JP2005104045A - Image forming method and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method which is applicable to color printing by a multi-function peripheral (MFP), in a manner suppressing excessive use of predetermined recording materials, and to provide an image forming device. <P>SOLUTION: When printing is carried out by the MFP 104 by using toners of yellow (Y), magenta (M), cyan (C), black (K), highlight magenta (M'), and highlight cyan (C'), based on received PDL (page description language) data, a density histogram is prepared for each of the colors of Y, M, C, K. Then it is determined whether or not an appearance frequency of a highlight component exceeds an arbitrary threshold value, based on the histogram of the M, and if the frequency does not exceed the threshold value, it is determined that the highlight magenta toner is not used. In the same manner it is determined whether or not an appearance frequency of a cyan highlight component exceeds an arbitrary threshold value, and if the answer is negative, it is determined that the highlight cyan toner is not used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming method and an image forming apparatus, and more particularly, to an image forming method and an image forming method for reducing the amount of a predetermined color recording material such as toner or ink in forming an image such as a color print. It relates to the device.

  Conventionally, an MFP (Multi Function Peripheral) is known to be connected to an external device such as a computer via a network and has a printer, a scanner, a FAX, and a copy function.

  When printing is performed by a conventional MFP printer, the MFP receives image data created by an external computer via a network, and outputs an image by a printer unit.

  For example, when printing in monochrome or color, the image output from the printer unit has high resolution and high gradation, so that the color recording material includes yellow, magenta, cyan, and black toner (dark toner). In addition, an image forming apparatus having a light color component (highlight component) toner (light toner) having a low hue density has been proposed (see Patent Document 1). The image forming apparatus described in Patent Document 1 decomposes image information converted into density data into image data for dark toner and image data for light toner for each color, and each decomposed image data The image is subjected to gamma correction, multi-value processing, and the like, and an image is formed with an exposure optical system corresponding to each color. However, in this image forming apparatus, even when there are few highlight components in the image data transmitted from the external computer via the network, printing is performed using the corresponding highlight component toner.

  In addition to yellow, magenta, cyan, and black, image formation with toners for specific hues (hues other than yellow, magenta, cyan, and black) that are difficult to express with yellow, magenta, cyan, and black An apparatus has been proposed, and even in this case, even when image data transmitted from an external computer via a network has a small specific hue, printing is performed using the corresponding specific hue toner.

JP 2002-49191 A

  Therefore, in the related art, for example, when performing color printing by an MFP including a printer unit having a highlight component toner or a specific hue toner in addition to yellow, magenta, cyan, and black toner, Even when it is not necessary to use a light component toner or a specific hue toner, these toners have been used in printing. For this reason, there has been a problem that the usage amount of the highlight component toner or the specific hue toner increases more than necessary. The same applies to an image forming apparatus (for example, an ink jet printer) that uses ink as a color recording material.

  The present invention has been made in view of such a problem, and an object of the present invention is to use a predetermined color recording material (for example, toner or ink for highlight component, toner or ink for specific hue). An object is to provide an image forming method and an image forming apparatus capable of suppressing use more than necessary.

  To this end, the present invention provides an image forming method for forming an image corresponding to image data supplied from the outside by using a color recording material by an image forming unit, wherein the image forming is performed with reference to the supplied image data. A histogram of density regarding the image data of a predetermined color recording material used by the means is created, and a density within a predetermined density range of the image data and having a density equal to or lower than a predetermined frequency of appearance is based on the created histogram. The image formation is performed without using the predetermined color recording material for data.

  According to another aspect of the present invention, there is provided an image forming apparatus for forming an image corresponding to image data supplied from outside using a color recording material by an image forming unit, wherein the image forming is performed with reference to the supplied image data. A histogram creating means for creating a density histogram relating to the image data of the predetermined color recording material used by the means; and a predetermined frequency of occurrence within the predetermined density range of the image data based on the created histogram. And determining means for determining not to use the predetermined color recording material for the following density data.

  As described above, according to the present invention, the density histogram relating to the image data of the predetermined color recording material used by the image forming unit is created by referring to the image data supplied from the outside. By performing image formation without using a predetermined color recording material with respect to data having a density within a predetermined density range of the image data and having a predetermined appearance frequency or less based on a histogram, a predetermined color recording material The amount used can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
In the present embodiment, when color printing is performed by an MFP including a printer unit having toners of six colors of yellow, magenta, cyan, black, highlight magenta, and highlight cyan, a histogram of each color is created to correspond to the corresponding high. The light portion is compared with an arbitrary threshold value, and it is determined whether or not the corresponding highlight component toner is used.

  FIG. 1 is a diagram showing an image communication system according to the present invention. In FIG. 1, a server 102, clients 103a and 103b (hereinafter, the client is also collectively referred to as 103), MFPs (Multi Function Peripherals) 104a, 104b, 104c and 104d capable of scanning, printing, etc. in full color. (Hereinafter, MFP is also collectively referred to as 104) and a one-drum color laser beam printer (LBP) 105 are connected via a network 101, and can communicate with each other using the network 101. Although not shown in FIG. 1, many clients and many MFPs are connected to the network 101. Furthermore, devices such as a scanner (not shown) and a FAX (not shown) are connected to the network 101.

  Various documents / graphics can be created / edited by operating application software that executes DTP (Desk Top Publishing) or a word processor in the client 103. The client 103 converts the created document / graphic into PDL (Page Description Language) and transmits the PDL data to the MFP 104 and the LBP 105 via the network.

  Further, the MFP 104 and the LBP 105 have communication means capable of exchanging information with the server 102 and the client 103 via the network 101, respectively, and transmit status data of the MFP 104 and the LBP 105 to the server 102 and the client 103, respectively. Thus, the server 102 and the client 103 can be notified of the information and status sequentially. On the other hand, the server 102 and the client 103 have utility software that operates by receiving status data or the like via the network 101, and processes the information received by the utility software to cause the MFP 104 and the LBP 105 to operate. Can be managed.

(Configuration of MFP 104)
FIG. 2 is a block diagram showing a configuration for controlling the MFP according to the present invention.
The MFP includes a control unit (not shown) that controls the entire MFP. The control unit includes a CPU that executes control, a ROM that stores a control program for the CPU, and a RAM that provides a work area for the CPU. 2 are also integrated and controlled by this control unit. In FIG. 2, a scanner unit 201 reads an image from an image on a sheet, an image on a film, or the like. An IP (Image Processing) unit 202 processes image data transmitted from the scanner unit 201. The FAX unit 203 transmits and receives images using a transmission line such as a telephone line, and is represented by a facsimile or the like. A NIC (Network Interface Card) unit 204 exchanges device information such as image data and status data with the client 103 via the network. The PDL unit 205 expands the page description language (PDL) received by the NIC unit 204 into an image signal. The core unit 206 temporarily stores an image signal and determines a transmission path of the image signal according to the purpose of use of the MFP 104. A PWM (Pulse Width Modulation) unit 207 compares the amplitude of the image signal with the amplitude of the carrier wave (triangular wave) and binarizes the image signal. The printer unit 208 is a color laser printer having yellow, magenta, cyan, black, highlight magenta, and highlight cyan, and forms an image based on the image data output from the core unit 206. A finisher unit 209 performs sorting processing and finishing processing of the sheet on which an image is formed by the printer unit 208. The display unit 210 can check the content of the image data without forming an image in the printer unit 208, or can check the appearance of the image (preview) before forming the image.

  In FIG. 2, a reading operation instruction in the scanner unit 201, an instruction for the number of sheets when the read image is output by the printer unit 208, and the like can be performed by the user in the scanner unit 201. Further, these instructions can be given by the client 103 or the like via the network 101.

(Configuration of the scanner unit 201)
FIG. 3 is a diagram showing a scanner according to the present invention. In FIG. 3, the document table glass 301 is disposed on the upper portion of the scanner unit 201. A document 302 to be read is placed on a document table glass 301. The illumination lamp 303 and the mirror 304 are disposed in the first mirror unit 310. Further, the mirror 305 and the mirror 306 are disposed in the second mirror unit 311. The first mirror unit 310 and the second mirror unit 311 are provided so as to be movable along a rail (not shown) in the arrow direction (sub scanning direction) in FIG. Can move at a predetermined speed v in the direction of the arrow in FIG. 3, and the second mirror 311 can move at a predetermined speed 1 / 2v in the direction of the arrow in FIG. As a result, the entire surface of the original 302 can be scanned. The lens 307 is disposed on the optical axis of the light reflected by the mirror 306. The CCD sensor 308 as a photoelectric conversion means is a color sensor of three color lines of R (red), G (green), and B (blue), and is arranged so that the light passing through the lens 307 forms an image. ing. With the above configuration, when the original 302 is irradiated with the illumination lamp 303 and the entire surface of the original 302 is scanned by moving the first mirror unit and the second mirror unit, the reflected light from the original 302 is reflected by the mirror 304, The light is reflected by 305 and 306, passes through the lens 307, and forms an image on the CCD sensor 308. The optical signal based on the imaged original 302 by the CCD sensor 308 is converted into an electric signal and transmitted to the IP unit 206.

(Configuration of IP unit 202)
FIG. 4 is a block diagram showing details of the IP unit according to the present invention. 4, an A / D converter (converter) 401 converts R, G, and B image signals transmitted from the CCD sensor 308 into 8-bit digital image signals RO, GO, and BO for each color. The shading correction unit 402 performs shading correction on each of the RO, GO, and BO colors using the reference white plate read signal. A line delay adjustment circuit (also referred to as a “line interpolation unit” in this specification) 403, with respect to a signal received from the shading correction unit 402, each color line sensor is arranged at a predetermined distance from each other in the CCD sensor 308. The spatial deviation in the sub-scanning direction resulting from being provided is corrected. The input masking unit 404 is an element that converts a reading color space determined by the spectral characteristics of the R, G, and B color filters in the CCD sensor 308 into an NTSC standard color space. The (RO, GO, BO) signal from the line interpolation unit 403 is converted into a standard (R, G, B) by a 3 × 3 matrix calculation using device-specific constants in consideration of various characteristics such as 303 spectral characteristics. ) Convert to signal. A luminance / density conversion unit (also referred to as “LOG conversion unit” in this specification) 405 includes a look-up table (LUT) RAM, and is a luminance signal proportional to the reflected light from the document (R, G , B) signals are converted into (Y (yellow) 1, M (magenta) 1, C (cyan) 1) signals which are density signals. An output masking / UCR circuit unit (also referred to as an “output masking unit” in this specification) 406 performs a process of replacing a portion that becomes an achromatic color by overlapping Y, M, and C colors with K (black). Accordingly, the (Y1, M1, C1) signal output from the LOG conversion unit 405 is changed to (Y, M, C, K, M ′ (highlight magenta), C ′ (high) according to the toner color of the printer unit 208. Light cyan)) signal. At this time, when the toner color of the printer unit 208 is Y, M, C, K, S (skin color), or R (red) or the like, if the color is different from the above color, , (Y, M, C) signals are corrected. The gamma conversion unit 407 is a look-up table (LUT) RAM (considering toner color characteristics with respect to the (Y, M, C, K, M ′, C ′) signals output from the output masking unit 406. The gradation characteristics are corrected using (not shown). The spatial filter 408 performs edge enhancement or smoothing on the gamma converted (Y, M, C, K, M ′, C ′) signal. The IP unit 202 includes an A / D conversion unit 401, a CPU (not shown), a ROM (not shown), and a RAM (not shown), and a portion excluding the A / D conversion unit 401 (402 to 408) can be realized as a function executed by the CPU. In this case, each function is executed from the A / D conversion unit 401 supplied on the RAM that functions as a work area by the CPU operating according to the program in the ROM. Is achieved by processing the data.

FIG. 5 is a block diagram showing details of the NIC unit and the PDL unit according to the present invention.
(Configuration of NIC unit 204)
The NIC unit 204 has an interface function to the network 101. For example, the NIC unit 204 receives information from an external device such as the client 103 using an Ethernet (registered trademark) cable such as 10Base-T / 100Base-TX. Information is transmitted to the outside such as the client 103. In the present invention, in addition to Ethernet (registered trademark), a network medium between an external device such as the client 103 and the MFP 104, for example, a token ring, FDDI (Fiber Distributed Data Interface) can be included. In FIG. 5, a transformer unit 601 converts the voltage of an information signal transmitted from an external device such as the client 103. The LAN controller unit 602 includes a first buffer memory (not shown) and a second buffer memory (not shown) in its interior, and whether the information signal received from the transformer unit 601 is necessary information on the first buffer memory. The information signal is transmitted to the second buffer memory. On the other hand, when transmitting information to an external device such as the client 103, the LAN controller unit 602 adds necessary information to the information signal received from the PDL unit 205. The transformer unit 601 converts the voltage of the information signal received from the controller 602, and transmits the information signal to a desired external device via the network.

(Configuration of PDL unit 205)
The PDL unit 205 converts PDL, which is a combination of image description elements such as character code, graphic code, and raster image data, into raster image data. In the present invention, the PDL may include a language for controlling a page printer such as PostScript (registered trademark), LIPS, HP-PCL, ESC / Page, and PRESCRIBE. In FIG. 5, the PDL data received from the NIC 204 is once stored in a large capacity memory 604 such as a hard disk (HDD) via the CPU unit 603, where it is managed and saved for each job. The CPU unit 603 includes a CPU (not shown), a ROM that stores an execution program for the CPU, and a RAM that provides a work area for the CPU. Rasterization called RIP (Raster Image Processing) is performed as necessary. Image processing is performed to develop the PDL data into a raster image. The developed raster image data is stored in units of pages for each job in a memory 605 that can be accessed at high speed, such as DRAM, for each color component of Y, M, C, K, M ′, and C ′. According to the situation, the data is transmitted again to the core unit 206 via the CPU unit 603. Further, the CPU executes the histogram creation regarding the density of the data in the memory 605 and the control procedure as shown in FIGS. 13 and 16 according to the program in the ROM, and details will be described later, but the data determined not to use the predetermined toner is described later. A process of outputting the included image data to the core unit 206 is executed.

(Configuration of core unit 206)
FIG. 6 is a block diagram showing details of the core unit according to the present invention. In FIG. 6, the bus selector 701 plays a role of traffic control in using the MFP 104 and the LBP 105. That is, the bus can be switched according to various functions in the MFP 104 and the LBP 105 such as a copying function, a network scan, a network printer, facsimile transmission / reception, or display display. The bus switching pattern for executing the various functions described above is shown below.
Copy function: scanner unit 201-> core unit 206-> printer unit 208
Network scan: scanner unit 201 → core unit 206 → NIC unit 204
Network printer: NIC unit 204 → core unit 206 → printer unit 208
Facsimile transmission function: scanner unit 201 → core unit 206 → FAX unit 203
Facsimile reception function: FAX unit 203 → core unit 206 → printer unit 208
Display display function: scanner unit 201 or FAX unit 203 or NIC unit 204 → core unit 206 → display unit 210

  The compression unit 702 compresses the image data output from the bus selector 701. In the present invention, this compression method can include a method for reducing the capacity of the data file, for example, JPEG, JBIG, ZIP, or the like. The memory unit 703 is a large-capacity memory such as a hard disk (HDD), and temporarily stores the image data compressed by the compression unit 702. The decompression unit 704 decompresses the compressed image data stored in the memory unit 703 according to the status of the printer unit 208 or the display unit 210, and transmits the decompressed image data to the printer unit 208 or the display unit 210. To do. The image data compressed by the compression unit 702 is managed for each job and stored in the memory unit 703 together with additional data such as a file name, a creator, a creation date and time, and a file size. At this time, if a job number and a password are further provided and stored together in the memory unit 703, the personal box function can be supported. This is a function for temporarily storing data and printing out only for a specific person (reading from the memory unit 703). When a printout instruction is issued for a job stored in the memory unit 703, the job is called from the memory unit 703 after authenticating with a password, and the decompression unit 704 decompresses the image and rasterizes it. It is also possible to return to the image and transmit the raster image data to the printer unit 208.

(Configuration of PWM unit 207)
7A and 7B are block diagrams showing details of the PWM unit according to the present invention. As shown in FIG. 7A, the multivalued image data that is color-separated into four colors Y, M, C, K, M ′, and C ′ output from the core unit 206 corresponds to each color. Each image is formed through the PWM section. The triangular wave generator 801 generates a triangular wave. A D / A converter (D / A conversion unit) 802 converts the digital image signal (multi-valued image data) from the core unit 206 that is input into an analog signal. The signal from the triangular wave generator 801 (a in FIG. 7B) and the signal from the D / A converter 802 (b in FIG. 7B) are compared in magnitude by the comparator 803, and FIG. A pulse-width-modulated signal such as c is sent to the laser drive unit 804, and Y, M, C, K, M ′, and C ′ are respectively Y, M, C, K, M ′, and C ′. 'It is converted into a laser beam by each laser oscillator 805. Then, each laser beam is scanned by the polygon scanner 913 to irradiate the respective photosensitive drums 917, 921, 925, 929, 933, and 937.

(Configuration of printer unit 208 of MFP 104)
FIG. 8 is a diagram showing an outline of a 6-drum type color printer unit according to the present invention. In FIG. 8, reference numeral 913 denotes a polygon mirror that receives six laser beams emitted from six semiconductor laser oscillators 805. One of them scans the photosensitive drum 917 through the mirrors 914, 915, 916, the next one scans the photosensitive drum 921 through the mirrors 918, 919, 920, the next one is 922, Scan the photosensitive drum 925 through 923, 924, scan the photosensitive drum 929 through the next one through 926, 927, 928, and scan the photosensitive drum 933 through the 930, 931, 932 through the next one. The next one scans the photosensitive drum 937 through mirrors 934, 935, and 936.

  On the other hand, 938 is a developing device that supplies yellow (Y) toner, forms a yellow toner image on the photosensitive drum 917 in accordance with the laser beam, and 939 is a developing device that supplies magenta (M) toner. , A magenta toner image is formed on the photosensitive drum 921 in accordance with the laser beam, and a developing unit 940 supplies cyan (C) toner. A cyan toner image is formed on the photosensitive drum 925 in accordance with the laser beam. , 941 is a developing unit that supplies magenta (M ′) toner for highlighting, and forms a magenta toner image for highlighting on the photosensitive drum 929 in accordance with the laser beam, and 942 is cyan (C ′ for highlighting). ), And a toner image of cyan for highlighting is formed on the photosensitive drum 933 in accordance with the laser beam, and 943 supplies black (K) toner. That a developing device in accordance with the laser beam to form a black toner image on the photosensitive drum 937. A full-color output image can be obtained by transferring the toner images formed on the drums of six colors (Y, M, M ′, C, C ′, K) to the sheet. In the present invention, yellow, magenta, cyan and black, which are normal toners, and highlight magenta and highlight cyan, which are light toners, are used as the six color toners to be used. , Skin color, red, etc. may be used.

  A sheet (paper) supplied from any one of the sheet cassettes 944 and 945 and the manual feed tray 946 passes through the registration roller 947 and is sucked onto the transfer belt 948 and conveyed. In synchronism with the timing of paper feeding, toner of each color is developed in advance on the photosensitive drums 917, 921, 925, 929, 933, and 937, and the toner is transferred to the sheet as the sheet is conveyed. The sheet on which the toner of each color has been transferred is separated from the transfer belt 948 and then conveyed by the conveyance belt 949, and the toner is fixed to the sheet by the fixing device 950. The sheet that has passed through the fixing device 950 is once guided downward by the flapper 953, and after the trailing edge of the sheet has passed through the flapper 953, the sheet is switched back and discharged. As a result, the sheets are discharged in a face-down state, and are in the correct order when printed in order from the first page.

  The six photosensitive drums 917, 921, 925, 929, 933, and 937 are arranged at equal intervals at a distance d, and the sheet is conveyed at a constant speed v by the conveyance belt 949. Timing synchronization is performed and the six semiconductor lasers 805 are driven.

(Configuration of display unit 210)
FIG. 10 is a block diagram showing details of the display unit according to the present invention. In FIG. 10, an inverse LOG conversion unit 1001 converts the image signal output from the core unit 206, which is YMCK data, into RGB data. The gamma conversion unit 1002 performs output conversion on the RGB data from the inverse LOG conversion unit 1001 using a look-up table in order to match the color characteristics of the display device 1004 such as CRT to be output. The converted image data is once stored in the memory unit 1003 and displayed on a display device 1004 such as a CRT. Here, the display unit 210 is used for a preview function for confirming an output image from the printer unit 208 in advance, a proof function for verifying whether an image output by the printer unit 208 is the intended one, or a print function. This is to eliminate waste of the print sheet when checking whether it is necessary.

(Configuration of finisher unit 209)
FIG. 11 is a diagram showing an outline of the finisher unit according to the present invention. In FIG. 11, the sheet exiting the fixing unit 950 of the printer unit 208 enters the finisher unit 209. The finisher unit 209 includes a sample tray 1101 and a stack tray 1102. Sheets are discharged by switching according to the type of job and the number of discharged sheets.

  The sorting method includes a bin sorting method in which a plurality of bins are allocated to each bin, and a shift sorting method in which an electronic sorting function and a bin (or tray), which will be described later, are shifted in the back / front direction and output sheets are allocated to each job. Sorting can be performed by these two sort methods. The electronic sort function is called collate. If the large-capacity memory described in the core unit 206 is provided, the buffer sort is used to change the buffered page order and the discharge order. The electronic sorting function can be supported by using the collate function. The group function is a function for sorting by page, while sorting is sorted by job.

  Further, when discharging the sheets to the stack tray 1102, it is possible to store the sheets before being discharged for each job and bind them by the stapler 1105 immediately before discharging. In addition to the above-described two trays, there are a Z-folder 1104 for folding paper into a Z-shape and a puncher 1106 for punching two (or three) holes for files. Each process is performed according to

  Further, the saddle stitcher 1107 binds the central part of the sheet at two places, and then folds the sheet in half by placing the central part of the sheet on a roller to create a booklet such as a weekly magazine or pamphlet. . The sheet created by the saddle stitcher 1107 is discharged to the booklet tray 1108.

  In addition, although not shown in FIG. 11, it is possible to add binding by glue (gluing) for bookbinding or cutting for aligning the end surface opposite to the binding side after binding.

  An inserter 1103 is for sending a sheet set on the tray 1110 to one of the trays 1101, 1102, and 1108 without passing through the printer. As a result, the sheet set on the inserter 1103 can be inserted (inserted) between the sheets fed into the finisher 209 portion. Assume that a sheet is set face-up by the user on the tray 1110 of the inserter 1103, and the pickup roller 1111 sequentially feeds the sheets from the uppermost sheet. Accordingly, the sheet from the inserter 1103 is discharged as it is to the trays 1101 and 1102 and is discharged face down. When sending to the saddle stitcher 1107, the face is aligned by sending it back to the puncher 1106 and then switching back.

(Description of network utility software)
Hereinafter, user utility software that operates on the server 102 and the client 103 will be described. A standardized database called MIB (Management Information Base) is built in the network interface part (NIC unit 204 + PDL unit 205) in the MFP 104 and MFP 105, and the network management protocol called SNMP (Simple Network Management Protocol) is used. It can communicate with a computer on the network, and can manage a scanner, a printer, a FAX, and the like connected to the network including the MFP 104 and the LBP 105. On the other hand, a software program called a utility operates on the computers 102 and 103, and necessary information can be exchanged using the MIB by using the above-described SNMP via the network. For example, it detects whether the finisher unit 209 is connected as equipment information of the MFP 104 and LBP 105, detects whether printing is currently possible as status information, or names and installation locations of the MFP 104 and LBP 105. By using the MIB, the user can confirm information on the MFP 104 and the LBP 105 connected to the network on the server 102 or the client 103. These pieces of information can also distinguish the server 102 and the client 103 and give restrictions to read / write. Therefore, by using this function, the user can obtain all information on the server 103 or the client 102 such as equipment information of the MFP 104 and the LBP 105, apparatus status, network settings, job history, usage status management, and control. Is possible.

(Configuration of LBP105)
The configuration of the LBP 105 will be described with reference to FIGS.
FIG. 9 is a diagram showing the configuration of the LBP according to the present invention. In FIG. 9, an LBP 105 uses a network interface card (NIC) unit 1204 that exchanges image data and device information using a network, a page description transmitted from the client 103 and the like output from the NIC unit 1204, and the like. A PDL unit 1205 that develops and outputs a language (PDL) into an image signal, a PWM unit 1207 that converts a signal output from the PDL unit 1205 into a PWM signal, and a printer unit 1208 are included.

  The configurations of the NIC unit, PDL unit, and PWM unit in FIG. 9 are the same as those of the MFP 104.

  FIG. 12 is a diagram showing an outline of a one-drum type color printer unit (printer unit 1208) according to the present invention. In FIG. 12, reference numeral 913 denotes a polygon mirror, which receives one laser beam emitted from the semiconductor laser 805, scans the photosensitive drum 917 through the mirror 914, and forms a latent image on the photosensitive member. The latent image on the photoreceptor reaches the color developing unit 961 and the black developing unit 960 while rotating counterclockwise. The developing units of the color developing unit 961 and the black developing unit 960 serve to put (develop) toner on the photosensitive member according to the electric charge charged as a latent image. When the image is black and white, only the black developer 960 is used, and when the image is color, both the color developer 961 and the black developer 960 are used. Next, the toner image generated on the photosensitive member 917 is transferred to a transfer drum 962 as an intermediate transfer member rotating clockwise. The transfer drum 962 completes image generation on the intermediate transfer member by making one rotation for black and white, four rotations for color, or six rotations.

  The color developing unit 961 rotates to contact any one of the yellow developing unit 961y, the magenta developing unit 961m, the cyan developing unit 961c, the highlighting magenta developing unit 961m ′, and the highlighting cyan developing unit 961c ′ with the photosensitive drum 917. To be controlled. First, when developing and transferring yellow toner, the color developing device rotates until it stops at the position shown in FIG. 12, and when the photosensitive drum 917 is subjected to laser exposure, the photosensitive drum 917 rotates in the clockwise direction. A yellow toner image is formed on the photosensitive drum 917 by the developing device 961y. In synchronization with this, the transfer drum 962 rotates counterclockwise, and yellow toner is transferred from the photosensitive drum. The circumference of the transfer drum is such that an A3 size image can be formed in the longitudinal direction. When A3 size image formation is performed, an A3 size original is read, and a yellow toner image for one A3 size image is formed on the transfer drum by the image signal.

  Next, when developing and transferring magenta toner, the color developing unit 961 rotates counterclockwise by 72 degrees, reads the original in the same manner as described above, and performs laser exposure on the photosensitive drum 917 by the image signal. The photosensitive drum 917 rotates in the clockwise direction in synchronism with the toner image, and a magenta toner image is formed on the photosensitive drum 917 by the magenta developing device 961m. In synchronization with this, the transfer drum 962 rotates counterclockwise, and magenta toner is transferred from the photosensitive drum 917 onto the transfer drum 962.

  Next, similarly, a highlight magenta toner image, a cyan toner image, and a highlight cyan toner image are sequentially transferred onto the transfer drum 962. Next, a black toner image is formed on the photosensitive drum 917 by the developing unit 960 and is similarly transferred onto the transfer drum 962. Reference numeral 960 denotes a cleaner for the photoconductor 917.

  On the other hand, the sheet fed from the upper cassette 970 or the lower cassette 971 by the pickup roller 972 or 973 is conveyed according to the sheet feeding roller 974 or 975, and further conveyed by the conveying roller 976 of 976 to the front of the registration roller.

  The fed sheet is controlled so as to come between the transfer drum 962 and the transfer belt 978 at the timing when the image formation on the transfer drum 962 is completed. When the sheet reaches here, the transfer belt 978 contacts the transfer drum 662, and the toner is transferred to the sheet. The image transferred to the sheet is fixed to the sheet by heat and pressure by a fixing roller 979.

  The sheet on which the image has been fixed is conveyed to either the face-up discharge port 980 or the face-down discharge port 981 specified in advance by the client 103 or the like (printer controller) and discharged. Thus, the image information sent from the client 103 or the like (printer controller) can be output.

Details of the operation of the PDL unit will be described below.
In the PDL unit 205, the CPU unit 603 converts the received PDL data into raster data, determines the density for each pixel in each of the colors Y, M, C, and K, and outputs magenta (M) and cyan (C). Create a histogram. In FIG. 5, density determination 606 and histogram creation 607 are described as blocks as functions executed by the CPU in the CPU unit 603, and the created histogram is stored in the memory 605. Only when the frequency of C ′ and M ′, which are the lighter portions of cyan and magenta (hereinafter referred to as highlight components), exceed a certain threshold from the created histogram, magenta toner for highlight component Print using highlight component cyan toner or both.

  FIG. 13 is a flowchart showing histogram determination processing according to the present invention. The control procedure shown in this flowchart is stored in the ROM in the CPU unit 603 of the PDL unit 205, and is executed by the CPU of the CPU unit 603.

  In FIG. 13, in step 11, the MFP receives PDL data.

  In step 12, the PDL data is expanded into raster data. In step 13, the density is determined for each pixel for each color of YMCK from the developed raster data, and a histogram is created. FIG. 14 is a diagram showing an example of a created histogram according to the present invention. In FIG. 14, the vertical axis represents frequency and the horizontal axis represents density. Also, in the same figure, the A part in the area lighter than the predetermined density is a light-colored part, that is, a highlight part, and the B part in the area darker than the predetermined density is a normal character or image part. is there. The threshold value X is a threshold value, and it is determined whether or not the highlight component is used by comparing this value with the A portion that is the highlight portion. The threshold value X can be changed as appropriate according to the status of the printer unit and the user's intention.

  In step 14, it is determined from the magenta histogram created in step 13 whether the magenta highlight portion exceeds an arbitrary threshold value. If the highlight portion of magenta exceeds an arbitrary threshold value, the process proceeds to step 15; otherwise, the process proceeds to step 16.

  In step 15, since the highlight portion of magenta exceeds an arbitrary threshold value, it is determined that highlight magenta toner (M ′ toner) is used, and the process proceeds to step 17.

  In step 16, since the highlight component of magenta does not exceed an arbitrary threshold value, it is determined not to use the highlight magenta toner, and the magenta toner for highlight in the corresponding data among the image data output from the PDL unit 205 is determined. , And the process proceeds to Step 18.

  In Step 17, in response to the decision to use the highlight magenta toner in Step 15, the normal color toner (ordinary toner), magenta toner (M toner) and the highlight component toner (light toner). Use ratio with M ′ toner is calculated. From the relationship between the density determined in consideration of the characteristics of the M toner and M ′ toner and the toner usage, the usage of M toner and M ′ toner is calculated from the magenta density used for each pixel. FIG. 15 is a diagram showing the relationship between the density of normal toner and light toner according to the present invention and the amount of toner used. In FIG. 15, the vertical axis represents toner usage, and the horizontal axis represents density. Based on the relationship shown in FIG. 15, the usage amounts of the normal toner and the light toner are calculated from the corresponding color density used for each pixel.

  In step 18, it is determined from the cyan histogram created in step 13 whether the cyan highlight portion exceeds an arbitrary threshold value. If the cyan highlight portion exceeds an arbitrary threshold value, the process proceeds to step 19, and if not, the process proceeds to step 20.

  In step 19, since the cyan highlight portion exceeds an arbitrary threshold value, it is determined to use highlight cyan toner (C ′ toner).

  In step 20, since the highlight component of cyan does not exceed an arbitrary threshold value, it is determined not to use the highlight cyan toner, and the highlight cyan toner in the corresponding data among the image data output from the PDL unit 205 is determined. Set the usage amount to zero.

  In step 21, in accordance with the decision to use highlight cyan toner in step 19, cyan toner (C toner) which is normal color toner (normal toner) and highlight component toner (light toner). The usage ratio with C ′ toner is calculated in the same manner as in Step 17. When the use ratio of C toner and C ′ toner is determined, the process ends.

  In the present embodiment, whether or not the highlight portion of the corresponding color based on the histogram created in Step 13 exceeds an arbitrary threshold value is determined in the order of magenta and cyan. You may go in order of magenta.

  The configuration, density determination, and histogram creation operations of the PDL unit 205 of the MFP 104 described above are exactly the same in the PDL unit of the LBP 105.

  As described above, according to the present embodiment, in the MFP including the printer unit having YMCK and M ′ (highlight magenta) C ′ (highlight cyan) toner, the color components of the document read by the scanner unit From the histogram, it is determined whether it is necessary to use M ′ or C ′ by calculating a histogram of the predetermined toner of the MFP. By not using light toner, it is possible to reduce toner consumption.

(Second Embodiment)
In this embodiment, when color printing is performed by an MFP including a printer unit having six toners of yellow, magenta, cyan, black, flesh color (S), and red (R), flesh color (S) and red (R). A histogram of the density is created and the peak of the frequency within the reproduction effect range for a specific hue toner is compared with an arbitrary threshold value to determine whether or not the corresponding specific hue toner is used.

  In this embodiment, the image communication system, the configuration of the MFP, and the configuration of the LBP are the same as those in FIGS. 1 to 12 described in the first embodiment. The characteristic part will be described in detail.

Details of the operation of the PDL unit 205 will be described below.
In the PDL unit 205, the CPU in the CPU unit 603 converts the received PDL data into raster data. In this case, the converted raster data is composed of six colors including SR in addition to the basic YMCK. After the conversion, the density is determined for each pixel for each of the colors Y, M, C, K, S, and R, and a skin color (S) and red (R) histogram is created. From the created histogram, if the frequency exceeds a certain threshold within the range (reproduction effect range) adapted to reproduce with the toner for flesh color or red, the flesh color toner or red toner, or Print using both.

  FIG. 16 is a flowchart showing a histogram determination process according to the present invention. The control procedure shown in this flowchart is stored in the ROM in the PDL unit 205 and is executed by the CPU in the CPU unit.

  In FIG. 16, in step 21, the MFP receives PDL data.

  In step 22, the PDL data is expanded into raster data.

  In step 23, the density is determined for each pixel for each color of YMCK and SR from the developed raster data, and a histogram is created. FIG. 17 is a diagram showing an example of a created histogram according to the present invention. In FIG. 17, the vertical axis represents frequency, and the horizontal axis represents density. Also, in the figure, the threshold value X is a threshold value, and by comparing this value with the peak of density within the reproduction effect range of the specific hue toner, it is determined whether or not the specific hue toner is used. I do. The threshold value X can be changed as appropriate according to the status of the printer unit and the user's intention.

  In step 24, it is determined from the skin color histogram created in step 23 whether or not the peak within the skin color reproduction effect range exceeds an arbitrary threshold value. If the peak within the skin color reproduction effect range exceeds an arbitrary threshold value, the process proceeds to step 25, and if the peak does not exceed the arbitrary threshold value, the process proceeds to step 26.

  In step 25, since the peak within the skin color reproduction effect range exceeds an arbitrary threshold value, it is determined to use the skin color toner.

  In step 26, since the peak within the skin color reproduction effect range does not exceed an arbitrary threshold value, it is determined not to use the skin color toner, and the amount of skin color toner used in the corresponding data among the image data output from the PDL unit 205 is determined. To zero.

  In step 27, in response to the decision to use the flesh color toner in step 25, the usage ratio between the toner of each color of YMC and the flesh color toner (S toner) which is a specific hue toner is calculated. From the relationship between the density determined in consideration of the characteristics of Y toner, M toner and C toner, and S toner and the amount of toner used, from the skin color density used for each pixel, Y toner, M toner and C toner, In addition, the usage amount of S toner is calculated. FIG. 18 is a diagram illustrating the relationship between the density of the Y toner, M toner, C toner, and specific hue toner according to the present invention and the amount of toner used. In FIG. 18, the vertical axis represents toner usage, and the horizontal axis represents density. Based on the relationship shown in FIG. 18, the usage amount of Y toner, M toner and C toner, and a specific hue toner is calculated from the corresponding color density used for each pixel.

  In step 28, it is determined from the red histogram created in step 22 whether or not the peak within the red reproduction effect range exceeds an arbitrary threshold value. When the peak within the red reproduction effect range exceeds an arbitrary threshold value, the process proceeds to step 29, and when the peak does not exceed the arbitrary threshold value, the process proceeds to step 30.

  In step 29, since the peak within the red reproduction effect range exceeds an arbitrary threshold value, it is determined to use red toner.

  In step 30, since the peak within the red reproduction effect range does not exceed an arbitrary threshold value, it is determined not to use red toner, and the amount of red toner used in the corresponding data among the image data output from the PDL unit 205 is determined. To zero.

  In step 31, in accordance with the decision to use red toner in step 29, the usage ratio between the YMC toner of each color and the red toner (R toner) that is a specific hue toner is calculated in the same manner as in step 27. To do. When the usage ratios of Y toner, M toner, C toner, and R toner are determined, the process ends.

  The configuration, density determination, and histogram creation operations of the PDL unit 205 of the MFP 104 described above are exactly the same in the PDL unit of the LBP 105.

  As described above, according to the present embodiment, in the MFP including the printer unit having YMCK and S (skin color) R (red) toner, the predetermined toner contained in the MFP is determined from the color components of the document read by the scanner unit. By calculating the histogram, it is determined from the histogram whether or not S or R needs to be used, and in the case of data having a small hue portion, by not using a specific hue toner such as S or R, It is possible to reduce toner consumption.

  The image forming apparatus using toner as a color recording material has been described above. However, the present invention can be applied to an image forming apparatus using ink as a color recording material.

It is a figure which shows the image communication system which concerns on this invention. 1 is a block diagram showing a configuration for controlling an MFP according to the present invention. FIG. It is a figure which shows the scanner which concerns on this invention. It is a block diagram which shows the detail of the IP part which concerns on this invention. It is a block diagram which shows the detail of the NIC part and PDL part which concern on this invention. It is a block diagram which shows the detail of the core part which concerns on this invention. It is a block diagram which shows the detail of the PWM part which concerns on this invention. It is a figure which shows the outline | summary of the 6 drum type color printer part which concerns on this invention. It is a figure which shows the structure of LBP which concerns on this invention. It is a block diagram which shows the detail of the display part which concerns on this invention. It is a figure which shows the outline | summary of the finisher part which concerns on this invention. 1 is a diagram illustrating an outline of a one-drum type color printer unit according to the present invention. FIG. It is a flowchart which shows the determination process of the histogram which concerns on this invention. It is a figure which shows an example of the created histogram which concerns on this invention. It is a figure which shows the relationship between the density | concentration of the normal toner and light toner based on this invention, and a toner usage-amount. It is a flowchart which shows the determination process of the histogram which concerns on this invention. It is a figure which shows an example of the created histogram which concerns on this invention. It is a figure which shows the relationship between the density | concentration and toner usage-amount of Y toner, M toner, and C toner which concern on this invention, and a specific hue toner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 201 Scanner part 202 IP part 203 FAX part 204, 1204 NIC part 205, 1205 PDL part 206 Core part 207, 1207 PWM part 208, 1208 Printer part 209 Finisher part 210 Display part 308 CCD sensor 401 A / D conversion part 402 Shading correction 403 Line interpolation unit 404 Input masking unit 405 LOG conversion unit 406 Output masking unit 407 Gamma conversion unit 408 Spatial filter 601 Transformer unit 602 LAN controller unit 603 CPU unit 604 Memory (HDD)
605 memory (DRAM)
701 Bus selector 702 Compression unit 703 Memory (HDD)
704 Expansion unit 801 Triangular wave generation unit 802 D / A conversion unit 804 Laser drive unit 1001 Inverse LOG conversion unit 1002 Gamma conversion unit 1003 Memory unit 1004 Monitor

Claims (8)

An image forming method for forming an image corresponding to image data supplied from outside using a color recording material by an image forming means,
A density histogram relating to the image data of a predetermined color recording material used by the image forming unit is created with reference to the supplied image data, and a predetermined density of the image data is based on the generated histogram. An image forming method characterized in that the image formation is performed without using the predetermined color recording material with respect to data having a density within a range and not exceeding a predetermined appearance frequency.   2. The image forming method according to claim 1, wherein the predetermined color recording material is a light density color recording material.   2. The image forming method according to claim 1, wherein the predetermined color recording material is a color recording material having a predetermined hue. An image forming apparatus that forms an image corresponding to image data supplied from outside using a color recording material by an image forming unit,
Histogram creation means for creating a density histogram for the image data of a predetermined color recording material used by the image forming means with reference to the supplied image data;
Determining means for deciding not to use the predetermined color recording material with respect to data having a density within a predetermined density range and not more than a predetermined frequency of appearance based on the generated histogram; An image forming apparatus.   5. The image forming apparatus according to claim 4, wherein the predetermined color recording material is a light density color recording material.   The image forming apparatus according to claim 4, wherein the predetermined color recording material is a color recording material having a predetermined hue.   4. The image forming method according to claim 1, wherein the image data supplied from outside is received via a network. 7. The image forming apparatus according to claim 4, wherein the image data supplied from the outside is received via a network.

Images