Patent Publication Number: US-6708012-B2

Title: Image forming apparatus and image forming method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image forming apparatus and an image forming method with which a raised print image is formed by transferring an image resulting from foaming toner and an image resulting from non-foaming toner onto a recording medium in correspondence to print image information and utilizing thermal expansion of the foaming toner. 
     2. Background Art 
     Conventionally, technology using embossing, technology using dot impact, and technology using foam paper and heat transfer film have been known as technology that forms a raised image on a recording medium such as recording paper. 
     However, in the conventional technology, there are problems in terms of cost, and problems in durability and preservability. The technology is therefore only used for limited purposes. 
     Thus, the present applicant has proposed image forming apparatus that form a raised image using foaming toner in JP-A-2000-131875 (Title of the invention: Image Forming Toner, Method of Preparing the Image Forming Toner, and Image Forming Apparatus and Method of Forming a Raised image Using the Image Forming Toner) and in JP-A-2001-194846 (Title of the invention: Image Forming Apparatus). 
     The technologies disclosed in these publications make it possible to easily and inexpensively form a raised image that has excellent durability and preservability with a common electrophotographic printer or copying machine by using foaming toner. 
     However, these technologies cannot form a full-color raised image simply by being able to form a monochromatic raised image. 
     SUMMARY OF THE INVENTION 
     In a case where a full-color raised image is to be formed using foaming toner, the full-color raised image cannot be formed by simply superposing plural foaming toners including respectively different coloring materials and transferring the foaming toners to a recording medium. The reason for this is because it is difficult to achieve full color resulting from color layering, because the foaming toners do not have light transmittance characteristics in a foamed state. 
     Thus, the present applicant has proposed a structure in which a full-color raised image that has excellent durability and preservability is inexpensively formed by transferring foaming toner onto a recording medium and transferring thereon non-foaming ordinary toners of respective colors. 
     However, in this structure, multiple transfer, in which plural toner images are transferred, becomes necessary when the toner images are transferred to an intermediate transfer body or to the recording medium. 
     In particular, because color transmittance is low, it is necessary for foaming toner forming a raised print to be directly formed on a recording medium such as paper in a final print. 
     Accordingly, when the foaming toner is transferred to an intermediate transfer body, the foaming toner must be transferred at the very last. 
     When three-dimensionally printing fine lines and small regions, problems arise in that reproduced fine lines and images of small regions are partially omitted, which results in an unclear image, because transfer and fixing to the recording paper is carried out in a state in which the foaming toner is similarly disposed on fine color toner images on the intermediate transfer body. 
     Thus, it is an object of the present invention to provide an image forming apparatus and an image forming method with which fine lines and small regions are reproduced as a raised image with excellent quality. 
     In order to achieve the object the invention provides an image forming apparatus that forms a raised print image by successively transferring foaming toner and non-foaming toner onto a recording medium in correspondence to print image information and heat-fixing onto the recording medium the foaming toner and the non-foaming toner that have been transferred onto the recording medium. The image forming apparatus includes an image processing section that image-processes the print image information so that transfer of an image resulting from the foaming toner is selectively prohibited in correspondence to a line width or size of an image to be transferred by the non-foaming toner onto the foaming toner. 
     The invention further provides an image forming apparatus including an image processing section that image-processes the print image information so that a line width or size of an image to be transferred by the non-foaming toner onto the foaming toner is corrected in correspondence to a line width or size of an image to be transferred by the non-foaming toner onto the foaming toner. 
     The invention further provides an image forming apparatus including an image processing section that image-processes the print image information. The image processing section separates the print image information into a first region that mainly includes text information and a second region that mainly includes image information. The image processing section selectively transfers the foaming toner to the entity of an image in the first region or the entity of an image in the second region. 
     The invention further provides an image forming method, including: transferring foaming toner onto a recording medium; transferring non-foaming toner onto the recoding medium, while selectively prohibiting transfer of an image resulting from the foaming toner in correspondence to a line width or size of an image to be transferred by the non-foaming toner onto the foaming toner; and heat-fixing onto the recording medium the foaming toner and the non-foaming toner to thereby form a raised print. 
     The invention further provides an image forming method, including: transferring foaming toner onto a recording medium; transferring non-foaming toner onto the recoding medium, while correcting a line width or size of an image to be transferred by the non-foaming toner onto the foaming toner in correspondence to a line width or size of an image to be transferred by the non-foaming toner onto the foaming toner; and heat-fixing onto the recording medium the foaming toner and the non-foaming toner to thereby form a raised print. 
     The invention further provides an image forming method, including: separating an image to be transferred to a recording medium into a first region and a second region, the first region mainly including text information, the second region mainly including image information; transferring foaming toner onto the recording medium, while selectively carrying out transfer of the foaming toner with respect to the entity of an image of the first region or the entity of an image of the second region; transferring non-foaming toner onto the recoding medium; and heat-fixing onto the recording medium the foaming toner and the non-foaming toner to thereby form a raised print. 
     The invention further provides a recording medium, including a medium body; and a raised print image formed on the medium body. The raised print image includes a first layer and a second layer. The second layer is superimposed on the first layer. The first layer is made from forming toner. The second layer is made from non-forming toner and is divided into a plurality of regions each forms small images smaller in size than the entity of the raised print image. Line widths or sizes of the small images are smaller than a predetermined line width or size. The plurality of regions are formed on at least a portion of the first layer formed successively on the medium body. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention may be more readily described with reference the accompanying drawings: 
     FIG. 1 is a view illustrating the internal structure of an image forming apparatus in the invention. 
     FIG. 2 is a view illustrating functional blocks of a controller section, a printer engine control section, and an IOT (image forming section), and signals that are inputted and outputted between the respective blocks. 
     FIG. 3 is a data image in a case where image information is described per region of text, images, and graphics as PDL (Page Description Language). 
     FIG. 4 is a view illustrating the content of Tag information for discriminating, at a pixel unit, whether raised printing is to be implemented or not (ordinary printing). 
     FIG. 5 is an image view of a print image when ordinary printing and raised printing have been selectively processed using as a boundary a set reference value. 
     FIG. 6 is an image view of an original image and a print image when fine lines and a small image region have been raised to a size of a constant reference value and raise-printed. 
     FIG. 7 is an image view of an image in which a macro region including fine lines and a small image region has been three-dimensionally printed. 
     FIG. 8 is a user interface for setting conditions for implementing raised printing. 
     FIG. 9 is a user interface for setting raised printing/ordinary printing per type of image region. 
     FIG. 10 is a flow chart of raised printing implementation region discrimination processing. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments for implementing raised printing that provide an image forming apparatus and an image forming method pertaining to the present invention will be described in detail below with reference to the attached drawings. 
     FIG. 1 is a view illustrating the internal structure of an image forming apparatus  1 . 
     The image forming apparatus  1  is structured by a controller section  20 , a printer engine control section  30 , and an image forming section (IOT)  40 . The controller section  20  receives user-designated information relating to raised printing and color information such as sRGB and image information created and edited by a PC (Personal Computer)  10  or the like, creates image data for printing from the information per image class (text, graphic, image), and carries out color conversion processing, color correction processing, and raised printing discrimination processing per pixel. 
     The printer engine control section  30  converts yellow (Y), magenta (M), cyan (C), and black (K) information (each being 8 bits) received per pixel and height (H) information (each being 8 bits), which has been converted and calculated from the color information or directly designated by user information, to a pulse signal that controls laser light carrying out image exposure at the image forming section  40  and sends the pulse signal. 
     The image forming section  40  is mainly structured by: laser drive units  41 Y to  41 H that scan-expose laser light; exposure units  42 Y to  42 H that emit laser light to photosensitive drums  43 Y to  43 H; the photosensitive drums  43 Y to  43 H that form electrostatic latent images; charge units  44 Y to  44 H that charge the photosensitive drums  43 Y to  43 H to a predetermined potential; developing units  46 Y to  46 H that form toner images on the photosensitive drums  43 Y to  43 H; primary transfer rolls  45 Y to  45 H for intermediately transferring the toner images formed on the photosensitive drums; a secondary transfer unit  48 ; and a fixing unit  53 . 
     The steps by which a raised color image is formed are carried out in the following order. 
     The laser drive units  41 Y to  41 H scan-expose laser light using a pulse signal modulated in accordance with a color gradation number of image data and emit the laser light toward the photosensitive drums  43 Y to  43 H using the exposure units  41 Y to  41 H. 
     The photosensitive drums  43 Y to  43 H are rotatingly driven along the directions of the arrows at a predetermined speed. After surfaces of the photosensitive drums  43 Y to  43 H have been pre-charged to a predetermined polarity (e.g., a negative polarity) and potential by the charge units  44 Y to  44 H, electrostatic latent images are formed thereon by the laser light being scan-exposed. 
     With respect to the electrostatic latent images formed on the photosensitive drums  43 Y to  43 H, toner images are respectively formed by the developing units  46 Y to  46 H that develop the foaming toner (H) and the four colors of yellow (Y), magenta (M), cyan (C), and black (K). 
     Additionally, the toner images formed on the photosensitive drums  43 Y to  43 H are multiply transferred to an intermediate transfer belt  57  by the primary transfer rolls  45 Y to  45 H. 
     All or part of the toner images of yellow (Y), magenta (M), cyan (C), black (K), and of a height (H) are transferred, in a state in which they have been successively superposed by the primary transfer rolls  45 Y to  45 H, onto the intermediate transfer belt  57  in correspondence to the height and colors of the image to be formed. 
     The toner images that have been multiply transferred onto the intermediate transfer belt  57  are conveyed at a predetermined timing to the secondary transfer unit  48  and transferred to a raised image recording paper  52 , which is supplied by a feed roller  51  from a paper supply tray  50  disposed at a lower part of the image forming apparatus  1 , by a pressure contact force and an electrostatic suction force of a backup roll  47  that supports the intermediate transfer belt  57  and a secondary transfer roll  49  that contacts the backup roll  47 . 
     After the raised image recording paper  52  to which the toner images have been transferred has been separated from the intermediate transfer belt  57 , it is conveyed to the fixing unit  53 , where the toner images are fixed onto the raised image recording paper  52  by a heat roll  54  and a pressure roll  55  of the fixing unit  53 , and then discharged to a stacker  56  of the image forming apparatus  1 , whereby the steps by which the raised color image is formed conclude. 
     Next, functional blocks of the controller section  20  and the printer engine control section  30  of FIG. 1, and data that is inputted and outputted between the processing blocks, are illustrated in FIG.  2  and will be described. 
     The controller section  20  is separated into the respective processing blocks of a PDL interpreting unit  21 , a color correction unit  22 , a gradation correction unit  23 , and a drawing unit  24 . The printer engine control section  30  is separated into the respective processing blocks of a screening processing unit  31  and a PWM (Pulse Width Modulation) processing unit  32 . 
     The controller section  20  receives: PDL (Page Description Language) d 11  that describes, per page unit, image information for raised printing that has been created and edited at the PC  10 ; an sRGB signal d 12  as color information; and user-designated information dl 3  necessary for raised print processing. 
     A data image of the PDL d 11  is one in which, as in image information  400  of FIG. 4, drawing content is described by classifying a target image for raised printing into image classes, which are an image region  401 , a text region  402 , and a graphic region  403 . 
     In a case where the target image is the image region  401 , information of an image file and the height and width of the region are described. 
     In a case where the target image is the text region  402 , information of character lines and the size and type of the file are described. 
     In a case where the target image is the graphic region  403 , information relating to the size, source, and type of figure to be drawn is described. 
     Information relating to the colors of the raised image is set in the sRGB signal d 12 . 
     The user-designated information d 13  includes the target region for raised print processing and setting items necessary for raised printing. 
     The PDL interpreting unit  21  interprets the descriptions per image class, and extracts the drawing target region per image class and drawing information such as size in the case of text and graphics. 
     Next, the color conversion unit  22  is once converted from the sRGB signal to a LAB color space. 
     The gradation correction unit  23  uses individual conversion tables, to which consideration of gradation characteristics of the printer engine control unit  30  has been given, and converts the colors of the image information expressed at the LAB color space to YMCK. 
     The drawing unit  24  carries out image conversion to a raster image using, as a basis, the drawing information extracted at the PDL interpreting unit  21  and the color information processed by the color conversion unit  22  and the gradation correction unit  23 . 
     At this time, the raised printing target/non-target per pixel is discriminated by “processing for discriminating raised printing target regions” (the details of which will be described later) using, as a basis, the user-designated information d 13  received from the PC  10  and the drawing information extracted at the PDL interpreting unit  21 . 
     The discrimination results are set per pixel to Tag information. 
     FIG. 3 is a view illustrating the content of Tag information  301 , which is expressed as a variable of 1 bit. 
     When the definition of the setting value is 0, the region is not a raised printing target (ordinary printing), and when the value is 1, the region is a raised printing target. 
     The screening processing unit  31  adjusts a constant density level per pixel of the raster image created at the drawing unit  24 , and is configured so that the light and shade of the image can be expressed on a printed matter. 
     The PWM processing unit  32  creates, in correspondence to pixel order, a pulse signal by referencing conversion tables for converting, to a laser irradiation amount, the YMCK color information that has been screening-processed at the screening processing unit  31 , creates a Y-color laser control signal d 31 , an M-color laser control signal d 32 , a C-color laser control signal d 33 , and a K-color laser control signal d 34 , and outputs these to the IOT  40 . 
     A foaming toner laser control signal d 35  is also outputted to the IOT  40  by converting, to a pulse signal, the YMCK color information adjusted at the screening processing unit  31  and a height calculated on the basis of the Tag information d 25 . 
     Next, three correction modes for reproducing, with excellent image quality, fine lines and small regions in three-dimensional print processing will be described. 
     The first correction mode is a mode that selectively processes raised prints and ordinary prints using a set reference value as a border. A print image in this case is illustrated in FIG.  5 . 
     Lines and text enclosed by hatched frames in FIG. 5 represent raised printing targets. Texts (4P)  501 , whose size is 4 point, and texts (8P)  502 , whose size is 8 point, are the text regions of the respective regions of the original image. | x    
     There are also a line (4P)  503 , whose size is 4 point, and a line (8P)  504 , whose size is 8 point, which are straight lines drawn as graphic regions. 
     Raised printing is set with regard to all of the text, image, and graphic image classes, and in a case where a border value discriminating raised printing and standard printing is set to “4P”, “Tag=0 (ordinary printing)” is set for the text (4P)  501  regions and “Tag=1 (raised printing)” is set for the text (8P)  502  regions in processing to discriminate regions for which raised printing is to be implemented. 
     Similarly, for the straight lines drawn as graphic regions, “Tag=0 (ordinary printing)” is set for the line (4P)  503  region, whose size is 4 point, and “Tag=1 (raised printing)” is set for the line (8P)  504  region, whose size is 8 point. 
     The second correction mode is a mode that three-dimensionally prints the fine lines and small image regions by raising them to a size of a constant reference value. A print image in this case is illustrated in FIG.  6 . 
     Lines and text enclosed by hatched frames in FIG. 6 represent the fact that they are to be raise-printed. 
     In an original image  610 , texts (4P)  611 , whose sizes are all 4 point, are the text regions, and lines (4P)  612 , whose sizes are 4 point, are drawn as graphic regions. 
     The raised print processing here is designated with regard to all texts, images, and graphics, and in a case where the designated value of raised printing implementation is “4P”, when there is a setting to fatten to “8P” and raise-print, the designated sizes of the graphic regions and text regions of the image information are enlarged to “8P”, and “Tag=1 (raised printing)” is set for the regions of the lines (8P)  622  and the texts (8P)  621  of a print image  620 . 
     Next, the third correction mode is a mode that raise-prints an entire region (hereinafter called a“macro region”) including fine lines and small image regions. A print image in this case is illustrated in FIG.  7 . 
     An image region  710  is structured by a text region  720 , a graphic region  730 , and an image region  740 , and the sizes of the text region  720  and the graphic region  730  are set at “4P”. 
     In a case where the sizes of the text region and the graphic region designated as for raised printing are equal to or less than the constant reference value, a macro region including the text and lines is raise-printed in place of raise-printing only the regions of the lines and text. 
     By doing so, with respect to text  721  (4P) and a line  731  (4P), an image is formed at an image drawn on a hill of the region  730  and the region  720  formed by raised printing. 
     Examples of setting items requiring user designation and examples of user interfaces therefor when the correction modes of FIGS. 5 to  7  described thus far are to be implemented are illustrated in FIGS. 8 and 9 and will be described. 
     A user interface  800  of FIG. 8 is a user interface that sets detailed implementation conditions when raised printing is to be implemented. 
     In the user-designated items, there are an implementation reference point value  801 , minimum point/dot correction  802 , macro region correction  803 , and a printable minimum dot number  804 . 
     The implementation reference point value  801  is a reference value when the determination of raised printing/ordinary printing is decided by the size of the lines and text. 
     The minimum point/dot correction  802  is an item that designates validity/invalidity of processing that carries out raised printing at a size that has been raised to the reference value in regard to a region in which the size of the lines and text of a raised printing target region falls below the reference value. 
     The macro region correction  803  is an item that selects validity/invalidity of correction processing that raise-prints a macro region including lines and text when the size of lines and text designated for raised printing falls below the implementation reference value and maintains the size of the lines and text. 
     The printable minimum dot number  804  is an item that designates an implementable minimum dot number in regard to ordinary printing and raised printing. 
     A user interface  900  of FIG. 9 is a user interface for separately designating raised printing/ordinary printing per image class (text, graphic, image) of image information. 
     Next, the processing order of the “processing for discriminating raised printing target regions” that discriminates targets/non-targets for raised printing at a pixel unit is illustrated in the flow chart of FIG.  10  and will be described using, as a basis, the modes illustrated thus far in FIGS. 5,  6 , and  7  and setting conditions resulting from the user interfaces illustrated in FIGS. 8 and 9. 
     The image information described by the PDL is analyzed, and the user-designated information relating to raised printing and drawing regions per image class are obtained (Step S 101 ). 
     Next, at the user interface of FIG. 9, it is determined whether the image class that the user has designated for raised printing is present in the image data (Step S 102 ). 
     When regions of the image class that the user has designated for raised printing are not in the image information (proceed to NO at Step S 102 ), “Tag=0 (standard printing)” is set for information of each pixel of the printing target region (Step S 106 ). 
     When there is an image class that has been designated for raised printing (proceed to YES at Step S 102 ), “Tag=1 (raised printing)” is set for the information of each pixel of the target region when the designated size of the target region is larger than standard point (Step S 109 ). 
     When the target region is equal to or less than the reference value (YES at Step S 103 ), it is determined whether size correction is to be rendered valid or invalid by the minimum point/dot correction  802  of the user interface  800  of FIG.  8 . 
     When size correction of the region is rendered valid (proceed to YES at Step S 104 ), the target region is enlarged to a size designated by the implementation reference point value  901  of the user interface  900  of FIG. 9, and “Tag=1 (raised printing)” is set for the information of each pixel of the target region (Step S 108 ). 
     When designation of size correction of the drawing region is invalid (proceed to NO at Step S 105 ), the macro region correction  803  of the user interface  800  of FIG. 8 determines whether or not it has been designated by the user. 
     When the macro region correction is valid (proceed to YES at Step S 105 ), “Tag=1 (raised printing)” is set for all pixel information in order to three-dimensionally print, as a single macro region, the entire image region equal to or less than the reference size of the text and graphic regions (Step S 107 ). 
     When the macro region correction is invalid (proceed to NO at Step S 105 ), “Tag=0 (standard printing)” is set for the information of each pixel of the target region. 
     The above is an example in which the three modes illustrated in FIGS. 5,  6 , and  7  for reproducing fine lines with excellent quality are discriminated and processed according to setting conditions by a single processing program. 
     In the case of the processing flow illustrated in FIG. 10, description was given with the assumption that setting processing is concluded by the user interfaces of FIGS. 8 and 9 before the “processing for discriminating raised printing target regions”. However, in Step S 102 , Step S 103 , Step S 104 , and Step S 105 , the determination conditions may be configured to an inquiry format by the user interface, and processing may be configured to processing in which alterations and input of setting values by the user are possible in the middle of the processing. 
     Additionally, the processing order of the determination processing of Step S 104  and Step S 105  may be reversed, and a mode that carries out correction processing of both Step S 108  and Step S 109  may also be added. 
     Moreover, the correction modes of FIGS. 5 to  7  may be selectable at the user interfaces and configured as processing modes that determine the correction mode at a higher step of processing of FIG.  10 . 
     As described above, according to the invention, when fine lines and small regions have been designated for raised printing, correction processing of raised printing is carried out using, as a basis, setting information per region class that a user has designated in advance, and is it possible to reproduce, with excellent quality, the fine lines and small regions.