JP2007047383A - Image printing device, image printing method and image printing program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately perform a large quantity of tint printing by using an automatic density adjustment function. <P>SOLUTION: When instructed to perform tint printing to print a specific tint in addition to background for image data, a color laser printer 20 obtains a development bias for a desired density by carrying out automatic density adjustment before the tint printing, and then carries out the tint printing by using the development bias. Accordingly, test printing for the tint printing is carried out immediately after the automatic density adjustment such that by the time that the large quantity of tint printing is started, the optimum density of tint printing has been set. Therefore, even in case where density fluctuates as the tint printing proceeds, the density does not greatly deviate from the density suitable for tint printing and the function of the tint is prevented from being greatly degraded. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image printing apparatus, an image printing method, and an image printing program.

Conventionally, in a normal copying machine, if unnecessary objects such as fine dust or dust adhere to the document to be copied, the image quality will deteriorate if you print even unnecessary objects together, Even if there is a small unnecessary object in the document to be copied, the unnecessary object is ignored without being printed. By utilizing this, an image printing apparatus equipped with a function enabling differentiation between an original and a copy has been developed. For example, in the image printing apparatus disclosed in Patent Document 1, a camouflage pattern created with dots that are so fine as to be ignored by a copier and a specific pattern created with dots that are not ignorable by a copier (for example, “copy prohibited”). And a copy-forgery-inhibited pattern including characters) is superimposed on the background of the image data and printed. In this way, when the background pattern is superimposed on the background and printed, the camouflage pattern and the specific pattern are intermingled when the background of the original printed material is seen, but the presence of the specific pattern is not noticed, but the printed material is copied. When you look at the background of the copy after copying with a machine, the camouflage pattern disappears and you notice the presence of the specific pattern. Therefore, according to this function, differentiation between the original and the copy can be easily realized.
JP 2001-197297 A

  However, when a large amount of copy-forgery-inhibited pattern printing is performed by an electrophotographic image printing apparatus such as a laser printer, the density decreases before the printing of all the sheets is completed, and for a printed matter after a certain number of sheets, a copying machine can be used. Even if the copy is made, there is a problem that the specific pattern contained in the background pattern is insufficient and the specific pattern does not appear on the copy because the copying machine cannot read. In order to solve this problem, it is conceivable to perform automatic density adjustment on a regular basis to optimize the image forming conditions. However, in this case, another problem arises. That is, before printing a large amount of copy-forgery-inhibited pattern in advance, perform a trial print for copy-forgery-inhibited pattern printing by manually setting various densities, and when copying the test print with a copying machine, a specific pattern is clearly displayed on the copy. In many cases, a large amount of tint block printing is performed by setting the density that appears in the image to a density suitable for tint block printing. However, automatic density adjustment is performed immediately after determining a density suitable for tint block printing by performing a test print. May be. As a result, when a large amount of copy-forgery-inhibited pattern printing is started, the density has already shifted from the density suitable for tint block printing. It may shift.

  On the other hand, a yellow trace pattern representing information related to printing (for example, the model name, serial number, manufacturer name, etc. of the printing apparatus) may be used as a background pattern, and this background pattern may be superimposed on the background of the image data and printed. In this case, a tracking pattern is printed on the background of the printed matter, but since it is printed in yellow, which is difficult to visually recognize, only the person who knows that the tracking pattern is printed usually notices its presence. Such a tracking pattern includes a plurality of dots and represents information related to printing depending on whether or not each dot is filled. However, the following problems occur. That is, before carrying out a large amount of copy-forgery-inhibited pattern printing in advance, a manual print operation is performed to set various densities, and a trial print for copy-forgery-inhibited pattern printing is performed. A density that can be clearly distinguished is set to a density suitable for tint block printing, and a large amount of tint block printing is often performed with that density set. However, automatic density adjustment is performed immediately after determining a density suitable for tint block printing by performing a test print. May be executed. As a result, when a large amount of copy-forgery-inhibited pattern printing is started, the density has already shifted from the density suitable for tint block printing. It may shift.

  The present invention has been made in view of such a problem, and provides an image printing apparatus, an image printing method, and an image printing program capable of appropriately performing a large amount of tint block printing using an automatic density adjustment function. Objective.

  The present invention adopts the following means in order to achieve the above-mentioned object.

The image printing apparatus of the present invention includes:
An electrophotographic printing mechanism that exposes a photoconductor to form an electrostatic latent image, develops the electrostatic latent image with toner, and transfers the toner image to a print medium;
When there is a copy-forgery-inhibited pattern printing command to add a predetermined copy-forgery-inhibited pattern to the background of the image data, before the copy-forgery-inhibited pattern printing is performed, the print mechanism is controlled to perform automatic density adjustment to form an image that has a desired density Print control means for determining the conditions and then controlling the printing mechanism to execute the tint block printing using the image forming conditions;
It is equipped with.

  In this image printing apparatus, when there is a copy-forgery-inhibited pattern print command for printing a predetermined copy-forgery-inhibited pattern in addition to the background of the image data, the print mechanism is controlled to perform automatic density adjustment before executing the copy-forgery-inhibited pattern print. The printing mechanism is controlled so as to obtain the image forming condition to be the density and then execute the tint block printing using the image forming condition. Here, considering the case of determining the density suitable for copy-forgery-inhibited pattern printing by performing a trial print for copy-forgery-inhibited pattern printing, the copy-forgery-inhibited pattern print test is performed immediately after the automatic density adjustment. Even if the density changes as the copy-forgery-inhibited pattern printing is advanced after that, the density suitable for printing is not greatly deviated from the density suitable for the copy-forgery-inhibited pattern printing. As a result, the function of the tint block is not greatly impaired. As described above, according to the present invention, a large amount of tint block printing can be appropriately performed using the automatic density adjustment function.

  In the image printing apparatus of the present invention, the predetermined tint block may be one in which a predetermined mark (a character, a figure, a symbol, a pattern, or a combination of two or more of these) appears on the copied material when the printed material is copied. Good. In this case, it is highly necessary to adjust the density appropriately because it depends on the density whether or not a predetermined mark appears on the copied material when the printed material is copied.

  In the image printing apparatus of the present invention, the predetermined tint block may be a tracking pattern representing information related to printing. In this case, whether or not a tracking pattern representing information related to printing can be clearly read depends on the density, and therefore there is a high need to appropriately adjust the density.

  In the image printing apparatus according to the aspect of the invention, the print control unit controls the printing mechanism to determine the density under a plurality of different image forming conditions when performing the automatic density adjustment to obtain the image forming conditions that achieve the desired density. A plurality of different patches may be developed, the density of the developed patch may be measured, and the measurement result may be used to obtain the image forming condition that achieves the desired density. In this way, automatic density adjustment can be performed appropriately.

  In the image printing apparatus according to the aspect of the invention, the printing control unit controls the printing mechanism to perform the automatic density adjustment at a higher frequency when performing the tint block printing than when performing normal printing other than the tint block printing. May be. In this way, when the background pattern printing is performed, the automatic density adjustment is performed before the density at the time of starting the background pattern printing is largely deviated, so that the density fluctuation range is narrowed. For example, when a predetermined mark is made to appear on a copy of a copy of a printed matter printed with a tint block, the copier clearly distinguishes the part of the predetermined mark contained in the tint block and the part other than the mark. It is necessary to set the density so that it is possible, and in order to read the information related to printing represented by the tracking pattern, it is necessary to set the density so that the information can be read accurately. In this case, it is preferable to narrow the allowable density fluctuation range as compared with normal printing.

  Here, the print control unit performs the automatic density adjustment more frequently than when performing the normal printing. When the copy-forgery-inhibited pattern printing prints a plurality of pages, immediately before starting the printing of each page. Alternatively, the automatic density adjustment may be executed. In this way, the density variation range when performing copy-forgery-inhibited pattern printing can be further narrowed. Further, the print control means may execute the automatic density adjustment in a simplified manner as compared with when performing the normal printing when performing the automatic density adjustment with a higher frequency than when performing the normal printing. Good. In this way, since the automatic density adjustment is executed at a high frequency, the density fluctuation range becomes narrower than that during normal printing. Therefore, it is often sufficient to adjust the density within the narrow density fluctuation range. It becomes possible to perform density adjustment in a simplified manner. In addition, when performing automatic density adjustment using multi-stage density patches, if at least the creation of the highest density patch is omitted, the amount of toner consumed by the automatic density adjustment will be reduced accordingly. Is.

The image printing method of the present invention includes:
The photosensitive member is exposed to form an electrostatic latent image, and the electrostatic latent image is developed with toner to form a toner image, and an electrophotographic printing mechanism that transfers the toner image to a printing medium is controlled to perform image printing. An image printing method using computer software,
(A) When there is a copy-forgery-inhibited pattern print command for printing a predetermined copy-forgery-inhibited pattern in addition to the background of the image data, the print mechanism is controlled to perform automatic density adjustment before executing the copy-forgery-inhibited pattern printing to obtain a desired density Obtaining image forming conditions,
(B) controlling the printing mechanism to execute the copy-forgery-inhibited pattern printing using the image forming conditions obtained in step (a);
Is included.

  In this image printing method, when there is a copy-forgery-inhibited pattern print command for printing a predetermined copy-forgery-inhibited pattern in addition to the background of the image data, the print mechanism is controlled to perform automatic density adjustment before executing the copy-forgery-inhibited pattern print. The printing mechanism is controlled so as to obtain the image forming condition to be the density and then execute the tint block printing using the image forming condition. Here, considering the case of determining the density suitable for copy-forgery-inhibited pattern printing by performing a trial print for copy-forgery-inhibited pattern printing, the copy-forgery-inhibited pattern print test is performed immediately after the automatic density adjustment. Even if the density changes as the copy-forgery-inhibited pattern printing is advanced after that, the density suitable for printing is not greatly deviated from the density suitable for the copy-forgery-inhibited pattern printing. As a result, the function of the tint block is not greatly impaired. As described above, according to the present invention, a large amount of tint block printing can be appropriately performed using the automatic density adjustment function. In this image printing method, steps for realizing the functions of the various image printing apparatuses described above may be added.

  The present invention is a program for causing one or more computers to execute each step of the above-described image printing method. This program may be recorded on a computer-readable recording medium (for example, hard disk, ROM, FD, CD, DVD, etc.), or from a computer via a transmission medium (communication network such as the Internet or LAN). It may be distributed to another computer, or may be exchanged in any other form. If this program is executed by one computer or distributed to a plurality of computers, each step of the above-described image printing method is executed, so that the same effect as the above-described image printing method can be obtained.

  FIG. 1 is a configuration diagram showing a schematic configuration of a digital multifunction peripheral 10 according to an embodiment of the present invention, FIG. 2 is a block diagram showing a schematic configuration of a color laser printer 20, and FIG. 3 is an A diagram of the digital multifunction peripheral 10 of FIG. FIG. 4 is a block diagram illustrating a schematic configuration of the scanner 70 in FIG. 4 and FIG. 5 illustrates a schematic configuration of the scanner 70 in the digital multifunction peripheral 10 in detail. It is a block diagram.

  As shown in FIG. 1, the digital multi-function peripheral 10 according to the present embodiment includes a color laser printer 20 that prints an image based on image data on a sheet, and an image on a document that is installed above the color laser printer 20 as image data. A scanner 70 for reading and an operation panel 90 provided in front of the scanner 70 for inputting instructions by the user and displaying various kinds of information are provided.

  First, the color laser printer 20 will be described in detail. As shown in FIG. 2, the color laser printer 20 includes a printer controller 30 that controls the entire color laser printer 20, an electrophotographic printer mechanism 41, and a printer ASIC 42 that controls the printer mechanism 41. Printer unit 40. Note that “ASIC” is an abbreviation for Application Specific Integrated Circuit.

  The printer controller 30 is configured as a microprocessor centered on a CPU 31, and stores various processing programs, as well as a ROM 32 that stores unique product information of the color laser printer 20 and a background pattern used for background pattern printing, A RAM 33 that temporarily stores data and stores data, a flash memory 34 that is electrically rewritable and retains data even when the power is turned off, and a job memory 35 that stores a print job are provided. Yes. The printer controller 30 is electrically connected to the printer ASIC 42 via the bus 38, outputs a print command signal to the printer ASIC 42, and inputs a print operation signal from the printer ASIC 42. The printer controller 30 is electrically connected to the scanner controller 75 of the scanner 70 and the operation panel 90 via the input / output port 37. That is, the printer controller 30 inputs image data from the scanner controller 75 and various command signals from the operation panel 90, and outputs display command signals to the operation panel 90. Further, the printer controller 30 exchanges signals with a plurality of computers 51 to 53 connected to the network via the network board 36. That is, the printer controller 30 inputs a print job from each of the computers 51 to 53 and outputs status information of the print job being processed to the computers 51 to 53 that are the transmission source of the print job. Also, the image data from the scanner controller 75 is output to the computers 51 to 53.

  The printer unit 40 includes a printer mechanism 41 and a printer ASIC 42. As shown in FIG. 3, the printer mechanism 41 is configured as a full-color electrophotographic printer mechanism that employs a single photoreceptor system and an intermediate transfer system, and has C (cyan), M (on the charged surface). The electrostatic latent images of the respective colors of magenta), Y (yellow), and K (black) are supplied from the photosensitive member 63 formed by the exposure device 62 and the toner cartridges 45C, 45M, 45Y, and 45K for each color. A developing device 61 that develops a toner image by attaching toner of each color to an electrostatic latent image formed on the photoreceptor 63, and a transfer belt as an intermediate transfer member that performs primary transfer so that the developed toner images of each color are superimposed. 64, and a secondary transfer unit 67 for secondary transfer of the four color toner images formed on the transfer belt 64 onto the paper P transported from the paper cassette 65 by the transport unit 66; Formed on the transfer belt 64, a fixing unit 68 that melts and fixes the four color toner images transferred onto the paper P onto the paper P, a discharge port 59 that discharges the paper P on which the toner image is fixed by the fixing unit 68, and the transfer belt 64. A density sensor 69 capable of measuring the density of the toner image. Among these, the developing device 61 is rotated so that the mounted toner cartridges 45C, 45M, 45Y, and 45K face the photoconductor 63, respectively. The exposure device 62 exposes the photoconductor 63 with a laser beam scanned by a polygon mirror that is rotationally driven by a motor to form an electrostatic latent image. As shown in FIG. 2, the printer mechanism 41 applies a primary transfer bias to a developing bias power source 43 that applies a developing bias to the developing portion of the developing device 61 and a transfer portion from the photoconductor 63 to the transfer belt 64. A transfer bias power source 44 that applies a secondary transfer bias to a transfer portion from the transfer belt 64 to the paper P is provided. The toner adhesion amount from the developing device 61 to the photosensitive member 63 can be adjusted by the voltage of the developing bias power supply 43, and the transfer efficiency from the photosensitive member 63 to the transfer belt 64 and the transfer efficiency from the transfer belt 64 to the paper P are adjusted. Can be adjusted by the voltage of the transfer bias power supply 44. The density sensor 69 measures the density by irradiating the image on the transfer belt 64 with infrared rays and measuring the amount of reflected light, and is connected so as to output a signal to the printer ASIC 42. On the other hand, the printer ASIC 42 is an IC chip having a function of controlling the printer mechanism 41, so that development data obtained by developing a print job in the job memory 35 into a bitmap image for each page is printed on the paper P. The printer mechanism 41 is controlled.

  Next, the scanner 70 will be described in detail. As shown in FIG. 4, the scanner 70 includes a scanner controller 75 that controls the entire scanner 70, and a scanner unit 80 that scans a document and reads it as image data.

  As shown in FIG. 4, the scanner controller 75 is configured as a microprocessor centered on the CPU 76, and stores a ROM 77 that stores various processing programs and the like, and temporarily stores data and saves data. RAM 78 is provided. The scanner controller 75 is electrically connected to the scanner ASIC 82 via the bus 79, outputs a scan command signal to the scanner ASIC 82, and inputs a scan operation signal from the scanner ASIC 82. The scanner controller 75 is electrically connected to the printer controller 30 and the operation panel 90 via the input / output port 74. That is, the scanner controller 75 outputs image data read by the scanner unit 80 to the printer controller 30, outputs a display command signal to the operation panel 90 to the operation panel 90, and various commands from the operation panel 90. Input signals.

  The scanner unit 80 includes a scanner mechanism 81 and a scanner ASIC 82. As shown in FIG. 5, the scanner mechanism 81 is configured as a general flatbed type image scanner, and a glass table 83 for setting a document so that an image to be scanned faces downward, and a document set on the glass table 83. And an exposure lamp 84 for irradiating light, and a color CCD sensor 85 for receiving reflected light reflected from the original and converting it into an electrical signal. When a scan command signal is input to the scanner ASIC 82, the exposure lamp 84 emits light, and guides and irradiates the original on the glass table 83 while making the light uniform. At this time, the color CCD sensor 85 reads the reflected light reflected by the document and converts it into digital data. This data is transmitted from the color CCD sensor 85 to the scanner ASIC 82 and stored in a predetermined area of the RAM 78 of the scanner controller 75.

  Next, the operation panel 90 will be described. As shown in FIG. 5, the operation panel 90 displays various input buttons 91 such as numeric keys and cursor keys that allow the user to input instructions to the color laser printer 20 and the scanner 70, and characters and numbers associated with key operations. And a liquid crystal screen 92 for displaying the processing status in the printer controller 30, the printer unit 40, the scanner controller 75, and the scanner unit 80, and setting the print density manually. Among these, the various input buttons 91 include a copy start switch 93 for starting copying, a scan start switch 94 for starting scanning, an information leakage prevention mode setting button 95 for setting an information leakage prevention mode, and an image in color. A print mode selection button 96 for selecting a color mode for printing or a monochrome mode for monochrome printing, a scan data transmission button for transmitting image data read by the scanner 70 to the computers 51 to 53, and the like are provided. Here, in the information leakage prevention mode, the setting can be changed only when the ID and password stored in the ROM 32 match the ID and password entered by the operator using the operation panel 90. It has become. Therefore, the information leakage prevention mode can be set and canceled only by a specific operator who knows the ID and password (for example, the administrator of the digital multifunction peripheral 10). When the information leakage prevention mode setting is canceled, the normal mode is set. When the print density is manually set on the liquid crystal screen 92, the liquid crystal screen 92 has a plurality of levels L (−2), L (−1), L (0), L (+1), and L (+2). A print density setting screen 98 to be selected by touching either of them is displayed. Among these, level L (0) is a recommended density, and when setting a density higher than this recommended density, either level L (+1) or L (+2) is selected. The density increases in this order. Further, when the density is set lower than the recommended density, either level L (-1) or L (-2) is selected. The density decreases in this order. The level selected by the operator on the print density setting screen 98 is stored as a print density level in the RAM 33. However, if no level is selected by the operator, the recommended level L (0) is automatically printed. Stored as a density level.

  Next, as an operation of the digital multi-function peripheral 10 of this embodiment configured as described above, a procedure for automatically executing density adjustment will be described first. The CPU 31 of the printer controller 30 reads and starts an automatic density adjustment routine stored in the ROM 32 at a predetermined timing (for example, every few seconds). FIG. 6 is a flowchart of an automatic density adjustment routine. When this automatic density adjustment routine is started, the CPU 31 first determines whether or not a predetermined interval has elapsed since the previous automatic density adjustment was executed (step S200). Incidentally, it is known that the printing density of the digital multi-function peripheral 10 varies depending on various conditions such as the environment in which it is used and the number of printed sheets. Therefore, by continuously using the digital MFP 10 in an experimentally harsh environment, the printing density is forcibly changed, and the degree to which the color tone obtained with use time deviates from the original correct color tone is investigated. An allowable density range that can be equated with the original correct color tone is determined, and an interval period is set so that automatic density adjustment is started before the allowable density range is exceeded. In the present embodiment, the interval period includes a default time Td used during normal printing and a shortened time Ts (<Td) used during tint block printing. This is because the permissible density range in the background pattern printing is narrower than that in the normal printing. This point will be described later. By the way, when the predetermined interval period has not elapsed since the time when the previous automatic density adjustment was executed in step S200, this routine is ended as it is, and the predetermined interval period has elapsed since the previous automatic density adjustment was executed. If this happens, the printer ASIC 42 is instructed to execute automatic density adjustment (step S210), and then this routine is terminated. The automatic density adjustment may be abbreviated as AIDC (Auto Image Density Control).

  Here, automatic density adjustment will be described. In the automatic density adjustment, a solid image (also referred to as a patch) for detecting each color density is experimentally formed on the transfer belt 64, and the density is automatically detected by the density sensor 69. This is a process performed to form an original color image by feeding back to image forming conditions such as exposure amount and developing bias. One of the automatic density adjustments is control for optimizing the developing bias in order to obtain a desired density. Usually, the relationship between the developing bias and the density shows a tendency that the density increases as the developing bias increases, but the tendency is easily changed by the influence of environmental changes such as the number of printed sheets, temperature, and humidity. Therefore, a patch corresponding to each development bias is created on the transfer belt 64 by performing exposure and development for each of the multistage development biases determined in advance for each color, and the density sensor 69 detects the density of each patch. Then, a characteristic representing the relationship between the developing bias and the density is derived from the detected density. FIG. 7 is an explanatory view showing the situation at this time. On the other hand, in the present embodiment, the reference density C is previously associated with each of the levels L (−2), L (−1), L (0), L (+1), and L (+2) on the print density setting screen 98. (-2), C (-1), C (0), C (+1), and C (+2) are assigned. For this reason, the development bias corresponding to the reference density determined for each level is derived on the basis of the characteristic representing the relationship between the development bias and the density obtained earlier, and the levels L (−2) and L (−1) are derived. ), L (0), L (+1), L (+2) and the corresponding developing bias are stored in the RAM 33 in association with each other. This data is used until the next automatic density adjustment is performed. The patch may be formed on the photoreceptor 63.

  Next, a procedure for printing an image on the paper P will be described as an operation of the digital multi-function peripheral 10 of the present embodiment. In the following description, it is assumed that the print mode selection button 96 is set to the color mode. When the CPU 31 of the printer controller 30 receives a print job from any of the computers 51 to 53 connected via the network or receives a print job from the scanner controller 75, the CPU 31 stores the print job in the job memory 35. The print processing routine stored in the ROM 33 is read and executed. FIG. 8 is a flowchart illustrating an example of a print processing routine.

  When this print processing routine is started, the CPU 31 of the printer controller 30 first determines whether or not the information leakage prevention mode is set by turning on the information leakage prevention mode setting button 95 (step S100). ). Here, the information leakage prevention mode is a mode for determining whether or not to print in addition to the image data a background pattern in which a predetermined mark such as “COPY” appears on the copied material when the printed material is copied. . If the information leakage prevention mode is set in step S100, the automatic density adjustment described above is executed (step S105), and then the interval period of the automatic density adjustment is set to a shortened time Ts shorter than the default time Td (step S110). ), A tint block pattern is read from the ROM 32 (step S115). In the present embodiment, the tint block pattern 100 shown in FIG. The copy-forgery-inhibited pattern 100 includes a camouflage pattern 102 created mainly with dots that are so small as to be ignored by the copying machine, and a specific pattern 104 ("COPY") created mainly with dots having a size that is not ignored by the copying machine. Character). Both patterns 102 and 104 have substantially the same density in appearance by changing the number of dots used and their distribution. However, when this is printed by a copying machine, the camouflage pattern 102 is hardly copied, whereas the specific pattern 104 is almost entirely copied. Therefore, when the copy is viewed, as shown in FIG. The camouflage pattern 102 is close to a solid color, and the character “COPY” appears in the specific pattern 104.

  Subsequently, the CPU 31 of the printer controller 30 develops one page of the print job in the job memory 35 into a bitmap image (step S120), and pattern data in which the tint block pattern read from the ROM 33 is periodically and repeatedly arranged. 1 page is developed into a bitmap image (step S125), and after the two bitmap images are superimposed, the tint block pattern is deleted from the overlapping portions of the image forming areas of both bitmap images (step S130). As a result, an image image in which a copy-forgery-inhibited pattern pattern is periodically and repeatedly arranged in a non-image forming area, that is, a white area of the bitmap image for one page of the print job is completed. The tint block pattern is printed in black. Subsequently, the CPU 31 reads the print density level set by the operator on the print density setting screen 98 (see FIG. 5) from the RAM 33 (step S135), and color-prints the previous image on the paper P at the print density level. A command is output to the printer ASIC 42 so as to do so (step S140). Color printing is performed by the printer ASIC 42 as follows. That is, first, an image for one page is color-separated into four colors of yellow, magenta, cyan, and black. Subsequently, after charging the surface of the photoconductor 63, an electrostatic latent image is formed on the surface of the photoconductor 63 by the exposure device 62 based on the yellow image of the color-separated image image, and the toner cartridge 45Y. The yellow toner supplied from the toner is attached to the electrostatic latent image on the photosensitive member 63 to develop the toner image, and the developed yellow toner image is primarily transferred to the transfer belt 64. The yellow developing bias at this time is the level read in step S135 (any one of the levels L (−2), L (−1), L (0), L (+1), and L (+2) in FIG. 5). However, since the automatic density adjustment is performed in the immediately preceding step S105, the development bias corresponding to each level is optimized so as to have a reference density predetermined for each level. It is in a fresh state. Thereafter, the developing device 61 is sequentially rotated, and charging, exposure, development, and primary transfer are similarly performed for magenta, cyan, and black. When the primary transfer is completed for all colors, the toner of each color is transferred to the transfer belt 64. A four-color toner image is formed by sequentially superimposing the images. Therefore, the superposed toner image on the transfer belt 64 is secondarily transferred to the paper P while transporting the paper P from the paper cassette 65 to the transport unit 66, and the four-color toner images secondarily transferred onto the paper P are fixed to the fixing unit. 68 to melt and fix. As a result, a color image for one page is printed on the paper P. Thereafter, the CPU 31 of the printer controller 30 determines whether or not there are pages to be printed (step S145), and when there are pages to be printed, the processing from step S120 is repeated again to print the pages to be printed. When there is no remaining, the interval of automatic density adjustment is returned to the default time d (step S175), and this print processing routine is terminated.

  As a result, when carrying out copy-forgery-inhibited pattern printing, automatic density adjustment is performed to optimize the density before the start of copy-forgery-inhibited pattern printing, and the interval period for automatic density adjustment is set to the shortened time Ts. Automatic density adjustment is executed every time the shortened time Ts elapses in the automatic density adjustment routine (see FIG. 6) until the end.

  On the other hand, when the information leakage prevention mode is not set in step S100, it is regarded as the normal mode, the interval period of automatic density adjustment is set to the default time Td (step S150), and the print job in the job memory 35 is set. One page is developed into a bitmap image (step S155), and the print density level (levels L (-2), L (-1), L (0), L (+1), L (in FIG. 5) is read from the RAM 33. +2) is read (step S160), and the previously developed bitmap image is color-printed on the paper P (step S165). Note that the value obtained by reading the development bias corresponding to each level from the RAM 33 is used as the development bias. Thereafter, it is determined whether or not there are pages to be printed (step S170). When there are pages to be printed, the processing from step S120 is repeated again. When there are no pages to be printed, this print processing is performed. End the routine.

  Next, the density fluctuation range will be described with reference to FIG. FIG. 10 is a graph showing the relationship between usage time and print density. (A) is a graph when normal printing is performed in the normal mode, and (b) is a graph when tint block printing is performed in the information leakage prevention mode. . The interval for automatic density adjustment is set to the default time Td during normal printing, while it is set to the shortened time Ts (<Td) during tint block printing. For this reason, if normal printing and copy-forgery-inhibited pattern printing are performed under the same operating environment conditions after executing automatic density adjustment, if the initial printing density gradually shifts to the high density side over time, the difference in interval period Immediately before the next automatic density adjustment is executed, the normal printing is shifted to the higher density than the background pattern printing. On the other hand, if the original print density gradually shifts to the low density side as time passes, normal printing will be performed at the time of copy-forgery-inhibited pattern printing just before the next automatic density adjustment is performed due to the difference in the interval period. It will shift to a lower density side. Therefore, the range of print density (density change range) that fluctuates from the end of automatic density adjustment to the next execution of automatic density adjustment is narrower during copy-forgery-inhibited pattern printing than during normal printing. Here, in order to make the specific pattern 104 (characters of “COPY”) appear in the copy when the printed matter with the tint block printed is copied, the copier can clearly distinguish the camouflage pattern 102 and the specific pattern 104 at the time of printing. It is necessary to set the concentration. For this reason, as in the present embodiment, it is preferable that the density fluctuation range is narrower than that in normal printing during tint block printing, in other words, it is preferable to shorten the interval period.

  Next, a case where automatic density adjustment is performed immediately before the background pattern printing and a case where it is performed immediately after the background pattern printing will be described with reference to FIG. FIG. 11 is a graph showing the relationship between usage time and print density. Here, before a large amount of tint block printing is performed in advance, the operator selects various print density levels (levels L (−2), L (−1), L (0), L (FIG. 5) on the print density setting screen 98. +1), L (+2)) is set to the optimum density at which a test pattern of tint block printing is performed, and when the printed material of the test printing is copied by a copying machine, the specific pattern 104, that is, the characters “COPY” appear on the copied material. Assume that the “background pattern printing optimum density” is obtained, and the density is set on the print density setting screen 98 so that the background pattern printing optimum density is obtained. In this embodiment, as shown in FIG. 11A, automatic density adjustment (AIDC) is performed immediately before the copy-forgery-inhibited pattern printing. In this case, since the copy-forgery-inhibited pattern printing test print is performed immediately after the automatic density adjustment, the optimum background pattern printing density is set when a large amount of background pattern printing is started. Even if the density is shifted to the high density side or the low density side due to the above or the like, there is no extremely large shift from the optimum background pattern printing density. For this reason, even if a large amount of tint block printing is performed, a result almost the same as the trial printing can be obtained. On the other hand, unlike the present embodiment, as shown in FIG. 11B, consider a case where automatic density adjustment is performed immediately after the start of tint block printing. In this case, a copy-forgery-inhibited pattern printing trial print is performed immediately before the automatic density adjustment.If the density is shifted to the upper limit on the high density side at the time of the trial printing, the optimum copy-forgery-inhibited pattern printing density is also set including the deviation. Will be. However, since the automatic density adjustment is executed immediately after the trial printing and the deviation is canceled, the density at the time when a large amount of tint block printing is started after the trial printing is already different from the optimum tint block printing density. . In this way, when a large amount of copy-forgery-inhibited pattern printing is started, it has already deviated from the optimum copy-forgery-inhibited pattern printing density. Is extremely large and shifts to the low density side. For this reason, when a large amount of copy-forgery-inhibited pattern printing is performed, the result is different from the trial printing.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The printer mechanism 41 of the present embodiment corresponds to the printing mechanism of the present invention, and the printer controller 30 and the printer ASIC 42 correspond to print control means. In the present embodiment, the operation of the digital multi-function peripheral 10 is described to clarify not only the image printing apparatus of the present invention but also an example of an image printing method.

  According to the digital multi-function peripheral 10 of the present embodiment described in detail above, when a copy-forgery-inhibited pattern printing command is issued, automatic density adjustment is performed before the copy-forgery-inhibited pattern printing is performed, and a development bias that achieves a desired density is obtained. The tint block printing is executed using the developing bias. For this reason, a test copy of copy-forgery-inhibited pattern printing is performed immediately after the automatic density adjustment, and since a high-quality copy-forgery-inhibited pattern print density is set at the time when a large amount of copy-forgery-inhibited pattern printing is started, the density is subsequently increased as the copy-forgery-inhibited pattern print is advanced. Even if it fluctuates, it does not deviate significantly from the density suitable for tint block printing, and the function of the tint block is not greatly impaired. Therefore, a large amount of tint block printing can be appropriately performed using the automatic density adjustment function. In addition, when performing copy-forgery-inhibited pattern printing, the density variation range is narrowed because automatic density adjustment is performed more frequently than in normal printing, so even if a large amount of copy-forgery-inhibited pattern printing is performed, the printed matter with the copy-forgery-inhibited pattern printed is copied. The specific pattern 104 (characters of “COPY”) can be clearly manifested in the copy of the time.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

For example, in the above-described embodiment, the copy-forgery-inhibited pattern pattern 100 in which a predetermined specific pattern 104 (the character “COPY”) appears as a copy-forgery-inhibited pattern is shown as a copy-forgery-inhibited pattern. 12) may be used as the background pattern. The tracking pattern 110 is a dot pattern composed of minute dots. In the present embodiment, the tracking pattern 110 is configured so that three rectangular areas of 3 vertical dots × 8 horizontal dots form a single pattern. In the tracking pattern 110, each rectangular area is capable of displaying two ²⁴ information by the presence or absence of dots for both configured by 24 dots. Of the three areas, the first area 111 represents a device manufacturing company code associated with the name of the company that manufactured the digital multifunction machine 10, and the second area 112 corresponds to the model name of the digital multifunction machine 10. The third area 113 represents an apparatus manufacturing number code associated with the manufacturing number (serial number) of the digital multi-function peripheral 10. When such a trace pattern 110 is used as a copy-forgery-inhibited pattern, in step S125, one page of the pattern data of the trace pattern 110 in which the dot patterns are periodically arranged repeatedly is developed into a bitmap image, and in step S130, printing is performed. The bit map image for one page of the job and the bit map image for one page of the pattern data are superimposed, and the tracking pattern 110 is deleted from the overlapping portions in the image forming areas of both bit map images. As a result, an image image in which the tracking patterns 110 are periodically and repeatedly arranged in a non-image forming area, that is, a white background area in a bitmap image for one page of the print job is completed. In this type of tracking pattern, the embedded information changes depending on whether or not the minute dots are filled. Therefore, a trial printing may be performed to set an appropriate density before performing a large amount of tint block printing. Even in such a case, since the automatic density adjustment is executed immediately before the start of the tint block printing, a large amount of tint block printing can be appropriately performed as in the above-described embodiment.

  In the above-described embodiment, the automatic density adjustment is executed more frequently than in normal printing by setting the interval period during tint block printing to a time shorter than the default time Td in normal printing. When performing a large amount of tint block printing, automatic density adjustment may be performed immediately before printing each page. Normally, the electrophotographic printing mechanism prints in units of pages, so when performing large amounts of copy-forgery-inhibited pattern printing, automatic density adjustment is most frequently performed at the timing immediately before printing each page. The fluctuation range can be further narrowed.

  Furthermore, in the above-described embodiment, automatic density adjustment during tint block printing is performed in the same manner as during normal printing. However, automatic density adjustment during tint block printing is simplified compared to automatic density adjustment during normal printing. Also good. During tint block printing, automatic density adjustment is performed at a high frequency, so the density fluctuation range is narrower than that during normal printing. Therefore, it is often sufficient to adjust the density within the narrow density fluctuation range. It becomes possible to perform density adjustment in a simplified manner. Specifically, when automatic density adjustment is performed using patches with different densities created with multi-level development bias, at least the highest density patch, that is, the patch created with the highest development bias is omitted during tint block printing. May be. This is economical because the toner consumed by the automatic density adjustment is reduced accordingly.

  Furthermore, in the above-described embodiment, the control for optimizing the developing bias is exemplified as the automatic density adjustment, but not only the developing bias but also the control for optimizing the charging bias and the exposure amount may be performed.

  In the above-described embodiment, the default time Td and the shortened time Ts are adopted as the interval period. However, the interval period does not need to be expressed in particular in time, and may be expressed in, for example, the number of printed sheets.

  Furthermore, in the above-described embodiment, the digital multifunction peripheral 10 has been described as an example of the present invention, but the present invention may be a color laser printer 20 in which the scanner 70 is removed from the digital multifunction peripheral 10.

1 is a configuration diagram showing a schematic configuration of a digital multi-function peripheral. 1 is a block diagram showing a schematic configuration of a laser printer in a digital multifunction peripheral. AA sectional drawing of FIG. 1 is a block diagram showing a schematic configuration of a scanner in a digital multi-function peripheral. 1 is a configuration diagram showing in detail a schematic configuration of a scanner in a digital multi-function peripheral. The flowchart of an automatic density adjustment routine. The perspective view when a patch is formed on a transfer belt. 6 is a flowchart of a print processing routine. Explanatory drawing of the copy-forgery-inhibited pattern in a printed matter and a copy. The graph showing the relationship between use time and printing density. The graph showing the relationship between use time and printing density. Explanatory drawing of a tracking pattern.

Explanation of symbols

10 Digital MFP, 20 Color Laser Printer, 30 Printer Controller, 31 CPU, 32 ROM, 33 RAM, 34 Flash Memory, 35 Job Memory, 36 Network Board, 37 I / O Port, 38 Bus, 40 Printer Unit, 41 Printer Mechanism, 42 Printer ASIC, 43 Development bias power supply, 44 Transfer bias power supply, 45C, 45M, 45Y, 45K Toner cartridge, 51, 52, 53 Computer, 59 Discharge port, 61 Developer, 62 Exposure unit, 63 Photoconductor, 64 Transfer belt, 65 paper cassette, 66 transport unit, 67 secondary transfer unit, 68 fixing unit, 69 density sensor, 70 scanner, 74 input / output port, 75 scanner controller, 76 CPU, 77 ROM, 8 RAM, 79 bus, 80 scanner unit, 81 scanner mechanism, 82 scanner ASIC, 83 glass stand, 84 exposure lamp, 85 color CCD sensor, 90 operation panel, 91 input button, 92 LCD screen, 93 copy start switch, 94 scan Start switch, 95 Information leakage prevention mode setting button, 96 Print mode selection button, 98 Print density setting screen, 100 Background pattern, 102 Camouflage pattern, 104 Specific pattern, 110 Tracking pattern, 111 First area, 112 Second area, 113 Third region.

Claims (9)

An electrophotographic printing mechanism that exposes a photoconductor to form an electrostatic latent image, develops the electrostatic latent image with toner, and transfers the toner image to a print medium;
When there is a copy-forgery-inhibited pattern printing command to add a predetermined copy-forgery-inhibited pattern to the background of the image data, before the copy-forgery-inhibited pattern printing is performed, the print mechanism is controlled to perform automatic density adjustment to form an image that has a desired density Print control means for determining the conditions and then controlling the printing mechanism to execute the tint block printing using the image forming conditions;
An image printing apparatus comprising: The predetermined background pattern is one in which a predetermined mark appears on the copied material when the printed material is copied.
The image printing apparatus according to claim 1. The predetermined background pattern is a tracking pattern representing information related to printing.
The image printing apparatus according to claim 1. The print control means develops a plurality of patches having different densities under a plurality of different image forming conditions by controlling the printing mechanism when performing the automatic density adjustment to obtain an image forming condition that achieves the desired density. Measure the density of the developed patch and use the measurement result to determine the image forming conditions that achieve the desired density.
The image printing apparatus according to claim 1. The print control means controls the printing mechanism to execute the automatic density adjustment at a higher frequency when performing the tint block printing than when performing normal printing other than the tint block printing.
The image printing apparatus according to claim 1. When executing the automatic density adjustment at a higher frequency than when performing the normal printing, the printing control means may automatically perform the automatic density adjustment immediately before starting the printing of each page when the tint block printing prints a plurality of pages. Perform density adjustment,
The image printing apparatus according to claim 5. The print control means executes the automatic density adjustment in a simplified manner compared to when performing the normal printing, when executing the automatic density adjustment at a frequency higher than that when performing the normal printing.
The image printing apparatus according to claim 5 or 6. The photosensitive member is exposed to form an electrostatic latent image, and the electrostatic latent image is developed with toner to form a toner image, and an electrophotographic printing mechanism that transfers the toner image to a printing medium is controlled to perform image printing. An image printing method using computer software,
(A) When there is a copy-forgery-inhibited pattern print command for printing a predetermined copy-forgery-inhibited pattern in addition to the background of the image data, the print mechanism is controlled to perform automatic density adjustment before executing the copy-forgery-inhibited pattern printing to obtain a desired density Obtaining image forming conditions,
(B) controlling the printing mechanism to execute the copy-forgery-inhibited pattern printing using the image forming conditions obtained in step (a);
An image printing method including:   The program for making one or more computers perform each step of the image printing method of Claim 8.

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