1.  Field of Invention
The present invention relates to a process for manufacturing an image recording body such as a plastic sheet using an image formed by an electrophotographic method image forming apparatus, and an apparatus for manufacturing the same.  More particularly, the invention relates to a process for manufacturing image recording bodies used in an information medium of non-contact or contact type, containing personal information and/or image information-recorded.  Examples of such an information medium are a photograph-containing cash card, a staff identity card, a student identity card, a membership identity card, a residents identity card, various licenses, and various qualification certificates.  Further examples of image recording bodies the invention relates to are identity verification image sheets and image display boards used, for example, in medical areas, and display labels.  The information also relates to an apparatus for manufacturing the same. 
2.  Description of the Related Art
In recent years, accompanied with developments in image formation techniques, means to form images of the uniform quality in large quantities and at low cost by various printing methods are know.  Examples are intaglio printing, letterpress printing, lithography printing, gravure printing and screen printing.  Such printing methods are also used in many cases for surface printing of an information medium which holds prescribed information, and can communicate with an external apparatus in a contact or non-contact manner, such as an IC-card, a magnetic card, an optical card, and combinations thereof. 
However, for example, in screen printing many printing plates corresponding to the number of images to be printed are necessary and, in the case of color printing, further, printing plates becomes necessary with the number of colors.  For this reason, these printing methods are unsuitable for application singly to discrete personal information (such as photographs, name, address, date of birth, and various licenses). 
In response to the aforementioned problems, an image forming device which is most popular currently is an image forming method with a printer, which adopts sublimation-type or melt-type thermal transfer using an ink ribbon.  These can easily print personal discrimination information.  However, there is still a problem that, when a printing rate is increased, resolution is decreased and, when the resolution is increased, the printing rate is reduced. 
In contrast, image formation (printing) by electrophotographic methods is performed by a method of forming a visible image (toner image) on an image carrying body surface.  This is done by: uniformly electrifying an image carrying body surface; irradiating this with light, in response to an image signal, to form an electrostatic latent image due to a potential difference between an exposed part and a non-exposed part; and, thereafter, electrostatically developing a color powder (image forming material) called toner, having a polarity opposite to (or the same as) the electrification.  In the case of a color image, color visible images are formed by repeating these processes a number of times, or aligning plural image formers.  These color images are transferred onto an image recording body, and this is fixed (fixation is solidification due to melting and cooling of a color powder mainly by heat), thereby, obtaining a color image. 
As described above, in an electrophotographic method, since electrostatic latent image on an image carrying body surface are electrically formed by image signals, not only can the same image be formed many times, but also different images can be easily handled, thereby, images can be formed.  In addition, since a toner image on an image carrying body surface can be almost completely transferred onto an image recording body surface, and a toner image slightly remaining on an image carrying body surface can be easily removed by a resin blade or brush, it is a printing method which can easily be prepared for small batch production of various article. 
The toner is usually formed by melting and mixing a heat-meltable resin and a pigment and, optionally, an additive such as an electrification controlling agent.  This kneaded product is then ground and finely-divided.  Further, the electrostatic latent images in the aforementioned electrophotographic method have considerably higher resolution than that of the finely-divided toner, and sufficient resolution can be expected compared to the resolution of the screen printing or thermal transfer using an ink ribbon. 
Regarding a color image, by using four primary colors of cyan, magenta, yellow and black as color toners, and mixing them, theoretically the same colors as that of printing can be reproduced.  In addition, in a color toner, since a toner resin and a pigment can be blended relatively freely, it is easy to increase image masking properties with toner. 
For using the aforementioned electrophotographic apparatus to manufacture various cards, there have already been several proposals (for example, see Japanese Patent Application Laid-Open (JP-A) Nos.2004-188603 and 2004-195973). 
In the apparatuses disclosed in them, a plastic sheet of high resolution can be produced at high productivity.  However, the following problems are present. 
That is, a light-transmissible film on which an image has been formed by an electrophotographic method is charged up, and the film tends to adsorb dust in the air unless the charge is removed.  Therefore, although a plastic sheet is manufactured inside a portion of a plastic sheet manufacturing apparatus, there is a very high possibility that dirt or dust is adhered to the light-transmissible film during positioning, heat-pressing, or conveying.  This dirt or dust made apparent as defects of the plastic sheet, and the quality of manufactured plastic sheet is thus deteriorated.