JP5625033B2 - Image forming apparatus and program - Google Patents

Description

  Embodiments described herein relate generally to an image forming apparatus and a program for forming an image on a recording medium.

  As an image forming material used for image formation by an image forming apparatus such as a printer or a multifunction peripheral (MFP), image formation such as ink or toner that is erased by decoloring, washing, or heating of a recording medium such as paper There are materials. If this type of erasable image forming material is used, it is possible to erase the image from the recording medium and recycle the recording medium.

  However, depending on the type of image forming material and the erasing conditions, the image may not be completely erased from the recording medium, and a trace may remain. In particular, the decolored mark is conspicuous in the solid portion (dark solid portion or the like) formed on the recording medium. In addition, if a light color image forming material is used or the gradation of an image is lowered in order to make the decoloration mark inconspicuous, it is difficult to read a thin line portion (thin characters, thin lines, etc.) in the image formed on the recording medium. turn into.

JP 2010-191430 A

  The problem to be solved by the present invention is to obtain a good image formation result in which a fine line portion is easy to visually recognize in an image formation using an erasable image forming material, and to make the erasure trace less noticeable after erasing the image. That is.

An image forming apparatus according to an embodiment includes: a gradation determined for each of the plurality of drawing objects included in image data including a plurality of drawing objects to which different attributes are assigned; A processor that generates print data converted based on reproduction information, and a print engine that forms an image based on the print data generated by the processor on a recording medium with a decolorable image forming material , There are a default mode in which printing is performed on a recording medium at a predetermined density, and an afterimage priority mode in which priority is given to making the erasure mark of printing on the recording medium less noticeable than the printing density on the recording medium. The attribute includes a first attribute indicating that the drawing object is a character and that the drawing object is an image. A second attribute and a third attribute indicating that the drawing object is a graphic, and the gradation reproduction information includes a first gradation in which the density of the image data is equal to the density of the print data A reproduction curve, a second gradation reproduction curve in which the density of the print data is equal to or lower than the first gradation reproduction curve, and a third in which the density of the print data is equal to or higher than the first gradation reproduction curve. A gradation reproduction curve, the first gradation reproduction curve for each of the afterimage priority mode and the default mode, and for each of the first attribute, the second attribute, and the third attribute, A memory in which a second gradation reproduction curve or the third gradation reproduction curve is set; and the processor includes the first image in the afterimage priority mode among the plurality of drawing objects included in the image data. 1's For those that are characteristic, the gradation is converted based on the first gradation reproduction curve, and for those that are the second attribute and the third attribute, conversion is performed more than the first gradation reproduction curve. The tone is converted based on the second tone reproduction curve in which the later tone is set low, and the first attribute of the default mode is converted based on the third tone reproduction curve. The gradation is converted, and the gradation having the second and third attributes is converted based on the first or second gradation reproduction curve .

1 is a block diagram showing a main configuration of a print system according to an embodiment. The figure which shows a mode that formation and deletion of an image are repeated with respect to one sheet of paper. The figure which shows the relationship between the printing density of decoloring toner, and the density of the erasure mark which remains after decoloring. The figure which shows the gradation reproduction curve which concerns on one Embodiment. 4 is a diagram showing an example of the data structure of a setting table according to the embodiment. FIG. 6 is a flowchart showing operations of the terminal device and the image forming apparatus according to the embodiment.

  An embodiment will be described with reference to the drawings.

FIG. 1 is a block diagram illustrating a main configuration of a printing system including a terminal device 1 that generates image data to be printed and an image forming apparatus 2 according to the present embodiment.
The terminal device 1 generates image data to be printed by the image forming apparatus 2 in accordance with a command input according to a user operation from a user input I / F 3 (Interface) 3 such as a keyboard, a mouse, or a touch panel. . For example, the terminal device 1 receives image data in which text data such as characters and symbols, graphic data such as line segments and figures, and image data such as bitmap data are arranged according to a command input from the user input I / F 3. Generate.

  The terminal device 1 also includes a printer driver 10 that controls image formation by the image forming device 2 and a communication I / F 11 that connects the terminal device 1 to the image forming device 2 in communication. The printer driver 10 is realized, for example, by executing a computer program for a printer driver corresponding to the image forming apparatus 2 by a CPU (Central Processing Unit) provided in the terminal device 1. When a command for instructing printing of image data is input from the user input I / F 3, the printer driver 10 displays PDL data 100 in which image data generated by the terminal device 1 is described in PDL (Page Description Language). The PDL data 100 is transmitted to the image forming apparatus 2 via the communication I / F 11.

  The PDL data 100 is vector image data including a drawing object having any attribute of text data, graphic data, and image data. The drawing object having the text data attribute includes information representing the font, size, position, color, and the like of the text data. The drawing object having the graphic data attribute includes information representing the type (graphic, line segment, etc.), shape, size, position, color, etc. of the graphic data. A drawing object having an attribute of image data includes image data and information indicating its size.

  The image forming apparatus 2 is, for example, an MFP, and includes a communication I / F 20, a CPU 21, a memory 22, a storage device 23, an operation panel 24, a RIP (Raster Image Processor) 25, a print engine 26, a bus line 27, and the like. The bus line 27 includes an address bus and a data bus, and connects the communication I / F 20, the CPU 21, the storage device 23, the operation panel 24, the RIP 25, and the print engine 26.

  The communication I / F 20 receives the PDL data 100 transmitted from the terminal device 1. The CPU 21 controls each unit of the image forming apparatus 2. The memory 22 includes, for example, a ROM (Read Only Memory) and an SRAM (Static Random Access Memory), stores various parameters necessary for image formation, and functions as a main memory of the image forming apparatus 2. The storage device 23 stores the PDL data 100 received from the terminal device 1 and raster image data (print data) for causing the print engine 26 to print. The operation panel 24 includes operation buttons for inputting various instructions, a display with a touch panel, and the like.

  The RIP 25 realizes a function of generating raster image data based on the PDL data 100 stored in the storage device 23 by executing a computer program stored in advance in a memory included in the RIP 25.

  In generating raster image data, the RIP 25 first performs color conversion processing on the PDL data 100. In the present embodiment, monochrome printing is assumed. Accordingly, in the color conversion process, the RIP 25 generates monochromatic data by monochromaticizing each drawing object included in the PDL data 100. Next, the RIP 25 emphasizes the edges of the drawing object by performing sharpness processing on the monochromatic data. The sharpness process is, for example, an HPF (High Pass Filter) process for monochromatic data. Finally, the RIP 25 performs TRC (Tone Reproduction Correction) processing for correcting the gradation value of each pixel in accordance with the gradation reproduction curve (gradation reproduction information) for the monochromatic data after the edge is enhanced, and gradation. Is subjected to halftone processing (halftone processing) represented by a set of binary pixels called halftone cells, to generate raster image data.

  In addition to color conversion processing, sharpness processing, TRC processing, and halftone processing, the RIP 25 is a line that corrects the line width to the minimum allowable line width for a thin line portion whose line width is smaller than the minimum allowable line width (for example, two lines). A width correction process may be executed.

  The print engine 26 forms an image on a sheet as a recording medium based on raster image data generated by the RIP 25 and stored in the storage device 23. The print engine 26 performs printing by, for example, an electrophotographic copying method using toner as an image forming material, and includes a photosensitive drum as an image carrier, a charger for uniformly charging the photosensitive drum, An exposure device that forms an electrostatic latent image corresponding to raster image data by exposing the photosensitive drum, and an electrostatic latent image by selectively attaching toner to the photosensitive drum corresponding to the electrostatic latent image. A developing device that visualizes the image as a toner image in a reversed state, and supplies the paper to the photoconductive drum and transfers the toner image on the photoconductive drum to the paper, thereby responding to the raster image data on the paper Form the image.

  In this embodiment, a decolorizable toner is used as the toner used in the print engine 26. As this type of toner, for example, a thermally decolorable toner containing a color developing compound, a developer, a binder resin, and the like as components can be used. Since the color-developable toner is preliminarily colored by the action of the developer, the user can recognize the color. When heat above the erasing temperature is applied to the colored toner, the binder resin softens, and the developer is likely to move mainly from the inside of the binder resin to the surface, and also moves into the paper that is the recording medium. It becomes easy to diffuse. For this reason, the color developing compound is not affected by the developer, and the color developing compound is decolored so that the color of the toner cannot be recognized.

  When erasing an image from a sheet on which an image is formed by the image forming apparatus 2, an image erasing apparatus (not shown) is used. For example, the image erasing apparatus erases the image formed on the sheet by applying heat equal to or higher than the erasing temperature to the sheet fed from the sheet feeding mechanism. The image forming apparatus 2 may include such an image erasing device.

  A problem that occurs when using a decolorizable toner will be described. FIG. 2 shows a state where image formation and image erasure are repeated on one sheet of paper P. The paper P shown in (a) is in an unused state. The paper P shown in FIG. 6B shows a state in which an image based on the PDL data 100a in which a dark black character “A” and a square which is a solid black graphic is arranged is formed with decolorable toner. . As the decolorizable toner used by the image forming apparatus 2 in the present embodiment, a toner having a density lower than that of a normal toner, for example, a blue toner is used in order to improve the decolorability. When such toner is used, the density of the image formed on the paper P becomes lighter than the original density indicated by the PDL data 100a. The paper P shown in (c) shows a state in which the image formed on the paper P shown in (b) is erased by the image erasing apparatus. The image is not completely erased, and an erase mark remains on the paper P. The erasure trace relating to the dark solid image is conspicuous compared with the erasure trace of the character because of a large density difference from the non-image formed portion of the paper P and a certain area. The sheet P shown in (d) shows a state in which an image based on the PDL data 100b in which a dark black character “B” and a circle that is a solid black graphic is arranged is formed with decolorable toner. . When image formation and erasure are repeated in this way, the paper P becomes dirty with the erasure trace of the solid portion (such as a dark solid coating portion), and it becomes difficult to reuse the paper P.

  FIG. 3 is a graph showing the relationship between the print density of the erasable toner on the paper P and the density of erasure marks remaining on the paper P after erasing. The higher the printing density by the decolorizable toner, the higher the density of the erasure mark. From such a relationship, in order to reduce the density of the erasure mark, for example, the density of the decolorizable toner itself may be reduced, or the gradation reproduction curve may be set so that the gradation value after conversion is lowered. It is done. However, when these measures are taken, thin line portions such as character portions formed on the paper P are also thinly printed and are difficult to see.

  In the present embodiment, in order to cope with such a problem, the gradation reproduction curve used by the RIP 25 for the TRC process is changed according to the attribute of the drawing object included in the PDL data 100. Specifically, after converting the tone reproduction curve of a drawing object that has a graphic data attribute that often includes solid areas more than the tone reproduction curve of a drawing object that has a character or image data attribute Is set so that the gradation value of the image becomes lower.

  Further, the image forming apparatus 2 uses a residual image priority mode that prioritizes making the erased trace inconspicuous, a density priority mode that prioritizes image density, and a default mode that takes between them.

A setting example of the gradation reproduction curve will be described with reference to FIGS.
The RIP 25 according to the present embodiment selectively uses three tone reproduction curves TRC1 (linear), TRC2 (light), and TRC3 (dark) shown in FIG. In the figure, the horizontal axis indicates the gradation (input density) of the pixel in the monochromatic data after sharpness processing, and the vertical axis indicates the gradation (output density) of the pixel after conversion in TRC processing. The gradation range is 00h to FFh (0 to 255). The gradation reproduction curve TRC1 is a straight line where input density = output density. The gradation reproduction curve TRC2 is a straight line whose output density is equal to or less than the gradation reproduction curve TRC1. The gradation reproduction curve TRC3 is a straight line whose output density is equal to or higher than the gradation reproduction curve TRC1.

  The tone reproduction curve used for each mode and the attribute of each drawing object is defined by the setting table 50 stored in the memory 22. An example of the data structure of the setting table 50 is shown in FIG. In this example, the setting table 50 defines a gradation reproduction curve TRC2 for a drawing object whose attribute is graphic data (GRAPHICS) and relates to a default mode, for a drawing object whose attribute is image data (IMAGE). A gradation reproduction curve TRC1 is defined, and a gradation reproduction curve TRC3 is defined for a drawing object whose attribute is text data (TEXT). Further, regarding the afterimage priority mode, the setting table 50 defines a gradation reproduction curve TRC2 for a drawing object whose attribute is graphic data (GRAPHICS), and a setting table 50 for the drawing object whose attribute is graphic data (IMAGE). A tone reproduction curve TRC2 is defined, and a gradation reproduction curve TRC1 is defined for a drawing object whose attribute is graphic data (TEXT). Regarding the density priority mode, the setting table 50 defines a gradation reproduction curve TRC1 for a drawing object whose attribute is graphic data (GRAPHICS), and a level for a drawing object whose attribute is graphic data (IMAGE). A tone reproduction curve TRC1 is defined, and a gradation reproduction curve TRC3 is defined for a drawing object whose attribute is graphic data (TEXT). As described above, in the afterimage priority mode, the gradation reproduction curve for the drawing object of each attribute is the same as or lower than that in the default mode. For this reason, an image formed on the paper in the afterimage priority mode has a lighter print density than the default mode and is less noticeable after erasure. In the density priority mode, a gradation reproduction curve for a drawing object of each attribute is the same as or higher than that in the default mode. For this reason, an image formed on a sheet in the density priority mode has a higher print density than the default mode and is easily noticeable after erasure.

  In the example of FIG. 5, the gradation reproduction curve (first gradation reproduction information) of a drawing object whose attribute is graphic data and the gradation reproduction curve (second floor) of a drawing object whose attribute is text data. As shown in FIG. 4, in any mode, the second gradation reproduction information has a lower converted gradation (output density) than the first gradation reproduction information. It is prescribed to be.

  In addition to the gradation reproduction curve, the setting table 50 defines the strength of sharpness processing in each mode and ON (valid) / OFF (invalid) of presence / absence of thin line limit (Thin Line Limit). In the example of FIG. 5, the setting table 50 shows that the sharpness processing strength in the default mode is high sharpness, the sharpness processing strength in the afterimage priority mode is weaker than the sharpness strength, and the sharpness processing strength in the density priority mode is high. Is stipulated. The setting table 50 defines ON (valid) for line width correction processing in the default mode, OFF (invalid) for line width correction processing in the afterimage priority mode, and ON (valid) for line width correction processing in the density priority mode. ing.

Next, the operation flow of the terminal device 1 and the image forming apparatus 2 will be described with reference to the flowchart of FIG.
When the user operates the user input I / F 3 to instruct printing of image data, a print job for printing the image data is generated. At this time, the printer driver 10 of the terminal device 1 first receives selection of a mode to be used for printing among the default mode, the afterimage priority mode, and the density priority mode (Act 11). The user can select a desired mode by operating the user I / F 3.

  After Act 11, the printer driver 10 generates PDL data 100 based on the image data to be printed (Act 12). Thereafter, the printer driver 10 sends, to the image forming apparatus 2 via the communication I / F 11, a print queue including mode information indicating the type of mode for which the selection has been accepted at Act 11 and the PDL data 100 generated at Act 12. Transmit (Act 13). Thus, the operation of the terminal device 1 is completed, and the next print job is awaited.

  On the other hand, the CPU 21 of the image forming apparatus 2 waits for reception of a print queue from the terminal apparatus 1 (Act 21). When the print queue transmitted from the terminal device 1 is received (Yes in Act 21), the CPU 21 saves the print queue in the storage device 23 and queues it in the print queue. Thereafter, when the print order of the print queue comes, the CPU 21 determines whether the mode indicated by the mode information included in the print queue is the default mode, the afterimage priority mode, or the density priority mode (Act 22). .

  When it is the default mode (“Default” in Act 22), the CPU 21 sets each parameter of the default mode defined in the setting table 50 stored in the memory 22 as a parameter used for the processing of the RIP 25 (Act 23).

  On the other hand, in the afterimage priority mode (“afterimage priority” in Act 22), the CPU 21 sets each parameter of the afterimage priority mode defined in the setting table 50 stored in the memory 22 as a parameter used for processing of the RIP 25 ( Act 24).

  On the other hand, in the case of the density priority mode (“Density priority” in Act 22), the CPU 21 sets each parameter of the density priority mode defined in the setting table 50 stored in the memory 22 as a parameter used for processing of the RIP 25 ( Act 25).

  After Act 23, Act 24, or Act 25, the RIP 25 performs processing according to the set parameters (Act 26). That is, the RIP 25 performs rasterization processing, sharpness processing, TRC processing, and halftone processing on the PDL data 100 related to the print queue stored in the storage device 23 to generate raster image data, and stores the raster image data in the storage device 23. In the sharpness processing, the RIP 25 performs the sharpness processing of the strength of the sharpness processing indicated by the parameter set in any of Acts 23 to 25. Further, in the TRC process, the RIP 25 reproduces the gradation of each drawing object included in the monochromatic data corresponding to each attribute of the drawing object indicated by the parameter set in any of Acts 23 to 25. Convert by curve. If the parameter set in any of Acts 23 to 25 indicates ON (valid) of the line width correction process, the RIP 25 does not satisfy the minimum line width in the process of generating raster image data. Correct the line width of thin lines such as characters and line segments to the minimum allowable line width.

  When the processing by the RIP 25 is completed, the CPU 21 outputs the raster image data of the print queue stored in the storage device 23 to the print engine 26 (Act 27). The print engine 26 forms an image based on the input raster image data on a sheet using decolorable toner, and discharges the sheet onto a discharge tray (not shown). The operation of the image forming apparatus 2 related to one print queue is thus completed.

  As described above, the image forming apparatus 2 according to the present embodiment converts the gradation of the drawing object included in the PDL data 100 (image data) based on the gradation reproduction curve determined for each attribute. Image data is generated, and an image based on the raster image data is formed on a sheet with decolorable toner. Thus, if the gradation reproduction curve is properly used for each attribute, an appropriate print density can be realized according to the attribute of the drawing object. For example, if the printing density of a drawing object having an attribute that often includes a solid portion (for example, graphic data) is lowered, the image erased trace can be made inconspicuous, and a drawing object having an attribute that often includes a thin line portion ( For example, if the print density of text data) is set high, a good image formation result that is easy to visually recognize can be obtained.

  In addition, since the image forming apparatus 2 according to the present embodiment performs sharpness processing on the monochromatic data after the color conversion processing and emphasizes the edge of the image, it is possible to obtain an image forming result that makes it easier to recognize the thin line portion. it can.

  The image forming apparatus 2 according to the present embodiment uses the default mode, the afterimage priority mode, and the density priority mode properly according to the user's selection. With this function, the user can select the afterimage priority mode if importance is placed on the inconspicuousness of image deletion traces, and the density priority mode can be selected if importance is placed on image visibility. Become.

  In addition, various suitable effects can be obtained from the configuration disclosed in the present embodiment.

The configuration disclosed in the present embodiment can be modified in various ways.
For example, the image forming apparatus 2 may form an image by an image forming method other than the electrophotographic copying method, for example, an ink jet method using an erasable ink.

  In addition, the relationship between the attributes of the drawing object and the gradation reproduction curve is not limited to that shown in FIG. 5, and may be changed as appropriate so as to obtain an optimum image forming condition.

  The computer program executed by the RIP 25 is not necessarily stored in the memory provided in the RIP 25 at the manufacturing stage of the image forming apparatus 2. For example, the image forming apparatus 2 may download the computer program from the network and store it in the memory of the RIP 25. Alternatively, the computer program recorded on the recording medium by the image forming apparatus 2 may be stored in a memory provided in the RIP 25. The recording medium may be in any form as long as it can store a computer program such as a CD-ROM or a memory card and can be read by the image forming apparatus 2. Further, the function obtained by the computer program may be realized in cooperation with the OS (Operating System) of the image forming apparatus 2 or the like.

  Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Terminal device, 2 ... Image forming apparatus, 3 ... User input I / F, 10 ... Printer driver, 21 ... CPU, 22 ... Memory, 23 ... Memory | storage device, 24 ... Operation panel, 25 ... RIP (processor), 26 ... print engine, 27 ... bus line, 50 ... setting table, 100 ... PDL data.

Claims (5)

Print data obtained by converting the gradation of each of the plurality of drawing objects included in image data composed of a plurality of drawing objects to which different attributes are assigned based on gradation reproduction information determined for each attribute. A processor to generate,
A print engine for forming an image based on the print data generated by the processor on a recording medium with an erasable image forming material;
Equipped with a,
A default mode in which printing is performed on the recording medium at a predetermined density, and an afterimage priority mode in which priority is given to making the erasure mark of printing on the recording medium less noticeable than the printing density on the recording medium. Have
The attribute includes a first attribute indicating that the drawing object is a character, a second attribute indicating that the drawing object is an image, and a third attribute indicating that the drawing object is a graphic. Including
The gradation reproduction information includes a first gradation reproduction curve in which the density of the image data and the density of the print data are equal, and a second in which the density of the print data is equal to or less than the first gradation reproduction curve. A gradation reproduction curve, and a third gradation reproduction curve in which the density of the print data is equal to or higher than the first gradation reproduction curve,
The first gradation reproduction curve, the second gradation reproduction curve, for each of the afterimage priority mode and the default mode, and for each of the first attribute, the second attribute, and the third attribute. Or a memory in which the third gradation reproduction curve is set,
The processor converts the gradation of the plurality of drawing objects included in the image data based on the first gradation reproduction curve for the first attribute of the afterimage priority mode, For the second attribute and the third attribute, the gradation is determined based on the second gradation reproduction curve in which the gradation after conversion is set lower than that of the first gradation reproduction curve. The first attribute of the default mode is converted based on the third gradation reproduction curve, and the first and second attributes are the first and second attributes. Alternatively, the gradation is converted based on the second gradation reproduction curve.
An image forming apparatus. The image forming apparatus according to claim 1, wherein the processor performs sharpness processing that emphasizes edges of the plurality of drawing objects included in the image data . A density priority mode that prioritizes the density of the image;
The memory includes the first gradation reproduction curve for each mode of the afterimage priority mode, the density priority mode, and the default mode, and for each attribute of the first attribute and the second attribute, A second gradation reproduction curve or the third gradation reproduction curve is set;
The image forming apparatus according to claim 1. Print data obtained by converting the gradation of each of the plurality of drawing objects included in image data composed of a plurality of drawing objects to which different attributes are assigned based on gradation reproduction information determined for each attribute. A processor to generate,
A print engine for forming an image based on the print data generated by the processor on a recording medium with an erasable image forming material;
Each of a default mode in which printing is performed on the recording medium at a predetermined density and an afterimage priority mode in which priority is given to making the erasure mark of printing on the recording medium less noticeable than the printing density on the recording medium. And a first attribute indicating that the drawing object is a character, a second attribute indicating that the drawing object is an image, and a third attribute indicating that the drawing object is a graphic, For each attribute, a first gradation reproduction curve in which the density of the image data and the density of the print data are equal, and a second gradation reproduction in which the density of the print data is equal to or less than the first gradation reproduction curve. A memory in which a curve and a third gradation reproduction curve in which the density of the print data is equal to or higher than the first gradation reproduction curve;
In the processor of the image forming apparatus comprising:
Among the plurality of drawing objects included in the image data, a function for converting the gradation based on the first gradation reproduction curve for the first attribute of the afterimage priority mode;
For the second attribute and the third attribute, the gradation is determined based on the second gradation reproduction curve in which the gradation after conversion is set lower than that of the first gradation reproduction curve. A function to convert,
For the first attribute of the default mode, the gradation is converted based on the third gradation reproduction curve, and for the second and third attributes, the first or second gradation reproduction is performed. A function to convert the gradation based on the curve;
A program to realize The program according to claim 4, for causing the processor to perform a function of performing a sharpness process for emphasizing edges of the plurality of drawing objects included in the image data .

Images