JP2006189721A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can realize ample reduction in electrostatic charge sounds, and to provide an image forming method. <P>SOLUTION: When a vibrating voltage, superposed with DC and AC, is applied to the surface of a latent image carrier 2, so as to electrostatically charge the surface of the latent image carrier 2, following conditions are satisfied: the phase difference between the vibration voltage, applied to an electrostatic charge section 4a and the vibration voltage applied to an electrostatic charge section 4b, the phase difference between the vibration voltage applied to the electrostatic charge section 4b and the vibration voltage applied to an electrostatic charge section 4c, and a phase difference between the vibration voltage applied to the electrostatic charge section 4c and the vibration voltage applied to the electrostatic charge section 4a are each regulated to be in the range of 26π/90 to 69π/180 radians. By doing so, the effect of sufficiently negating the vibrations with each other is acted, between the electrostatic charge sounds generated by the electrostatic charge section 4a, the electrostatic charge sounds generated by the electrostatic charge section 4b, and the electrostatic charge sounds generated by the electrostatic charge section 4c. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and an image forming method, and more specifically, an image forming apparatus and an image forming apparatus that form an image by charging a surface of a latent image carrier by applying an oscillating voltage in which direct current and alternating current are superimposed. Regarding the method.

  Conventionally, as an image forming apparatus such as an electrophotographic apparatus (a copying machine, a printer, etc.), an electrostatic recording apparatus, etc., as a means for performing a neutralization process on a latent image carrier such as a photoconductor and a dielectric, and other charged objects. In general, a non-contact type charging means that uses a corona discharge device and exposes the surface of an object to be charged to the generated corona is common.

  In recent years, since the power supply can be reduced in pressure and has the advantage that ozone is generated in a very small amount, a roller-type or blade-type conductive member is brought into contact with a charged body as a charging member. Contact charging means for charging the surface of the object to be charged by applying a voltage to the charging member in close proximity is adopted in a relatively low-speed model and has become the mainstream (for example, see Patent Documents 1 to 3 below). ).

  As such contact or proximity charging means, a DC application method in which only a DC voltage is applied to the charging member for charging treatment, and an oscillating voltage by superimposing an AC voltage and a DC voltage (the voltage value periodically changes with time). There is a DC + AC application method in which a charging process is performed by applying a voltage.

  By the way, for example, when a contact charging member having the same width as that of the latent image carrier is used in an image forming apparatus having a wide width such that the charging surface width of the latent image carrier is about 1 m, the charging member is bent or processed. It is difficult to perform uniform charging due to the influence of poorness. Further, such a long contact charging member has not been practically available in terms of manufacturing cost.

  Accordingly, various methods for uniformly charging the surface of the latent image carrier in a wide-width image forming apparatus to which the contact charging method is applied have been studied. For example, Patent Document 4 discloses a plurality of contact charging methods. A charging device in which members are distributed in a direction orthogonal to the moving direction of the surface to be charged is disclosed.

  However, the DC + AC application type contact or proximity charging means is an effective means for uniformly charging the object to be charged, but it causes a problem of so-called “charging noise”.

  That is, due to the alternating voltage component of the oscillating voltage applied to the contact or proximity charging member, a charging sound is generated when the charged body and the charging member vibrate and strike each other. This charged sound seems to be annoying, and it can be said that countermeasures are indispensable in recent years, with the demand for noise reduction in office machines such as copiers and printers.

  Here, in order to reduce the charging sound, it is conceivable to lower the frequency of the AC voltage. However, if the frequency of the AC voltage is lowered, charging unevenness is likely to occur, and in an image forming apparatus such as an electrophotographic apparatus. There is a limit to speedup. In addition, when an input pixel density is increased to improve image quality in an image forming apparatus in which image input is a digital signal, such as a laser beam printer, there is a problem that uneven charging due to a decrease in frequency is more likely to appear. Therefore, there is a demand for an image forming method that reduces the charging noise without lowering the frequency of the AC voltage.

As such an image forming method, conventionally, two charging members are used, and the charging voltage generated by the two charging members by shifting the phases of the oscillating voltages applied to the respective charging members to opposite phases, that is, by shifting by π radians. An image forming method is known in which sounds are canceled out to achieve noise reduction (see Patent Document 5 below).
JP-A 63-149668 JP-A 63-149669 JP-A 63-168667 JP-A-8-305128 JP-A-4-44060

  However, when the inventor uses the image forming method described in Patent Document 5, the charging noise cannot be sufficiently reduced, and the charging noise becomes larger than when one charging member is used. I found.

  Accordingly, an object of the present invention is to provide an image forming apparatus and an image forming method capable of realizing a sufficient reduction in charging noise.

  The above object is achieved by the present invention described below.

  That is, the first image forming apparatus of the present invention applies a vibration voltage in which direct current and alternating current are superimposed on the surface of the latent image carrier and the surface of the latent image carrier to charge the surface of the latent image carrier. One or more image forming units including at least a charging unit, an exposure unit that exposes a charged region on the surface of the latent image carrier to form a latent image, and a developing unit that develops the latent image; The charging means has three or more charging parts capable of applying the vibration voltage to the surface of the latent image carrier, and a set of charging parts is constituted by three of the charging parts. In the two charging units arbitrarily selected from the set of charging units, between the vibration voltage applied to one charging unit and the vibration voltage applied to the other charging unit So that the phase difference becomes 26π / 90 to 69π / 180 radians And a control means for controlling the charging means.

  According to the first image forming apparatus of the present invention, in one image forming unit, an oscillating voltage in which direct current and alternating current are superimposed is applied to the surface of the latent image carrier by the charging means, and the surface of the latent image carrier. Is charged, and the charged region on the surface of the latent image carrier is exposed by the exposure means to form a latent image. Then, the latent image is developed by the developing unit to form an image. Then, when charging the surface of the latent image carrier, the control unit applies the voltage to one charging unit between two charging units arbitrarily selected from a set of three charging units. The charging means is controlled so that the phase difference between the oscillating voltage and the oscillating voltage applied to the other charging portion is 26π / 90 to 69π / 180 radians. By doing in this way, the effect | action which mutually cancels a vibration fully among the charging sounds each generate | occur | produced by three charging parts of a set of charging parts acts. As a result, the charging noise is greatly reduced.

  In the image forming apparatus, the three charging units constituting a set of charging units are arranged substantially parallel to a linear direction orthogonal to the moving direction of the latent image carrier surface and are adjacent to each other. It is preferable that the end portions of the charging regions of the portions are arranged so as to overlap.

  As described above, in a wide-width image forming apparatus in which the charging surface width of the latent image carrier is about 1 m or more, when a contact charging member having the same width as the latent image carrier is used, It is difficult to perform uniform charging due to the influence of the deflection of the charging member and poor workability. In view of this, the three charging portions are arranged substantially parallel to a linear direction orthogonal to the moving direction (circumferential direction) of the surface of the latent image carrier so that the end portions of the charging regions of the adjacent charging portions overlap each other. As a result, the length of each charging portion can be shortened, and even if the latent image carrier is long, the surface of the latent image carrier can be charged sufficiently uniformly and without leakage. Furthermore, as described above, the charging sound generated in each of the three charging units has an effect of mutually canceling vibrations, so that the charging sound can be sufficiently reduced.

  Further, the first image forming apparatus of the present invention is particularly effective when the three charging units constituting a set of charging units are in contact with or close to the surface of the corresponding latent image carrier, This is particularly effective when in contact. This is because, in such a case, the generation of charging noise becomes a problem.

  In the first image forming apparatus of the present invention, the three charging units constituting a set of charging units may be separated from the surface of the corresponding latent image carrier. Even in such a case, if the three charging parts are arranged in the vicinity of the surface of the latent image carrier, the charging sound is generated as in the case where the charging part is in contact with or close to the surface of the latent image carrier. This can be a problem.

  The second image forming apparatus of the present invention charges the surface of the latent image carrier by applying a vibration voltage in which direct current and alternating current are superimposed on the surface of the latent image carrier and the latent image carrier. Three or more image forming units including at least a charging unit, an exposure unit that exposes a charged region on the surface of the latent image carrier to form a latent image, and a developing unit that develops the latent image. In each of the image forming units, the charging unit has a charging unit capable of applying the vibration voltage to the surface of the corresponding latent image carrier, and 3 of the image forming units. Between the two charging units, a set of charging units is constituted by the three charging units, and two charging units arbitrarily selected from the set of charging units are applied to one charging unit. Applied to the oscillating voltage and the other charged part That the phase difference between the oscillating voltage, characterized in that it comprises control means for controlling said charging means so as to 26π / 90~69π / 180 radians.

  According to the second image forming apparatus of the present invention, in each of the three or more image forming units, an oscillating voltage in which direct current and alternating current are superimposed is applied to the surface of the latent image carrier by the charging unit. The surface of the image carrier is charged, and the charged area on the surface of the latent image carrier is exposed by the exposure means to form a latent image. Thereafter, the latent image is developed by the developing means to form an image. Here, a set of charging units is constituted by charging units included in three of the image forming units. Then, when charging the surface of the latent image carrier in each image forming unit, the control unit applies the voltage to one charging unit between two charging units arbitrarily selected from a set of charging units. Each charging means is controlled so that the phase difference between the oscillating voltage and the oscillating voltage applied to the other charging unit is 26π / 90 to 69π / 180 radians. By doing in this way, the effect | action which mutually cancels a vibration fully works between each charging sound which generate | occur | produces by three charging parts of a set of charging parts. As a result, the charging noise is greatly reduced.

  In order to form a full-color image, at least three color images of yellow, magenta, and cyan are stacked. Usually, four color images obtained by adding black to the above three colors are stacked. That is, in an image forming apparatus for forming a full-color image, there are many image forming apparatuses in which a plurality of image forming units are arranged in order to stack a plurality of color images. Therefore, if each charging unit in at least three of the plurality of image forming units constitutes a set of charging units, the charging sound generated from the three image forming units can be greatly reduced. Note that the second image forming apparatus of the present invention is expected to have a charging noise reduction effect even if the number of image forming units is four or more if at least three of the image forming units form a mute unit pair. can do.

  Further, in the second image forming apparatus of the present invention, the charging unit in all the image forming units constituting the image forming apparatus forms a set of charging units. It is preferable to reach at That is, it is preferable that the second image forming apparatus of the present invention is provided with a multiple of 3 image forming units, and the charging units in the image forming unit each constitute a set of charging units.

  Further, the second image forming apparatus of the present invention is particularly effective when the three charging units constituting a set of charging units are in contact with or close to the surface of the corresponding latent image carrier, This is particularly effective when in contact. This is because, in such a case, the generation of charging noise becomes a problem.

  In the second image forming apparatus of the present invention, the three charging units constituting a pair of charging units may be separated from the surface of the corresponding latent image carrier. Even in such a case, if the three charging portions are arranged in the vicinity of the surface of the corresponding latent image carrier, the charging portion is charged in the same manner as when the charging portion is in contact with or close to the surface of the latent image carrier. This is because sound generation can be a problem.

  The image forming method of the present invention also includes a charging step of charging the surface of the latent image carrier by applying an oscillating voltage in which direct current and alternating current are superimposed on the surface of the latent image carrier, An exposure step of exposing a charged area on the surface to form a latent image; and a development step of developing the latent image. In the charging step, a set of charging portions including three charging portions is used, The phase difference between the oscillating voltage applied to one charging unit and the oscillating voltage applied to the other charging unit between two charging units arbitrarily selected from a set of charging units is 26π. The vibration voltage is applied to the surface of the latent image carrier so as to be / 90 to 69π / 180 radians.

  According to the image forming method of the present invention, the surface of the latent image carrier is charged with an oscillating voltage in which direct current and alternating current are superimposed on the surface of the latent image carrier, and a charged region on the surface of the latent image carrier is formed. Exposure to form a latent image. Then, the latent image is developed to form an image. When charging the surface of the latent image carrier, the vibration voltage applied to one charging unit and the other charging unit between two charging units arbitrarily selected from a set of charging units. The phase difference between the applied oscillating voltage is set to 26π / 90 to 69π / 180 radians. By doing in this way, the effect | action which mutually cancels a vibration fully among the charging sounds each generate | occur | produced by three charging parts of a set of charging parts acts. As a result, charging noise is greatly reduced.

  In the image forming method of the present invention, the set of charging units may be included in one image forming unit, and between the charging units included in each of the three image forming units. A pair may be formed.

  According to the image forming apparatus and the image forming method of the present invention, the charged sound generated by the three charged portions of the set of charged portions has a function of sufficiently canceling vibration between the charged sounds. Can be sufficiently reduced.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments. In all the drawings, the same or equivalent components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic configuration diagram showing a first embodiment of an image forming apparatus according to the present invention, and shows a schematic configuration of an image forming apparatus having only an image forming unit for forming an image of a predetermined color on a sheet. .

  As shown in FIG. 1, the image forming apparatus 100 includes an image forming unit 50 and a conveyance belt 51 that conveys the sheet 1 as a recording sheet to the image forming unit 50. The image forming unit 50 forms an image of a predetermined color on the paper 1 transported by the transport belt 51.

  The image forming unit 50 includes a cylindrical electrophotographic photosensitive member 2 which is a latent image carrier, and charging rolls 4a, 4b and 4c which are a pair of charging units constituting charging means (the charging roll 4c is shown in FIG. 1). (Not shown), a charging bias applying power source 5 for applying an oscillating voltage in which direct current and alternating current are superimposed between the electrophotographic photosensitive member 2 and the charging rolls 4a, 4b and 4c, An exposure device 6 capable of exposing the surface imagewise, a developing device 8 capable of developing an electrostatic latent image formed by exposure by the exposure device 6 to form an image, and an image obtained by the developing device 8 The transfer roll 10 serving as a transfer means for transferring the toner onto the paper 1 as a transfer medium and the residual contaminants such as transfer residual toner on the surface of the electrophotographic photosensitive member 2 are removed to clean the surface of the electrophotographic photosensitive member 2. Mechanical cleaning It includes a cleaning blade 12 as a grayed means. Further, the image forming unit 50 is applied to the phase difference between the vibration voltage applied to the charging roll 4a and the vibration voltage applied to the charging roll 4b, the vibration voltage applied to the charging roll 4b, and the charging roll 4c. And the phase difference between the vibration voltage applied to the charging roll 4c and the vibration voltage applied to the charging roll 4a are 26π / 90 to 69π / 180 radians, respectively. Thus, a control device 14 is provided as a control means for controlling the charging rolls 4a, 4b and 4c. The charging rolls 4a, 4b and 4c, and the charging bias application power source 5 constitute a charging unit.

  In addition, the electrophotographic photosensitive member 2 is supported by a support 9 and can rotate at a predetermined rotation speed in the direction of arrow A in FIG. The set of charging rolls 4a, 4b, 4c, the exposure device 6, the developing device 8, the transfer roll 10, and the cleaning blade 12 described above are sequentially arranged along the rotation direction (circumferential direction) of the electrophotographic photosensitive member 2. Has been.

  2A and 2B are views showing the positional relationship between the electrophotographic photosensitive member 2 and the charging rolls 4a, 4b, and 4c in the image forming apparatus 100 shown in FIG. 1, and FIG. It is a figure, (b) is a top view. As shown in FIGS. 2A to 2B, in the present embodiment, the charging rolls 4a and 4c are in a direction (electrophotographic) orthogonal to the moving direction of the surface of the electrophotographic photoreceptor 2 (arrow A direction in the figure). They are arranged at a predetermined interval along the rotation axis direction of the photosensitive member 1. In addition, the charging roll 4b charges the surface of the electrophotographic photosensitive member 1 that has not been charged by the charging rolls 4a and 4c so that both ends of the charging area by the charging roll 4b are respectively charged by the charging rolls 4a and 4c. It arrange | positions so that it may overlap with an edge part. That is, the charging rolls 4a, 4b, and 4c constituting a set of charging units are arranged substantially parallel to the linear direction orthogonal to the moving direction of the surface of the electrophotographic photosensitive member 2, and are adjacent to each other. The charging regions are arranged so that the ends of the charging regions overlap.

  Returning to FIG. 1, all three charging rolls 4a, 4b, 4c are urged against the surface of the electrophotographic photosensitive member 2 by a spring (not shown). The charging rolls 4a, 4b, and 4c are attached so as to be rotatable with respect to the spring. Accordingly, the charging rolls 4a, 4b, and 4c are driven to rotate at the same peripheral speed as the electrophotographic photosensitive member 2 due to friction with the electrophotographic photosensitive member 2, and function as contact charging means. Note that some drive means may be attached to the charging rolls 4 a, 4 b, 4 c and rotated at a peripheral speed different from that of the electrophotographic photosensitive member 2.

  A vibration voltage is applied between the electrophotographic photosensitive member 2 and the charging rolls 4a, 4b, and 4c by a charging bias application power source 5, so that the surface of the electrophotographic photosensitive member 2 is uniformly charged. . In general, the voltage applied to the charging unit includes a DC voltage or an oscillating voltage obtained by superimposing an AC voltage on the DC voltage. In the image forming apparatus 100 of the present embodiment, the oscillating voltage is used for charging. This is for achieving uniformity and environmental stabilization.

  The control device 14 includes a phase difference between an oscillating voltage applied to the charging roll 4a and an oscillating voltage applied to the charging roll 4b via the charging bias applying power source 5, and an oscillating voltage applied to the charging roll 4b and the charging roll. The phase difference between the vibration voltage applied to 4c and the phase difference between the vibration voltage applied to the charging roll 4c and the vibration voltage applied to the charging roll 4a are 26π / 90 to 69π / 180 radians, respectively. So as to control.

  The electrophotographic photosensitive member 2 is rotationally driven by a driving member or a driving system (not shown).

  Next, a process of forming an image on the paper 1 by the image forming apparatus 100 having the above configuration, that is, an image forming method using the image forming apparatus 100 will be described.

  First, the electrophotographic photosensitive member 2 is rotationally driven by a driving member or a driving system at a predetermined peripheral speed (process speed) in a clockwise direction (arrow A direction) in the drawing (FIG. 1). Then, following the rotation of the electrophotographic photosensitive member 2, the charging rolls 4a, 4b, and 4c rotate, and a vibration voltage is applied to each of the charging rolls 4a, 4b, and 4c by the charging bias application power source 5, and the electrophotographic photosensitive member is applied. The surface of the body 2 is uniformly charged to a predetermined polarity and potential. At this time, the waveform of the superimposed alternating voltage includes a sine wave, a rectangular wave, a triangular wave, a pulse wave, and the like, but from the viewpoint of ease of application including manufacturing costs, a harmonic component is not included. A sine wave is preferred. The magnitude and frequency of the applied oscillating voltage are as follows. That is, the DC voltage is preferably positive or negative 50 to 2,000 V, particularly preferably 100 to 1,500 V, depending on the required charging potential of the electrophotographic photosensitive member 2. The alternating voltage to be superimposed is preferably such that the peak-to-peak voltage is 400 to 3,000 V, more preferably 800 to 2,500 V, and still more preferably 1,200 to 2,500 V. The frequency of the AC voltage is 50 to 20,000 Hz, preferably 100 to 5,000 Hz.

  Next, the surface of the electrophotographic photosensitive member 2 that has been charged is exposed by the exposure device 6, and an electrostatic latent image corresponding to target image information is formed on the surface of the electrophotographic photosensitive member 2.

  Subsequently, the electrostatic latent image is developed as a toner image by the developing device 8.

  On the other hand, the paper 1 is carried on the transport belt 16 and fed from a paper feed mechanism (not shown).

  Then, the tip of the toner image formed on the surface of the electrophotographic photosensitive member 2 at a predetermined timing, that is, at the transfer portion, is transferred to a transfer portion which is a pressure nip portion between the electrophotographic photosensitive member 2 and the transfer roll 10. It is inserted at the timing when the predetermined position of the recording paper matches. Thus, the toner image formed on the surface of the electrophotographic photosensitive member 2 is transferred onto the surface of the paper 1.

  As described above, the image forming apparatus 100 forms an image of a predetermined color on the surface of the paper 1.

  In the image forming process, an oscillating voltage is applied to the charging rolls 4 a, 4 b, 4 c of the image forming apparatus 100 by the control device 14 via the charging bias applying power source 5. At this time, the phase difference between the vibration voltage applied to the charging roll 4a and the vibration voltage applied to the charging roll 4b, the vibration voltage applied to the charging roll 4b, and the vibration voltage applied to the charging roll 4c. And the phase difference between the oscillating voltage applied to the charging roll 4c and the oscillating voltage applied to the charging roll 4a are set to 26π / 90 to 69π / 180 radians, respectively. By doing so, there is an effect of sufficiently canceling vibrations between the charging sound generated by the charging roll 4a, the charging sound generated by the charging roll 4b, and the charging sound generated by the charging roll 4c. work. Therefore, the charging noise is greatly reduced, and the charging noise can be sufficiently reduced.

  The surface of the electrophotographic photosensitive member 2 that has passed through the transfer portion and has finished transferring the toner image onto the paper 1 is cleaned by the cleaning blade 12 to remove residual contaminants such as transfer residual toner, and is cleaned to the next surface. It is used for image formation.

  In addition, the sheet 1 on which the toner image is formed by the image forming apparatus 100 is separated from the surface of the electrophotographic photosensitive member 2 and conveyed to a fixing unit (not shown) to be subjected to a toner image fixing process.

  Next, the components of the image forming unit 50 will be described more specifically.

  The electrophotographic photosensitive member (latent image carrier) 2 has a photosensitive layer formed on the outer peripheral surface of a cylindrical substrate. The base material of the electrophotographic photosensitive member 2 is basically not particularly limited as long as it can be formed into a cylindrical shape, but metals such as aluminum and stainless steel are preferable in consideration of moldability, workability, strength, and the like. It is.

  The photosensitive layer provided on the outer periphery of the substrate is not particularly limited, and a known photoconductive material may be formed by a known means. However, considering that the charging rolls 4a and 4b are in contact with the photosensitive layer, it is preferable to use a photosensitive layer having an organic photoconductive material formed on the basis of a resin. The photosensitive layer mainly composed of the organic photoconductive material includes a single-layer photosensitive layer having both functions of charge generation ability and charge transport ability, and a laminated photosensitive layer in which a plurality of layers separated from each other are laminated. In the image forming apparatus of the present invention, the photosensitive layer may have any structure, but a laminated photosensitive layer is generally used.

  It is desirable to provide an undercoat layer on the surface of the substrate. As the undercoat layer, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, epoxy resin, polyurethane resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, Examples thereof include various resins such as silicon-based resins and melamine-based resins, and those obtained by adding a zirconium compound, a titanium compound, or the like to these resins.

  A photosensitive layer is provided on the outer periphery of the substrate (when an undercoat layer is provided on the surface of the substrate, the outer periphery of the undercoat layer is referred to hereinafter). The photosensitive layer is formed by applying a coating solution prepared by dispersing or mixing a charge generation material and / or a charge transport material, a binder resin, and a solvent to the outer periphery of the substrate and drying. Therefore, the photosensitive layer is composed of a charge generation material and / or a charge transport material and a binder resin.

  At this time, when a single-layer type photosensitive layer is formed, a coating solution prepared by dispersing or mixing a charge generating substance, a charge transporting substance, a binder resin and a solvent is applied to the outer periphery of the substrate and dried. Therefore, the photosensitive layer is composed of a charge generation material, a charge transport material, and a binder resin. On the other hand, when forming a laminated photosensitive layer, a charge generation layer forming coating solution prepared by dispersing or mixing a charge generation material, a binder resin and a solvent, and the charge transport material, the binder resin and A charge transport layer forming coating solution prepared by mixing a solvent is prepared separately, and these coating solutions are sequentially applied and dried on the outer periphery of the substrate. Therefore, the photosensitive layer includes a charge generation layer containing a charge generation material and a binder resin, and a charge transport layer containing a charge transport material and a binder resin.

  Examples of the charge generating substance include azo pigments, disazo pigments, quinone pigments, quinocyanine pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, quinacridone pigments, pyrylium salts, azurenium salts, and trigonal selenium. It is done.

  Examples of the charge transport material include a polyaromatic compound such as anthracene, pyrene, phenanthrene, coronene, or indole, carbazole, oxazole, isoxazole, thiazole, imidazole, pyrazole, oxadiazole, pyrazoline in the main chain or side chain. And compounds having a skeleton of a nitrogen-containing cyclic compound such as hyadiazole and triazole, and other hole transporting materials such as hydrazone compounds.

  Examples of the binder resin include polycarbonate, polyarylate, polystyrene, polymethacrylates, styrene-methyl methacrylate copolymer, polyester, styrene-acrylonitrile copolymer, polysulfone, polyvinyl acetate, polyacrylonitrile, polyvinyl butyral, polyvinyl pyrrolidone, methyl cellulose. , Hydroxymethylcellulose, cellulose esters and the like.

  As the solvent (solvent) for preparing the coating solution, a solvent having high volatility and a vapor density larger than that of air is preferably used. For example, n-butylamine, diethylamine, ethylenediamine, isopropanolamine, triethanolamine N, N-dimethylformamide, acetone, methyl ethyl ketone, cyclohexanone, benzene, 4-methoxy-4-methylpentanone, dimethoxymethane, dimethoxyethane, 2,4-pentadione, anisole, methyl 3-oxobutanoate, monochlorobenzene, toluene , Xylene, chloroform, 1,2-dichloroethane, dichloromethane, tetrahydrofuran, dioxane, methanol, ethanol, isopropanol, 1-butanol, ethyl acetate, butyl acetate, dimethyl sulfoxide, Ruserusorubu, ethyl cellosolve, methyl cellosolve, and the like methyl cellosolve acetate.

  As a driving member for rotationally driving the electrophotographic photosensitive member 2, a member for driving transmission and bearings in the image forming apparatus 100 called a gear or a flange is used. Is provided at at least one of the ends. As materials for these members, metals such as aluminum, resin molded products such as polycarbonate, and the like are used in terms of moldability, workability, slidability, and durability.

  The charging rolls 4a, 4b, 4c are for charging the surface of the electrophotographic photosensitive member 2 by applying a vibration voltage to the surface of the electrophotographic photosensitive member 2, and the materials for the charging rolls 4a, 4b, 4c are as follows: An elastic material imparted with conductivity is suitable. The charging rolls 4a, 4b, and 4c are usually configured by forming an elastic layer on the surface of a roll body as a core material and further forming a resistance layer thereon. Furthermore, a protective layer can be provided outside the resistance layer as necessary.

  The material of the roll body as the core material has conductivity, but generally iron, copper, brass, stainless steel, aluminum, nickel, etc. are used. In addition, as the material of the roll body, a resin molding material in which conductive particles or the like are dispersed can be used. As the material of the elastic layer, an elastic material having conductivity or semiconductivity is used. Generally, a rubber material in which conductive particles or semiconductive particles are dispersed is used.

  As the rubber material, EPDM, polybutadiene, natural rubber, polyisobutylene, SBR, CR, NBR, silicone rubber, urethane rubber, epichlorohydrin rubber, SBS, thermoplastic elastomer, norbornene rubber, fluorosilicone rubber, ethylene oxide rubber, etc. are used. .

Examples of conductive particles or semiconductive particles include carbon black, zinc, aluminum, copper, iron, nickel, chromium, titanium, and other metals, ZnO—Al ₂ O ₃ , SnO ₂ —Sb ₂ O ₃ , In ₂ O _3. Metal oxides such as —SnO ₂ , ZnO—TiO ₂ , MgO—Al ₂ O ₃ , FeO—TiO ₂ , TiO ₂ , SnO ₂ , Sb ₂ O ₃ , In ₂ O ₃ , ZnO, and MgO can be used. These materials may be used alone or in combination of two or more.

The resistance layer and the protective layer are obtained by dispersing conductive particles or semiconductive particles in a binder resin and controlling the resistance. As the binder resin, acrylic resin, cellulose resin, polyamide resin, methoxymethylated nylon Ethoxymethylated nylon, polyurethane resin, polycarbonate resin, polyester resin, polyethylene resin, polyvinyl resin, polyarylate resin, polythiophene resin, polyolefin resin such as PFA, FEP, PET, styrene butadiene resin and the like are used. As the conductive particles or semiconductive particles, the same carbon black, metal, and metal oxide as the elastic layer are used. The resistivity of the resistance layer and the protective layer is preferably 10 ³ to 10 ¹⁴ Ωcm, more preferably 10 ⁵ to 10 ¹² Ωcm, and further preferably 10 ⁷ to 10 ¹² Ωcm. Moreover, the film thickness of a resistance layer and a protective layer becomes like this. Preferably it is 0.01-1,000 micrometers, More preferably, it is 0.1-500 micrometers, More preferably, it is 0.5-100 micrometers.

  Moreover, antioxidants, such as hindered phenol and hindered amine, fillers, such as clay and kaolin, and lubricants, such as silicone oil, can be added to a resistance layer and a protective layer as needed.

  The resistance layer and the protective layer can be formed by preparing a coating solution by dissolving and dispersing each of the above materials in an appropriate solvent, and applying the coating solution to an object to be coated. Conventionally known means such as a blade coating method, a wire bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method can be employed as the means for applying.

  The exposure device 6 can expose the surface of the electrophotographic photosensitive member 2 imagewise to form an electrostatic latent image. Examples of the exposure device 6 include conventionally known laser beam scanning exposure means, Examples thereof include slit exposure means, and any of these can be applied.

  The developing device 8 is capable of forming an image by developing the latent image formed on the surface of the electrophotographic photosensitive member 2 by being exposed by the exposure device 6. Examples include a developing device using powder toner.

  As the transfer roll 10, conventionally known transfer means capable of copying an image of toner or the like developed by the developing device 8 onto the paper 1 is employed.

  The cleaning blade 12 is in direct contact with the surface of the electrophotographic photosensitive member 2 and mechanically removes residual contaminants such as toner, paper dust, and dust adhering to the surface. As the cleaning means, a blade type such as a cleaning blade shown in FIG. 1 is used, but other known types such as a brush and a roll can also be applied. The cleaning blade 12 may also be used as the charging rolls 4a and 4b. In this case, the charging rolls 4 a and 4 b not only charge the surface of the electrophotographic photosensitive member 2 but also have a function of cleaning the surface of the electrophotographic photosensitive member 2.

  The fixing unit is not particularly limited as long as it can fix the image formed on the sheet 1 to the sheet 1, and any conventionally known fixing unit using heat and / or pressure, or fixing unit using a solvent, etc. A fixing unit can be employed depending on the purpose.

  Next, a second embodiment of the image forming apparatus according to the present invention will be described. FIG. 3 is a schematic configuration diagram showing a second embodiment of the image forming apparatus according to the present invention. Three image forming units capable of forming a full color image by stacking three color images of yellow, magenta, and cyan. 1 shows a schematic configuration of an image forming apparatus having the same.

  An image forming apparatus 200 shown in FIG. 3 includes an image forming unit 200Y for forming a yellow image on a sheet 118, an image forming unit 200M for forming a magenta image on a sheet 118, and a cyan image. The image forming unit 200C for forming the image on the paper 118 and three image forming units are arranged in parallel.

  The image forming unit 200Y includes a rotating drum type electrophotographic photosensitive member 102Y as a latent image carrier, a charging roll 104Y as a charging unit, and vibration between the electrophotographic photosensitive member (latent image carrier) 102Y and the charging roll 104Y. A charging bias applying power source (not shown) for applying a voltage, an exposure device 108Y that can expose the surface of the electrophotographic photosensitive member 102Y like an image, and a latent image formed by exposure by the exposure device 108Y can be developed. The developing device 110Y includes a transfer roll 112Y as a transfer unit, and a cleaning blade 114Y as a mechanical cleaning unit.

  Here, as the electrophotographic photosensitive member 102Y, one having the same configuration as the electrophotographic photosensitive member 2 described in the first embodiment can be used.

  The charging roll 104Y charges the surface of the electrophotographic photosensitive member 102Y by applying a vibration voltage to the surface of the electrophotographic photosensitive member 102Y. In addition to the configuration in which the electrophotographic photosensitive member 102Y is charged by one roll as shown in FIG. 3, the charging roll 104Y has, for example, a configuration in which a plurality of rolls are arranged in parallel and charged by each roll, Alternatively, a configuration in which a plurality of rolls are arranged in series, a voltage is applied from a roll on the front side, and the voltage is transmitted and charged by a roll in contact with the surface of the electrophotographic photosensitive member may be employed. As the charging roll 104Y, one having the same configuration as the charging rolls 4a, 4b, 4c described in the first embodiment can be used.

  As shown in FIG. 3, the charging roll 104Y is urged against the surface of the electrophotographic photosensitive member 102Y by a spring 120Y with a pressing force, and is driven to rotate at the same peripheral speed as that of the electrophotographic photosensitive member 102Y without any driving means. Functions as a charging means. Note that some driving means may be attached to the charging roll 104Y and rotated at a peripheral speed different from that of the electrophotographic photosensitive member 102Y.

  A vibration voltage is applied between the electrophotographic photosensitive member 102Y and the charging roll 104Y by a charging bias application power source, and the surface of the electrophotographic photosensitive member 102Y is uniformly charged. In general, a DC voltage or an oscillating voltage obtained by superimposing an AC voltage on the DC voltage is used as the applied voltage. However, the oscillating voltage is preferable from the viewpoint of uniform charging and environmental stability. In the present invention, the charging noise when applying the vibration voltage is effectively reduced. The waveform of the AC voltage to be superimposed is not limited to a sine wave, but may be a rectangular wave, a triangular wave, a pulse wave, or the like. From the viewpoint of sound, a sine wave that does not include a harmonic component is preferable.

  The magnitude of the voltage is preferably a positive or negative 50 to 2,000 V, particularly preferably 100 to 1,500 V, depending on the required photoreceptor charging potential as a DC voltage. As the alternating voltage to be superimposed, the peak-to-peak voltage is preferably 400 to 3,000 V, more preferably 800 to 2,500 V, and still more preferably 1,200 to 2,500 V. The frequency of the AC voltage is 50 to 20,000 Hz, preferably 100 to 5,000 Hz.

  The exposure device 108Y can form an electrostatic latent image by exposing the surface of the electrophotographic photosensitive member 102Y in an image-like manner. Examples of the exposure device 108Y include a conventionally known laser beam scanning exposure means, document image, and the like. And any of these can be applied.

  The developing device 110Y can develop the latent image formed on the surface of the electrophotographic photosensitive member 102Y by being exposed by the exposure device 108Y. As the developing device 110Y, for example, a conventionally known powder toner And a developing device using.

  The transfer roll 112Y employs conventionally known transfer means capable of copying an image of toner developed by the developing device 110Y onto the paper 118.

  The cleaning blade 114Y, which is a mechanical cleaning means, is in direct contact with the surface of the electrophotographic photosensitive member 102Y and mechanically removes residual contaminants such as toner, paper dust, and dust adhering to the surface. is there. In the present embodiment, a blade type such as the cleaning blade 114Y shown in FIG. 3 is used, but other known types such as a brush and a roll can also be applied. Alternatively, the cleaning unit 114Y may be used as a cleaning unit and a charging unit by supplying power using a conductive blade. In this case, an oscillating voltage in this embodiment described later may be applied to the cleaning blade 114Y.

  A process of forming a yellow color on the paper 118 by the image forming unit 200Y having the above configuration will be described. The electrophotographic photoreceptor 102Y is rotationally driven by a drive member / drive system (not shown) at a predetermined peripheral speed (process speed) in the clockwise direction (arrow A direction) in the drawing. Following the rotation of the electrophotographic photosensitive member 102Y, the charging roll 104Y rotates and a vibration voltage is applied by a charging bias application power source, and the surface of the electrophotographic photosensitive member 102Y is uniformly charged to a predetermined polarity and voltage.

  Next, the surface of the charged electrophotographic photosensitive member 102Y is exposed by the exposure device 108Y, and an electrostatic latent image corresponding to target image information is formed on the surface of the electrophotographic photosensitive member 102Y. Further, the electrostatic latent image is developed as a toner image by the developing device 110Y.

  On the other hand, a paper 118 as a recording paper is carried by a conveyance belt 116 from a paper feeding mechanism (not shown) and fed, and is a pressure nip portion between the electrophotographic photosensitive member 102Y and a transfer roll 112Y as a transfer means. The electrophotographic photosensitive member is inserted into the transfer portion at a predetermined timing (at the transfer portion, the leading edge of the toner image formed on the surface of the electrophotographic photosensitive member 102Y coincides with the predetermined position of the recording paper). The toner image formed on the surface of the body 102Y is transferred to the surface of the paper 118.

  As described above, a yellow image is formed on the paper 118 by the image forming unit 200Y. The surface of the electrophotographic photosensitive member 102Y that has passed the transfer site and has transferred the toner image onto the paper 118 is cleaned to remove residual contaminants such as transfer residual toner by the cleaning blade 114Y, and is repeatedly cleaned to form an image. Provided.

  The image forming units 200M and 200C are for forming a magenta image on the image forming unit 200M and a cyan image on the paper 118 in the image forming unit 200C, respectively. Except that the phase of the oscillating voltage applied to the charging rolls 104M and 104C is different from the phase of the oscillating voltage applied to the charging roll 104Y of the image forming unit 200A. It has the same configuration. Here, the phase of the oscillating voltage applied to the charging rolls 104M and 104C is the phase difference between the oscillating voltage applied to the charging roll 104Y and the oscillating voltage applied to the charging roll 104M, and is applied to the charging roll 104M. The phase difference between the vibration voltage applied to the charging roll 104C and the phase difference between the vibration voltage applied to the charging roll 104C and the vibration voltage applied to the charging roll 104Y are respectively It is controlled to be 26π / 90 to 69π / 180 radians. In FIG. 3, members having the same parts except for the end (Y, M, or C) of the reference numerals attached to the image forming unit 200Y, the image forming unit 200M, and the image forming unit 200C have the same functions. Detailed description of each member of the image forming units 200M and 200C will be omitted.

  Further, in the image forming apparatus 200, the phase difference of the oscillating voltages applied to the charging portions (charging rolls 104Y, 104M, 104C) of the image forming unit 200Y, the image forming unit 200M, and the image forming unit 200C is 26π / 90. A control device (not shown) is provided as a control unit for controlling the charging rolls 104Y, 104M, and 104C via a charging bias application power source corresponding to each charging unit so that the energy becomes ˜69π / 180 radians.

  As described above, the paper 118 on which the yellow image is formed is moved in the direction of the arrow X in FIG. 3 while being held on the conveyance belt 116 as it is, and the electrophotographic photosensitive member 102M and the transfer as the transfer means are transferred. A predetermined timing (a front end portion of a toner image (including a blank portion) formed on the surface of the electrophotographic photosensitive member 102M at the transfer portion) and a front end portion of the recording paper at a transfer portion which is a press nip portion with the roll 112M for use The magenta toner image formed on the surface of the electrophotographic photosensitive member 102M is laminated on the yellow toner image already formed on the surface of the paper 118. . Similarly, the cyan color is laminated on the paper 118 on which the yellow and magenta images are formed.

  The sheet 118 on which the cyan toner images are stacked by the image forming unit 200C is separated from the surface of the electrophotographic photosensitive member 102C, and is conveyed to a fixing unit (not shown) to undergo a toner image fixing process.

  The fixing means is not particularly limited, and any fixing means such as conventionally known heat and / or pressure fixing or solvent fixing can be employed depending on the purpose. In this way, a full color image is formed on the paper 118.

  In the present embodiment, the electrophotographic photosensitive member 102Y, the electrophotographic photosensitive member 102M, and the electrophotographic photosensitive member 102M are formed by the charging roll 104Y of the image forming unit 200Y, the charging roll 104M of the image forming unit 200M, and the charging roll 104C of the image forming unit 200C. An oscillating voltage is applied to each of the photoconductors 102C, and the oscillating voltages are adjusted so that the phase difference is 26π / 90 to 69π / 180 radians. That is, in the image forming apparatus 200, the charging roll 104Y in the image forming unit 200Y, the charging roll 104M in the image forming unit 200M, and the charging roll 104C in the image forming unit 200C constitute a set of charging units.

  Thus, in the set of charging units, the phase difference between the vibration voltage applied to the charging roll 104Y and the vibration voltage applied to the charging roll 104M, the vibration voltage applied to the charging roll 104M, and charging. The phase difference between the vibration voltage applied to the roll 104C and the phase difference between the vibration voltage applied to the charging roll 104C and the vibration voltage applied to the charging roll 104Y are respectively 26π / 90 to 69π. By setting to / 180 radians, there is an effect that sounds generated by the respective oscillating voltages cancel each other, and as a result, the charged sound is greatly reduced.

  The present invention has been described above with reference to the embodiments. However, the present invention merely shows an embodiment of an image forming apparatus and an image forming method to which the present invention can be applied, and the present invention is of course limited thereto. Instead, a specific member or the like can be replaced with a known member as long as it has the configuration of the present invention. For example, in the first to second embodiments, the phase differences of the oscillating voltages applied to the charging rolls 4a, 4b, and 4c and the oscillating voltages applied to the charging rolls 104Y, 104M, and 104C during charging, respectively. These phase differences are all 26π / 90 to 69π / 180 radians. Each phase difference of this oscillating voltage is preferably 11π / 36 to 13π / 36 radians, and more preferably 1π / 3 radians. When the phase difference of the oscillating voltage is 26π / 90 to 69π / 180 radians, the charging noise can be sufficiently reduced as compared with the case where the phase difference of the oscillating voltage is zero or π radians. Specifically, the sound pressure of the charged sound can be set to about 30% or less of the sound pressure when the phase difference of the oscillating voltage is zero or π radians. Further, when the phase difference of the oscillating voltage is 11π / 36 to 13π / 36 radians, the sound pressure of the charged sound is about 20% or less of the sound pressure when the phase difference of the oscillating voltage is zero or π radians. It can be. When the phase difference of the oscillating voltage is 1π / 3 radians, the sound pressure of the charged sound can be set to about 10% or less of the sound pressure when the phase difference of the oscillating voltage is zero or π radians.

  Further, the first embodiment shows a first image forming apparatus of the present invention having a configuration in which a set of charging units is formed in one image forming unit. The second embodiment, 3 shows a second image forming apparatus of the present invention having a configuration in which a set of charging units is formed by charging units included in each of three image forming units. Each of the image forming apparatuses includes at least one set of charging units, and the three charging units constituting the set of charging units include a first charging unit, a second charging unit, and a third charging unit, respectively. Phase difference between the oscillating voltage applied to the first charging unit and the oscillating voltage applied to the second charging unit, the oscillating voltage applied to the second charging unit and the first charging unit. The phase difference between the oscillating voltage applied to the third charging unit and the phase difference between the oscillating voltage applied to the third charging unit and the oscillating voltage applied to the first charging unit are: It is controlled to be 26π / 90 to 69π / 180 radians. By doing in this way, it is possible to realize a sufficient reduction in charging noise. In the second image forming apparatus of the present invention, each image forming unit may have a plurality of charging units. At this time, the vibration voltage of at least one charging unit included in the first image forming unit among the three image forming units, the vibration voltage of at least one charging unit included in the second image forming unit, If the phase difference between the vibration voltage of at least one charging unit included in the image forming unit 3 is 26π / 90 to 69π / 180 radians, the charging noise reduction effect of the present invention can be obtained.

  In the first to second embodiments, a charging roll is used as a charging unit constituting the charging unit used in the present invention. However, the charging unit is not limited to a roll shape, but a brush shape, a blade shape, or Any of a pin electrode shape and the like may be used.

  Further, in the first embodiment, the case where the first image forming apparatus of the present invention has one image forming unit has been described. However, the first image forming apparatus of the present invention has at least one image forming unit. Therefore, the image forming unit may have a plurality of image forming units. In the case where the first image forming apparatus of the present invention has four image forming units, images of four colors of yellow, magenta, cyan and black are formed by these four image forming units. If color images are stacked on the paper 1, a full-color image can be formed. In the second embodiment, the second image forming apparatus of the present invention has three image forming units for forming images of three colors of yellow, magenta, and cyan, and a full color image is formed by the three image forming units. However, an image forming unit that forms a black image may be included.

  In the first and second embodiments, the transport belts 51 and 116 are used to transport the paper to the image forming unit. However, a transport drum may be used instead of the transport belts 51 and 116.

  Further, when the image forming apparatus of the present invention has a plurality of image forming units, belt-shaped or drum-shaped intermediate transfer members are used, and images of each color are transferred or laminated from the plurality of image forming units to the intermediate transfer member. You may use the system which transfers on the surface of the paper 1,118 above.

  Furthermore, although the case where the charging unit includes a set of charging rolls has been described in the first embodiment, the charging unit used in the present invention may include a plurality of sets of charging rolls. In this case, a plurality of sets of charging rolls are arranged along the circumferential direction of the electrophotographic photosensitive member 2. Even in this case, the charging noise can be sufficiently reduced.

  Furthermore, in the first embodiment, the charging rolls 4a, 4b, 4c are in contact with the surface of the electrophotographic photosensitive member 2, but the charging rolls 4a, 4b, 4c are not necessarily in contact with the surface of the electrophotographic photosensitive member 2. You don't have to. For example, the charging rolls 4 a, 4 b, 4 c are arranged in the vicinity of the surface of the electrophotographic photosensitive member 2, and a large charging sound is generated as if the charging rolls 4 a, 4 b, 4 c are in contact with the surface of the electrophotographic photosensitive member 2. In such a case, the image forming method of the present invention can be applied. Note that the vicinity of the surface is, for example, a case where the minimum distance between the surface of the charging roll 4a, 4b or 4c and the surface of the electrophotographic photosensitive member 2 is 0.1 mm or less. Such proximity charging is performed, for example, by mixing a resin roll slightly larger than the diameter of the charging roll on the axis of the charging roll, and using this on the surface of the electrophotographic photosensitive member or flanges fitted to both ends thereof. It can implement | achieve by making it contact. Also in the second embodiment, the charging roll does not necessarily need to be in contact with the surface of the electrophotographic photosensitive member, and may be in a close state as described above.

  In the first embodiment, the case where three charging units are provided and these constitute a set of charging units has been described. However, in the present invention, all charging units are not necessarily a set of charging units. If there is at least one set of charging portions, the charging sound from the set of charging portions is reduced, so that the effect of the present invention can be obtained. Therefore, the number of charging parts may be four or more. In addition, from the viewpoint of achieving the quietness of the entire apparatus at a high level, it is preferable that all the charging units constitute a set of charging units. In this case, the number of charging units is a multiple of three.

  Furthermore, in the second embodiment, the case where the image forming unit has three image forming units and each charging unit constitutes a set of charging units has been described. However, the charging units in all the image forming units are not necessarily one. The charging unit of the set may not be configured. If there is at least one set of charging portions, the charging sound from the set of charging portions can be reduced, so that the effects of the present invention can be obtained. Therefore, the number of image forming units may be four or more. Note that, from the viewpoint of achieving a high level of quietness of the entire apparatus, it is preferable that the charging units included in all the image forming units constitute a set of charging units, and each image forming unit has one charging unit. The number of image forming units is a multiple of three.

  Hereinafter, the present invention will be described more specifically with reference to examples.

<Production of electrophotographic photoreceptor>
An aluminum substrate having an outer diameter of 80 mmφ, a length of 965 mm, and a thickness of 1 mm was prepared as the substrate of the electrophotographic photosensitive member. Then, an undercoat layer, a charge generation layer, and a charge transport layer formed in the following manner were sequentially laminated and applied to the aluminum substrate, and a photosensitive layer was formed to produce an electrophotographic photosensitive member.

(1) Formation of undercoat layer Coating solution A having the following composition was applied on the surface of an aluminum substrate by a dipping method and dried at 150 ° C. for 10 minutes to form an undercoat layer having a dry film thickness of 1.0 μm. .

[Composition of coating liquid A]
-Zirconium compound represented by the following structural formula (1): 20 parts by mass-Silane coupling agent represented by the following structural formula (2): 2 parts by mass-Polyvinyl butyral resin represented by the following structural formula (3) : 2 parts by mass-1-butanol: 70 parts by mass

(2) Formation of charge generation layer Coating solution B obtained by dispersing a mixed solution having the following composition in a sand mill using glass beads having a diameter of 1 mmφ for 5 hours was applied onto the undercoat layer by a dipping method. The film was dried at 100 ° C. for 10 minutes to form a charge generation layer having a dry film thickness of 0.2 μm.

[Composition of coating liquid B]
-Chlorgallium phthalocyanine: 5 parts by mass-Vinyl chloride-vinyl acetate copolymer represented by the following structural formula (4): 5 parts by mass-n-butyl acetate: 200 parts by mass

(3) Formation of charge transport layer On the charge generation layer, a coating liquid C having the following composition was applied by an immersion method and dried at 120 ° C. for 60 minutes to form a charge transport layer having a dry film thickness of 25 μm. .

[Composition of coating liquid C]
-Charge transport material represented by the following structural formula (5): 1 part by mass-Polycarbonate resin represented by the following structural formula (6): 1 part by mass-Monochlorobenzene: 2 parts by mass-Tetrahydrofuran: 4 parts by mass

Example 1
As the electrophotographic photoreceptor 2 of the image forming apparatus 100 shown in FIG. 1, the electrophotographic photoreceptor produced as described above was mounted. The charging rolls 4a, 4b and 4c are provided with a conductive elastic layer in which carbon black is dispersed in urethane rubber on the peripheral surface of a core metal made of stainless steel (made of SUS304) having an outer diameter of 6 mmφ, and the conductive elastic layer A layer made of N-methoxymethylated nylon was laminated as a protective layer on the surface, and an outer diameter of 12 mmφ was used. These three charging rolls 4a, 4b, and 4c were arranged as shown in FIGS. As described above, the image forming apparatus (laser beam printer) of Example 1 was manufactured.

  The exposure device 6 is an LED, the developing device 8 is a one-component developing device, the transfer roll 10 is a transfer roller, the image fixing device is a heating roller and a pressure roller, and the cleaning blade 12 is a polyurethane cleaning blade.

  In the image forming apparatus, the oscillating voltage E1 applied to the electrophotographic photosensitive member 2 by the charging roll 4a, the oscillating voltage E2 applied to the electrophotographic photosensitive member 2 by the charging roll 4b, and the electrophotographic by the charging roll 4c. The oscillating voltage E3 applied to the photosensitive member 2 can be turned on and off, and each phase difference can be controlled to 1π / 3 radians. Further, the image forming apparatus can be driven to rotate only the electrophotographic photosensitive member 2 (in this case, of course, the charging rolls 4a, 4b, and 4c are also driven to rotate), and has been modified so as not to generate other various operating sounds. . Note that the image forming apparatus operates under the following conditions.

(Operating conditions)
・ Print speed: 9 sheets per minute (A0)
・ Process speed: 105mm / sec
The vibration voltage E1, the vibration voltage E2, and the vibration voltage E3:
DC applied voltage ... 700v
AC applied voltage: sine wave, peak-to-peak voltage of 1.0 KV, frequency of 700 Hz
-Printer input pixel density: 600 dpi

  The image forming apparatus thus obtained was tested for the effect of reducing charging noise during image formation as follows.

  That is, the image forming apparatus was installed in an anechoic room with a background noise of 30 dB (A), and a noise meter “NL-02A” (manufactured by Lion Co., Ltd.) was installed at a position away from the image forming apparatus. At this time, the microphone position of the sound level meter was set at a location 50 cm away from the surface of the electrophotographic photosensitive member.

  In this state, in the image forming apparatus, the vibration voltage E1, the vibration voltage E2, and the vibration voltage E3 are not applied, and only the electrophotographic photosensitive member 2 is rotationally driven, and the sound pressure [dB (A)] at this time is set as the noise. This was measured by a meter and used as noise data for the comparison test.

  Subsequently, for the image forming apparatus, the phase difference between the vibration voltage E1 and the vibration voltage E2 is 1π / 3 radians, the phase difference between the vibration voltage E2 and the vibration voltage E3 is 1π / 3 radians, and the vibration voltage E3 An electrophotography is performed in the same manner as in the comparative test except that the oscillating voltage is applied to each of the charging rolls 4a, 4b, and 4c while adjusting the phase difference with the oscillating voltage E1 to be 1π / 3 radians. Only the photosensitive member 2 was driven to rotate, and the sound pressure [dB (A)] was measured. The difference between the obtained sound pressure [dB (A)] and the sound pressure [dB (A)], which is the noise data of the comparison test, was used as the charged sound in Example 1. The results are summarized in Table 1 below.

(Comparative Example 1)
An image forming apparatus was obtained in the same manner as in Example 1 except that an image forming apparatus that can control the phases of the oscillating voltage E1, the oscillating voltage E2, and the oscillating voltage E3 to all the same phase was used.

  In the image forming apparatus thus obtained, an electron voltage was applied in the same manner as in the comparative test, except that the voltage was applied while adjusting the vibration voltage E1, the vibration voltage E2, and the vibration voltage E3 to be in phase. Only the photographic photoreceptor 2 was driven to rotate, and the sound pressure [dB (A)] was measured. The difference between the obtained sound pressure [dB (A)] and the sound pressure [dB (A)], which is the noise data of the comparison test, was used as the charged sound in Comparative Example 1. The results are summarized in Table 1 below.

  From the results shown in Example 1 and Comparative Example 1, according to the image forming method of Example 1, it was possible to sufficiently reduce the charging noise, whereas according to the image forming method of Comparative Example 1, It was found that charging noise could not be reduced sufficiently.

  From this result, it was confirmed that according to the image forming apparatus and the image forming method of the present invention, the charging noise can be sufficiently reduced.

1 is a schematic configuration diagram illustrating an embodiment of a first image forming apparatus of the present invention. (A)-(b) is a figure which shows the positional relationship of the electrophotographic photoreceptor and charging roll in the image forming apparatus 100 shown in FIG. 1, (a) is a perspective view, (b) is an upper surface. FIG. It is a schematic block diagram which shows one Embodiment of the 2nd image forming apparatus of this invention.

Explanation of symbols

  2, 102Y, 102M, 102C ... electrophotographic photosensitive member (latent image carrier), 4a, 4b, 4c, 104Y, 104M, 104C ... charging unit (charging means), 6, 108Y, 108M, 108C ... exposure apparatus (exposure) Means), 8, 110Y, 110M, 110C ... developing device (developing means), 9 ... support, 14 ... control device (control means), 50, 200Y, 200M, 200C ... image forming unit, 100,200 ... image forming apparatus.

Claims (6)

A latent image carrier;
Charging means for charging the surface of the latent image carrier by applying an oscillating voltage in which direct current and alternating current are superimposed on the surface of the latent image carrier;
Exposure means for exposing a charged region on the surface of the latent image carrier to form a latent image;
One or more image forming units including at least developing means for developing the latent image,
The charging means has three or more charging portions capable of applying the vibration voltage to the surface of the latent image carrier;
A set of charging units is constituted by three of the charging units,
In two charging units arbitrarily selected from the set of charging units, a phase difference between an oscillating voltage applied to one charging unit and an oscillating voltage applied to the other charging unit is An image forming apparatus comprising: a control unit that controls the charging unit so as to be 26π / 90 to 69π / 180 radians.   The three charging units constituting the set of charging units are respectively arranged substantially in parallel with a linear direction orthogonal to the moving direction of the surface of the latent image carrier, and in the charging regions of the charging units adjacent to each other. The image forming apparatus according to claim 1, wherein the end portions overlap with each other. A latent image carrier;
Charging means for charging the surface of the latent image carrier by applying an oscillating voltage in which direct current and alternating current are superimposed on the surface of the latent image carrier;
Exposure means for exposing a charged region on the surface of the latent image carrier to form a latent image;
Three or more image forming units including at least developing means for developing the latent image,
In each of the image forming units, the charging unit includes a charging unit capable of applying the vibration voltage to the surface of the corresponding latent image carrier.
Between three of the image forming units, a set of charging units is constituted by the three charging units,
In two charging units arbitrarily selected from the set of charging units, a phase difference between an oscillating voltage applied to one charging unit and an oscillating voltage applied to the other charging unit is An image forming apparatus comprising: a control unit that controls the charging unit so as to be 26π / 90 to 69π / 180 radians.   The three charging parts constituting the set of charging parts are in contact with or in close proximity to the surface of the corresponding latent image carrier, respectively. The image forming apparatus described.   The image according to any one of claims 1 to 3, wherein the three charging units constituting the set of charging units are separated from the surface of the corresponding latent image carrier. Forming equipment. A charging step of charging the surface of the latent image carrier by applying an oscillating voltage in which direct current and alternating current are superimposed on the surface of the latent image carrier;
An exposure step of exposing a charged area on the surface of the latent image carrier to form a latent image;
At least a developing step for developing the latent image,
In the charging step, a vibration voltage applied to one charging unit between two charging units arbitrarily selected from the set of charging units using a set of charging units including three charging units. And applying the oscillating voltage to the surface of the latent image carrier so that the phase difference between the oscillating voltage applied to the other charging portion is 26π / 90 to 69π / 180 radians. An image forming method.

Images