JP2004219929A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that can determine continuity of target pixels and neighboring pixels in an array comprising a plurality of low-resolution image data to reduce printing dots, and can reduce the printing dots based on the determination results of the continuity. <P>SOLUTION: The continuity of the target pixels and neighboring pixels is determined by entering the target pixels Dc22 and neighboring pixels Dc11 to 13, 21, 23, 31-33 into AND gates 65a to 65h among data arrays Dc11 to 33 of main scanning direction × sub scanning direction = three pixels × three lines, which are created in a data delay part 50. When the data array of three pixels × three lines created at the data delay part 50 is a pattern as shown in Fig.9(1), pattern determination results Dd1a to 8a which are obtained by entering the target pixels Dc22 (black pixels) and neighboring pixels Dc11 to 13, 21, 23, 31-33 into the AND gates 65a to 65h are shown in Fig.9(2). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus that achieves both print quality and toner saving.
[0002]
[Prior art]
2. Description of the Related Art In recent years, apparatuses equipped with various modes (for example, energy saving mode) have been provided in copiers, printers, and the like in consideration of the global environment. Further, a toner save mode for reducing consumed toner has also been widely used.
On the other hand, as digital copiers have become printers, it is necessary to support low-resolution to high-resolution inputs for output from personal computers. At this time, the input needs to correspond to a resolution of about 100 dpi to 1200 dpi, and the output resolution is 1200 dpi, so it is necessary to perform density conversion.
In this case, when the density conversion and the toner save are combined, the usual method is to apply the toner save to the image after the density conversion.
There are the following technologies related to the conventional toner save mode.
[Patent Document 1]
JP-A-09-325655
[Patent Document 2]
JP-A-08-123257
[Patent Document 3]
JP-A-09-030042
[0003]
As a conventional technique relating to the toner save mode, there is a technique disclosed in Patent Document 1 in addition to a technique of superimposing a specific black and white pattern of nxn pixels and image data to unconditionally mask a portion corresponding to white. It has been proposed to reduce the print density by forcibly setting a specific bit to 0 in a plurality of bits of input data in the toner save mode. In particular, by lowering the print density by setting the lower half of the half bit or the upper half of the bit to 0, it prevents the print quality from being unconditionally masked and whitened. It has been proposed.
Further, in the technique disclosed in Patent Document 2, the print quality of one dot is unconditionally narrowed in several steps in the toner save mode, and unconditionally masked to white to reduce the deterioration of print quality. It is preventing.
Further, in the technique disclosed in Patent Document 3, a point at which an image changes from white to black is used as an edge portion of the image, and toner save processing is prohibited from there for a certain period of time. It has been proposed to obtain a toner saving effect while improving printing quality by preventing toner saving.
[0004]
[Problems to be solved by the invention]
However, the techniques disclosed in Patent Documents 1 to 3 are techniques for preventing the disappearance of one dot line when there is no density conversion, and do not consider the case where image data is increased by density conversion. Therefore, in such a case, there is a problem that the print quality is deteriorated when the toner save is performed.
[0005]
Therefore, a first object of the present invention is to determine the continuity of a target pixel and peripheral pixels in an array composed of a plurality of low-resolution image data to reduce print dots when the toner save mode is set, An object of the present invention is to provide an image forming apparatus capable of obtaining high-quality printing quality while reducing toner consumption by reducing the number of printing dots based on the result of the continuity determination.
A second object of the present invention is to determine the direction of high-resolution image data as a print pixel so as to maintain continuity in a direction in which images are determined to be continuous, and determine that images are not continuous. An object of the present invention is to provide an image forming apparatus capable of obtaining high-quality printing quality while reducing toner consumption by setting the direction of high-resolution image data as a non-printing pixel.
A third object of the present invention is that when the arrangement of a target pixel and a peripheral pixel of an array composed of a plurality of low-resolution image data matches a specific pattern, both the target pixel and the peripheral pixel are not print pixels but have continuity. An object of the present invention is to provide an image forming apparatus capable of obtaining higher quality print quality while reducing toner consumption by using a specific portion of high resolution image data as a print pixel.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, an image forming unit that forms an image on a predetermined sheet based on the acquired image data, and when the image forming unit forms an image, the image forming unit performs the image formation in a normal mode or a toner consumption amount. Mode specifying means for specifying whether or not to perform the operation in the toner save mode for reducing image density, and density conversion for generating high-resolution image data by increasing low-resolution image data by m × n times (m and n are integers of 2 or more) Means, an array generating means for generating an array composed of a plurality of low-resolution image data, and continuity of the pixel of interest and peripheral pixels and a data array from the array of image data generated by the array generating means having a specific pattern. A pattern determination unit that determines whether or not the image data is density-converted by the density conversion unit, and the continuity or specificity of a target pixel and a peripheral pixel determined by the pattern determination unit. A toner saving unit that generates high-resolution image data in which the amount of data to be printed is reduced based on a result of the determination as to whether or not the pattern matches the turn. The first object is achieved by the image forming unit forming an image using image data in which the amount of data to be printed by the toner saving unit is reduced.
[0007]
According to a second aspect of the present invention, in the first aspect of the present invention, the pattern determining unit includes a target pixel and a peripheral pixel of an array composed of a plurality of low-resolution image data before density conversion generated by the array generating unit. By determining the relationship, when both the target pixel and the peripheral pixel are print pixels, it is determined that the image is continuous in the direction of the peripheral pixel, and either the target pixel or the peripheral pixel is a non-print pixel In this case, it is determined that there is no continuity in the image, and in the direction in which the image is determined to be continuous, high-resolution image data in that direction is used as a print pixel so as to maintain continuity, and the image is not continuous. The second object is achieved by setting high-resolution image data in that direction as non-printing pixels.
[0008]
According to a third aspect of the present invention, in the first aspect of the present invention, the pattern determination unit includes a target pixel and a peripheral pixel of an array composed of a plurality of low-resolution image data before density conversion generated by the array generation unit. When the relationship is determined and the arrangement of the target pixel and the peripheral pixels matches a specific pattern, the third object is achieved by setting a specific portion of the high-resolution image data as a print pixel.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a diagram illustrating the appearance of a digital copying machine as an embodiment of an image forming apparatus. The digital copying machine 1 includes a main body 10, a mass paper feeding device (hereinafter, LCT) 11, and a finisher 12 for performing sorting, punching, stapling, and the like. An apparatus (hereinafter referred to as an ADF) 13 and an operation unit 14 for performing a reading mode, setting of a copy magnification, setting of a paper feed stage, setting of post-processing by the finisher 12, display to an operator, and the like are provided.
Further, the lower side of the main body 10 and the LCT 11 have paper feed units 15 and 16, and the finisher 12 has a paper discharge unit 17. The interior of the digital copying machine 1 incorporates well-known mechanisms and control devices of the digital copying machine, such as an exposure optical system, a paper feeding and conveying system, a developing system, a fixing system, and a paper discharging system, thereby realizing the operation as a copying machine. are doing.
[0010]
That is, by placing a document on the ADF 13 and pressing a copy start key on the operation unit 14, the document is supplied onto a contact glass (not shown) below the ADF 13, and the document is illuminated by an illumination system (not shown). Read by optical system. Then, after performing various corrections and processing on the read image data, a writing system irradiates a beam with a laser diode based on the image data and forms an electrostatic latent image on a photosensitive member (not shown).
Thereafter, through a so-called electrophotographic process, a copy image is formed on a sheet fed from the sheet feeding unit 15 or 16 instructed by the operation unit 14, and post-processing such as sorting, punching, and stapling is performed by the finisher 12. Then, the paper is discharged to the paper discharge unit 17. The digital copying machine 1 also has a printer function, and can receive image data from a host computer (not shown) via a network (not shown) and perform image formation in the same manner.
[0011]
FIG. 2 is a block diagram related to the image data processing portion of the digital copying machine 1.
As image data at the time of copying, the reading processing unit 10 performs various corrections such as shading correction on image data read at 600 dpi by a CCD line sensor (not shown), and performs 8-bit (256 gradations) per pixel as image data Da. To output to the image processing unit 20. The image processing section 20 performs image quality correction by performing MTF correction, scaling processing, and the like, converts the data into 1-bit (two-gradation) data Db, and outputs the data to the writing processing section 30.
The image data at the time of printing includes print data Dn input from a personal computer (not shown) via a network or the like. The print data Dn is 1 bit (two gradations) and has a resolution of 150, 200, 300, 400, or 400. There are various cases such as 600 dpi and 1200 dpi. The image processing unit 20 basically does not perform any image quality correction processing, only performs format conversion so as to be able to interface with the writing processing unit 30, and reads and processes the data read and processed by the reading processing unit 10. The mode is switched between the copy mode and the print mode and output as image data Db.
[0012]
In the write processing unit 30, the image data Db is increased by m × n times (m and n are maximum 8) in the main scanning direction and the sub-scanning direction in accordance with the writing density by the density conversion unit 80 to obtain Df, and is further increased. Then, a 3-bit signal Dh indicating the main scanning position of the pixel and a 3-bit signal Dv indicating the sub-scanning position are generated. The image data Db is delayed in the main scanning direction and the sub-scanning direction by the data delay unit 50 to form a data array Dc11-33 of (main scanning direction × sub-scanning direction) = 3 × 3 pixels, and the image data Dc11 To 33 are output to the pattern determination unit 60.
The pattern determination unit 60 determines continuity from the density of the target pixel Dc22 and the densities of the peripheral pixels Dc11 to 13, 21, 23, and 31 to 33, and also determines the continuity of the target pixel Dc22 and the peripheral pixels Dc11 to 13, 21, 23, and It is determined whether or not the arrangement of 31 to 33 matches a specific pattern, and pattern data Dd1 to Dd8 are output.
[0013]
The pattern data Dd1 to Dd8 are input to the data thinning section 40, and when the toner save mode is designated as a printing condition from a personal computer (not shown), the image data Df subjected to density conversion by the density conversion section 80 and the positions of pixels are indicated. By combining with the signals Dh and Dv, the data is thinned out and output as the light emission data De. Then, by writing a laser diode (not shown) based on the light emission data De, writing to a photoconductor (not shown) is performed at 1200 dpi.
The control unit 70 is connected to the operation unit 14 and a personal computer (not shown). During a copy operation, the reading processing unit 10 performs image processing based on a mode setting for reading a document set on the operation unit 14 and a toner save mode. The image processing unit 20 and the writing processing unit 30 are controlled by a command from a personal computer (not shown) during printing.
The reading processing unit 10, the image processing unit 20, and a personal computer (not shown) and a network for connecting the personal computer are well-known technologies, and are not special features in the present invention.
[0014]
Next, an image control signal between the image processing unit 20 and the writing processing unit 30 will be described with reference to FIG.
The image control signals include XLSYNC, which is a synchronization signal in the main scanning direction of the image, XLGATE, which indicates an image valid period in the main scanning direction, XFGATE, which indicates an image valid period in the sub-scanning direction, and CLK which synchronizes image data. There is. The image data Db is synchronized for each line by XLSYNC, and is output from the image processing unit 20 in synchronization with the pixel clock CLK while XFGATE and XLGATE are at “L” level.
[0015]
FIG. 16 shows an embodiment of the density converter 80, and FIG. 17 shows a timing chart for explaining the operation. Hereinafter, the operation of the density conversion unit 80 will be described with reference to these drawings.
The density converter 80 changes the speed of a write clock and a read clock of a first-in-first-out RAM (hereinafter, FIFO) to convert data output from the image processor 20 at low density into high-density data. In the main scanning direction and the sub-scanning direction in accordance with the scanning processing unit 30. In this embodiment, a case where 600 dpi data is input as the image data Db is shown. In this case, the write processing unit 30 needs to double the data in both the main scanning direction and the sub-scanning direction in order to write at 1200 dpi.
[0016]
The output image data Db of the image processing unit 20 is input to the FIFOs 81 and 82 and is written in synchronization with the write clock CLK while the write enable signal WEB is at “L” level, and the read enable signal REB is set to “L”. The signal is read out in synchronization with the read clock RCK during the “level” period. The write enable signal WEB and the read enable signal REB are generated from toggle signals which are alternately inverted by XLSYNC which is a synchronization signal in the main scanning direction. The toggle signal is transmitted to the FIFO 81 via the WEB, and the toggle signal is transmitted via the inverter 83. The inverted signal is referred to as REB, and the inverted signal of the toggle signal for the FIFO 82 is referred to as WEB, and the toggle signal is referred to as REB, so that the FIFOs 81 and 82 are switched to the write / read mode by toggle.
[0017]
In addition, by setting the write / reset signal WRST to be XLSYNC and the read / reset signal to be XLSYNC2 having a half cycle of XLSYNC, the same data is read twice in one cycle of XLDSYNC to double the data amount in the sub-scanning direction. ing. At this time, a signal that counts up in synchronization with XLSYNC2 is output as a signal Dv that indicates the position of the doubled data in the sub-scanning direction.
In FIG. 17, the data amount at the time of writing per line differs from the data amount at the time of reading because the period of the write clock is different from the period of the read clock. This is faster than the cycle of the write clock, and the FIFOs 81 and 82 also fulfill the role of speed conversion.
[0018]
Each output data DO of the FIFOs 81 and 82 is input to the selector 84, and the output of the FIFO performing the read operation is selected by the toggle signal and output from the selector 84.
The output data from the FIFOs 81 and 82 switched and output by the selector 84 is further latched by a flip-flop (FF) at RCK2 having a frequency twice as high as that of the read clock CLK, so that the data changes every two clocks of RCK2. The density conversion is realized by doubling the data amount in the main scanning direction.
In addition, it also outputs a pixel position signal Dh indicating the pixel position in the main scanning direction whether the doubled data is the first data or the second data.
When it is desired to increase by three times in the main scanning direction and the sub-scanning direction, instead of XLSYNC2, XLSYNC3 having a cycle of 1/3 of XLSYNC is used as the read reset signal RRST, and the read clock RCK is set to be three times the write clock CLK. What is necessary is just to use the frequency clock RCK3.
[0019]
FIG. 3 shows an embodiment of the data delay unit 50, and FIG. 4 shows a timing chart for explaining the operation. Hereinafter, the operation of the data delay unit 50 will be described with reference to FIGS.
The data delay unit 50 delays the data Db output from the image processing unit 20 line by line in synchronization with XLSYNC using a FIFO, and further delays the data of each line in pixel units in synchronization with a clock. A data array of 3 pixels in the scanning direction × 3 pixels in the sub-scanning direction is generated.
The data Db output from the image processing unit 20 is input to the FIFO 51. In the FIFO 51, XLSYNC is used for both the write reset signal WRST and the read reset signal RRST, XLGATE is used for both the write enable signal WEB and the read enable signal REB, and CLK is used for both the write clock signal WCK and the read clock signal RCK. Can be obtained.
[0020]
The data Db1 delayed by one line is further delayed similarly by one line in the FIFO 52 to become data Db2 delayed by two lines. The data Db is combined to obtain three lines of data at the same time. By inputting the data Db, Db1 and Db2 to the F / Fs 53a to 53c, the outputs Dc13, 23 and 33 of the F / Fs 53a to c become data obtained by delaying the image data Db, Db1 and Db2 by one clock. The data is further delayed by the F / Fs 54a to 54c and the F / Fs 55a to 55c in synchronization with the clock CLK.
Thus, image data Dc12, 22, 32, Dc11, 21, 31 are obtained, and a 3 × 3 matrix is formed by Dc11 to Dc33. Then, these image data are output to the pattern determination unit 60 and used for the determination by the pattern determination unit 60. At this time, Dc22 becomes a target pixel, and Dc11 to 13, 21, 23, and 31 to 33 become peripheral pixels.
[0021]
FIG. 6 shows a block of the pattern determination unit 60. Hereinafter, the operation of the pattern determination unit 60 will be described with reference to FIG.
The pattern judging section 60 includes a basic pattern judging section 61 and a special pattern judging section 62. In the basic pattern judging section, a data array of main scanning direction × sub-scanning direction = 3 pixels × 3 lines created by the data delaying section 50 is used. The continuity is determined by looking at a combination of the target pixel Dc22 and Dc11-13, 21, 23, and 31-33 of each peripheral pixel among the Dc11-33, and it is determined that the continuity is determined by the data thinning unit 40 at the subsequent stage. The determined direction is a print pixel, and the direction determined not to be continuous is a non-print pixel.
[0022]
The special pattern determination unit 62 determines whether or not the combination of the target pixel Dc22 and Dc11 to 13, 21, 23, and 31 to 33 of each peripheral pixel matches a specific pattern. Then, when they match, a specific portion having a determination result according to the matched pattern is set as a print pixel regardless of the continuity determined by the basic pattern determination unit 61. Then, the pattern determination results Dd1a to Dd8a of the basic pattern determination unit 61 and the pattern determination results Dd1b to Dd8b of the special pattern determination unit 62 are ORed by the OR gate 63. It is a printing pixel.
[0023]
FIG. 8 shows an example of the configuration of the basic pattern determination section 61. Hereinafter, the operation of the basic pattern determination unit 61 will be described with reference to FIG.
Of the data array Dc11-33 of the main scanning direction × the sub-scanning direction = 3 pixels × 3 lines created by the data delay unit 50, the target pixel Dc22 and Dc11-13, 21,23,31-33 of each peripheral pixel are stored. The continuity of the target pixel and the peripheral pixels is determined by inputting the signals to the AND gates 65a to 65h, respectively.
That is, when the two pixels are both at the “H” level (black pixel), it is determined that they are continuous, and the pattern determination result is set to the “H” level, and at least one of the pixels is at the “L” level (white pixel). In this case, it is determined that they are not continuous, and the pattern determination result is set to the “L” level. In particular, when the target pixel Dc22 is at the "L" level (white pixel), no thinning data is generated in the toner save mode, so that the pattern determination results Dd1a to Dd1a to 8a are set to the "L" level regardless of the peripheral pixels.
[0024]
Therefore, when the data array of 3 pixels × 3 lines created by the data delay unit 50 has a pattern as shown in FIG. 9A, the target pixel Dc22 (black pixel) and the peripheral pixels Dc11 to 13, 21, and 23 are provided. , 31-33 to the AND gates 65a-h, the pattern determination results Dd1a-8a obtained as shown in FIG. 9 (2).
[0025]
Next, the special pattern determination unit 62 will be described.
The special pattern determination unit 62 prepares a pattern shown in FIG. 13 as a special pattern. FIGS. 13 (1) to 13 (4) show a case where only one side of the peripheral pixel is a print pixel, and FIGS. 13 (5) to 13 (8) show a case where print pixels are arranged so as to surround each corner. ing. FIG. 14 shows which part of the pattern determination results Dd1b to 8b is forcibly set as a print pixel when the special patterns (1) to (8) shown in FIG. 13 are applied. .
Then, when the pattern matches the pattern (1) or (3) in FIG. 13, the pattern determination results Dd4 and D5 are determined as print pixels regardless of continuity, and when the pattern matches the pattern (5) in FIG. Indicates that the pattern determination result Dd1b is a print pixel regardless of continuity.
[0026]
FIG. 7 shows an example of the configuration of the special pattern determination section 62 for the patterns (1), (3), and (5) of FIG. Hereinafter, the special pattern determination unit 62 will be further described with reference to FIG.
The decision circuit corresponding to the pattern shown in (1) and (3) of FIG. 13 is constituted by AND gates 66a and 66b and the OR gate 67, and is constituted by the AND gate 68. 13 is a determination circuit corresponding to the pattern shown in (5).
[0027]
In the AND gate 66a, of the data array Dc11-33 of the main scanning direction × sub-scanning direction = 3 pixels × 3 lines created by the data delay section 50, the target pixel Dc22 and the peripheral pixels Dc11-13 are directly used as Dc21. , 23, 31-33 are inverted and input, so that the outputs Dd4c and Dd5c are at "H" level when the data array matches the pattern of FIG. Similarly, in the AND gate 66b, when the data array matches the pattern of FIG. 13C, the outputs Dd4d and Dd5d become "H" level.
[0028]
Then, since the outputs of the AND gates 66a and 66b are ORed by the OR gate 67, the Dd4b and Dd5b of the output of the OR gate 67 become "H" level when they finally match one of the patterns.
Further, since Dc12, Dc21, and Dc22 are inputted as they are to the AND gate 68, the output Dd1b becomes “D” when all three pixels are print pixels irrespective of other pixels as shown in the pattern of FIG. H "level.
By forming circuits in the same manner for the other patterns in FIG. 13, an "H" level can be output when the patterns match.
[0029]
FIG. 10 shows an embodiment of the data thinning section 40. Hereinafter, the operation of the data thinning unit 40 will be described with reference to FIG.
In the data thinning section 40, Dd 1 to Dd 8 as a result of determining whether the pixel continuity determined by the pattern determining section 60 matches the specific pattern, the image data Df subjected to density conversion by the density converting section 80, Image data De for performing toner save in the toner save mode is generated based on the signals Dh and Dv indicating the image positions of the main scan and the sub scan after the conversion, the toner save mode setting signal, and the double density setting signal.
The data thinning section 40 is composed of the combination circuits 41a to 41h and a selector 42 for switching the output of the combination circuits 41a to 41h according to the double density setting. It is possible to switch between printing and non-printing based on the determination results Dd1 to Dd8 of the continuity of the target pixel and peripheral pixels determined by the pattern determination unit 60 on the data Df.
[0030]
That is, when the pattern determination results Dd1 to Dd8 are “H”, the peripheral pixels Dc11 to Dc13, Dc21, Dc23, and Dc31 to Dc33 corresponding to the target pixel Dc22 and Dd1 to Dd8 are all continuous black pixels, or Since the pattern matches the specific pattern, in this case, the outputs of the corresponding combinational circuits 41a to 41h are set to the "H" level (printing) in order to maintain continuity.
Conversely, when the pattern determination results Dd1 to Dd8 are "L", they are not continuous, or when the target pixel is white, they are set to "L" level (no printing). When the toner save mode is not set, the image data Df is output without any processing.
In the selector 42, the outputs Dg1 to Dg8 of the combination circuits 41a to h and the data Df subjected to the density conversion processing are switched and output according to the pixel position signals Dh and Dv in the main scanning / sub-scanning direction after the double density setting or the double density.
[0031]
FIG. 11 shows pixel positions at 2, 3, 4, 6, and 8 times higher density and the output of the selected combinational circuit. As shown in FIG. 11, as for the data after the density conversion and the thinning-out, the data Df subjected to the density conversion processing is output as it is in the vicinity of the center except when the double is set.
For the peripheral pixels, the outputs Dg1 to Dg8 processed by the combination circuits 41a to h based on Dd1 to D8 obtained by determining the continuity of the peripheral pixel corresponding to the position and the pixel of interest by the pattern determination unit 60. Switch to output.
That is, in the direction in which the pattern determination unit 60 determines that there is continuity, in order to maintain continuity, the pixel is not replaced with a non-printing pixel for toner saving, but remains as a printing pixel. On the other hand, by replacing the non-continuous pixels with the non-printing pixels in the direction determined to have no continuity, it is possible to perform toner saving while maintaining good printing quality.
Then, an image is formed based on the image data thinned out by the data thinning unit 40.
[0032]
Next, effects of the embodiment will be described using actual images.
12 and 15 are diagrams for explaining the effect of the present embodiment, and show a case where the toner save mode is performed on the input data of FIG.
12B and FIG. 15A, an image obtained by three-fold density conversion of the portion enclosed by squares in both the main scanning and the sub-scanning is shown in FIG. (E) shows a thinning-out pattern when image data is masked with a specific black-and-white pattern according to the related art. In this example, the amount of toner consumption is suppressed to about 70% (11/16) with the size of 4 × 4 pixels (repetition in □).
[0033]
The result of thinning out the image data of (b) by the thinning pattern of (e) is (f). In such a case where thinning is performed in a fixed pattern, continuity of image data and the like are not taken into consideration, so that toner consumption can be reduced, but printing quality is obviously degraded.
On the other hand, when the toner saving is performed by using the method of the present embodiment in consideration of the continuity between the target pixel and the adjacent pixel using the basic pattern, the result of (c) is obtained. In consideration of the above, the thinning is performed, so that the toner consumption can be reduced. In addition, deterioration of print quality can be reduced. Further, the result of adding the determination result based on the special pattern becomes (d), and as shown in the figure, it is possible to suppress white spots in the line generated in FIG. In this case, it is possible to prevent the solid portion from being removed or to remove the corner portion of the end portion, and the effect of lowering the toner consumption is slightly reduced, but higher printing quality can be obtained.
[0034]
Whether to perform thinning in the data thinning unit 40 using the determination result of the special pattern determination unit 62 in addition to the determination result of the basic pattern determination unit 61 is switched by, for example, designating the degree of reduction in toner consumption. You may. That is, when priority is given to the reduction of the toner consumption, the data thinning unit 40 thins out using only the determination result of the basic pattern determining unit 61. On the other hand, when the reduction of the toner consumption is not the highest priority, higher print quality can be obtained by using the determination result of the special pattern determination unit 62.
As described above, in the present method, when the toner save mode is applied to the image data subjected to the density conversion, the output of the image processing unit 20 outputs a 3 × 3 array of the image before the density conversion by the data delay unit 50. And the pattern determining unit 60 determines whether the continuity of the target pixel and the peripheral pixels and the specific pattern match, and based on the result, the data thinning unit 40 performs density conversion in the density converting unit 80. Since the image data is switched between performing and not performing the thinning of the image data, high printing quality can be obtained without impairing the continuity of the image while effectively reducing the toner consumption.
[0035]
【The invention's effect】
According to the first aspect of the present invention, when the toner save mode is set, in order to reduce the number of print dots, the continuity between the target pixel and the peripheral pixels in the array composed of a plurality of low-resolution image data and the specific pattern match. By judging whether or not the printing is performed, and reducing the number of printing dots based on the judgment result, it is possible to obtain high-quality printing quality while reducing toner consumption.
According to the second aspect of the present invention, when both the target pixel and the peripheral pixel in the array composed of a plurality of low-resolution image data are print dots, it is determined that they are continuous in that direction, and one of the target pixel and the peripheral pixel is determined. If it is a non-print dot, it is determined that the image is not continuous, and the direction of the high resolution image data is set as a print pixel so as to maintain continuity in the direction determined to be continuous. By setting the direction of high-resolution image data as a non-printing pixel in the direction determined not to exist, it is possible to obtain high-quality printing quality while reducing toner consumption.
[0036]
According to the third aspect of the present invention, when the arrangement of the target pixel and the peripheral pixels of the array composed of a plurality of low-resolution image data matches a specific pattern, both the target pixel and the peripheral pixels are not print pixels but have continuity. Even if it is not necessary, a specific portion of the high-resolution image data is not a non-printing pixel but a printing pixel, so that it is possible to obtain higher quality printing quality while reducing toner consumption.
[Brief description of the drawings]
FIG. 1 is a diagram showing the appearance of a digital copying machine as an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a block diagram related to an image data processing unit of the digital copying machine.
FIG. 3 is a diagram illustrating an embodiment of a data delay unit.
FIG. 4 is a diagram showing a timing chart for explaining an operation;
FIG. 5 is a diagram illustrating an image control signal between an image processing unit and a writing processing unit.
FIG. 6 is a block diagram illustrating a configuration of a pattern determination unit.
FIG. 7 is a diagram illustrating a special pattern determination unit.
FIG. 8 is a diagram illustrating an example of a configuration of a basic pattern determination unit.
9A is a diagram illustrating a 3 × 3 input image array, and FIG. 9B is a diagram illustrating a pattern determination result.
FIG. 10 is a diagram illustrating an example of a data thinning unit.
FIG. 11 is a diagram illustrating pixel positions at 2, 3, 4, 6, and 8 times the density and outputs of a selected combinational circuit.
FIG. 12 is a diagram illustrating an output effect according to the present embodiment.
FIG. 13 is a diagram showing a 3 × 3 input image array of a special pattern.
FIG. 14 is a diagram showing a pattern determination result of a special pattern.
FIG. 15 is a diagram illustrating an output effect according to the present embodiment.
FIG. 16 is a diagram illustrating an example of a density conversion unit.
FIG. 17 is a diagram showing a timing chart for explaining the operation of this embodiment.
[Explanation of symbols]
10 Main unit (read processing unit)
20 Image processing unit
30 Write processing unit
40 Data thinning unit
50 Data delay section
60 pattern judgment unit
70 control unit
80 Density converter

Claims (3)

Image forming means for forming an image on a predetermined sheet based on the acquired image data,
A mode designating unit for designating whether to perform image formation in the image forming unit in a normal mode or in a toner save mode for reducing toner consumption;
Density conversion means for increasing low-resolution image data by m × n times (m and n are integers of 2 or more) to generate high-resolution image data;
Array generating means for generating an array composed of a plurality of low-resolution image data;
Pattern determination means for determining whether the continuity of the pixel of interest and peripheral pixels or the data array matches a specific pattern from the array of image data generated by the array generation means,
Reduce the amount of data to be printed based on the image data subjected to density conversion by the density conversion unit and the continuity of the target pixel and peripheral pixels determined by the pattern determination unit and the determination result as to whether or not they match a specific pattern. And a toner saving means for generating high-resolution image data.
An image forming apparatus, wherein when the toner saving mode is designated by the mode designating means, the image forming means forms an image using image data in which the amount of data to be printed is reduced by the toner saving means. The pattern determination unit determines the relationship between the target pixel and the peripheral pixels in an array composed of a plurality of low-resolution image data before density conversion generated by the array generation unit, and both the target pixel and the peripheral pixels are print pixels. At some point, it is determined that the image is continuous in the direction of the surrounding pixels, and if either the pixel of interest or the surrounding pixel is a non-printing pixel, it is determined that the image is not continuous, and the image is continuous. For the direction determined to be continuous, the high-resolution image data in that direction is used as the print pixel so as to preserve continuity, and for the direction determined to be non-continuous, the high-resolution image data in that direction is not used. The image forming apparatus according to claim 1, wherein the image forming apparatus is a printing pixel. The pattern determination unit determines a relationship between a target pixel and a peripheral pixel of an array composed of a plurality of low-resolution image data before density conversion generated by the array generation unit, and determines an arrangement of the target pixel and the peripheral pixel. 2. The image forming apparatus according to claim 1, wherein a specific portion of the high-resolution image data is set as a print pixel when the pattern matches the pattern.

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