belt 41 as the intermediate transfer member generates discharge products such as ozone. It is comprised by the charging device 100 which can prevent. Therefore, it is possible to prevent the discharge product from adhering to the photoreceptor 31 and the transfer belt 41. Therefore, when the image forming apparatus 200 forms a recorded image on the recording paper 60, it is possible to prevent occurrence of image defects such as white spots and image flow caused by the discharge products adhering to the photoreceptor 31 or the transfer belt 41. can do. Further, since generation of ozone having a strong oxidizing power is prevented, it is possible to prevent the components constituting the image forming apparatus 200 from being oxidized and deteriorated.

  Further, since the pre-intermediate charging unit 120 and the pre-recording charging unit 130 included in the image forming apparatus 200 are configured by the charging device 100, the generation of corona wind can be prevented. Therefore, it is possible to prevent the toner images formed on the photosensitive member 31 and the transfer belt 41 from being charged in a disordered state. Further, since the pre-intermediate charging unit 120 and the pre-recording charging unit 130 charge the toner image, the charge amount of the toner image can be increased, so that the toner image can be transferred with improved transfer efficiency. it can.

  Further, in the image forming apparatus 200, the charging means for charging the photosensitive member 31 and the transfer belt 41 is configured by the charging device 100 with improved ion utilization efficiency. Therefore, even when the photoconductor 31 and the transfer belt 41 are driven at high speed, the photoconductor 31 and the transfer belt 41 can be sufficiently charged. Therefore, the charging unit constituted by the charging device 100 can be applied to a high-speed image forming apparatus having a high printing processing speed.

〔Example〕
Next, examples and comparative examples using the ion generating element of the present invention will be described. Here, the relationship between the method for producing the coat layer 6 of the ion generating element 21 and its characteristics will be described. First, for the coat layer 6, the following production conditions (parameters) were changed to produce an ion generating element (Examples 1 to 10) and an ion generating element for comparison (Comparative Example 1). Three points of uniformity, image quality uniformity, and durability were evaluated. In addition, each ion generating element was produced with the manufacturing method and size which were demonstrated in the said embodiment.

<Coating layer preparation conditions>
(1) Printing of discharge electrode As described in the above embodiment, the ion generating element 21 is manufactured by pressure bonding (WIP) the upper dielectric 4a and the lower dielectric 4b with a press jig. Here, the discharge electrode 1 is formed on the upper dielectric 4a by screen printing. However, when the discharge electrode 1 is formed after the WIP process, the discharge electrode 1 is formed on the upper dielectric 4a as shown in FIG. It is formed in a state of being exposed from the upper surface. On the other hand, when the WIP process is performed after the discharge electrode 1 is formed, the discharge electrode 1 is buried in the upper dielectric 4a by applying pressure by a press jig as shown in FIG. 1B. . In Examples 1 to 10, the discharge electrode 1 was formed before the WIP process. That is, in Examples 1 to 10, the discharge electrode 1 is formed in a state of being buried in the upper dielectric 4a. In Comparative Example 1, the discharge electrode 1 was formed after the WIP process.

(2) Number of times of coating layer treatment As the number of times of treatment of the coating layer, two types were prepared: one time only and two times. Example 1 and Comparative Example 1 were performed only once, and Examples 2 to 10 were performed twice.

(3) Formation of coat layer As a method for forming the coat layer, formation by screen printing or formation by dipping was performed. In Example 1 and Comparative Example 1, the first coating process is performed by screen printing, and the second coating process is not performed. In Examples 2-8, the coating treatment was performed by screen printing for the first time and the second time. In Example 9, the first coating treatment was performed by screen printing, and the second coating was performed by dipping.

(3) Screen mesh at the time of screen printing As a screen mesh at the time of screen printing, 400 meshes per inch (mesh 400) or 500 meshes per inch (mesh 500) was used. In Examples 1-3, 5-7, 9, 10, and Comparative Example 1, mesh 400 was used for screen printing of the first coating process, and in Examples 4 and 8, screen printing of the first coating process was used. , Mesh 500 was used. In addition, the mesh 400 was used in the second printing process of Examples 2, 4 and 10, and the mesh 500 was used in the second coating process of Examples 3 and 5-8.

(4) Printing direction during screen printing The printing direction during screen printing is the vertical direction when printing in the same direction as the longitudinal direction of the discharge electrode, and the horizontal direction when printing in the same direction as the short direction of the discharge electrode. It was. In the screen printing of the first coating process in Examples 1 to 10 and Comparative Example 1, the vertical direction was used. In the screen printing of the second coating process of Examples 2 to 4, 10, the horizontal direction was used. In the screen printing of the second coating process of Examples 5 to 8, the vertical direction was used.

(5) Coating material In the case of screen printing, the coating material used was the same LTCC as the dielectric 4 made into a paste form with an organic solvent. On the other hand, in the case of dipping, a glass-based coating material having a lower viscosity was used. Specifically, in Example 9, a modified silica-based coating material (trade name: Skymic, variety: HRC-clear-, viscosity 4.8 mPa · s) manufactured by Osaka Organic Chemical Industry Co., Ltd. was used.

  The screen-printed coating layer 6 is fired at the same time as the dielectric 4. However, since the firing temperature of the dipping coating material is as low as 150 to 180 ° C., in Example 9, the dielectric 4 was fired at 850 ° C. Then, it dipped and baked at 150-180 degreeC.

(6) Viscosity of coating material The LTCC paste for screen printing was used by changing the viscosity to three levels (150 Pa · s, 100 Pa · s, 50 Pa · s) by diluting with a solvent. For the screen printing of the first coating process of Examples 1, 9, 10 and Comparative Example 1, those of 150 Pa · s were used. For the screen printing of the first coating process of Examples 2 to 6 and 8, 100 Pa · s was used. For the screen printing of the first coating process in Example 7, 50 Pa · s was used. In addition, 100 Pa · s was used for the screen printing of the second coating process of Examples 2 to 5, 7, 8, and 10. For screen printing of the second coating process in Example 6, 50 Pa · s was used.

  Table 1 below shows a summary of the ion generating elements manufactured under different conditions as described above.

<Evaluation experiment>
(1) Discharge uniformity An evaluation method of discharge uniformity of an ion generating element will be described with reference to FIGS. FIG. 6 is a view showing a measuring apparatus 300 for measuring the discharge distribution of the ion generating element 21, FIG. 6 (a) is a view from above, and FIG. 6 (b) is a view from the front. The measurement apparatus 300 includes a measurement electrode 301, a counter electrode 3, a measurement electrode moving mechanism 302, a motor 303, and an ammeter 304.

  The measurement electrode 301 is a stainless steel electrode having a width of 2 mm and a height of 5 mm (w × h), and is attached to the measurement electrode moving mechanism 302. The measurement electrode moving mechanism 302 includes a ball screw, and is configured to move the measurement electrode 301 by the rotation of the motor 303. The measurement electrode 301 is grounded via an ammeter 304 so that the discharge current flowing into the measurement electrode 301 can be measured.

  Furthermore, a grounded counter electrode 3 made of stainless steel is disposed on the back surface of the measurement electrode 301. Further, the ion generating element 21 is fixed by a holding member (not shown) at a position separated from the measurement electrode 301 by a predetermined interval (g = 5 mm).

  Then, by applying a voltage to the ion generating element 21 and generating ions, the measuring electrode 301 is moved along the longitudinal direction of the ion generating element 21, and the current flowing into the measuring electrode 301 is measured by the ammeter 304. Then, the discharge current distribution in the longitudinal direction of the ion generating element 21 is measured.

  FIG. 7 is a diagram illustrating an example of discharge current distribution data measured using the measurement apparatus 300. From such discharge current distribution data, a variation coefficient (standard deviation ÷ average value) of the discharge current distribution was obtained, and discharge uniformity was evaluated based on the following criteria. A coefficient of variation of 10% or less is “◎”, a coefficient of variation of 10-20% is “◯”, a coefficient of variation of 20-30% is “◯ △”, and a coefficient of variation is 30-40%. Those having a coefficient of variation of 40-60% were evaluated as “Δx”, and those having a coefficient of variation of 60% or more were evaluated as “x”.

(2) Image Quality Uniformity Image quality uniformity was evaluated when each of the ion generating elements produced above was used for the pre-recording transfer charging unit 130. Specifically, the pre-recording transfer charging unit 130 is formed using each of the produced ion generating elements, and the pre-recording transfer charging unit 130 is applied to the Sharp color complex machine MX-4500 which is the image forming apparatus 200. did. In this pre-recording charging means 130, the ion generating element 21 is arranged to face the transfer belt 41 so that the gap g between the discharge electrode and the transfer belt is 5 mm, and the counter electrode 3 is placed on the transfer belt 41. It is disposed so as to be in close contact with the discharge electrode 1 through the transfer belt 41. In this state, a pulsed voltage was applied to the discharge electrode 1 such that a counter electrode current of about 10 μA flows through the counter electrode 3. At this time, in the image forming apparatus 200, a halftone image was printed on the recording paper, and visual evaluation (six levels) was performed on the uniformity of the halftone image on the recording paper. That is, the evaluation is performed by paying attention to the level and the number of white stripes and black stripes that impair the image quality (uniformity) of the halftone image, and “◎”, “O”, “◯ Δ”, “Δ”, “ΔX”, and “×” were used.

(3) Durability A method for evaluating the durability of the ion generating element will be described with reference to FIG. FIG. 8 is a view showing an evaluation apparatus 400 for evaluating the durability of the ion generating element 21. The evaluation device 400 includes the counter electrode 3 and an ammeter 401. The counter electrode 3 is a stainless steel electrode, and is configured to measure the discharge current flowing into the counter electrode 3 by being grounded via an ammeter 401. Further, the ion generating element 21 is fixed by a holding member (not shown) at a position separated from the counter electrode 3 by a predetermined interval (g = 5 mm).

  Then, while applying a voltage to the ion generating element 21 and leaving it in a state in which ions are generated, an ammeter 401 measures a change with time of the discharge current flowing into the counter electrode 3, and the discharge current is reduced to the initial 1 / The durability of the ion generating element 21 was evaluated on the basis of the following criteria, using the time taken to decrease to 2 as an index. “◎” indicates that the discharge current 1/2 reduction time is 300 hours or more, “◯” indicates that the discharge current 1/2 reduction time is 200 to 300 hours, and “1/2” discharge current reduction time. What is 150-200 hours is "O", what is a discharge current 1/2 reduction time is 100-150 hours, is "B", and discharge current 1/2 reduction time is 50-100 hours Was “Δ ×”, and “1/2” was the discharge current half reduction time of 50 hours or less.

<Evaluation results>
Table 1 shows the conditions of the coating layer of each ion generating element produced as described above and the results of the evaluation experiment of each ion generating element.

(1) Printing process of discharge electrode From the result of comparison with Comparative Example 1 and Example 1, the discharge electrode was printed before WIP (Example 1) rather than printing the discharge electrode after WIP (Comparative Example 1). However, it can be seen that the discharge uniformity, the image quality uniformity, and the durability are improved, and the effect of improving the durability is particularly remarkable (× →）).

  If the discharge electrode is printed before WIP, the discharge uniformity and the image quality uniformity are improved. When the discharge electrode is printed before WIP, the discharge electrode is placed inside the dielectric as shown in FIG. This is because the surface to be printed becomes a flat state because it is buried, and it becomes easier to form the coat layer more uniformly. In addition, as shown in FIG. 5A, the reason for the improvement in durability is that when the discharge electrode is printed after WIP, a step is generated between the discharge electrode and the upper surface of the upper dielectric. This is because the coating layer is thinner than other parts, whereas when the discharge electrode is printed before WIP, the coating layer on the discharge electrode can be formed to the same thickness as the other parts. is there.

(2) Number of coating layer treatments From the results of Example 1 and Example 10, simply increasing the number of coating layer treatments resulted in a thicker coating layer (from 10 μm to 15 μm), Conversely, the discharge uniformity and the image quality uniformity deteriorate. However, from the results of Example 10 and Examples 2 to 8, by reducing the viscosity of the coating material or increasing the number of screen meshes, the layer thickness of the coating layer is controlled to be thin (Example 8). It can be seen that the discharge uniformity and the image quality uniformity are improved as compared with the first coating example. The reason for this will be described with reference to FIG.

  FIG. 9A is a diagram showing that the first coat layer 6a is formed by screen printing using a high-viscosity paste, and FIG. 9B is a diagram illustrating a case where 2 is formed on the first coat layer 6a. It is a figure which shows that the coat layer 6b of the 2nd time was formed by screen printing. The uniformity of the discharge is affected by the uniformity of the coating layer thickness. If the coating layer is thin or has pinholes or voids, excessive discharge (black streak-like image defects) will occur. Too little (white streak-like image defect).

As shown in FIG. 9A, when the first coat layer 6a is formed by screen printing, variations in the layer thickness occur due to pressure fluctuations accompanying the movement of the squeegee, pressure fluctuations in the longitudinal direction, and the like. In addition, since the paste viscosity is high, pinholes 61a and voids are easily generated. Therefore, by using a low-viscosity paste or by using a high-definition screen mesh and printing a plurality of times more thinly, the second coating is applied on the first coating layer 6a as shown in FIG. 9B. Thus, the coat layer 6 coated with the coat layer 6b is formed. In the coat layer 6 as shown in FIG.
(A) The thickness unevenness of the coat layer is alleviated.
(B) The pinhole generated in the first printing is overcoated.
(C) The number and size of pinholes are reduced by the low-viscosity paste.

  As a result, the discharge uniformity in the longitudinal direction of the ion generating element is improved, the occurrence of image defects such as black stripes or white stripes can be prevented, and the image quality uniformity is also improved.

  Further, from the comparison of Examples 2 to 4, the first and second coating processes are performed with different screen meshes (Examples 3 and 4) rather than with the same screen mesh (Example 2). It can be seen that the image quality and image quality uniformity are improved.

  Similarly, from the comparison of Examples 5 to 7, the first and second coating treatments are performed with pastes having different viscosities (Examples 6 and 7) rather than being performed with pastes having the same viscosity (Example 5). It can be seen that the discharge uniformity and the image quality uniformity are improved.

  The reason for this is that in Example 3 and Example 6, the coating thickness formed in the second time is thinner than the coating thickness formed in the first time, so that the coating thickness unevenness generated in the first time is more effective. This is because the correction can be performed uniformly. Moreover, it is because the pinhole, the crack, etc. which have arisen at the first time can be covered (closed) more effectively.

  Also, since the coating material and the underlying dielectric material are the same LTCC, the coating material and the dielectric material have good wettability, but since the discharge electrode is silver palladium, the wettability between the coating material and the discharge electrode is Is not good. As described above, when the wettability between the printing surface and the coating material is not good, as shown in Example 4 and Example 7, it is also effective to perform the treatment under the condition that the first time is thinner and the second time is thicker. . The reason for this is that the first coat is a temporary coat, and the base is prepared by printing thinner with a low-viscosity paste or high-definition screen mesh, and the second coat is coated on the same material. This is because printing can be performed more uniformly.

  In the present embodiment, the case where the coating layer is processed twice has been described. However, the present invention is not limited to two times, and the same effect can be obtained in three or more times. Needless to say, you can.

(3) Printing direction From the comparison result between Example 3 and Example 5, the discharge uniformity and image quality of the second printing direction in the vertical direction (Example 5) are higher than in the horizontal direction (Example 3). It can be seen that the uniformity is good. The reason for this is that, in screen printing, printing unevenness is more likely to occur in the squeegee direction (squeegee width direction) than in the printing direction (squeegee movement direction), so the final printing direction matches the longitudinal direction of the discharge electrode. This is because the influence of printing unevenness can be more easily solved.

(4) Processing method From the comparison result between Example 10 and Example 9, as a second processing method, the coating layer by dipping (Example 9) is more uniform in discharge and image quality than screen printing (Example 10). It can be seen that the uniformity is good.

  The reason for this will be described with reference to FIG. FIG. 5A shows that the first coat layer 6a is formed by screen printing using a high-viscosity paste, and FIG. 5B shows the first coat layer 6a on the first coat layer 6a. It is a figure which shows that the coating layer 6c of the 2nd time was formed by dipping.

  As described above, the uniformity of the discharge is affected by the uniformity of the layer thickness of the coat layer 6, and if there are pinholes 61 a, voids 61 b, and cracks 61 c in the coat layer 6, excessive discharge (black streak-like image defects) is caused. Become. As shown in FIG. 5A, when the first coating layer 6a is formed by screen printing with a paste material having a high viscosity, it is formed by firing simultaneously with the ceramic substrate. Voids 61b and cracks 61c are likely to occur. Therefore, as shown in FIG. 5B, the ion generating element 21 after baking is coated with the coating layer 6c for the second time by dipping using a coating material having a lower viscosity, thereby producing 1 by screen printing. The pinhole 61a, void 61b, and crack 61c of the second coat layer (overcoat layer) 6a are filled with the coating material. Then, the coating material 6 without the pinhole 61a, the void 61b, and the crack 61c can be formed by baking a coating material at the temperature of 150-180 degreeC.

  As a result, the discharge uniformity in the longitudinal direction of the ion generating element 21 is improved, and the occurrence of black stripe-like image defects can be prevented.

  In addition, as a coating method of such a low-viscosity coating material, it is not necessarily limited to dipping, and it goes without saying that any coating method such as spray coating or roll coating can be applied.

  The present invention is not limited to the above-described embodiments and examples, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  In addition, it goes without saying that the present invention includes a numerical range other than the numerical range shown in the present specification as long as it is within a reasonable range that does not contradict the gist of the present invention.

  The present invention relates to pre-transfer charging for charging a toner image formed on an image carrier such as a photosensitive member or an intermediate transfer member before transfer in an image forming apparatus using an electrophotographic method, or charging a photosensitive member. It can be used for latent image charging or toner preliminary charging for assisting toner charging in the developing device.

(A) is a figure which shows the state which the discharge electrode of the ion generating element was exposed from the upper surface of a dielectric material, (b) is a figure which shows the state in which the discharge electrode of the ion generating element was buried inside the dielectric material. It is a figure which shows the structure of the charging device which concerns on this invention which has the ion generating element which concerns on this invention. (A) is a figure which shows the structure of the ion generator which has an ion generating element which concerns on this invention, (b) is a side view of the ion generating element which concerns on this invention. It is explanatory drawing which shows the principal part structure of the image forming apparatus which concerns on this invention. (A) is the figure which formed the 1st coat layer by the coating process by screen printing, (b) is the figure which formed the 2nd coat layer by the coating process by dipping. It is a figure which shows the measuring apparatus which measures the discharge distribution of an ion generating element, (a) is a top view, (b) is a front view. It is the figure which showed an example of the discharge current distribution data measured using the measuring apparatus 300 shown in FIG. It is a figure which shows the evaluation apparatus which evaluates durability of an ion generating element. (A) is a figure showing that the first coat layer was formed by clean printing, and (b) is a figure showing that the second coat layer was formed by clean printing. It is a figure explaining the charging mechanism in the charging device of a corona discharge system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Discharge electrode 2 Induction electrode 3 Counter electrode 4 Dielectric 4a Upper dielectric (dielectric)
4b Lower dielectric layer 6 Coat layer 6a First coat layer 6b Second coat layer 6c Second coat layer (dipping)
7 Discharge voltage application means (voltage application means)
DESCRIPTION OF SYMBOLS 11 To-be-charged body 12 Toner 20 Ion generating means 21 Ion generating element 31 Photoconductor (electrostatic latent image carrier)
41 Transfer belt 100 Charging device 110 Charging means before latent image formation (charging device)
120 Pre-intermediate transfer charging means (charging device)
130 Pre-recording transfer charging means (charging device)
200 Image forming apparatus

Claims (8)

A discharge electrode and an induction electrode are provided opposite to each other with a dielectric interposed therebetween, and a voltage is applied to give a potential difference between the discharge electrode and the induction electrode. An ion generating element for generating,
The ion generating element is characterized in that the discharge electrode is buried in the dielectric, and a surface other than the surface in contact with the dielectric is covered with a coat layer.   The ion generating element according to claim 1, wherein the coat layer is formed of a plurality of layers. A discharge electrode and an induction electrode are provided opposite to each other with a dielectric interposed therebetween, and a voltage is applied to give a potential difference between the discharge electrode and the induction electrode. A method for producing an ion generating element for generating,
A burying step of placing the discharge electrode buried in the dielectric, and
A method of manufacturing an ion generating element, comprising: a coating treatment step of coating a surface of the discharge electrode other than the surface in contact with the dielectric with a coating layer after the burying step.   The method for manufacturing an ion generating element according to claim 3, wherein the coating process includes a plurality of coating processes.   5. The method of manufacturing an ion generating element according to claim 3, wherein a plurality of types of coating processes are performed in the coating process.   3. A charging device comprising: the ion generating element according to claim 1; and voltage applying means for applying a voltage so as to give a potential difference between the discharge electrode and the induction electrode.   An image forming apparatus comprising the charging device according to claim 6 as a charging device for charging an electrostatic latent image carrier.   An image forming apparatus comprising: the charging device according to claim 6 as a charging device for pre-transfer charging that applies a charge to the toner carried on the carrier.

Images