JP2006251736A - Processing cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process cartridge reduced in size and cost, and outputting an image without impairing image quality and an image forming apparatus. <P>SOLUTION: The miniaturization of a belt photoreceptor size, the approximate shape unification of developing, exposing and electrostatic charging means, and the size and cost reduction over the entire part of the apparatus, are realized without impairing image quality etc., by arranging EH developing means in superposition by using the belt photoreceptor. The miniaturization of the cartridge and ease of maintenance are also realized by making each unit of the developing cartridges attachable and detachable. Further, a cartridge desired by a user is applicable regardless of its size and number of the cartridges by using a casing corresponding to the respective developing cartridges. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic process cartridge and an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine thereof, and in particular, toner particles are generated by a phase-shift electric field in a developing device installed in the image forming apparatus. The present invention relates to a process cartridge and an image forming apparatus using an electrostatic conveyance member having a movable electrostatic conveyance surface.

  Conventionally, as an image forming apparatus such as a copying machine, a printer, and a facsimile machine, an electrostatic latent image is formed on an image carrier, and a developer (hereinafter referred to as “toner particles”) that is powder is attached to the latent image. Thus, an electrophotographic system for developing as a toner image is known.

  Here, the invention disclosed in Patent Document 1 is known as a developing device for developing a latent image. Patent Document 1 relates to a developing device that moves toner particles in a horizontal direction and a vertical direction on the surface of an electrostatic conveying member by applying energy of a phase-shifting electric field to toner particles that are powder. In such a developing device, the toner particles are transferred to a developing area which is a facing portion between the image carrier and the developing device by a phase shift electric field, and adhere to an image portion of a latent image on the image carrier in the developing area.

  Further, downsizing of the image forming apparatus is also progressing, and the inventions disclosed in Patent Documents 2 and 3 are known. Patent Document 2 discloses an image forming apparatus that can easily maintain, replace, and replenish a charging device and a developing device, and can maintain a positional accuracy between various devices and obtain a good image, in particular, by superimposing toner images. The present invention relates to a color image forming apparatus capable of obtaining a good color image.

Patent Document 3 relates to a developing device having a high degree of freedom, and an image forming apparatus including the developing device, in which the developer can be reliably conveyed and can be reduced in size, and the arrangement position is not particularly limited.
JP 2003-280388 A JP-A-8-339110 Japanese Patent No. 3530124

  The image-on-image type color image forming apparatus is capable of high-speed image formation equivalent to the tandem method regardless of one photoconductor, easy color registration, one transfer process and high stability. It has many excellent features such as high image quality. However, the developing device needs to develop the second and subsequent colors without disturbing the toner image on the photosensitive member, and the conventional dry one-component or dry two-component development method has not been satisfactorily put into practical use.

  In this regard, Fuji Xerox Co., Ltd. has put this image-on-image-type color image forming apparatus into practical use by using the powder cloud development system under the trade name “iGen (registered trademark) 3”. However, the configuration of the developing device is complicated and extremely large, and is not small and low cost.

  Since the developing device using the electrostatic toner transport means is non-magnetic and non-contact with respect to the photosensitive member in the developing area, and the developing electric field does not reverse in one direction, Even if there are contaminants such as toner images and paper dust, they do not flow into the developing device, so they are ideal for small, low-cost image-on-image color image forming devices that have not been put to practical use. In particular, the issue was how to achieve miniaturization.

  The image-on-image type image forming apparatus sequentially arranges the charging, exposing, and developing processes for a plurality of colors for one photoconductor. Therefore, when a photoconductor drum is used, the diameter can be increased if a space for sequentially arranging the image is secured. It becomes extremely large and becomes larger than conventional tandem systems. In particular, the exposure units are arranged radially around the photosensitive drum, and the space efficiency is extremely reduced.

  In order to avoid this, there is a proposal to arrange a small LEDA light source inside the transparent photosensitive member, but it is inferior in uniformity of light quantity and pixel pitch and unfavorable in terms of cost as compared with the current mainstream laser exposure means. In addition, the transparent photoconductor has a narrow selection of base materials, which causes a significant cost increase.

  In view of the above problems, an object of the present invention is to provide a process cartridge and an image forming apparatus which can be reduced in size and cost and can output an image without impairing image quality.

  In order to achieve the above object, an invention according to claim 1 is a process cartridge having a developing means for developing an electrostatic latent image on an image carrier and detachable from an image forming apparatus main body. An electrostatic conveyance member having an electrostatic conveyance surface capable of moving toner particles by a phase-shifting electric field, a toner storage unit for storing toner particles for use in development, and from the toner storage unit to the electrostatic conveyance surface It has a supply means for supplying toner particles and a charging means for charging the image carrier. The image carrier can be detached from the process cartridge body, and the charging means and the developing means are integrated. It is characterized by being.

  According to a second aspect of the present invention, in the process cartridge according to the first aspect, the integrated charging unit and the developing unit are separable.

  A third aspect of the present invention is the process cartridge according to the first aspect, further comprising at least two or more process cartridges arranged in the same posture, wherein the two or more process cartridges can be detached from the image forming apparatus at the same time. It is characterized by being.

  According to a fourth aspect of the present invention, in the process cartridge according to the first aspect, each of the four color process cartridges of black, magenta, cyan, and yellow arranged in the same posture has four colors in the same posture. And a process cartridge having a complementary color other than the above cartridges, and at least two of the process cartridges are removable from the image forming apparatus at the same time.

  According to a fifth aspect of the present invention, in the process cartridge according to any one of the first to fourth aspects, the image forming apparatus further includes an exposure unit for exposing the electrostatic latent image on the image carrier. The charging unit and the developing unit are integrated.

  According to a sixth aspect of the present invention, the process cartridge according to the fifth aspect further includes an indicating member for arranging the plurality of process cartridges in the same posture and a sensor for recognizing a color of the process cartridge. In the image forming apparatus, process cartridges having an arbitrary color and number desired by the user are installed.

  According to a seventh aspect of the present invention, in the process cartridge according to the sixth aspect, the support member supports a process cartridge having a size different from that of the process cartridge installed in the image forming apparatus.

  According to an eighth aspect of the present invention, in the process cartridge according to any one of the first to seventh aspects, the charging means is a scotron charger system.

  A ninth aspect of the present invention is the process cartridge according to any one of the first to seventh aspects, wherein the charging means is a non-contact charging roller system.

  According to a tenth aspect of the present invention, in the process cartridge according to any one of the first to seventh aspects, the charging means is a solid discharge system.

  According to an eleventh aspect of the present invention, in the process cartridge according to any one of the first to tenth aspects, the image carrier has a belt shape.

  According to a twelfth aspect of the present invention, the process cartridge according to any one of the second to eleventh aspects can be used in common for each color in the initial state of the image forming apparatus.

  A thirteenth aspect of the present invention is an image forming apparatus in which the process cartridge according to any one of the first to twelfth aspects can be loaded.

  As described above, according to the process cartridge and the image forming apparatus of the present invention, it is possible to reduce the size and cost, and to output an image without impairing the image quality.

  In the present invention, the EH developing means developed by the inventors is non-magnetic and non-contact with respect to the photosensitive member in the developing area, and the developing electric field does not reverse in one direction. Even if there is a contaminant such as a toner image or paper dust on the photosensitive member, it does not flow into the developing device, has high development sensitivity, and has a required charging potential of 2 compared to the conventional developing method (approximately 450 V). Paying attention to the fact that development is possible at 300V or less, which is / 3 or less, and the developing means are arranged in a superposed manner using a belt photoreceptor, the belt photoreceptor size is reduced, development, exposure, and charging means are made in a substantially common shape. Further, it is possible to reduce the size and cost of the entire apparatus without impairing the image quality.

Embodiments of the present invention will be described below in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.
FIG. 1 is a block diagram illustrating an example when the process cartridge according to the present exemplary embodiment is applied to an image forming apparatus.

  The image forming apparatus in the present embodiment includes an image carrier 11, a transfer roller 2, a fixing device 3, writing devices 4K, 4M, 4C, and 4Y, a paper feeding device 5, and developing cartridges 6K, 6M, 6C, 6Y. Note that K, M, C, and Y in the writing device 4 and the developing cartridge 6 represent toners of black, magenta, cyan, and yellow, respectively.

  The image carrier 11 is a negatively charged organic photosensitive member configured in a belt shape, and is provided so as to be rotated in the direction of an arrow by a rotation driving mechanism (not shown). Developing cartridges 6K, 6M, 6C, and 6Y, and a charging device to be described later are opposed to the image carrier 11 for each color, and toner images are sequentially transferred onto the image carrier 11 as the image carrier 11 moves. (Single pass color system).

  The paper feeding device 5 stores a transfer material such as a recording paper, and starts conveying the transfer material when an image is formed. The fixing device 3 is for fixing an unfixed toner image formed on the transfer material.

  At the time of image formation, the transfer material sent from the paper feeding device 5 is conveyed to the contact portion between the image carrier 11 and the transfer roller 2. Then, the full color image formed on the image carrier 11 at the contact portion between the image carrier 11 and the transfer roller 2 is transferred onto the transfer material by the voltage applied to the transfer roller 2. Thereafter, when the transfer material reaches the fixing device 3, the toner image on the transfer material is fixed on the transfer material by being heated while being sandwiched between the heating roller 3 a and the pressure roller 3 b, and can be transferred onto the transfer material. A visual image is formed.

  Reference numerals 6K, 6M, 6C, and 6Y denote developing cartridges for developing black, magenta, cyan, and yellow toner images, respectively. As shown in FIG. 3, the developing cartridge can be detached from the space opened when the image carrier 11 is retracted, and can be replaced by an operator.

  The writing devices 4K, 4M, 4C, and 4Y are devices for writing latent images corresponding to black, magenta, cyan, and yellow, respectively, on the charged image carrier 11 according to image information. Various devices such as an optical scanning device using a polygon and an LED array can be used.

  FIG. 2 is a block diagram showing the configuration of the developing cartridge 6. Since each color developing cartridge 6 has the same structure, only one will be described.

  The developing cartridge 6 of the present embodiment includes a charging device 12, a developing device 13, and a cleaning device 14.

  The charging device 12 is for uniformly charging the surface of the image carrier 11. In this embodiment, corona charging is adopted. If non-contact charging means such as corona charging is used, the image carrier 11 can be charged without disturbing the toner image formed by the upstream developing cartridge 6.

  The charging device 12 and the developing device 13 are integrated by the casing 1 and can be attached and detached simultaneously when the developing cartridge 6 is replaced. In addition, the charging device 12 and the developing device 13 can be detached from the casing 1 separately.

  The developing device 13 includes a roller-shaped electrostatic conveyance member 13a having a plurality of electrodes for generating an electric field for conveying, developing, and collecting toner particles that are powder. The electrostatic transport member 13a faces the image carrier 11 in a non-contact manner with a gap of 50 to 1000 μm, preferably 150 to 400 μm, at the time of image formation.

The configuration of the electrostatic transfer member 13a will be described in detail with reference to FIG.
FIG. 4 is an enlarged cross-sectional view of the surface of the electrostatic transport member 13a on the image carrier 11 side.

  The electrostatic transport member 13a includes a plurality of electrodes 102, 102, 102,... On the support substrate 101 as a set, arranged at a predetermined interval along the toner moving direction, and a transport surface thereon. A surface protective layer 103 made of an inorganic or organic insulating material that is a protective film that covers the surface of the electrode 102 is laminated.

As the support substrate 101 in this embodiment, an insulating film such as SiO ₂ is formed on a substrate made of an insulating material such as a glass substrate, a resin substrate, or a ceramic substrate, or a substrate made of a conductive material such as SUS. Or a substrate made of a material that can be flexibly deformed, such as a polyimide film, can be used.

  The electrode 102 is formed by forming a conductive material such as Al or Ni—Cr on the support substrate 101 in a thickness of 0.1 to 10 μm, preferably 0.5 to 2.0 μm, and patterning it into a required electrode shape. is doing. The width L in the powder traveling direction of the plurality of electrodes 102 is 1 to 20 times the average particle diameter of the powder to be moved, and the distance R in the powder traveling direction of the electrode 102 is also moved. The average particle size of the body is 1 to 20 times.

As the surface protective layer 103, for example, SiO ₂ , TiO ₂ , TiO ₄ , SiON, BN, TiN, Ta ₂ O _5, etc. are formed in a thickness of 0.5 to 10 μm, preferably 0.5 to 3 μm. And formed.

  In FIG. 4, a line extending from each electrode 102 represents a conductive line for applying a voltage to each electrode 102. Of the overlapping portions of each line, only the portions indicated by black circles are electrically connected, and the other portions are electrically insulated. Different driving voltages of n phases are applied to the electrodes 102 from the power source on the main body side. In this embodiment, a case where a three-phase driving voltage is applied (n = 3) will be described. However, the present invention can be applied to any natural number n satisfying n> 2 as long as toner particles are conveyed. .

  In the present embodiment, each electrode 102 is connected to one of the contact points S11, S12, S13, S21, S22, and S23 on the process cartridge side. Each contact is connected to a power source on the main body side that provides drive waveforms V11, V12, V13, V21, V22, and V23 when the process cartridge is mounted on the main body of the image forming apparatus. Here, the contact points S11, S12, S13, S21, S22, and S23 on the process cartridge side are exposed to the outside of the process cartridge (the outer wall surface of the developing cartridge 6) as shown in FIG. Then, power is supplied from the main body side power supply by connecting to the main body side contact.

  The electrostatic transport member 13a transports toner particles to the vicinity of the image carrier 11, and also transports the toner particles that have not contributed to development after passing through the development region, and the latent image carrier 11 It is divided into a development area for forming toner images by attaching toner particles to the image. The development area exists only in the area close to the image carrier 11. On the other hand, the conveyance area exists on the entire circumference other than the development area on the circumference of the electrostatic conveyance member 13a. Hereinafter, a region where the toner particles can move by the phase electric field is referred to as an “electrostatic transfer surface”.

  In the case of the present embodiment, the entire surface of the electrostatic transport member 13a is an electrostatic transport surface. In the transport region, drive waveforms V11, V12, and V13 are applied to the electrodes 102, and in the development region, drive waveforms V21, V22, and V23 are applied to the electrodes 102.

  Next, the principle of electrostatic conveyance of toner in the electrostatic conveyance member 13a will be described. By applying an n-phase driving waveform to the plurality of electrodes 102 of the electrostatic transfer member 13a, a phase-shift electric field (traveling wave electric field) is generated by the plurality of electrodes 102 and charged on the electrostatic transfer member 13a. The toner particles move in the transport direction in response to a repulsive force and / or suction force.

  For example, with respect to the plurality of electrodes 102 of the electrostatic transfer member 13a, as shown in FIG. 5A, a three-phase pulse-shaped drive waveform that changes between the ground G (0 V) and the positive voltage +. Are applied at different timings. At this time, as shown in FIG. 5 (B), the negatively charged toner T is present on the electrostatic transport member 13a, and “G”, “G”, Assuming that “+”, “G”, and “G” are applied (1), the negatively charged toner T is positioned on the “+” electrode 102.

  At the next timing, “+”, “G”, “G”, “+”, and “G” are applied to the plurality of electrodes 102, respectively (2). The negatively charged toner T has a repulsive force acting on the left “G” electrode 102 and an attracting force acting on the right “+” electrode 102. It moves to the electrode 102 side of “+”.

  Further, at the next timing, “G”, “+”, “G”, “G”, and “+” are respectively applied to the plurality of electrodes 102 as shown in FIG. Therefore, the negatively charged toner T further moves to the “+” electrode 102 side.

  In this way, by applying a multi-phase driving waveform with varying voltages to the plurality of electrodes 102, a traveling wave electric field is generated on the electrostatic transport member 13 a, and the negatively charged toner has this traveling wave electric field. Move in the direction of travel. In the case of positively charged toner, it is similarly moved in the same direction by reversing the change pattern of the drive waveform.

  Here, in the present embodiment, in the transport region of the electrostatic transport member 13a, three-phase drive waveforms (drive pulses) V11, V12, and V13 are applied to each electrode 102 as shown in FIG. These three-phase drive waveforms V11, V12, V13 are obtained by setting the + 100V application time ta of each phase to about 33%, which is 1/3 of the repetition period tf (this is referred to as “carrier voltage pattern”). is there. Further, it is known from the applicant's research that this drive waveform is a waveform suitable for high-speed conveyance of toner particles in the conveyance region.

  On the other hand, in the development region, three-phase drive waveforms (drive pulses) V21, V22, and V23 are applied to each electrode 102 as shown in FIG. In these three-phase drive waveforms V21, V22, V23, the application time ta of + 100V or 0V of each phase is set to about 67%, which is 2/3 of the repetition period tf (this is called “development voltage pattern”). It is. In addition, in the development region, it is preferable that toner particles are positively launched toward the image carrier, and it is known from the applicant's research that the drive waveform in FIG. 7 is suitable for launching toner particles. .

  Even when the driving waveform of the developing voltage pattern is applied, a force in the lateral direction is also received except for the toner positioned at the center of the 0V electrode. Therefore, not all toners are launched at the same time, and some toners move in the horizontal direction. Conversely, even when a drive waveform of a carrier voltage pattern is applied, depending on the position of the toner, there is a case where the rising distance is larger than when the toner is launched obliquely at a large angle and moves horizontally.

  Therefore, the drive waveform pattern applied to each electrode 102 in the transport region is not limited to the transport voltage pattern shown in FIG. 6 described above, and the drive waveform pattern applied to each electrode 102 in the development region is also described above. It is not limited to the development voltage pattern shown in FIG.

  Up to this point, the case where the driving waveform has three layers has been described, but when this is generalized to the n-phase, the driving waveform is as follows.

  When a traveling wave electric field is generated by applying an n-phase (n is an integer of 3 or more) pulsed voltage (driving waveform) to each electrode, the voltage application time per phase is {repetition cycle time × ( By setting the voltage application duty to be less than (n-1) / n}, the efficiency of conveyance and development can be increased. For example, when a three-phase driving waveform is used, as described above, the voltage application time ta of each phase is set to less than about 67%, which is 2/3 of the repetitive cycle time tf, and four-phase driving is performed. When using a waveform, it is preferable to set the voltage application time ta of each phase to less than 75%, which is 3/4 of the repetition cycle time.

  On the other hand, the voltage application duty is preferably set to {repetition cycle time / n} or more. For example, when a three-phase driving waveform is used, it is preferable to set the voltage application time ta of each phase to about 33% or more, which is 1/3 of the repetition cycle time tf.

  That is, a time is set between the voltage applied to the target electrode and the voltages applied to the upstream adjacent electrode and the downstream adjacent electrode in the traveling direction such that the upstream adjacent electrode repels and the downstream adjacent electrode sucks. By doing so, the efficiency can be improved. In particular, when the driving frequency is high, the toner on the electrode of interest is set by setting it within the range of {repeat cycle time / n} or more and less than {repeat cycle time × (n−1) / n}. It becomes easy to obtain the initial speed with respect to.

  In the above description, the electrostatic transport member is described as being considered to be the best mode. However, if the desired transport / development performance can be obtained, the distance between the electrodes 102 is different between the development region and the transport region. Thus, the direction of the electric field may be adjusted, or the distance between the electrodes and the drive waveform may be the same in the development area and the conveyance area.

  Further, the developing device 13 is provided with a supply roller 13b for supplying toner particles to the electrostatic transport member 13a, and a magnetic brush is formed at a portion facing the supply roller 13b and the electrostatic transport member 13a. Yes. On the surface of the supply roller 13b, a nonmagnetic sleeve is formed in which a nonmagnetic material such as aluminum, brass, stainless steel, or conductive resin is formed into a cylindrical shape. This non-magnetic sleeve is rotated clockwise by a rotation drive mechanism (not shown).

  A doctor blade 13c for restricting the height of the developer chain spike, that is, the amount of developer on the sleeve, is installed on the upstream side portion of the development area in the developer transport direction. The doctor gap, which is the distance between the doctor blade 13c and the nonmagnetic sleeve, is set to 0.4 mm. Furthermore, two screws 13d for pumping up the developer in the developing device 13 to the supply roller 13b while stirring the developer in the region opposite to the image carrier 11 when viewed from the supply roller 13b are installed.

  In the supply roller 13b described above, a magnet roller body (magnet roller) that forms a magnetic field is provided in a fixed state so as to cause rise of developer on the peripheral surface of the nonmagnetic sleeve. The carrier of the developer rises in a chain shape on the non-magnetic sleeve so as to follow the normal magnetic field lines emitted from the magnet roller body. The charged toner is attached to the carrier that has spikes in the chain shape, thereby forming a magnetic brush. The magnetic brush is transferred in the same direction as the nonmagnetic sleeve by the rotation of the nonmagnetic sleeve.

  The magnet roller body includes a plurality of magnetic poles (magnets). Specifically, as shown in FIG. 8, the development main magnetic pole P <b> 1 that causes the developer to rise in the development region, the magnetic pole P <b> 4 and the magnetic pole P <b> 5 for pumping up the developer onto the nonmagnetic sleeve, A magnetic pole P6 for transporting the developer to the development area, a magnetic pole P2 for transporting the developer in the post-development area, and an agent separation magnetic pole P3 are provided.

  In this embodiment, the magnet roller body is composed of 6-pole magnets P1 to P6, but may be composed of 8 or 12 poles. In FIG. 8, the curve drawn on the surface of the supply roller 13b shows an outline of the normal magnetic force pattern, and the symbols “N” and “S” indicate the polarity of the surface side of the supply roller 13b of each magnetic pole. , N pole and S pole, respectively.

  In the developing means 13, toner particles and a magnetic carrier (not shown) are stored. In carrying out the present invention, it is not necessary to specifically limit the carrier particles and the toner particles, but the aspects in the present embodiment will be described below.

  The toner particles of the present embodiment are those obtained by radical polymerization in a state where a styrene or acrylic polymerizable monomer is dispersed in water together with a polymerization initiator as a binder resin, or a polyester resin is dispersed in water. And polymerized by a polyaddition reaction. Then, a non-magnetic toner particle having a weight average particle diameter of about 5 μm is obtained by adding a colorant, a charge control agent, and the like to granulate.

The magnetic carrier of the present embodiment, magnetization in the magnetic field of one kOe is, 30 emu / cm ³ or more, it is desirable that the carrier in 200 emu / cm ³ or less. If the amount of magnetization is low magnetization of 200 emu / cm ³ or less, preferably 140 emu / cm ³ or less, the magnetic interaction between adjacent magnetic brushes becomes small, and the ears of the formed magnetic brush are dense and , Get shorter.

As a result, uniform supply of toner particles to the electrostatic transport member 13a can be achieved. On the other hand, when the magnetization amount of the magnetic carrier is less than ³⁰ emu / cm ³ , the developer transport performance is poor. Therefore, the magnetization of the magnetic carrier is 30 emu / cm ³ or more, preferably, is preferably 80 emu / cm ³ or more. In the present embodiment, a resin magnetic carrier in which a magnetic material generated by a polymerization method including at least a binder resin and a magnetic metal oxide and a nonmagnetic metal oxide is dispersed is used as the magnetic carrier.

Specifically, magnetite (Fe ₃ O ₄ ) is used as the magnetic metal oxide. As the binder resin for dispersing and binding the metal oxide, a resin obtained by polymerizing vinyl monomers such as styrene and ethyl acrylate is used. A carrier in which a magnetic material is dispersed in a binder resin may be used as it is. However, it may be used as a carrier core, and an insulating resin may be used as a coating agent, and the carrier core surface may be used as a coated magnetic carrier.

  The amount of magnetization is determined by placing a magnetic carrier packed in a cylindrical container in an external magnetic field of 1 kilo-Oersted with an oscillating magnetic field type magnetic property automatic recording device manufactured by Riken Denshi Co., Ltd. It can be calculated by multiplying the strength of magnetization obtained by measurement at that time by the true specific gravity of the carrier.

  Next, the operation of the process cartridge in this embodiment will be described.

  The image forming apparatus of the present embodiment is an image forming apparatus that can function as a copying machine and a printer. When functioning as a copier, the image information read from the scanner is subjected to various image processing such as A / D conversion, MTF correction, gradation processing, and the like, and converted into writing data. When functioning as a printer, image information in a format such as a page description language or a bitmap transferred from a computer or the like is subjected to image processing and converted into write data.

  Prior to image formation, the image carrier 11 begins to rotate in the direction of the arrow in FIG. 2, that is, in the counterclockwise direction so that the moving speed of the surface becomes a predetermined measure. The charging device 12 is rotated in conjunction with the rotation of the image carrier 11. At this time, a DC voltage of −100 V and an AC voltage with an amplitude of 1200 V and a frequency of 2 kHz are applied to the core of the charging device 12 from the charging bias application power source. As a result, the surface of the image carrier 11 is charged to about −100V.

  The writing device 4 (4K, 4M, 4C, 4Y) exposes the charged image carrier 11 according to the writing data. That is, by changing the potential of the image portion by light irradiation, a difference from the potential of the non-image portion not irradiated with light is generated, and an electrostatic latent image is formed by this potential contrast.

  The electrostatic latent image formed on the image carrier 11 by the writing device 4 is developed by the developing device 13. Then, when toner particles adhere to the image portion, the toner image is visualized on the image carrier 11. In the development by the phase-shift electric field, the toner particles move while jumping off the surface of the electrostatic conveyance member 13a, and when they approach the image carrier 11, they are attached so as to be attracted to the image portion and developed. In the present embodiment, a voltage of −50 V is applied to the electrostatic transfer substrate 13a, and a voltage of −250V is applied to the supply roller 13b. As a result, an electric field for guiding toner particles is formed from the supply roller 13b to the electrostatic transport substrate 13a and from the electrostatic transport substrate 13a to the image portion on the image carrier 11.

  Simultaneously with the timing at which the toner image formed on the image carrier 11 reaches the transfer portion corresponding to the facing portion between the transfer roller 2 and the image carrier 11, the transfer material is conveyed from the paper feeding device 5. The toner image on the image carrier 11 is transferred to a transfer material by a voltage applied to the transfer roller 2. The transferred toner image is fixed on a transfer material by the fixing device 3 and an image is output.

  On the other hand, toner remaining on the image carrier 11 without being transferred (transfer residual toner) is cleaned by the cleaning device 14, and the surface of the image carrier 11 after cleaning is used for the next image formation. .

  Next, an operation for forming a toner image on the image carrier will be described.

  First, the surface of the image carrier 11 is uniformly charged by the charging device 12. Even when a toner image has already been formed on the image carrier 11, the surface of the image carrier 11 including the toner image is uniformly charged. Next, a light beam corresponding to the image information is emitted from the writing device 4. Since the light beam passes between the charging device 12 and the developing cartridge 6, the light beam is irradiated onto the image carrier 11 that has already been uniformly charged, and the image is a negatively charged photoconductor. On the surface of the carrier 11, a region corresponding to the image portion is neutralized to form a latent image.

  As described above, the developing cartridge 6 attaches toner particles to the image portion of the latent image formed on the image carrier 11 and visualizes the latent image as a toner image. The above charging, light beam irradiation, and development steps are repeated at the portion facing each developing cartridge 6 as described above, and a full-color image in which four color toner images are superimposed on the image carrier 11 is formed. become.

  Note that the image forming apparatus according to the present embodiment does not include a cleaning member for collecting the transfer residual toner particles on the surface of the image carrier 11. The transfer residual toner particles remain on the surface of the image carrier 11, but are charged by the charging devices 12 provided in the four developing cartridges 6 and eventually transferred to a transfer material and removed from the image carrier 11. Is done. When the transfer residual toner particles are transferred to the transfer material, some image disturbance occurs, but if the transfer residual toner particles are slightly disturbed, they are not visually recognized.

  In the image forming apparatus of this embodiment, a plurality of cartridges can be attached and detached simultaneously. FIG. 10 is a diagram showing a case where a plurality of cartridges are attached and detached simultaneously. As described above, the developing cartridges 6K, 6M, 6C, and 6Y are cartridges in which a developing cartridge and a charging device for developing black, magenta, cyan, and yellow toner images are integrated.

  As shown in FIG. 10, the developing cartridge can be detached from the space opened by retracting the image carrier 11, and can be replaced by an operator. Of the developing cartridges 6K, 6M, 6C, and 6Y, at least two cartridges (6M, 6C, and 6Y in FIG. 10) are packaged by the casing 2 and can be attached and detached simultaneously.

  Furthermore, it is possible to add another cartridge of the four-color cartridge described above. FIG. 11 is a diagram showing a case in which, in addition to the four color cartridges, additional cartridges are added and detached at the same time.

  The developing cartridges 6K, 6M, 6C, and 6Y are cartridges in which a developing cartridge and a charging device for developing black, magenta, cyan, and yellow toner images are integrated. In addition to the process colors black, magenta, cyan, and yellow, in order to develop color toner R, G, and B (red, green, and blue) toner images to improve color reproducibility. And a space where a developing cartridge for developing a gray toner image can be added.

  On the other hand, it is conceivable to add a developing cartridge for the decoloring toner. Further, a writing device corresponding to the increased number of developing cartridges is added. As shown in FIG. 11, the developing cartridge can be detached from the space opened by the image carrier 11 being retracted, and can be replaced by an operator. Further, at least two cartridges (6M, 6C, and 6Y in FIG. 11) of the process color developing cartridge and the increased developing cartridge described above are packaged by the casing 3 and can be attached and detached simultaneously.

  Further, according to the process cartridge of this embodiment, since a plurality of units in the cartridge are integrated, they can be attached and detached at the same time during maintenance or the like. An example is shown in FIG.

  The charging device 12 is for uniformly charging the surface of the image carrier 11. In this embodiment, corona charging is adopted. If non-contact charging means such as corona charging is used, the image carrier 11 can be charged without disturbing the toner image formed by the upstream developing cartridge.

  The charging device 12 and the developing device 13 are integrated by the casing 4 and can be attached and detached simultaneously when the developing cartridge 6 is replaced. Further, the charging device 12 and the developing device 13 can be detached from the casing 4 separately.

  Further, a writing device 4 ′ is installed between the charging device 12 and the developing device 13. The writing device 4 'is also integrated with the charging device 12 and the developing device 13 by the casing 4, and can be attached and detached at the same time when the developing cartridge is replaced. Various devices such as a small LED array and an optical scanning device using polygons can be used as the writing device.

  Further, according to the process cartridge of this embodiment, cartridges of any color and number can be installed. An example is shown in FIG.

  The developing cartridges 6K, 6M, 6C, and 6Y are cartridges in which a developing cartridge and a charging device for developing black, magenta, cyan, and yellow toner images are integrated. Furthermore, in addition to the process colors black, magenta, cyan and yellow, in order to improve color reproducibility, a developing cartridge for developing toner images of R, G and B (red, green and blue), A space is provided in which a developing cartridge for developing a gray toner image can be added.

  On the other hand, it is conceivable to add a developing cartridge for the decoloring toner. FIG. 13 shows a case where a color process cartridge is used, but other configurations such as black and red developing cartridges are also conceivable. Of course, it is possible to use only a single black color. In this case, a plurality of cartridges of the same color can be placed in an unused space.

  As an advantage of this configuration, since development can be dispersed, the durability of the cartridge can be improved, the amount of toner stored can be increased, and the like. The developing cartridge can be detached from the space opened by the image carrier 11 being retracted, and can be replaced by an operator.

  Further, the durability of the cartridge can be improved by increasing the size of the cartridge that is frequently used. As shown in FIG. 14, since the use of a single black color is expected to be more than the use of a color, the 6K black developer cartridge is a 6M, 6C, 6Y magenta, cyan, yellow developer cartridge. In comparison with the above, the volume of the cartridge is increased and the toner storage capacity is increased.

  In addition, since the charging device 12, the writing device 4, and the developing device 13 can be enlarged, there is a margin in process design. Therefore, it is possible to increase the process line speed in the black single color. Furthermore, the rigidity of the housing is improved and the durability is improved. In addition, when a single black color is not frequently used, a black developing cartridge having the same volume as the 6M, 6C, 6Y magenta, cyan, yellow developing cartridge is placed at the position of the 6K black developing cartridge in the casing 6. Insert it.

  In this embodiment, by using a non-contact charging unit, the image carrier can be charged without disturbing the toner image formed by the upstream developing cartridge. FIG. 15 is realized by providing a non-contact charging roller as a non-contact charging unit, and FIG. 16 is realized by providing a solid discharge element. Since each color developing cartridge has the same structure, only one will be described.

  FIG. 15 is a diagram showing a case where a non-contact charging roller is used in the process cartridge of the present embodiment. In FIG. 15, the non-contact charging roller 12 </ b> A is a charging device for uniformly charging the surface of the image carrier 11. The non-contact charging roller 12A applies a voltage to a conductive roller installed with a gap of about 50 μm to 100 μm between the surface of the image carrier 11 and corona discharge generated in the gap. This is a charging method. Further, an AC bias may be applied in order to stabilize charging. Since it is a non-contact charging means like the corona charging method, the image carrier 11 can be charged without disturbing the toner image formed by the upstream developing cartridge.

  FIG. 16 is a diagram showing a case where a solid discharge element is used in the process cartridge of the present embodiment. In FIG. 16, the solid discharge element 12 </ b> B is a charging device for uniformly charging the surface of the image carrier 11. In the charging method using a solid discharge element, a strip-shaped electrode is formed with a thin insulator plate such as ceramic interposed therebetween. When a high frequency AC bias is applied thereto, ions are generated by creeping corona discharge and charged. Since it is a non-contact charging means like the corona charging system, the image carrier 11 can be charged without disturbing the toner image formed by the upstream developing cartridge.

  15 and 16, the charging device 12 and the developing device 13 are integrated by a casing, and can be attached and detached simultaneously when the developing cartridge 6 is replaced. Further, the charging device 12 and the developing device 13 can be detached from the casing 4 separately.

  A writing device 4 ′ is installed between the charging device 12 and the developing device 13. The writing device 4 'is also integrated with the charging device 12 and the developing device 13 by the casing 4, and can be attached and detached at the same time when the developing cartridge is replaced. Various devices such as a small LED array and an optical scanning device using polygons can be used as the writing device.

  Furthermore, the process cartridge according to the present embodiment is designed to share colors, and when the image forming apparatus is in an initial state, toner can be replenished so that only the carrier is contained in the developing device in the cartridge. Is possible. It is also conceivable to supply toner and carrier in a state where nothing is contained. The advantage of standardizing each cartridge color is that there is no distinction between process cartridges by color, so the number of cartridges in each office can be reduced, and the number of cartridges carried by service personnel can also be reduced. .

  In addition, this Embodiment is not limited to what was mentioned above, A various change is possible in the range which does not deviate from the meaning. For example, a system to which the present embodiment can be applied is depicted as a development-type full-color machine using an electrostatic conveyance member, but this is only depicted as a representative example of an image forming apparatus, and an intermediate transfer belt. Needless to say, the present invention can also be applied to a color image forming apparatus, a monochrome image forming apparatus, and the like using a transfer drum, an intermediate transfer drum, and the like.

FIG. 2 is a block diagram illustrating a case where a process cartridge according to an exemplary embodiment is applied to an image forming apparatus. 2 is a block diagram illustrating a configuration of a developing cartridge 6 in the present embodiment. FIG. 3 is a diagram illustrating a case where the process cartridge according to the present embodiment is detached from a space opened by the image carrier 11 being retracted. It is sectional drawing to which the image carrier 11 side surface of the electrostatic conveyance member 13a was expanded. (A) is a figure which shows the case where a three-phase pulse-like drive waveform is applied to the electrode 102 at different timings, and (B) is a diagram of the negatively charged toner T applied in (A). It is a figure which shows a position typically. This is an application example of a three-phase drive waveform when the carrier voltage pattern is set to about 33%. This is an application example of a three-phase drive waveform when the development voltage pattern is set to about 67%. It is a figure which shows the magnet roller body in the process cartridge of this embodiment. FIG. 3 is a block diagram showing a configuration when viewed from the side wall of the developing cartridge 6 in the present embodiment. In this embodiment, it is a figure which shows the case where a several cartridge is attached or detached simultaneously. In this embodiment, it is a figure which shows the case where another cartridge is added to the cartridge installed beforehand and it attaches and detaches simultaneously. It is a block diagram which shows the case where the some unit in the process cartridge in this embodiment is united. In this embodiment, it is a figure which shows the case where the cartridge of arbitrary colors and the number is installed. In this embodiment, it is a figure which shows the case where the magnitude | size of a cartridge is changed. It is a figure which shows the case where a non-contact charging roller is used as a charging means in the process cartridge in this embodiment. It is a figure which shows the case where a solid discharge element is used as a charging means in the process cartridge in this embodiment.

Explanation of symbols

2 Transfer roller 3 Fixing device 3a Heating roller 3b Pressure roller 4K, 4M, 4C, 4Y, 4 'Writing device 5 Paper feeding device 6K, 6M, 6C, 6Y Developing cartridge 11 Image carrier 11ak, 11am, 11ac, 11ay Conveying roller 12 Charging device 13 Developing device 13a Electrostatic conveying member 13a
13b Supply roller 13c Doctor blade 13d Screw 14 Cleaning device 101 Support substrate 102 Electrode 103 Surface protective layer

Claims (13)

A process cartridge having a developing means for developing an electrostatic latent image on an image carrier and removable from an image forming apparatus main body,
An electrostatic conveyance member having an electrostatic conveyance surface to which toner particles can move by a phase-shifting electric field;
A toner storage section for storing toner particles for use in development;
Supply means for supplying the toner particles from the toner storage unit to the electrostatic transfer surface;
Charging means for charging the image carrier,
The image carrier is
Detachable from the process cartridge body,
A process cartridge in which the charging unit and the developing unit are integrated.   2. The process cartridge according to claim 1, wherein the integrated charging unit and the developing unit are separable. It further has at least two or more process cartridges arranged in the same posture,
The process cartridge according to claim 1, wherein two or more of the process cartridges are removable from the image forming apparatus at the same time. Process cartridges of four colors of black, magenta, cyan, and yellow arranged in the same posture,
A process cartridge having complementary colors other than the cartridges of the four colors in the same posture;
2. The process cartridge according to claim 1, wherein at least two of the process cartridges are removable from the image forming apparatus at the same time. An exposure means for exposing the electrostatic latent image on the image carrier;
The process cartridge according to claim 1, wherein the exposure unit, the charging unit, and the developing unit are integrated. An instruction member for arranging the plurality of process cartridges in the same posture;
A sensor for recognizing the color of the process cartridge;
6. The process cartridge according to claim 5, wherein the process cartridge of any color / number desired by a user is installed in the image forming apparatus. The support member is
The process cartridge according to claim 6, wherein the process cartridge having a size different from that of the process cartridge installed in the image forming apparatus is supported.   The process cartridge according to claim 1, wherein the charging unit is a scotron charger system.   The process cartridge according to claim 1, wherein the charging unit is a non-contact charging roller system.   The process cartridge according to claim 1, wherein the charging unit is a solid discharge method.   The process cartridge according to claim 1, wherein the image carrier has a belt shape.   The process cartridge according to claim 2, wherein the process cartridge can be used in common for each color in an initial state of the image forming apparatus.   An image forming apparatus capable of loading the process cartridge according to claim 1.

Images