JP2009223027A - Color toner separation method, color toner separation device, process cartridge, image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To separate and reuse a color mixture toner by using an original engine configuration of image formation. <P>SOLUTION: The color mixture toner is supplied to a developing device K through a path 1, charged into negative charges and formed into a thin layer on a photoreceptor that is uniformly charged into positive charges. The photoreceptor is irradiated with near IR light in a path 2 to destaticize the photoreceptor surface except for a region where black toner particles are present. In a transferring step, a bias potential that is a little lower than the initial charging potential of the photoreceptor is applied to a transfer belt so as to transfer the residual color mixture toner except for the black toner onto the transfer belt, while leaving the black toner on the photoreceptor. The remaining black toner is recovered through a path 3 by a cleaner K, conveyed to the developing device K through the path 1 and prepared to the next image formation. The residual color mixture toner is recovered by a cleaner C of a photoreceptor C in an upstream side, next to the first photoreceptor, via an intermediate transfer belt, shown as a path 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

    The present invention relates to a color toner separation method, a color toner separation apparatus, and a process cartridge using the same, which are used in an image forming apparatus using an electrophotographic process such as a copying machine, a facsimile machine, a printer, and a composite machine thereof.

  A quadruple tandem system as shown in FIGS. FIG. 1 is an overall configuration diagram illustrating a multifunction peripheral as an example of a quadruple tandem image forming apparatus, FIG. 2 is an enlarged view illustrating an image forming unit thereof, and FIG. 3 is a schematic diagram illustrating a main part. In this image forming apparatus, four toner containers corresponding to the respective colors (yellow, magenta, cyan, and black) are detachable (replaceable) in the toner container accommodating portion 31 above the image forming apparatus main body 100 as shown in the figure. It is installed freely. An intermediate transfer unit 10 is disposed below the toner container housing portion 31, and is designed to correspond to each color (yellow, magenta, cyan, black) so as to face the intermediate transfer belt 8 of the intermediate transfer unit 10. Image portions 6Y, 6M, 6C, and 6K are juxtaposed.

  Referring also to FIG. 2, the image forming unit 6Y corresponding to yellow includes a photosensitive drum 1Y, a charging unit 4Y disposed around the photosensitive drum 1Y, a developing device 5Y (developing unit), and a cleaning unit 2Y. , A static elimination unit (not shown) and the like. Then, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on the photosensitive drum 1Y, and a yellow image is formed on the photosensitive drum 1Y. The other three image forming units 6M, 6C, and 6K have substantially the same configuration as the image forming unit 6Y corresponding to yellow except that the color of the toner to be used is different, and correspond to the respective toner colors. Form an image. Therefore, in the following description, the description of the other three image forming units 6M, 6C, and 6K will be omitted as appropriate, and the image forming unit 6Y corresponding to yellow will be described.

  The photosensitive drum 1Y is driven to rotate clockwise in FIG. 2 by a drive motor (not shown). Then, the surface of the photosensitive drum 1Y is uniformly charged at the position of the charging unit 4Y (charging process). Thereafter, an electrostatic latent image corresponding to yellow is formed on the surface of the photosensitive drum 1Y by exposure scanning at the irradiation position of the laser beam L emitted from the exposure device 7 (exposure process).

  Thereafter, the electrostatic latent image on the surface of the photosensitive drum 1Y is developed at a position facing the developing device 5Y to form a yellow toner image (developing step). Thereafter, the toner image on the photosensitive drum 1Y is transferred onto the intermediate transfer belt 8 at a position facing the intermediate transfer belt 8 and the first transfer bias roller 9Y (primary transfer step).

  At this time, a small amount of untransferred toner remains on the photosensitive drum 1Y, but the untransferred toner remaining on the photosensitive drum 1Y at a position facing the cleaning unit 2Y is mechanically removed by the cleaning blade 2a. Collect (cleaning process). Finally, the residual potential on the photosensitive drum 1Y is removed at a position facing a neutralization unit (not shown), and a series of image forming processes executed on the photosensitive drum 1Y is completed.

  The image forming process described above is performed in the other image forming units 6M, 6C, and 6K in the same manner as the yellow image forming unit 6Y, and the toner images of the respective colors formed on the respective photosensitive drums are superimposed on the intermediate transfer belt 8. And a color image is formed on the intermediate transfer belt 8.

  The intermediate transfer unit 15 includes an intermediate transfer belt 8, four primary transfer bias rollers 9Y, 9M, 9C, and 9K, a secondary transfer backup roller, a cleaning backup roller, a tension roller, an intermediate transfer cleaning unit 10, and the like. . These may be unitized so as to be detachable from the image forming apparatus main body 100 as a so-called process cartridge unit. The intermediate transfer belt 8 is stretched and supported by three rollers, and is moved in the direction of the arrow in FIG. 2 by rotational driving of one of the rollers.

  The four primary transfer bias rollers 9Y, 9M, 9C, and 9K respectively sandwich the intermediate transfer belt 8 with the photosensitive drums 1Y, 1M, 1C, and 1K to form a primary transfer nip. A transfer bias opposite to the polarity of the toner is applied to the primary transfer bias rollers 9Y, 9M, 9C, and 9K. The intermediate transfer belt 8 travels in the direction of the arrow in the figure and sequentially passes through the primary transfer nips of the primary transfer bias rollers 9Y, 9M, 9C, and 9K, and on the photosensitive drums 1Y, 1M, 1C, and 1K. Are transferred onto the intermediate transfer belt 8 so as to be primarily transferred.

  Thereafter, the color transfer toner image formed on the intermediate transfer belt 8 is formed at a position where the secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 with the secondary transfer roller 19 to form a secondary transfer nip. Then, the image is transferred onto the transfer material P such as transfer paper conveyed to the position of the secondary transfer nip.

  At this time, since the untransferred toner that has not been transferred to the transfer material P remains on the intermediate transfer belt 8, the untransferred toner on the intermediate transfer belt 8 is collected at the intermediate transfer cleaning position, and the intermediate transfer belt 8 is recovered. The series of transfer processes executed above is completed.

  Note that the transfer material P to be transported to the position of the secondary transfer nip is transported from a paper feed unit 26 disposed below the apparatus main body 100 via a paper feed roller 27, a registration roller pair 28, and the like. A plurality of transfer materials P such as transfer paper are stored in the paper supply unit 26, and the paper supply roller 27 is driven to rotate counterclockwise in FIG. Feed toward the pair of 28 rollers.

  The transfer material P conveyed to the registration roller pair 28 is temporarily stopped at the position of the roller nip of the registration roller pair 28 whose rotation driving has been stopped, and the registration roller pair 28 is synchronized with the color image on the intermediate transfer belt 8 in timing. Is driven to convey the transfer material P toward the secondary transfer nip.

  The transfer material P to which the color image has been transferred at the position of the secondary transfer nip is conveyed to the fixing unit 20, and the color image transferred to the surface by the heat and pressure of the fixing roller and the pressure roller is transferred to the transfer material. Fix on P. Thereafter, the transfer material P passes through between the rollers of the paper discharge roller pair 29 and is discharged out of the apparatus, and sequentially stacked on the stack unit 30. This completes a series of image forming processes in the image forming apparatus. In the figure, reference numeral 32 denotes a document image reading unit.

  The configuration and operation of the developing device in the image forming unit will be described with reference to FIG. 2 (in FIG. 2, the portion other than the portion denoted by Y in relation to FIG. 1 is indicated without Y, but in the following description, The same applies to the developing devices of other colors, and the developing device 5Y includes a developing roller 51Y that faces the photosensitive drum 1Y, a doctor blade 52Y that faces the developing roller 51Y, and a developer. It is composed of two conveying screws 55Y disposed in the accommodating portions 53Y and 54Y, a density detection sensor 56Y for detecting the toner density in the developer, etc. The developing roller 51Y includes a magnet fixed inside, a magnet A two-component developer G composed of a carrier and a toner is accommodated in the developer accommodating portions 53Y and 54Y. It communicates with a toner conveying pipe through the opening formed in upwardly.

  The operation of the developing device 5Y will be described. The sleeve of the developing roller 51Y rotates in the direction of the arrow in FIG. The developer G carried on the developing roller 51Y by the magnetic field formed by the magnet moves on the developing roller 51Y as the sleeve rotates. The developer G in the developing device 5Y is adjusted so that the toner ratio (toner concentration) in the developer is within a predetermined range. That is, according to the toner consumption in the developing device 5Y, the toner stored in the toner container is supplied into the developer storage portion 54Y via the toner supply portion.

  Thereafter, the toner replenished in the developer accommodating portion 54Y is circulated through the two developer accommodating portions 53Y and 54Y while being mixed and stirred together with the developer G by the two conveying screws 55Y (in the direction perpendicular to the paper surface in FIG. 2). ). The toner in the developer G is attracted to the carrier by frictional charging with the carrier, and is carried on the developing roller 51Y together with the carrier by the magnetic force formed on the developing roller 51Y. The developer G carried on the developing roller 51Y is conveyed in the direction of the arrow in FIG. 2, and the developer amount is adjusted to an appropriate amount at the position of the doctor blade 52Y, and then to the position (developing region) facing the photosensitive drum 1Y. Transport. The toner is attracted to the latent image formed on the photosensitive drum 1Y by the electric field formed in the development area. Thereafter, the developer G remaining on the developing roller 51Y reaches above the developer containing portion 53Y as the sleeve rotates, and is detached from the developing roller 51Y at this position. Cleaner Y basically collects only yellow toner as the transfer residue of the yellow image, but cleaner M reversely transfers the yellow toner that is reversely transferred from the magenta toner as transfer residue, and cleaner C reversely transfers the cyan toner as the transfer residue. The yellow toner, magenta toner, and yellow toner, magenta toner, and cyan toner, which are reversely transferred from the black toner as the transfer residual, are collected in the cleaner K.

  Therefore, the toner collected by the cleaner Y can be returned directly to the developing device Y. However, since the toner collected by other cleaners is mixed, when it is returned directly to each developing device, In the long term, the color will change significantly. Therefore, these toners including toner collected from the intermediate transfer cleaner have to be discarded as waste toner.

  Although not shown, even in an image forming system in which color toners are sequentially developed on a single photoconductor, the collected toner resulting from an ideal transfer not being performed is mixed and therefore very reusable. It was difficult.

  Up to now, there has been no proposal for a mechanism for separating and reusing all the mixed-color toner in a full-color image forming device. At the same time, even if a new mechanism is constructed, the machine size and Increasing initial costs and reducing machine reliability had to be avoided as much as possible.

Japanese Patent Laid-Open No. 08-240961 Japanese Unexamined Patent Publication No. 06-059467

  An object of the present invention is to realize separation and reuse of mixed color toners by using the original image forming engine configuration itself.

  The color toner separating method according to the first aspect of the present invention is a color toner used in a color electrophotographic process in which all or a part of the toner adhering to the photoreceptor after passing through the transfer process is supplied to the developing device. In the toner separation method, a single toner layer is formed by the developing device on the photoreceptor uniformly charged with a polarity opposite to the toner charging polarity in the developing step in the developing device, and the toner layer On the other hand, only the process color toner carried by the developing device is irradiated with light having a wavelength having strong absorption, and in the transfer step immediately after that, only the remaining mixed color toner other than the process color toner is mainly removed from the photoreceptor. It is characterized by being removed by electrotransfer.

  According to a second aspect of the present invention, in the color toner separating method according to the first aspect, when one or more photoconductors are present, the mixed color toner removed by electrostatic transfer from the photoconductor is one of the photoconductors. It is characterized in that it is supplied to a photoreceptor located in the upstream transfer process.

  According to a third aspect of the present invention, there is provided the color toner separation method according to the second aspect, wherein the remaining mixed color toner removed from the photoconductor by an electrostatic transfer process is transported to the photoconductor one upstream. It is characterized by performing via.

  According to a fourth aspect of the present invention, in the color toner separation method according to any one of the first to third aspects, the four photoconductors that form yellow, magenta, cyan, and black toner images are arranged in tandem. The black toner transfer process is characterized as the most downstream process of the transfer process that is multiplexed with yellow, magenta, and cyan.

  According to a fifth aspect of the present invention, in the color toner separation method according to any one of the first to third aspects, the four photoconductors that form yellow, magenta, cyan, and black toner images are arranged in tandem. The transfer process of the yellow toner is the most downstream process of the transfer process in which magenta, cyan, and black are multiplexed.

  The color toner separating apparatus according to claim 6 is a unit for uniformly charging the photosensitive member with a polarity opposite to the toner charging polarity in the developing step, and all or the toner adhering to the photosensitive member after passing through the transfer step. A means for supplying a part to a developing device for visualizing the photoconductor, a means for forming a thin toner layer in a non-stacked state by the developing device, and the toner layer, Only the process color toner carried by the developing device emits light having a wavelength having strong absorption, and the remaining mixed color toner other than the process color toner carried by the developing device is electrostatically transferred from the photosensitive member in the immediately subsequent transfer step. And removing means.

  A process cartridge according to a seventh aspect is characterized in that it is integrated with at least the photosensitive member and / or the developing device.

  An image forming apparatus according to claim 8 uses the color toner separation method according to any one of claims 1 to 5.

  An image forming apparatus according to a ninth aspect uses the color toner separating apparatus according to the sixth aspect.

  An image forming apparatus according to a tenth aspect uses the process cartridge according to the seventh aspect.

  According to the present invention, it is possible to increase the effective usage rate of the toner, reduce the running cost, and reduce the waste by separating and recovering and reusing the mixed color toner that has been discarded so far by an inexpensive method.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

  First, the principle of extracting a specific color from the mixed color toner will be described with reference to FIGS.

  FIG. 4 shows an example of the spectral absorptance of the color toner used. Yellow, magenta, and cyan toners generally have strong absorption in the blue, green, and red wavelength regions, respectively, and black toner is visible light. It shows that it has strong absorption over the entire region and near infrared region.

  FIG. 3 shows the process concept of the present invention for extracting black toner from these four color mixed toners. First, the surface of the photosensitive member is uniformly charged as shown in FIG. 5A by a charging means having a discharge mechanism (not shown). Here, an example of charging with a positive charge is shown, but charging with a negative charge may be used. Here, as shown in FIG. 5B, the mixed color toner particles charged with a charge opposite in polarity to the charged polarity of the photosensitive member, that is, a negative charge (or a positive charge when the photosensitive member is charged with a negative charge) are formed into a thin layer. Form. At this time, the arrangement of the mixed color toner particles may be random or sparse, but it is necessary to prevent the toner particles from being stacked (that is, all the mixed color toner particles are in contact with the photoreceptor). Next, as shown in FIG. 5C, light of a wavelength that only the black toner particles of the four color toner particles absorb, that is, near-infrared light here is uniformly irradiated through the mixed color toner layer. . Then, the irradiation light reaches the photoconductor in the area where the color toner particles other than black are adhered and in the area where the mixed color toner particles are not adhered. As a result, as shown in FIG. The charge on the surface of the photoreceptor in the region other than the attached region disappears. The black toner particles having a negative charge are bound to the surface of the photoconductor on which the positive charge remains with a strong force, so that the adhesion to the photoconductor is larger than that of the other color toner particles. Further, when a transfer body to which a bias potential having an absolute value higher than the surface potential of the neutralized photosensitive region is applied, the electrostatic force that attracts the color toner particles other than black to the transfer body generates black toner particles. Big enough than that. As a result, only the black toner particles remain on the photosensitive member, and the other color toners can be transferred to the transfer member.

  In this way, only the black toner can be extracted from the four color mixed toners. Although not shown in the figure, the toner mixture process of irradiating red, green, or blue light to the remaining mixed color toner from which the black toner has been removed is used to sensitize cyan, magenta, or yellow toner particles, respectively. The toner particles can be extracted on the body, and the toner particles of all four colors can be extracted on individual photoconductors through the same process for the remaining two color mixed toners.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
The configuration of the full-color engine shown in FIG. 6 is basically the same as that shown in FIG. 3, but in order to provide a function of separating mixed-color toner, a black image photosensitive member (photosensitive member K), a cyan image. Irradiation that can irradiate near infrared, red, and green light between the developing process and the transferring process of the photosensitive member for photosensitive member (photosensitive member C) and the photosensitive member for magenta image (photosensitive member M), respectively. Means are provided. These light irradiating means need only have a function of uniformly irradiating the photosensitive member, not for exposing the electrostatic latent image, and can be configured to be very small and simple and inexpensive. Here, an LED light source of each emission wavelength was used. By the way, these light irradiation means are not used during normal toner image formation, and mixed color toners in areas different from the toner image area (such as during machine standby when not printing and between images during continuous printing). It operates when it becomes the mode which isolates.

  The four photoconductors (photoconductor K to photoconductor Y) are all the same. Here, for example, a single-layer positively charged photoconductor as described in Patent Document 2 may be used. As can be seen from the above description of the principle, since the photosensitive member needs to have a high latent image resolution in the size of one toner particle, a single layer in which charge generation by exposure is performed near the surface of the photosensitive member. It is preferable to use a type of photoreceptor. Rather than a single layer type, a photoconductor in which the charge generation layer is in the vicinity of the surface of the photoconductor and the charge transport layer is in the deep layer of the photoconductor is also suitable. (Generally used photoreceptors have a charge generation layer in the deep layer and a charge transport layer on the surface layer. Therefore, it is generally difficult to obtain an electrostatic latent image contrast by shading of toner particles, but it can be applied. .)

  When a certain amount of printing operation is performed in the normal image forming mode, yellow toner is used for cleaner Y, magenta toner and yellow toner mixed toner is used for cleaner M, and cyan toner, magenta toner, and yellow toner are used for cleaner C. The mixed color toner is collected in the cleaner K, and all four mixed color toners are collected.

  In the toner separation mode, first, the secondary transfer roller and the intermediate transfer cleaner are separated from each other. Then, an appropriate amount of the mixed color toner of the cleaner K is supplied to the developing device K via a toner conveyance path of pass 1 (not shown). The mixed color toner appropriately charged with a negative charge in the developing device forms a thin layer on the uniformly positively charged photoreceptor through the developing process. At this time, by appropriately setting the relationship between the rotational speed of the photosensitive member and the developing roller, and the charged potential of the photosensitive member and the applied potential to the developing roller, the color mixture toner layer formed on the photosensitive member is made one layer or less. . In the process of pass 2, near-infrared light is uniformly irradiated, and the surface of the photoreceptor other than the area where the black toner particles are present is discharged according to the principle based on FIG. In the subsequent transfer process, by applying a bias potential slightly lower than the initial charging potential of the photosensitive member to the transfer belt side, the mixed color toner other than the black toner (hereinafter referred to as remaining mixed color toner) is transferred to the transfer belt, and black The toner remains on the photoreceptor.

  The remaining black toner is collected by the cleaner K via the pass 3 and transported again to the developing device K via the pass 1 to prepare for the next image forming mode. The remaining color mixture toner is collected by the cleaner C of the photosensitive member C on the upstream side through the intermediate transfer belt as in pass 4. In pass 4, the photosensitive member potential and the transfer unit bias are set so that the residual color toner does not transfer to the photosensitive member Y and the photosensitive member M and to the photosensitive member C. Hereinafter, separation of the mixed color toner in the cleaner C (the remaining mixed color toner composed of magenta toner and yellow toner here is the cleaner M), and the mixed color toner in the cleaner M is sequentially separated so that the mixed color toner in each photoconductor cleaner is The separated state is returned to the developing device for each color.

  Further, the mixed toners of the four colors in the intermediate transfer belt cleaner are returned to the developing units of the respective colors through the above-described process by being conveyed to the cleaner K in advance. However, in the mixed color toner in the intermediate transfer belt cleaner, impurities other than the toner component such as paper dust are mixed, and therefore, there is a case where a separate impurity removing unit or the like is required although not described here.

  According to the present invention, it is possible to extract only a specific color from the mixed color toner while making the best use of the image forming engine configuration itself. Further, since the residual color mixture toner that has been removed in the electrostatic transfer process of a photoconductor among a plurality of photoconductors can be mixed with the color mixture toner of the photoconductor on the upstream side having the same color mixing component, this upstream side Further, only the specific process color toner can be extracted from the photoreceptor. Further, by sequentially applying this process to all the photoconductors, it is possible to separate all the mixed color toners into the respective colors.

  Further, according to the present invention, since a new mechanism for transporting the remaining mixed color toner is not required, color toner separation with a simple mechanical configuration is realized. Further, since the mixed color toner including the black toner (light absorption wavelength range is very broad) is mixed only in the black station, the process colors can be separated in the other color stations. For example, if the transfer sequence is yellow, magenta, black, and cyan, even if the mixed color toner layer is irradiated with red light that is complementary color of cyan toner at the cyan station at the final stage, not only cyan toner but also reverse transfer is performed. Even mixed black toner is absorbed by light, so that it is impossible to separate only cyan toner. The same applies when the transfer order of black is further upstream. Further, since black toner is not mixed into the color developing device, the variation in color can be suppressed to the minimum.

  In addition, according to the present invention, in principle, other color toners are not mixed with yellow, which has a large color change due to mixing of other colors. In addition, it is possible to realize an apparatus that extracts only a specific color from the mixed color toner while making maximum use of the image forming engine configuration itself.

Overall configuration diagram showing a multifunction peripheral as an example of a four-tandem image forming apparatus Enlarged view showing the imaging unit Schematic showing the main part of the full color engine The figure which shows the example of the spectral absorptance of color toner Diagram showing an example of changes in the surface charge of the photoreceptor during development FIG. 3 is a schematic view corresponding to FIG. 3 showing a main part of a full-color engine according to an embodiment of the present invention.

Explanation of symbols

1: Photosensitive drum 2: Cleaning unit 2a: Cleaning blade 4: Charging unit 5: Developing unit 6: Image forming unit 7: Exposure unit 8: Intermediate transfer belt 9: First transfer bias roller 10: Intermediate transfer unit 26: Supply Paper section 27: Paper feed roller 28: Registration roller pair 29: Paper discharge roller pair 30: Stack section 31: Toner container storage section 32: Reading section 51: Development roller 52: Doctor blade 53, 54: Developer storage section 55: Conveying screw 56: Density detection sensor 100: Image forming apparatus main body L: Laser light P: Transfer material G: Two-component developer

Claims (10)

A color toner separation method used in a color electrophotographic process for supplying all or a part of toner adhering to a photoreceptor after passing through a transfer step to a developing device,
A single toner layer is formed by the developing device on the photoreceptor uniformly charged with a polarity opposite to the toner charging polarity in the developing step in the developing device,
Only the process color toner carried by the developing device is irradiated to the toner layer with a wavelength having a strong absorption, and in the transfer step immediately after that, only the remaining mixed color toner other than the process color toner is mainly exposed to the photosensitive layer. A color toner separation method, wherein the toner is removed by electrostatic transfer from a body. 2. The color toner separation method according to claim 1, wherein when one or more photoconductors are present, the color mixture toner removed by electrostatic transfer from a photoconductor is a photoconductor positioned in a transfer step one upstream of the photoconductor. A color toner separation method comprising supplying to a body. 3. The color toner separation method according to claim 2, wherein the residual color toner removed from the photoconductor by an electrostatic transfer step is transported to the photoconductor upstream by a transfer belt. Color toner separation method. 4. The color toner separation method according to claim 1, wherein when the four photoconductors for forming yellow, magenta, cyan and black toner images are arranged in tandem, the black toner transfer step is performed. A color toner separation method characterized by being the most downstream step of a transfer step that is multiplexed with yellow, magenta, and cyan. 4. The color toner separation method according to claim 1, wherein when the four photoconductors for forming yellow, magenta, cyan and black toner images are arranged in tandem, the yellow toner transfer step is performed. A color toner separation method characterized by being the most downstream step of a transfer step that is multiplexed with magenta, cyan, and black. Means for uniformly charging the photosensitive member with a polarity opposite to the toner charging polarity in the developing step;
Means for supplying all or part of the toner adhering to the photoconductor after passing through the transfer step to a developing device for visualizing the photoconductor;
Means for forming a thin toner layer without being laminated by the developing device;
Means for irradiating the toner layer with light having a wavelength in which only the process color toner carried by the developing device has strong absorption;
And a means for electrostatically transferring and removing only the remaining mixed color toner other than the process color toner carried by the developing device from the photosensitive member in the immediately subsequent transfer step. A process cartridge comprising at least a photosensitive member and / or a developing device. An image forming apparatus using the color toner separation method according to claim 1. An image forming apparatus using the color toner separating apparatus according to claim 6. An image forming apparatus using the process cartridge according to claim 7.