Patent Publication Number: US-8115976-B2

Title: Image formation apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to an image formation apparatus such as a copier, printer, facsimile machine, multi-function device, and more particularly to an image formation apparatus provided with a function of removing an image from a recording material where the image is formed after image information on the recording material is used. 
     BACKGROUND ART 
     With the spread of printers, analog copying machines, digital copying machines, printers, and the like employing electrophotography, ink-jet recording methods, and thermal transfer recording methods, a large amount of paper has been consumed. Paper generally used as recording materials is made from pulp gained from wood as recyclable resources. In a process for manufacturing paper, a lot of energy is consumed so as to extract cellulose fiber from wood in a pulping process and to dry paper in a papermaking step. 
     Although destructive lumbering for manufacturing paper has been reduced because of growing awareness of environmental issues, all paper is not made from wood logged from managed forests, so that it is an important social issue to prevent further deterioration of the global environment by protecting forests through control on paper consumption. 
     Further, because paper contains inorganic components which are noncombustible and imputrescible, when paper is disposed of, waste requiring landfilling is generated at a certain rate. However, it has become difficult to find waste landfill sites, so that the control on paper consumption is an important social issue also in this point of view. 
     In order to deal with these problems, in conventional methods, when paper on which information is recorded is no longer necessary, such paper is collected and dissolved into pulp at paper factories for recycling. Although these methods require no wood resources any further, substantially the same energy is consumed for transportation for collection, re-pulping, and re-papermaking as in a case where paper is manufactured from fresh pulp. Moreover, paper made from recycled pulp has quality problems such as reduced rigidity and whiteness, bleeding upon printing, and the like, so that a mix rate of recycled pulp in high-quality paper conventionally used as paper for recording information must be limited to about 30%. Further, upon collecting and recycling paper as recording materials on which information is recorded, paper on which information is recorded is circulated outside companies and outside homes which are uncontrolled areas, so that this poses problems in terms of confidentiality maintenance and privacy protection. 
     In recent years, management of information such as personal information has been strictly required, and it is desired that recording materials having information be not distributed outside each of information control areas including rooms, floors, divisions, buildings, offices, and the like. 
     As a method for resolving the above-mentioned problems, there have been proposed a method and a device for removing an image on a recording material that has been used so as to reuse the recording material. For example, as a method for removing a formed image on a recording material by transferring the image to an image peeling member, Patent Document 1 discloses a method and a device in which paper on which an image is formed by electrophotography is impregnated with liquid containing water, the paper and the image peeling member are brought into pressure contact in a heated status while adhesion between the paper to be used as a recording material and an image forming substance is reduced, and the image forming substance having thermoplasticity is separated and removed from the paper. 
     Patent Document 2 discloses a recording material having a mold release agent on a surface having a sheet-like shape, in which a mark is attached so as to discriminate from regular paper. Patent Document 3 discloses a device in which an endless belt having heat-melting resin on a surface thereof is used and an image formed on a recording material processed using release agent is separated and removed by thermal transfer. Patent Documents 4 and 5 disclose a method and a device in which an image on a recording material is removed by abrading and polishing the image using a grinding stone, a rubber roller, and the like so as to reuse the recording material on which the image is formed by electrophotography. 
     Other than the above-mentioned methods, there have been proposed various types of methods for removing or eliminating color of images. However, in any of these methods, applicable image forming substances, recording materials, image formation processes are limited when images are desired to be completely removed. Thus, when a recording material on which an image is formed by various types of image formation apparatuses is mixed in an image removal device, or various types of recording materials are mixed in the image removal device, depending on combinations other than specific combinations, levels of removal and color elimination of images are reduced, so that image information remaining after an image removal process may be readable or a number of times allowed for repeatedly using the recording materials may be reduced. 
     Patent Documents 5, 6, and 7 disclose examples of using the image formation apparatus and the image removal device integrally or in combination. In these Patent Documents, images are recorded on recording materials immediately after the image forming substances are removed by the image removal device from the recording materials. 
     As disclosed in these Patent Documents, by using the image formation apparatus and the image removal device integrally or in a connected manner, the necessity of setting again the recording materials in the image formation apparatus is eliminated. However, it is not possible to prevent mixing of recording materials other than those having an image formed by a specific image formation apparatus. 
     In Patent Document 8, the applicant proposed an image formation and removal system in which only a specific recording material on which an image is formed in a specific image formation process by a specific image formation apparatus is subjected to an image removal process, so that image forming substances on the recording material are securely removed and it is possible to prevent generation of jam and the like resulting from failure of separation of the recording material and an image peeling member which may be occurred in a process for removing the image forming substances. 
     However, even when the image formation apparatus and the image removal device are integrated, few proposal to sufficiently utilize characteristics of the integrated image formation apparatus and the image removal device has been made. 
     Patent Document 1: Japanese Laid-Open Patent Application No. 7-56472 
     Patent Document 2: Japanese Laid-Open Patent Application No. 4-67043 
     Patent Document 3: Japanese Laid-Open Patent Application No. 4-64472 
     Patent Document 4: Japanese Laid-Open Patent Application No. 4-234056 
     Patent Document 5: Japanese Laid-Open Patent Application No. 6-89068 
     Patent Document 6: Japanese Laid-Open Patent Application No. 10-171318 
     Patent Document 7: Japanese Laid-Open Patent Application No. 7-175384 
     Patent Document 8: Japanese Laid-Open Patent Application No. 2005-128046 
     DISCLOSURE OF INVENTION 
     It is a general object of the present invention to provide an improved and useful image formation apparatus in which the above-mentioned problems are eliminated. 
     A more specific object of the present invention is to provide an image formation apparatus that has a reduced number of components, reduced environmental load, and is capable of removing images at low cost. Paper conventionally used for image formation is commercially available at a relatively low price, so that when an image removal function is provided to the image formation apparatus, by reusing a recording material, preferably, a cost becomes lower than purchasing new paper. Thus, the image formation apparatus to which the image removal function is provided is required to have a practical functionality and a simple structure. 
     Another specific object of the present invention is to provide an image formation apparatus capable of quickly removing image information before such information is read by someone who is not supposed to know. In other words, another specific object of the present invention is to provide a function of removing important confidential information from the recording material preferentially over other information and making it possible to confirm the removal of the confidential information recorded on the recording material. 
     Another specific object of the present invention is to reduce defects generated when an image formation apparatus and an image removal device are integrated or when both devices are combined as a unit. In other words, another specific object of the present invention is to prevent consumption of excessive electric power resulting from operation of both devices at the same time. In order to obtain merits generated when the image formation apparatus and the image removal device are integrated or when both devices are combined as a unit, functions common to both devices are preferably obtained by operating parts common to both devices as much as possible so as to simplify structures of both devices. In view of this, another specific object of the present invention is to prevent generation of trouble upon performing functions using the common parts and obtain functions preferable for users. 
     Another specific object of the present invention is to prevent generation of trouble such as residual images remaining after an image removal process, generation of jam, and the like. 
     Another specific object of the present invention is to provide an image formation apparatus detachably including an image removal device in accordance with user preference. 
     According to one aspect of the present invention, there is provided an image formation apparatus comprising: a manual paper feed unit supplying a recording material; an image formation unit receiving the recording material from the manual paper feed unit; an image removal device removing an image recorded on the recording material; an installation unit detachably installing the image removal device on the image formation apparatus; and a switching unit switching whether the recording material fed from the manual paper feed unit is supplied to the image removal device installed using the installation unit or to the image formation-unit. 
     According to another aspect of the present invention, there is provided an image formation apparatus comprising: a manual paper feed unit supplying a recording material; an image formation unit receiving the recording material from the manual paper feed unit; an image removal device disposed on the image formation apparatus, the image removal device removing an image recorded on the recording material; and a switching unit switching whether the recording material fed from the manual paper feed unit is supplied to the image removal device or to the image formation unit. 
     According to another aspect of the present invention, in the image formation apparatus, the recording material includes a reusable medium from which a formed image is removed by the image removal device and a general recording material which is not supplied to the image removal device and has a formed image that is not removed. 
     According to another aspect of the present invention, in the image formation apparatus, the reusable medium includes a recording material to which at least one agent having repellency to image forming substance is provided so as to reduce fixation on an image forming substance. 
     According to another aspect of the present invention, the image formation apparatus includes: a first paper feed cassette storing the reusable medium; and a second paper feed cassette storing the general recording material. 
     According to another aspect of the present invention, the image formation apparatus includes: a selection unit allowing a user to select a first image formation mode for forming an image on the reusable medium and a second image formation mode for forming an image on the general recording material; and a control unit performing control so as to form an image on the reusable medium when the first image formation mode is selected and to form an image on the general recording material when the second image formation mode is selected using the selection unit. 
     According to another aspect of the present invention, in the image formation apparatus, the reusable medium has discrimination information for recognizing reusability of the reusable medium, a first conveying path for supplying the recording material to the image formation unit and a second conveying path for supplying the recording material to the image removal device partially share a common path for conveying the recording material, and a recognition unit judging the discrimination information of the reusable medium is disposed on the common path for conveying the recording material. 
     According to another aspect of the present invention, in the image formation apparatus, an image is formed in the image formation unit when a recording material appropriate for an image formation mode is detected before recording materials inappropriate for the image formation mode selected using the selection unit are successively detected for a predetermined number of times, an image formation operation by the image formation unit is stopped when inappropriate recording materials are successively detected for the predetermined number of times, and ejection is performed without performing the image formation operation when inappropriate recording materials are successively detected for less than the predetermined number of times. 
     According to another aspect of the present invention, the image formation apparatus includes: a warning unit outputting warning information for notifying that an inappropriate recording material is set when inappropriate recording materials are successively detected by the recognition unit for a predetermined number of times. 
     According to another aspect of the present invention, in the image formation apparatus, the discrimination information in the reusable medium includes discrimination information recorded in an IC chip disposed on the reusable medium in an integrated manner. 
     According to another aspect of the present invention, in the image formation apparatus, after the image removal device is installed on the image formation apparatus, even when an image removal process operation is being performed successively by the image removal device, if an image formation instruction is input, the image removal process operation is suspended and an image formation operation is preferentially performed, and then after the image formation operation is ended, the image removal process operation is resumed. 
     According to another aspect of the present invention, in the image formation apparatus, after the image removal device is installed on the image formation apparatus, even when an image removal process operation is being performed on a recording material by the image removal device, the recording material being conveyed from a paper feed cassette disposed on the image formation apparatus or the image removal device, if an image removal process instruction is input for a recording material supplied from the manual paper feed unit, the image removal process operation on the recording material conveyed from the paper feed cassette is suspended and an image removal process operation on the recording material conveyed from the manual paper feed unit is preferentially performed, and then after the image removal process operation is ended, the image removal process operation on the recording material conveyed from the paper feed cassette is successively resumed. 
     According to another aspect of the present invention, the image formation apparatus includes: a control unit performing an interrupt control, wherein after the image removal device is installed on the image formation apparatus, even when an image formation operation is being performed successively or an image removal process operation is being performed successively on a recording material by the image removal device, the recording material being conveyed from a paper feed cassette disposed on the image formation apparatus or the image removal device, if an image removal process instruction is input for a recording material supplied from the manual paper feed unit, the image formation operation or the image removal process operation on the recording material conveyed from the paper feed cassette is temporarily suspended and an image removal process operation on the recording material conveyed from the manual paper feed unit is preferentially performed, and then after the image removal process operation is ended, the suspended image formation operation or the image removal process operation on the recording material conveyed from the paper feed cassette is resumed. 
     According to another aspect of the present invention, in the image formation apparatus, even when an image removal process operation is being performed successively by the image removal device, if an image formation instruction is input, the image removal process operation is suspended and an image formation operation is preferentially performed, and then after the image formation operation is ended, the image removal process operation is resumed. 
     According to another aspect of the present invention, in the image formation apparatus, even when an image removal process operation is being performed on a recording material by the image removal device, the recording material being conveyed from a paper feed cassette disposed on the image formation apparatus or the image removal device, if an image removal process instruction is input for a recording material supplied from the manual paper feed unit, the image removal process operation on the recording material conveyed from the paper feed cassette is suspended and an image removal process operation on the recording material conveyed from the manual paper feed unit is preferentially performed, and then after the image removal process operation is ended, the image removal process operation on the recording material conveyed from the paper feed cassette is successively resumed. 
     According to another aspect of the present invention, the image formation apparatus includes: a control unit performing an interrupt control, wherein even when an image formation operation is being performed successively or an image removal process operation is being performed successively on a recording material by the image removal device, the recording material being conveyed from a paper feed cassette disposed on the image formation apparatus or the image removal device, if an image removal process instruction is input for a recording material supplied from the manual paper feed unit, the image formation operation or the image removal process operation on the recording material conveyed from the paper feed cassette is temporarily suspended and an image removal process operation on the recording material conveyed from the manual paper feed unit is preferentially performed, and then after the image removal process operation is ended, the suspended image formation operation or the image removal process operation on the recording material conveyed from the paper feed cassette is resumed. 
     According to the present invention, the image removal device is configured to be detachably installed. When the image removal device is installed using the installation unit, the recording material on which an image is formed is supplied via the switching unit to the image removal device from the manual paper feed unit included in the image formation apparatus. Thus, it is possible to provide the image removal device added as an optional device at low cost and having a simple structure. Further, it is possible to perform the image removal process on the recording material where highly-confidential image information is formed through an interrupt control using the manual paper feed unit employed for image formation. 
     According to the present invention, the image formation apparatus comprises: the manual paper feed unit supplying the recording material; the image formation unit receiving the recording material from the manual paper feed unit; the image removal device removing an image recorded on the recording material; the installation unit detachably installing the image removal device on the image formation apparatus; and the switching unit switching whether the recording material fed from the manual paper feed unit is supplied to the image removal device installed using the installation unit or to the image formation unit. Thus, it is possible to perform the image removal process on the recording material where highly-confidential image information is formed through an interrupt control using the manual paper feed unit employed for image formation. 
     According to the present invention, a reusable medium includes a recording material to which at least one agent having repellency to image forming substance is provided so as to reduce fixation on an image forming substance. Thus, it is possible to form an image on the reusable medium when image information formed on the recording material is used only for a short period of time and to form an image on general recording material in other cases. And, it is possible to provide a system including an image formation function and an image removal function with a simple structure at low cost and reduced environmental load along with effects mentioned above. 
     According to the present invention, the image formation apparatus includes: the first paper feed cassette storing the reusable medium; and the second paper feed cassette storing the general recording material. Thus, it is possible to form an image on the reusable medium when image information formed on the recording material is used only for a short period of time and to form an image on general recording material in other cases. And, it is possible to provide a system including an image formation function and an image removal function with a simple structure at low cost and reduced environmental load along with effects mentioned above. 
     According to the present invention, the image formation apparatus includes: the selection unit allowing a user to select a first image formation mode for forming an image on the reusable medium and a second image formation mode for forming an image on the general recording material; and the control unit performing control so as to form an image on the reusable medium when the first image formation mode is selected and to form an image on the general recording material when the second image formation mode is selected using the selection unit. Thus, when the user is assumed in advance to use image information formed on the recording material only for a short period of time, it is possible to form an image on the reusable medium securely capable of being subjected to the image removal process so as to reduce environmental load and to provide a system including the image formation function and the image removal function with a simple structure at low cost and reduced environmental load along with the effects mentioned above. 
     According to the present invention, the reusable medium has discrimination information for recognizing reusability of the reusable medium, the first conveying path for supplying the recording material to the image formation unit and the second conveying path for supplying the recording material to the image removal device partially share a common path for conveying the recording material, and the recognition unit judging the discrimination information of the reusable medium is disposed on the common path for conveying the recording material. Thus, it is not necessary to dispose a recognition unit dedicated only to the image removal device. Further, the path for conveying the recording material is shared with the image formation apparatus and the image removal device, so that it is possible to provide an image formation and removal system with a simple structure at low cost and reduced environmental load. 
     According to the present invention, in the image formation apparatus, an image is formed in the image formation unit when a recording material appropriate for an image formation mode is detected before recording materials inappropriate for the image formation mode selected using the selection unit are successively detected for a predetermined number of times, and an image formation operation by the image formation unit is stopped when inappropriate recording materials are successively detected for the predetermined number of times, and ejection is performed without performing the image formation operation when inappropriate recording materials are successively detected for less than the predetermined number of times. Thus, even when the user erroneously mixes general paper in the first paper feed cassette where only those reusable media must be stored or when the user erroneously mixes a reusable medium in the second paper feed cassette where only general paper must be stored by contrast, it is possible to form an image on an intended recording material and complete an image formation operation. When inappropriate recording materials are detected successively for a set number of times, an image formation operation is stopped, so that it is possible to avoid unnecessary conveying of a recording material when the user erroneously sets a large amount of recording materials in the paper feed cassette. Further, an image to be removed is securely formed on the reusable medium, so that it is possible to reduce an amount of paper consumption and environmental load and to securely form image information on general paper so as to distribute such information required to be formed on general paper to customers, outside companies, or outside divisions. 
     According to the present invention, the image formation apparatus includes a warning unit outputting warning information for notifying that an inappropriate recording material is set when inappropriate recording materials are successively detected by the recognition unit for a predetermined number of times. Thus, it is possible to notify the user that the inappropriate recording material is set and prompt the user to set an appropriate recording material. 
     According to the present invention, the discrimination information in the reusable medium includes discrimination information recorded in an IC chip disposed on the reusable medium in an integrated manner. Thus, it is possible to store various types of information concerning the reusable medium and provide various types of detection forms, thereby readily managing reusable media. 
     According to the present invention, even when an image removal process operation is being performed successively by the image removal device, if an image formation instruction is input, the image removal process operation is suspended and an image formation operation is preferentially performed, and then after the image formation operation is ended, the image removal process operation is resumed. Thus, the image formation operation and the image removal operation are not performed at the same time. Further, excessive power consumption is avoided and complexity and difficulty of control are eliminated. Moreover, the image formation operation requiring high speed is promptly performed, so that reduction of operational efficiency by the user is minimized even when the image removal operation is performed. 
     According to the present invention, even when an image removal process operation is being performed on a recording material by the image removal device, the recording material being conveyed from a paper feed cassette disposed on the image formation apparatus or the image removal device, if an image removal process instruction is input for a recording material supplied from the manual paper feed unit, the image removal process operation on the recording material conveyed from the paper feed cassette is suspended and an image removal process operation on the recording material conveyed from the manual paper feed unit is preferentially performed, and then after the image removal process operation is ended, the image removal process operation on the recording material conveyed from the paper feed cassette is successively resumed. In accordance with this, the user sets the recording material on which highly-confidential information is recorded in the manual paper feed unit and the image removal process is immediately started. As a result, the image is removed in the presence of the user and it is possible to confirm whether reading of such information becomes impossible. Thus, it is possible to use the image removal device connected to the image formation apparatus as having the same function as a shredder and reuse the reusable medium from which the image is removed. 
     According to the present invention, an interrupt control is performed such that even when an image formation operation is being performed successively or an image removal process operation is being performed successively on a recording material by the image removal device, the recording material being conveyed from a paper feed cassette disposed on the image formation apparatus or the image removal device, if an image removal process instruction is input for a recording material supplied from the manual paper feed unit, the image formation operation or the image removal process operation on the recording material conveyed from the paper feed cassette is temporarily suspended and an image removal process operation on the recording material conveyed from the manual paper feed unit is preferentially performed, and then after the image removal process operation is ended, the suspended image formation operation or the image removal process operation on the recording material conveyed from the paper feed cassette is resumed. In accordance with this, the user sets the recording material in which highly-confidential information is recorded in the manual paper feed unit and the image removal process is immediately started. As a result, the image is removed in the presence of the user and it is possible to confirm whether reading of such information becomes impossible. Thus, it is possible to use the image removal device connected to the image formation apparatus as having the same function as a shredder and reuse the reusable medium from which the image is removed. 
     Other objects, features and advantage of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram showing an image removal device when it is detached and an image formation apparatus according to an embodiment of the present invention; 
         FIG. 2  is a schematic diagram showing an image formation apparatus including an image removal device installed thereon; 
         FIG. 3  is a schematic diagram showing an embodiment of a guide unit and operation thereof; 
         FIG. 4  is a schematic diagram showing an embodiment of a switch unit and operation thereof; 
         FIG. 5  is a perspective view showing an embodiment of an installation unit; 
         FIG. 6  is a schematic diagram showing a structure of a guide unit disposed on an image removal unit and operation thereof; 
         FIG. 7  is a block diagram showing a control unit and constituent elements connected thereto; 
         FIG. 8A  is an enlarged perspective view showing a structure of a cleaning unit of an image removal unit; 
         FIG. 8B  is an enlarged front view showing the cleaning unit; 
         FIG. 9  is a flowchart showing an embodiment of control by a control unit; 
         FIG. 10  is a flowchart showing another embodiment of control by a control unit; 
         FIG. 11  is a flowchart showing another embodiment of control by a control unit; 
         FIG. 12  is a flowchart showing another embodiment of control by a control unit; 
         FIG. 13  is a flowchart showing another embodiment of control by a control unit; 
         FIG. 14  is a flowchart showing another embodiment of control by a control unit; 
         FIG. 15  is a plan view showing an embodiment of a mechanism as a media separation unit; and 
         FIG. 16  is a schematic diagram showing another embodiment of an image formation apparatus integrally including an image removal device. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     The present invention is described in detail based on the embodiments illustrated in the drawings. An image formation apparatus referenced at  1  in  FIG. 1  shows an example of a color image formation apparatus for forming an image by electrophotography and a method for forming an image and elements of the apparatus are well-known as a tandem type color electrophotographic device. This image formation apparatus is assumed to have functions of a digital multi-function device. In order to add a copying function, a scanner unit used as an image reading device not shown in the drawings is added other than a structure shown in  FIG. 1 . When the image formation apparatus is used as a facsimile machine, a communication interface and a memory unit storing information (not shown in the drawings) are added. When the image formation apparatus is used as a printer, a data input unit and a memory unit storing information are added in the same manner. 
     In  FIG. 1 , a portion surrounded by a housing A used as an apparatus body shows an image formation apparatus  1  including an image formation unit  1 B and a portion surrounded by a housing B shows an image removal device  2  installed on and detached from the housing A of the image formation apparatus  1 . 
     The image formation unit  1 B is configured to form an image by electrophotography in which toner images of yellow (Y), magenta (M), cyan (C), and black (K) are formed on photoconductors as separate image carriers, respectively, the toner images formed on each photoconductor are transferred to an intermediate transfer body and the images transferred to the intermediate transfer body are transferred to a recording material conveyed from a paper feed unit, and the toner images formed on the recorded medium are heated and pressurized for fixation by a fixation unit  140 . 
     A drum unit used as stations for forming images of each of yellow (Y), magenta (M), cyan (C), and black (K) is constructed using elements of a conventionally used electrophotographic device. In other words, the drum unit includes: drum-like or belt-like photoconductors  101 Y,  101 M,  101 C, and  101 K in which metal and the like having a photoconductor layer is used as a substrate; charging units  102 Y,  102 M,  102 C, and  102 K including a charging roller, a wire charger, and the like, the charging units  102 Y,  102 M,  102 C, and  102 K uniformly charging the photoconductors  110 Y,  101 M,  101 C, and  101 K; a light irradiation unit (not shown in the drawings) exposing each of uniformly charged photoconductors in accordance with an image to be formed such as laser, LED, light emitter-liquid crystal light valve; developers  103 Y,  103 M,  103 C, and  103 K internally having a magnetic roller and a toner conveying roller, the developers  103 Y,  103 M,  103 C, and  103 K creating visual images of electrostatic latent images using powder toner formed on each photoconductor through the light irradiation; corona wire chargers  105 Y,  105 M,  105 C, and  105 K controlling charge of toner powder images formed on each photoconductor; electric field applying units  106 Y,  106 M,  106 C, and  106 K including a roller or a corona wire for transferring toner powder images formed on each photoconductor to an intermediate transfer belt  117  as an intermediate transfer body; cleaning units  107 Y,  107 M,  107 C, and  107 K removing powder toner remaining on each photoconductor after transfer, and the like. 
     In addition to these constituent elements, it is possible to add a suitable and conventionally used element as appropriate. For example, in order to remove electric charge on each photoconductor after images are transferred, it is possible to dispose an electricity removal unit such as an alternating-current charger, a light irradiator, and the like. Also, it is possible to construct a control system in which a voltage detection unit detecting voltage charged on each photoconductor and a voltage control unit controlling voltage applied to the charger are disposed such that surface potential charged on each photoconductor is maintained at a constant level even in a case of deterioration resulting from an environmental change or repetition of use. When removal of toner on each photoconductor is unnecessary after images are transferred, it is possible to eliminate the cleaning units  107 Y,  107 M,  107 C, and  107 K. Further, when charging the toner powder images formed on each photoconductor is unnecessary, it is possible to eliminate the corona wire chargers  105 Y,  105 M,  105 C, and  105 K. 
     The intermediate transfer belt  117  is an endless belt mainly made of resin having a volume resistivity of about 10 8  to 10 12  Ωcm. The intermediate transfer belt  117  is disposed so as to have inscribed circles of rollers  111 ,  112 ,  113 , and  114  and is provided with suitable tension from a tension application mechanism not shown in the drawings. In order to remove toner remaining on the intermediate transfer belt  117 , a belt cleaning unit such as a brush, roller, or the like removing powder toner on a belt surface may be disposed on the periphery of the intermediate transfer belt  117 . Further, depending on necessity, an electricity removal unit or a charge unit may be disposed so as to remove or uniform electric charge remaining on the intermediate transfer belt  117  after powder toner is transferred to a recording material. 
     A recording material  171  ( a  to  d ) or a recording material  172  where a final image is formed is stored in plural paper feed cassettes  161   a ,  161   b ,  161   c , and  161   d  disposed on a paper feed unit  161  positioned below the image formation unit  1 B or stored in a manual paper feed tray  162  constituting a manual paper feed unit disposed on a lateral face of the housing A as shown in  FIG. 2 . In accordance with conditions and the like selected by the user, one of the paper feed cassettes or the manual paper feed tray  162  is selected and the recording material  171  ( a  to  d ) or the recording material  172  is sent to a first conveying path  50  via paper feed runners  160   a ,  160   b ,  160   c , and  160   d  disposed in the vicinity of each paper feed cassette or a paper feed runner  160   e  disposed in the vicinity of the manual paper feed tray  162 , the first conveying path  50  supplying the recording material to the image formation unit  1 B. The recording material  171  ( a  to  d ) or the recording material  172  that has been fed is conveyed to the image formation unit  1 B via pairs of paper feed rollers  166   a ,  166   b ,  166   c ,  166   d ,  170   a ,  170   b ,  170   c ,  170   d ,  170   e , and  170   f  disposed on the first conveying path  50 . 
     The toner powder images formed on the intermediate transfer belt  117  are transferred to the recording material  171  ( a  to  d ) or the recording material  172  in an image transfer unit where an electric field application unit  180  such as a voltage application roller, a corona wire charger, and the like is disposed. 
     The toner powder images transferred on the recording material  171  ( a  to  d ) or the recording material  172  are softened and fixed by the fixation unit  140  including a heating member  141  such as a thermal belt or a heating roller internally having a heating unit  143  such as a halogen lamp and a pressure roller  142  having a silicone rubber layer on a surface thereof. A recording material  173  on which the toner images are fixed are ejected to a paper ejection tray  163  disposed on a top portion of the housing A via a pair of rollers  170   g  for conveying a recording material and a pair of paper ejection rollers  167 . 
     As shown in  FIG. 1 , above the paper feed cassette  161   a , there are disposed a collection tray  164  for collecting non-image recording material  171  ( a  to  d ), a collection conveying path  54  for connecting the first conveying path  50  to the collection tray  164 , a pair of collection rollers  168  disposed on the collection conveying path  54 , and a guide unit  220  guiding the recording material in the first conveying path  50  to the collection conveying path  54 . The guide unit  220  is disposed on a branching portion  502  between the first conveying path  50  and the collection conveying path  54  as shown in  FIG. 3 . 
     The guide unit  220  includes a guide flap  222  disposed on a rotation shaft  221  and a driving unit  223  switching a position of the guide flap  222  by rotating the rotation shaft  221 . The guide flap  222  is configured to be positioned at a conveying position for conveying the recording material from the first conveying path  50  to the image formation unit  1 B, the conveying position being indicated by a solid line, and at a collection position for guiding the recording material to the collection conveying path  54 , the collection position being indicated by a two-dot chain line shown in  FIG. 3 . These positions are switched as appropriate by driving the driving unit  223 . As shown in  FIG. 7 , the driving unit  223  is connected to a control unit  80  included in the image formation apparatus  1  and is driven based on a driving signal from the control unit  80 . The control unit  80  is constructed using a conventionally used computer including a ROM, RAM, CPU, timer, and the like. The control unit  80  controls driving of the driving unit  223  such that the guide flap  222  is positioned at the collection position when the recording material is not a reusable media and positioned at the conveying position when the recording material is a reusable medium. 
     Image formation is possible using special toner whose color is eliminated from light and heat and toner containing wax components, fluorine resin, silicone resin, surface-active agent, and the like. However, preferably, toner generally employed for electrophotography is used so as to form an image in the same image formation apparatus when an image having preferable fixation is required for distribution outside the information control areas such as other divisions or companies, drawing up a contract, and the like. In other words, in the image formation apparatus  1  and the image removal device  2 , conventionally used toner for electrophotography may be used as an example of image forming substances. More specifically, image forming substances containing the following components may be used. 
     Examples of conventionally used coloring material used for image forming substances include: 
     black pigment such as carbon black, iron oxide, and the like; 
     yellow pigment such as C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 15, C.I. Pigment Yellow 17, C.I. Pigment Yellow 93, C.I. Pigment Yellow 94, C.I. Pigment Yellow 138, C.I. Pigment Yellow 155, C.I. Pigment Yellow 156, C.I. Pigment Yellow 180, C.I. Pigment Yellow 185, and the like; 
     magenta pigment such as C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment Red 5, C.I. Pigment Red 16, C.I. Pigment Red 48:1, C.I. Pigment Red 53:1, C.I. Pigment Red 57:1, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 139, C.I. Pigment Red 144, C.I. Pigment Red 166, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 222, and the like; and 
     cyan pigment such as C.I. Pigment Blue 15, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 16, C.I. Pigment Blue 60, and the like. When powder toner is used as image forming substances, these coloring materials are used from 0.5% to 20% by weight, preferably, from 1% to 10% by weight. 
     When a thermal transfer method is used for the image removal device  2 , preferably, image forming substances having thermoplasticity is used. Examples of resin components providing image forming substances with thermoplasticity include conventionally used toner materials for electrophotography. 
     In other words, examples of resin components include polyester resin, styrenes such as polystyrene, poly-chlorostyrene, polyvinyl toluene, and polymers of substitution products thereof; styrene copolymers such as styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-methyl chloromethaacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer; polymethylmethacrylate, polybutylmethacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic resin, rosin, modified rosin, terpene resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, and the like. When powder toner is used as image forming substances, these resin components are used from 60 to 99.5% by weight of an entire toner, preferably, from 80 to 97% by weight. 
     When the toner powder images are fixed on the recording material by a heat fixing unit and the images are removed through a thermal transfer method in which the toner on the recording material is transferred to an image peeling member, it is important that a glass transition point (Tg), fusing temperature, and viscoelastic property of components of thermoplastic resin are within a suitable range. When the glass transition point ranges from 40 to 100° C., or preferably from 50 to 70° C., it is possible to fix at a relatively low temperature, remove the image forming substances from the recording material, and obtain preferable preservation stability for the toner. 
     When measurement frequency is 20 Hz, storage elastic modulus of the components of thermoplastic resin is 10000 dyne/cm 2  preferably at not less than 80° C., more preferably from 90 to 160° C. 
     Conventional materials are used for toner as appropriate including charge control agent, release agent, external additive, and the like. Examples of the charge control agent include nigrosine dye, triphenylmethane dye, molybdic acid chelate pigment, rhodamine dye, alkoxylamine, quarternary ammonium salt, fluorine-containing activating agent, metal salt of salicylic acid, and metal salt of salicylic acid derivative, and the like. 
     Components of the release agent are added to as to prevent adhesion of toner to a fixing roller or a fixing belt (prevention of hot offset) upon fixing when the heat fixing unit is used. Examples of waxes to be used as release agent having a melting point of 60 to 110° C. include carnauba wax, montan wax, bees wax, paraffin wax, microcrystalline wax, and the like. 
     The external additive is added so as to assist flowability, development, charge of powder toner and is usually added so as to cover a surface of particles made of coloring material and resin. Examples of inorganic particles to be used as external additive include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatom earth, chromium oxide, ceric oxide, ferric oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, and the like. Preferably, a primary particle size of these inorganic particles ranges from 2 nm to 5 nm, more preferably from 5 nm to 500 nm. Preferably, an amount of inorganic particles used in toner ranges from 0.01 to 5% by weight of an entire amount of image forming substances, more preferably from 0.01 to 2.0% by weight. 
     Conventional manufacturing methods including mixing and milling, dispersion polymerization, suspension polymerization, and the like may be uses as a method for manufacturing powder of image forming substance from the above-mentioned materials. 
     The image formation apparatus  1  according to the present embodiment is constructed such that the image removal device  2  is detachably installed as an optional unit on the housing A. However, the image formation apparatus  1  and the image removal device  2  may be integrally combined and connected in, advance so as to be constructed as an image formation apparatus. 
     The image removal device  2  added and connected to the housing A as an optional unit employs a thermal transfer method as an image removal method in which toner on a recording material is transferred to an image peeling member. In  FIGS. 1 and 2 , the recording material from which an image is to be removed after use of image information formed as an image is stored in the fourth paper feed cassette  161   d  in the paper feed unit  161  or set in the manual paper feed tray  162 , for example, and is supplied to the image formation unit  1 B. 
     In the housing A, there are disposed a installation unit  200  detachably enabling installation of the image removal device  2  on the housing A and a switch unit  210  switching supply of the recording material  171  or the recording material  172  to the image removal device  2  or the image formation apparatus  1 . 
     As shown in  FIG. 5 , the installation unit  200  includes plural pins  201  and  202  formed on a side plate  1 A of the housing A positioned on a first conveying path  50  side, perforations  203  and  204  formed on a side plate  2 A positioned on a side of the following second and third conveying paths  51  and  52  of the image removal device  2 , the perforations  203  and  204  capable of being detachably engaged with each pin, and screws not shown in the drawings. In the present embodiment, the image removal device  2  is positioned when the pins  201  and  202  are inserted into the perforations  203  and  204 , respectively, and is mechanically installed on the image formation apparatus  1  as shown in  FIGS. 1 to 2  using the screws not shown in the drawings. In this case, using a connector not shown in the drawings, the control unit  80  disposed on the image formation apparatus  1  and a power supply not shown in the drawings are connected to the image removal device  2 . 
     In the installation unit  200 , instead of the pins  201  and  202  disposed on the side plate  1 A of the image formation apparatus  1 , plural opening portions extending in the vertical or lateral direction may be formed and a hook portion capable of being detachably engaged with each opening portion may be formed on the image removal device  2  side. The image removal device  2  may be installed on the housing A by inserting each hook portion into the opening portion and sliding the hook portion downward or sliding the hook portion in the lateral direction. 
     As shown in  FIG. 4 , the switch unit  210  is disposed on the branching portion  502  between the first conveying path  50  and the second conveying path  51 . The switch unit  210  includes a flap  212  disposed on a rotation shaft  211  and a driving unit  213  switching a position of the flap  212  by rotating the rotation shaft  211 . The guide flap  212  is configured to be positioned at a first position for conveying the recording material from the first conveying path  50  to the image formation unit  1 B, the first position being indicated by a solid line, and at a second position for guiding the recording material to the second conveying path  51 , the collection position being indicated by a two-dot chain line shown in  FIG. 4 . These positions are switched as appropriate by driving the driving unit  213 . As shown in  FIG. 7 , the driving unit  213  is connected to the control unit  80  and is driven based on a driving signal from the control unit  80 . The control unit  80  controls driving of the driving unit  213  such that the flap  212  is positioned at the second position when an image on the recording material is removed and positioned at the first position upon image formation. 
     In other words, in the first conveying path  50 , a recording material conveying path  501  common to the second conveying path  51  is constructed from the paper feed unit  161  and the manual paper feed tray  162  to the branching portion  502  between the first conveying path  50  and the second conveying path  51 . The recording material fed from the paper feed unit  161  and the manual paper feed tray  162  is conveyed through the recording material conveying path  501  to the branching portion  502  and destination is switched by the switch unit  210 . 
     As shown in  FIGS. 1 and 2 , the image removal device  2  includes a block  192  constructed using aluminum internally having a halogen lamp  193  as a heat source, a pressure roller  191  having an elastic member such as silicon rubber, fluorine-containing rubber, polyurethane rubber, and the like on a surface thereof, the pressure roller  191  being made of stainless steel, aluminum, iron, and the like and forming a nip portion N when in contact with the block  192 , an image peeling member  194  having an endless belt-like shape for transferring toner formed on a recording material, a rotating cleaning blade  196  having a spiral shape, a container  198  for storing separated toner, the second conveying path  51  for supplying the recording material to the nip portion N, the third conveying path  52  for returning the recording material passed through the nip portion N to the first conveying path  50 , pairs of conveying rollers  185   a ,  185   b ,  185   c , and  185   d  disposed on the second and third conveying paths  51  and  52  as conveying units, a pair of paper ejection rollers  169  and a paper ejection path  55  for ejecting the recording material (reusable medium) from the third conveying path  52  to a medium ejection tray  165 , and a guide unit  60  guiding the recording material (reusable medium) to the first conveying path  50  or the paper ejection path  55 . 
     The image peeling member  194  is made of metal such as nickel, stainless steel, and the like or polymer compound such as polyethylene terephthalate, polyimide, aramid, polyethylene naphthalate, polyetheretherketone, and the like. The image peeling member  194  is installed so as to have inscribed elements of the block  192 , a cleaning backup roller  197 , and a tension roller  195 . The nip portion N is formed between the pressure roller  191  and the block  192  where pressure is added from a pressure unit such as a spring not shown in the drawings, water pressure, air pressure, and the like. 
     In the vicinity of the block  192 , there is disposed a temperature detection unit not shown in the drawings, the temperature detection unit being selected from a thermistor, thermocouple, platinum resistance, infrared sensor, and the like. A signal from the temperature detection unit is input to the control unit  80 . Lighting of the halogen lamp  193  in the block  192  is controlled by the control unit  80  using the input signal, so that surface temperature of the block  192  is controlled to be constant within a range from 80 to 150° C., for example. 
     The medium ejection tray  165  is disposed on a top portion of the housing B and is detachably installed on the image formation apparatus  1  in an integral manner with the image removal device  2 . A reusable medium from which an image is basically removed is ejected to the medium ejection tray  165 . 
     As shown in  FIG. 6 , the guide unit  60  is disposed on a branching portion between the third conveying path  52  and the paper ejection path  55 . The guide unit  60  includes a flap  62  disposed on a rotation shaft  61  and a driving unit  63  switching a position of the flap  62  by rotating the rotation shaft  61 . The flap  62  is configured to be positioned at a reuse position for guiding a recording material  174  (reusable medium) from which an image is removed to the paper ejection path  55 , the reuse position being indicated by a solid line, and at a paper ejection position for guiding the reusable medium in an inappropriate status to the first conveying path  50 , the paper ejection position being indicated by a two-dot chain line shown in  FIG. 6 . These positions are switched as appropriate by driving the driving unit  63 . As shown in  FIG. 7 , the driving unit  63  is connected to the control unit  80  and is driven through the driving signal from the control unit  80 . The control unit  80  controls driving of the driving unit  63  such that the flap  62  is positioned at the reuse position in a case of the reusable medium from which an image is removed and positioned at the paper ejection position in a case of the reusable medium in the inappropriate status. The reusable medium in the inappropriate status refers to a reusable medium from which an image is not completely removed. 
     The recording material  171   d  or the recording material  172  to be used as a reusable medium from which an image is removed is conveyed in the recording material conveying path  501  by the pairs of paper feed rollers  166   d ,  166   c ,  166   b ,  166   a , and  170   a , guided to the second conveying path  51  by the switch unit  210 , and guided to the nip portion N formed using the pressure roller  191  and the block  192  by the pair of conveying rollers  185   a  and  185   b . The recording material  171   d  or the recording material  172  is heated and pressurized while passing through the nip portion N and toner on the recording material is pressurized in a softened status, so that the toner is adhered to the image peeling member  194 . 
     An edge portion disposed downstream relative to the block  192  has a curvature of about 1 to 5 mm radius. Since the image peeling member  194  is conveyed in accordance with the curvature, the recording material and the image peeling member  194  are separated due to rigidity of the recording material. In this case, by using a reusable medium as a recording material in which adhesion to toner is adjusted to be reduced in comparison with adhesion to the image peeling member  194 , the toner on the recording material is transferred to the image peeling member and an image formed on the recording material is removed. 
     The toner transferred to the image peeling member  194  from the recording material is scraped off by the rotating spiral-shaped cleaning blade  196  and is collected in the container  198  disposed below the cleaning blade  196 . The recording material  174  from which an image is removed is guided to the paper ejection path  55  by the guide unit  60  shown in  FIG. 6  after passing through the pairs of conveying rollers  185   c  and  185   d , and then stocked in the medium ejection tray  165  by the pair of paper ejection rollers  169 . 
       FIG. 8A  and  FIG. 8B  are a perspective view and a front view showing a schematic structure of a cleaning unit removing toner from the image peeling member  194 . The cleaning unit is constructed using the roller-shaped cleaning blade  196  having a spiral-shaped edge on a circumferential portion and being driven for rotation and the cleaning backup roller  197 . Predetermined pressure loading is applied between the cleaning blade  196  and the cleaning backup roller  197  by a biasing unit selected from a spring, water pressure unit, air pressure unit, and the like not shown in the drawings. An elastic body is formed on a surface portion  199  of the cleaning backup roller  197  using rubber of relatively low hardness having a JIS-A hardness of about 20, sponge, and the like. The cleaning backup roller  197  and the cleaning blade  196  form a nip (width W). The cleaning blade  196  is rotated in an opposite direction relative to a conveying direction of the image peeling member  194 . 
     The reusable medium used in the present invention is a recording material including compounds for reducing fixing power to the image forming substances at least in the vicinity of a surface thereof or compositions for removing a portion of a surface layer along with the image forming substances when physical energy such as light, heat, and the like is applied or water washing is performed by a washing unit, for example. A substrate thereof may be any of paper having cellulose fiber as a main body, synthetic paper made of plastic film having a foam structure and the like, polyethylene terephthalate (PET), polypropylene (PP), and film made of thermoplastic resin such as acetate film. However, paper is most preferably used as a substrate in view of the facts that a manufacturing cost is moderate, electric charge does not remain for a long time when the recording material is charged in the image formation apparatus, electric shock is not provided to the user, and the paper is capable of being dissolved into cellulose fiber and recycled when a repetition of reuse becomes difficult. 
     When paper is used as a substrate, the substrate may be made from any of wood such as chemical pulp and mechanical pulp, nonwood cellulose fiber such as bagasse and kenaf, recycled pulp of waste paper gained from used paper after deinking, pulp gained from dissolved waste sheet, and the like. 
     Examples of the compounds for reducing fixing power to the image forming substances include fluorine compound, silicon compound, surface-active agent containing a straight-chain or branched higher alkyl group or alkenyl group, wax, and polymer compound. More specifically, examples of the compounds for reducing fixing power to the image forming substances include saponified alkenyl succinic anhydride, fatty acid alkali salt such as sodium stearate, potassium lauryl, sodium behenate, and potassium oleate, alkyl phosphate alkali salt such as monostearyl sodium phosphate and distearyl sodium phosphate, dialkyl sulfosuccinate such as dodecylbenzene sulfonate, dodecyl sulfonate, dihexyl sulfosuccinate, and dioctyl sulfosuccinate, anionic surface-active agent such as alkyl ether acetate, alkylnaphthalenesulfonate, alkyl ether sulfate, alkyl sulfate of alkylamide sulfate, and alkyl ether phosphate, ether esters such as polyoxyethylene nonylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl phenyl ether, polyoxyethylene dodecyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene glycerine fatty acid ester, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene sorbitol fatty acid ester, esters such as polyethylene glycol fatty acid ester, fatty monoglyceride, polyglyceryl fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, and sucrose fatty acid ester, nonionic surface-active agent such as aliphatic alkanolamide, polyoxyethylene fatty acid amide, polyoxyethylene alkylamine, and alkylamine oxide, cationic surface-active agent such as alkylamine salt and alkyl quaternary ammonium salt, fatty acids such as stearic acid, lauric acid, palmitic acid, and behenic acid, fatty amides such as lauric acid amide, stearic acid amide, and oleic amide, N-substituted fatty acid amides such as N-oleyl stearic acid amide, N-oleyl oleic amide, N-stearyl oleic amide, N-stearyl stearic acid amide, N,N′-ethylene-bis oleic amide, N,N′-ethylene-bis lauric acid amide, N,N′-methylene-bis stearic acid amide, and N,N′-ethylene-bis behenic acid amide, alcohols such as lauryl alcohol, stearyl alcohol, cetyl alcohol, ceryl alcohol, myristyl, alcohol, melissyl alcohol, myricyl alcohol, cello-melissyl alcohol, oleyl alcohol, gadoleyl alcohol, and zoomaric alcohol, amines such as oleylamine, dodecyl amine, dioctadecylamine, and tetradecylamine, ketones such as laurone and stearone, phosphate compounds such as lauryl phosphate and stearyl phosphate, phosphate esters such as stearyl phosphate ester, lauryl phosphate ester, and behenyl phosphate ester, natural waxes such as candelilla wax, carnauba wax, rice bran wax, bees wax, lanolin, spermaceti wax, sumac wax, and montan wax, silicon resin, fluorine resin, and polymer containing a straight-chain or branched alkyl group with a carbon number of 6 or more or an alkenyl group with a carbon number of 6 or more as a side chain. Specific examples of such compounds include acrylic ester polymer and methacrylate ester polymer containing a straight-chain or branched alkyl group with a carbon number of 6 or more or an alkenyl group with a carbon number of 6 or more. 
     More specific examples include polymers and copolymers containing monomers of acrylic ester and methacrylate ester such as stearyl (straight-chain C18) acrylic ester, stearyl (straight-chain C18) methacrylate ester, cetyl (straight-chain C16) acrylic ester, cetyl (straight-chain C16) methacrylate ester, mistyryl (straight-chain C14) acrylic ester, mistylic (straight-chain C14) methacrylate ester, lauryl (straight-chain C12) acrylic ester, and lauryl (straight-chain C12) methacrylate ester. 
     A required level of reduction of fixing power to the image forming substances changes depending on materials constituting the image forming substances, especially, in accordance with factors such as resin component, surface smoothness of the substrate, adhesion of the image peeling member relative to the image forming substances in the image removal device, and the like. So as to adjust fixing power to toner, to fix the above-mentioned compounds in the vicinity of a surface of the recording material, and the like, it is possible to mix polymer which does not reduce the fixing power to the image forming substances, more specifically, compounds such as polyvinyl alcohol, starch, polyacrylic acid, polymethacrylic acid, polyacrylic ester, polymethacrylic acid ester, polyvinyl acetate, styrene-butadiene copolymer, and the like with the above-mentioned compounds reducing the fixing power to the image forming substances and to provide the mixture to the reusable medium. Further, it is possible to mix white pigment such as calciumcarbonate, kaoline, clay, talc, titaniumoxide, zinc oxide, and the like with the compounds reducing the fixing power to the image forming substances and to provide the mixture to the reusable medium. 
     The reusable medium used in the present invention is provided with information for indicating a reusable medium in order to discriminate the reusable medium from a general recording material incapable of removing an image. Preferably, the information for indicating as a reusable medium is not erased upon forming image information thereon or removing an image therefrom. Moreover, the information preferably allows the image formation apparatus  1  and the image removal device  2  to readily recognize the information as a reusable medium and the user to readily recognize the information by visual observation. It is possible to record such discrimination information on the reusable medium as a barcode, for example, using UV curable ink, dye ink, and the like through a printing method, ink-jet recording method, and the like. Further, it is also preferable to dispose a cutout or a hole on the reusable medium as a method for providing discrimination information. In order to enable the image formation apparatus  1  or the image removal device  2  to recognize the reusable medium, discrimination information may be printed using ink absorbing light having a wavelength unrecognizable for human eyes such as ultraviolet rays or infrared rays, ink emitting fluorescence, and magnetic ink, and an IC chip responding to electromagnetic waves may be disposed in which the discrimination information is stored. 
     As shown in  FIG. 7 , the image formation apparatus  1  includes a selection unit  90  for allowing the user to arbitrarily select modes using a key  91  for selecting a first image formation mode in which an image is formed on the reusable medium on the assumption that the image information formed for recording is used for a short period of time and the reusable medium is subjected to a process for removing the image forming substances after the use and a key  92  for selecting a second image formation mode in which an image is formed on paper as a general recording material. The selection unit  90  is connected to the control unit  80 . As shown in  FIG. 9 , the control unit  80  is configured to control operation of the image formation apparatus  1  such that when the key  91  is operated (step D 1 ) so as to select the first image formation mode, an image is formed on the reusable medium (step D 2 ) and when the key  92  is operated (step D 3 ) so as to select the second image formation mode, an image is formed on a general recording material (step D 4 ). 
     In the present embodiment, although the keys  91  and  92  are employed as the selection unit  90 , for example, selection may be performed using a selection unit such as a dial, stick, or the like. Moreover, when the image formation apparatus  1  is connected to an external information processing terminal via a network, namely, when the image formation apparatus  1  is connected to a computer capable of accessing the network, for example, the selection unit  90  may be a user interface on a display connected to the computer. The image formation apparatus  1  includes a warning unit  230  outputting warning information so as to notify that an appropriate recording material is not set. As shown in  FIG. 7 , the warning unit  230  is disposed on an operation panel  231  and is connected to the control unit  80 . 
     In the present embodiment, at least one of the paper feed cassettes  161   a  to  161   d  constituting a portion of the paper feed unit  161  is configured to be set as a paper feed cassette for storing a reusable medium. Preferably, a paper type indication unit such as a dial, lever, or the like capable of changing a position thereof in accordance with paper type is disposed on the paper feed cassette so as to allow the user to recognize that the reusable medium is stored. 
     For example, in  FIGS. 1 and 2 , the paper feed cassette  161   d  is used as a first paper feed cassette for reusable media and the paper feed cassettes  161   a ,  161   b , and  161   c  are used as second paper feed cassettes for general recording materials. 
     A sensor  181  used as a recognition unit is disposed on the recording material conveying path  501 , the sensor  181  detecting the discrimination information provided to the reusable medium. A specific recognition unit depends on the discrimination information provided to the reusable medium. For example, when a cutout or a hole is disposed, a simple recognition unit detecting the cutout or the hole may be used merely combining a light-emitting element such as an LED and a light-receiving element such as a photoelectric cell. However, when reading an image pattern such as a bar code, two-dimensional bar code, and the like and a special pattern indicating a reusable medium, it is necessary to use a recognition unit capable of reading an image pattern such as a line sensor prepared by disposing a CCD element on a line. 
     In the first image formation mode for forming an image on the reusable medium, preferably, the image formation apparatus  1  provides discrimination information to a portion of the reusable medium so as to clearly indicate that the image is formed by an image formation apparatus capable of removing the image. The discrimination information is formed using the same image forming substances as the image forming substances for recording other information on the reusable medium so as to be removed by the image removal device  2 . When the first image formation mode is selected, by providing the reusable medium with discrimination information indicating that the image is formed by a specific image formation apparatus, it is possible to discriminate a reusable medium on which an image is formed by an image formation apparatus incapable of removing the image between a reusable medium from which an image can be removed. 
     In other words, when simply detecting the presence or absence of the discrimination information provided to the reusable medium in advance, it is impossible to recognize a mixed reusable medium on which an image is formed by an image formation apparatus other than a specific image formation apparatus and the image forming substances are not removed therefrom because of mismatching of physical properties of the image forming substances and conditions of image formation. Accordingly, it is not possible to prevent trouble when the image is not completely removed in the image removal device  2 , the image peeling member  194  and the reusable medium are not separated and jam is generated, or the image peeling member becomes unusable. However, by discriminating images and determining which image formation apparatuses have formed such images, it is possible to exclude those reusable media having images that have not been formed by the specific image formation apparatus  1  and prevent failure of elimination of images. 
     Preferably, the sensor  181  detects not only the discrimination information provided to the reusable medium in advance but also the presence or absence of the above-mentioned discrimination information provided when an image is formed in the first image formation mode of the image formation apparatus  1 . The discrimination information provided when the image is formed in the first image formation mode of the image formation apparatus  1  may be a pattern unreadable for the user such as a bar code or a character pattern such as “reusable paper”. Moreover, the discrimination information may be selected from several types of patterns prepared by the user in advance or the discrimination information may be a pattern arbitrarily created by the user and stored through reading. 
     In  FIGS. 1 and 2 , the sensor  181  functions as a unit detecting the discrimination information indicating the reusable medium formed on the reusable medium upon image formation. When the image removal device  2  is installed, upon image removal, the sensor  181  also functions as a unit detecting the presence or absence of the discrimination information provided when an image is formed on the reusable medium in the first image formation mode. As shown in  FIGS. 1 and 2 , by disposing the sensor  181  on the recording material conveying path  501 , only a single set of sensors effectively functions upon image formation and image removal and provides great effects in that the apparatus is simplified, the number of components is reduced, and a cost and environmental load are reduced. 
     In the present embodiment, the reusable medium is stored only in the specific paper feed cassette  161   d  shown in  FIGS. 1 and 2 . When the user selects the first image formation mode, a recording material on which an image is to be formed is controlled to be supplied from the paper feed cassette  161   d . Thus, there is little possibility that the image is formed on a recording material which is not a reusable medium in the first image formation mode. However, the user may erroneously mix a general recording material with reusable media in the paper feed cassette  161   d . In view of this, the sensor  181  detects the presence or absence of the discrimination information on the recording material conveyed upon each image formation instruction. 
     In other words, in the control unit  80 , as shown  FIG. 10 , when the key  91  is operated in step E 1  so as to select the first image formation mode, a recording material is fed from the paper feed cassette  161   d , and the sensor  181  detects the discrimination information indicating a reusable medium in step E 2 , the driving unit  223  shown in  FIG. 3  is driven and the guide flap  222  is positioned at the conveying position in step E 3 , the recording material is conveyed to the image formation unit  1 B, the toner powder images formed in the image formation operation are transferred in step E 4 , and the images are fixed using the fixation unit  140 , thereby completing an image formation job. 
     On the other hand, if the discrimination information indicating a reusable medium is not detected on the recording material on which an image is to be formed by the sensor  181  in step E 2 , a signal of the sensor  181  is input to the control unit  80 . Thereafter, an instruction for changing the conveying direction of the recording material is output from the control unit  80 , the driving unit  223  shown in  FIG. 3  is driven, and the guide flap  222  is positioned at the collection position in step E 5 . Thus, the image is not formed on the recording material and the recording material is ejected to the collection tray  164  through the pair of collection rollers  168  in step E 6 . 
     Another embodiment of control by the control unit  80  is described in the following. 
     As shown in a flowchart of  FIG. 11 , when the key  91  is operated in step F 1  so as to select the first image formation mode and an image formation instruction for forming an image is issued thereafter, whether a recording material to be supplied is a reusable medium is judged in step F 2 . If the recording material is a reusable medium, in step F 3 , the driving unit  223  is driven, the guide flap  222  is positioned at the conveying position, and the recording material is conveyed to the image formation unit  1 B. In step F 4 , the toner powder images formed in the image formation operation are transferred and the images are fixed using the fixation unit  140 , thereby completing the image formation job. 
     On the other hand, in step F 2 , if the discrimination information indicating a reusable medium is not detected, the process proceeds to step F 5  so as to add +1 to a counter not shown in the drawings and the process proceeds to step F 6  so as to judge whether a count value reaches a predetermined times, namely, whether a predetermined number of sheets set in advance are successively counted. When the count value reaches the predetermined times since non-reusable media are successively counted, namely, when the discrimination information indicating a reusable medium is not detected for ten sheets successively, the process proceeds to step F 7  so as to stop the image formation process and the process proceeds to step F 8 . 
     In step F 8 , the fact that image formation cannot be performed in the first image formation mode since reusable media are not supplied is notified to the user by operating the warning unit  230 . In other words, the fact that inappropriate recording media are set is notified to the user. 
     The warning unit  230  may be a display disposed on the operation panel  231  or a user interface on a display connected to a computer issuing a printing instruction when the image formation apparatus is connected to the computer. Further, a form of warning may be voice, sound, lighting/flickering of a lamp and the like. 
     By controlling the image formation apparatus in this manner, even when the user erroneously mixes a general recording material in the paper feed cassette  161   d  where only those reusable media must be stored, if image information is used only for a short period of time, it is possible to securely record such information on the reusable medium and end the image formation operation without stopping the operation. Thus, it is possible to eliminate waste of recording materials and reduce environmental load. Moreover, it is possible to reduce a possibility that a general recording material on which an image is formed is mixed in the image removal device, prevent trouble such as generation of jam in the image removal device  2 , and eliminate a loss of time resulting from stopping of the image formation operation. 
     The same operation is performed in a case where an image is formed in the second image formation mode. If the discrimination information indicating a reusable medium is detected by the sensor  181  on a recording material on which an image is to be formed, the driving unit  223  is driven and the guide flap  222  is positioned at the collection position, so that the image is not formed on the reusable medium and the reusable medium is ejected to the collection tray  164  via the pair of collection rollers  168 . Then, the next recording material is supplied from the paper feed cassette in which a selected type of paper is set. If the discrimination information indicating a reusable medium is not detected by the sensor  181 , the driving unit  223  is driven and the guide flap  222  is positioned at the conveying position, so that a general recording material is conveyed to the image formation unit, the toner powder images formed in the image formation operation is transferred, and the transferred images are fixed in the fixation unit  140 , thereby completing the image formation job. 
     The same process as in the first image formation mode is performed if the discrimination information on the reusable medium is successively detected even when the second image formation mode is selected and an image formation instruction is issued. By controlling the image formation apparatus in this manner, even when the user erroneously mixes a reusable medium in the paper feed cassette where only those general recording materials must be stored, an image is not formed on the reusable medium and it is possible to securely record such information on the general recording material and end the image formation operation. 
     Thus, it is possible to prevent a stop of the image formation operation and eliminate a loss of time generated from printing only a specific page again. Further, it is possible to prevent mixing of the reusable medium and formal documents such as documents, contracts, and the like submitted to customers, government and public offices, outside companies, and outside divisions. 
     Another embodiment of control by the control unit  80  is described in the following. 
     When the image removal device  2  is installed on the image formation apparatus  1 , the reusable medium used as a recording material from which a formed image is to be removed is usually stored in the paper feed cassette  161   d  as mentioned above, for example, and conveyed to the image removal device  2 . When an image removal process is performed, the sensor  181  detects not only whether the recording material being conveyed has information for indicating a reusable medium but also the presence or absence of the discrimination information provided when the image is formed in the first image formation mode of the image formation apparatus  1 . 
     If one of both set of information is not detected, the control unit  80  of the image formation apparatus judges that the image forming substances cannot be removed from the conveyed recording material and the control unit  80  is capable of positioning the guide flap  222  using the driving unit  223  such that the recording material is ejected to the collection tray  164 . In other words, on the collection tray  164 , a recording material inappropriate upon image formation is ejected and a recording material inappropriate upon image removal is ejected. The ejection of such inappropriate paper is caused by erroneous operation of the user and the like. Usually, a large number of recording materials are not ejected to the collection tray  164 . 
     Upon image formation and image removal, preferably, the collection tray  164  to which the inappropriate recording materials are ejected is shared as mentioned above, so that it is possible to reduce the number of components, environmental load, and a cost. 
     Another embodiment of control by the control unit  80  is described in the following. 
     When the image removal device  2  is installed on the image formation apparatus  1 , it is possible to perform the image formation operation and the image removal operation at the same time. However, as shown in  FIG. 1 , when the recording material conveying path  501  in which portions of the second conveying path  51  and the first conveying path  50  are shared is disposed, problems are generated in that control becomes difficult upon operation at the same time and electric consumption becomes excessively large, for example. Thus, the control unit  80  preferably controls such that the image formation operation and the image removal operation are not performed at the same time. 
     In general, the image formation operation requires high speed and a ratio of actual period of time for the image formation operation to working hours at the offices is small. By contrast, normal image removal operation in which the reusable medium is conveyed from the paper feed cassette  161   d  does not require urgency in many cases. Accordingly, while a normal successive image removal process is being performed in which the reusable medium is conveyed from the paper feed cassette  161   d  as in step G 1  shown in  FIG. 12 , if the user presses a print button  232  disposed on the operation panel  231  shown in  FIG. 7  or an instruction for the image formation operation is input (step G 2 ) by issuing a printing instruction from a driver of the user interface of the computer connected to the image formation apparatus via the network, for example, after the image removal process on the reusable medium ejected from the paper feed unit  161  is ended in step G 3 , the image formation process is preferentially performed immediately in step G 4 . Then, when an entire image formation operation is ended in step G 5 , it is possible to perform an interrupt control in step  6  such that the image removal process in operation is resumed. By contrast, even when the successive image removal process is being performed, if the instruction for the image formation operation is not input in step G 2 , the process proceeds to step G 7  and the image removal process operation is continued. 
     By performing control in this manner, the user is capable of performing the image formation process and the process for removing an image from the reusable medium without reducing operational efficiency. Moreover, it is possible to prevent the electric consumption from becoming excessively large resulting from performing the image formation process and the image removal process at the same time. Further, it is possible to simplify control operation and the control unit  80 . 
     Another embodiment of control by the control unit  80  is described in the following. 
     The process for removing an image from the reusable medium is controlled to be automatically continued while the reusable medium is present in the dedicated paper feed cassette  161   d . The process for removing an image from the reusable medium is performed not only on the reusable medium fed from the paper feed cassette  161   d  but also on the reusable medium fed from the manual paper feed tray  162 . The process for removing an image from the reusable medium fed from the manual paper feed tray  162  is performed only through an image removal process start button  233  disposed on the operation panel  231  shown in  FIG. 7 . The image removal process on the reusable medium fed from the manual paper feed tray  162  is given priority over any image formation process operation and the image removal process on the reusable medium fed from the paper feed cassette  161   d.    
     In step H 1  shown in  FIG. 13 , while a normal successive image removal process is being performed in which the reusable medium is conveyed from the paper feed cassette  161   d , if the image removal process start button  233  is turned on in step H 2 , for example, after the process on a single sheet of the reusable medium ejected from the paper feed unit  161  is ended in step H 3 , the process operation for removing an image is immediately performed on the reusable medium fed from the manual paper feed tray  162  in step H 4 . This operation is given priority until the reusable medium from the manual paper feed tray  162  runs out. When the image removal process is ended in H 5 , an interrupt control is performed in step H 6  such that the image removal process or the image formation process in operation is resumed. 
     In this manner, by performing control such that the process for removing an image from the reusable medium fed from the manual paper feed tray  162  is given priority over any operation, the user is capable of removing image information on the reusable medium in which especially highly-confidential information is recorded without allowing many persons to see the image information and is capable of confirming whether the information is securely removed. In other words, it is possible to use the image removal device  2  connected to the image formation apparatus so as to protect confidentiality in the same manner as a shredder and reuse the reusable medium. 
     Another embodiment of control by the control unit  80  is described in the following. 
     In the image removal device  2  shown in  FIG. 1 , a sensor  182  is disposed on the third conveying path  52 . The sensor  182  is a detection unit detecting whether there is a remaining image on the reusable medium used as a recording material from which an image is removed. The sensor  182  is disposed based on the fact that an image may remain on the reusable medium after the image removal process when writing is performed using writing materials incapable of removal by the image removal process or when a number of reuse of the reusable medium becomes large and an image is incompletely removed. 
     It is possible to construct the sensor  182  using a line image sensor including a CCD. As shown in  FIG. 14 , for example, in step J 1 , the presence or absence of a remaining image on the reusable medium after the image removal process is judged based on an output from the sensor  182 . If the remaining image is judged to be present, the driving unit  63  is driven and the flap  62  is moved to the paper ejection position in step J 2 , so that the reusable medium having the remaining image is returned to the first conveying path  50  and the reusable medium is ejected to the paper ejection tray  163  as a non-reusable medium via a pair of conveying rollers  185   e , the fixing roller  141 , the pair of conveying rollers  170   g , and the pair of paper ejection rollers  167  in step J 3 , without ejecting the reusable medium to the medium ejection tray  165 . On the other hand, if the remaining image is judged to be absent in step J 1 , the driving unit  63  is driven and the flap  62  is moved to the reuse position in step J 4  and the reusable medium is ejected to the medium ejection tray  165  as a reusable media in step J 5 . 
     As mentioned above, the image formation process and the image removal process are not performed at the same time, so that the reusable medium having the remaining image after the image removal process is not inserted between recording materials on which an image is formed at a single image formation instruction. 
     When a multi-stage paper ejection device such as a conventional sorter is installed on the image formation apparatus  1 , the reusable medium having the remaining image after the image removal process may be controlled to be ejected to other bin separate from the recording material on which an image is formed based on the image formation instruction. Or, as shown in  FIG. 15 , a rack  240  may be disposed in a movement direction of the medium ejection tray  165  and a driving motor  242  may be disposed on the housing B of the image removal device  2 , the driving motor  242  rotating a pinion gear  241  meshing with the rack  240  by a certain angle. Then, the reusable medium having the remaining image after the image removal process is ejected to the medium ejection tray  165  in the same manner as the reusable medium having no remaining image. When ejecting the reusable medium having the remaining image, by driving the driving motor  242  and shifting the medium ejection tray  165  in a direction orthogonal relative to a paper conveying direction, the reusable medium may be controlled to be stocked such that the reusable medium  174  from which an image is completely removed and a reusable medium  174 A having the remaining image are readily separated. 
     The above-mentioned description is based on the assumption that the image removal device  2  is installed on the image formation apparatus  1 . However, the user may not require the reuse of the recording material using the reusable medium. Further, although plural image formation apparatuses  1  are required, the image removal device  2  may not necessarily be connected to each of the image formation apparatuses  1 . Moreover, the installed image removal device  2  may become no longer necessary and the user may wish to detach the image removal device  2 . In a case where the image removal device  2  is not installed, by having a common structure for the image formation apparatus  1  and allowing the image removal device  2  to be detachably installed, it is possible to install and detach the image removal device  2  as appropriate and add the image removal function so as to meet user demands and to simplify the structure of the image removal device  2  and reduce environmental load and a cost. 
     In particular, as in the present invention, it is possible to simplify the structure of the image removal device  2  installed on the image formation apparatus  1  by sharing the paper feed unit of the recording material such as the paper feed cassette, the manual paper feed unit, the conveying path, and the sensor  181  used as a recognition unit for the discrimination information between the image formation apparatus  1  and the image removal device  2 , and disposing the control unit  80  controlling an entire portion on the image formation apparatus  1  when the image removal device  2  is installed on the image formation apparatus  1 . 
     Further, the image formation apparatus  1  and the image removal device  2  are not operated at the same time, so that it is possible to share a driving system, a direct-current power supply, and the like of the image formation apparatus  1  and the image removal device  2  between the image formation apparatus and the image removal device and to use such elements through switching with a clutch or a switch. However, those users wishing to have the image formation apparatus  1  and the image removal device  2  from the beginning may be provided with an image formation apparatus in which the image formation function and the image removal function are stored in a single housing A. 
     In other words, as shown in  FIG. 16 , the image formation apparatus may include the image formation unit to which the recording material is supplied at least from the manual paper feed tray  162 , the image removal device  2  disposed on the housing A and removing an image recorded on the recording material, and the switch unit  210  switching whether the recording material fed from the manual paper feed tray  162  is supplied to the image removal device or the image formation unit. 
     In the above-mentioned image formation unit, a technique for forming an image by the most common electrophotography is employed as an image formation method in which an electrostatic latent image is formed on each of photoconductors, development is performed using dry toner, and toner powder images are transferred to the recording material. However, the present invention is not limited to this and electrophotography such as an electrostatic recording method, toner jet recording method, ion flow printing, and the like may be used where photoconductors are not used. 
     Further, the image formation method is not necessarily limited to electrophotography but includes a magnetic recording process in which thermoplastic image forming substances are used for image formation and a thermal transfer method. When an image is formed by an ink-jet method using thermofusible solid ink, it is possible to remove the image forming substances by thermally transferring the substances to the image peeling member and apply the present invention to an image formation apparatus using these image formation methods. 
     Moreover, as clearly understood from the principle of the present invention, it is possible to apply the present invention to methods for removing an image from the recording material even when the image is not thermally transferred to the image peeling member. For example, such image removal methods may include a method for washing out an image using water, organic solvent, and the like, a method for removing the image by scraping, and a method for eliminating colors of coloring materials using heat, light irradiation, and the like. 
     In the embodiments, the reusable medium is described as a recording material to which an agent having repellency to image forming substance is provided so as to reduce adhesion to the image forming substances. However, recording materials in which a substance swelling with water and the like is provided and adhesion to the image forming substances is reduced when a separation solution such as water is provided may be used as the reusable medium. Also, it is possible to use recording materials in which resin having resistance of abrasion such as UV-curable resin is coated and image forming substances can be scraped off from a surface as the reusable medium and to use recording materials in which compounds for eliminating color of image forming substances through a chemical reaction with the image forming substances are provided as the reusable medium. When these recording materials are used, an image removal device capable of performing image removal for each reusable medium may be used. 
     Although the manual paper feed tray  162  installed on the image formation apparatus  1  is configured to be shared, a paper feed cassette dedicated to reusable medium may be disposed on the manual paper feed tray  162  on the image removal device  2 . 
     The present invention is not limited to the specifically disclosed embodiment, and variations and modifications may be made without departing from the scope of the present invention. 
     The present application is based on Japanese priority application No. 2006-206659 filed Jul. 28, 2006, the entire contents of which are hereby incorporated herein by reference.