JP2004009533A - Inkjet recording device, recording method, and storing medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reproduce an image density to be recorded in taking capacity of an absorbable ink per unit area by a recording medium into consideration. <P>SOLUTION: Inputted image data is binarized (201). In addition, a limiting value to the number of discharging dots per unit area is calculated in advance from a parameter such as kind of an output medium (202). Then, it is judged whether discharging is performed or not in accordance with an output value of the binarization processing 201, and when it can not be performed, feedback of information restricting the discharging dots is performed to the binarization processing (203). When the information restricting the discharging dots is received, a processing of a case where the discharging dots are not placed at the position in the binary processing, is performed. When it is judged that outputting can be performed as it is by the discharging dots restricting processing 203, a corresponding dot pattern is outputted (204). <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording apparatus, a recording method, and a storage medium, and more particularly, to an ink jet recording apparatus capable of reproducing the density of an image to be recorded while considering the amount of ink that can be absorbed by the recording medium. The present invention relates to a recording device, a recording method, and a storage medium.
[0002]
[Prior art]
2. Description of the Related Art A recording device such as a printer, a copying machine, and a facsimile is configured to record an image formed of a dot pattern on a recording medium (recording material) such as paper or a plastic thin plate based on image information. Such a recording apparatus can be classified into an ink jet method, a wire dot method, a thermal method, a laser beam method, and the like according to the recording method.
[0003]
Of the above methods, the ink jet recording apparatus is configured to eject and fly ink (recording liquid) droplets from the ejection openings of a recording head and to adhere the ink droplets to a recording medium for recording. Easy.
[0004]
In recent years, many recording apparatuses have been used, and high-speed recording, high resolution, high image quality, low noise, and the like have been required for these recording apparatuses. The ink jet recording apparatus is used for a relatively small recording apparatus as a recording apparatus meeting such a demand, and is rapidly spreading.
[0005]
An ink jet recording apparatus uses a recording head in which a plurality of ink ejection ports (nozzles) are arranged in an integrated manner in order to improve a recording speed and the like, and includes a plurality of recording heads which eject inks of different colors, respectively, corresponding to color. Are often used.
[0006]
In order to satisfy the demand for high resolution and high quality, halftone processing methods such as a dither method and an error diffusion method are used as a method for faithfully reproducing the gradation of image information with these inkjet recording apparatuses.
[0007]
These gradation reproduction methods enable excellent gradation recording when the resolution of the recording apparatus is sufficiently high (about 1000 dots / inch or more). However, when the resolution of the printing apparatus is low (about 360 to 720 dots / inch), the printing dots in the highlight portion are conspicuous, and the image is likely to be rough due to discontinuity of pixels.
[0008]
Therefore, in order to further increase the number of gradations, a method of making the recording dots themselves multi-valued has been performed.
[0009]
For example, there is known a method of controlling a voltage or a pulse width applied to a recording head to modulate the diameter of a recording dot attached to a recording medium to obtain a gradation. However, this method is highly dependent on the environment, the diameter of the recording dots is not stable, and the size of the minimum recording dot that can be recorded is limited, and it is difficult to reproduce gradations stably.
[0010]
There is a density modulation method that changes the density of dots in a matrix while keeping the dot size constant. However, a large area is required to increase the number of gradations, so that the resolution deteriorates.
[0011]
Therefore, as a method of improving a gradation characteristic and obtaining a high-density and high-gradation image by using an ink jet recording apparatus, a method in which a plurality of droplets are landed on substantially the same location on a recording medium to form one dot ( Pixel), and a so-called multi-droplet method of expressing gradation by changing the number of droplets to be landed, or at least two types of recording dots having different densities of the same color using a plurality of inks having different densities. A recording method that reproduces the gradation by using the above method, a method that combines the two, and the like have been proposed and put to practical use.
[0012]
[Problems to be solved by the invention]
The amount of ink that the recording medium can absorb per unit area is constant depending on the type of recording medium, and if ink droplets are ejected exceeding this amount, it will overflow without being completely absorbed into the area to be recorded, This leads to deterioration of image quality.
[0013]
Using the above-described method, for example, using two types of dark and light inks, a ternary process is performed for each dot to be printed with either no ink, light ink, or dark ink, thereby performing multi-tone printing. In the case where the density of the light ink is set to 50% of the density of the dark ink, the printing of the image having the density of 50% is realized by discharging the light ink to each dot in the recording area.
[0014]
Therefore, for example, when color recording is performed using four types of inks of cyan, magenta, yellow, and black, when recording a color using a plurality of inks such as green, red, and dark green, the ejection of the total ink is performed. There is a possibility that the amount (implantation amount) exceeds the capacity that the recording medium can absorb.
[0015]
In such a case, for example, if the amount of ink ejected with respect to the density of 50% is 100% of the capacity that can be absorbed by the recording medium, printing with three colors of ink will result in a portion having a density of 50% or more. The amount of ink ejected from the recording medium greatly exceeds the allowable amount of the recording medium, which is 300% of the capacity that can be absorbed, and causes deterioration in the image quality of the recorded image.
[0016]
That is, in the conventional printing apparatus, when determining the combination of inks used for performing appropriate color reproduction, the capacity of the ink that can be absorbed by the printing medium is not considered. As a result, image degradation occurs in a portion where the amount of ejected ink exceeds the capacity of ink that can be absorbed. Alternatively, if the combination of the used inks does not exceed the capacity of the ink that can be absorbed, there is a problem that a desired density or color cannot be reproduced.
[0017]
The present invention has been made in view of the above situation, and an ink jet recording apparatus capable of reproducing the density of an image to be recorded while considering the amount of ink that the recording medium can absorb per unit area. It is an object to provide a recording method and a storage medium.
[0018]
[Means for Solving the Problems]
A first aspect of the inkjet recording apparatus of the present invention that achieves the above object is an inkjet recording apparatus that performs recording by discharging ink droplets from an inkjet recording head onto a recording medium,
Reading means for reading out the value of each pixel of the image data to be recorded in a predetermined order,
A binarizing unit that outputs binary data indicating whether or not to eject an ink droplet in accordance with the value of the pixel read by the reading unit;
Storage means for storing, for each pixel, restriction information indicating whether or not ejection of ink droplets is possible;
The binary data is output when binary data indicating ejection of ink droplets is output from the binarization unit and the corresponding restriction information stored in the storage unit indicates that ink droplets can be ejected. Determination output means for performing
And limiting change means for changing, when the binary data indicating the ejection of the ink droplet is output from the determination output means, the limit information for a pixel to be read later by the reading means.
[0019]
A second aspect of the inkjet recording apparatus of the present invention that achieves the above object is inkjet recording that performs multi-tone recording by ejecting a plurality of ink droplets or ink droplets having different densities from an inkjet recording head according to pixel values. A device,
Reading means for reading out the value of each pixel of the image data to be recorded in a predetermined order,
Multi-gradation means for outputting gradation data indicating the number or density of ink droplets to be ejected in accordance with the value of the pixel read by the reading means;
Storage means for storing, for each pixel, restriction information corresponding to an acceptable amount of ink droplets;
A gradation changing unit for changing the gradation data with reference to the restriction information;
A limit changing unit that changes the limit information for a pixel that is read later by the reading unit in accordance with the gray scale data output from the gray scale changing unit.
[0020]
Further, the above object is also achieved by an ink jet recording method corresponding to the first and second aspects of the ink jet recording apparatus of the present invention, and a storage medium storing the method.
[0021]
That is, reading is performed to read out the value of each pixel of the image data to be recorded in a predetermined order, and in accordance with the value of the read out pixel, binary data indicating whether or not to eject an ink droplet is output. When restriction information indicating whether droplet ejection is possible is stored for each pixel, binary data indicating ejection of ink droplets is output, and when the corresponding restriction information indicates that ejection of ink droplets is possible, , And outputs the binary data, and changes the restriction information for the pixels to be read later.
[0022]
In this way, when there is a pixel that ejects ink, information for restricting ink ejection is sequentially transmitted, and control is performed so that the amount of ink ejected in a predetermined area unit does not exceed the amount that can be absorbed by the recording medium. And the macroscopic (macro) density of the image to be recorded can be reproduced.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0024]
In the embodiment described below, a printer will be described as an example of a recording apparatus using an inkjet recording method.
[0025]
In this specification, “recording” (also referred to as “printing”) means not only the case where significant information such as characters and figures is formed, but also whether a person is visually perceived as significant or insignificant. Irrespective of whether or not the surface is obtained so as to obtain, a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or a case where the medium is processed is also referred to.
[0026]
Here, the term “recording medium” refers not only to paper used in a general recording apparatus, but also to a wide range such as cloth, plastic film, metal plate, glass, ceramics, wood, leather, etc. which can accept ink. Shall say.
[0027]
Further, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly as in the definition of “recording (printing)”, and when applied on a recording medium, an image or pattern , A liquid that can be used for forming a pattern or the like, processing a recording medium, or treating ink (for example, coagulation or insolubilization of a colorant in ink applied to a recording medium).
[0028]
In the following description, ejecting ink droplets onto a recording medium is referred to as “strike” of ink or “strike” of ink, and the amount of ink ejected per unit area is referred to as “strike amount”.
[0029]
First, a mechanical configuration and a control configuration common to the following embodiments will be described with reference to FIGS.
[0030]
<Schematic description of the device body>
FIG. 11 is an external perspective view showing an outline of a configuration of an ink jet printer IJRA which is a typical embodiment of the present invention. In FIG. 11, the carriage HC that engages with the spiral groove 5004 of the lead screw 5005 that rotates via the driving force transmission gears 5009 to 5011 in conjunction with the forward / reverse rotation of the drive motor 5013 has pins (not shown). Then, it is supported by the guide rail 5003 and reciprocates in the directions of arrows a and b. On the carriage HC, an integrated type ink jet cartridge IJC containing a recording head IJH and an ink tank IT is mounted.
[0031]
Reference numeral 5002 denotes a paper pressing plate, which presses the recording paper P against the platen 5000 in the moving direction of the carriage HC. Reference numerals 5007 and 5008 denote photocouplers, which are home position detectors for confirming the presence of the carriage lever 5006 in this area and switching the rotation direction of the motor 5013.
[0032]
Reference numeral 5016 denotes a member that supports a cap member 5022 that caps the front surface of the print head IJH. Reference numeral 5015 denotes a suction device that suctions the inside of the cap, and performs suction recovery of the print head through an opening 5023 in the cap. Reference numeral 5017 denotes a cleaning blade. Reference numeral 5019 denotes a member that allows the blade to move in the front-rear direction. These members are supported by a main body support plate 5018. It goes without saying that the blade is not limited to this form and a known cleaning blade can be applied to the present embodiment.
[0033]
Reference numeral 5021 denotes a lever for starting suction for suction recovery. The lever 5021 moves with the movement of the cam 5020 engaging with the carriage, and the driving force from the driving motor is controlled by a known transmission mechanism such as clutch switching. Is done.
[0034]
These capping, cleaning, and suction recovery are configured so that desired operations can be performed at the corresponding positions by the action of the lead screw 5005 when the carriage comes to the area on the home position side. If the above operation is performed, any of the embodiments can be applied.
[0035]
<Description of control configuration>
Next, a control configuration for executing the recording control of the above-described apparatus will be described.
[0036]
FIG. 12 is a block diagram showing a configuration of a control circuit of the inkjet printer IJRA. In the figure showing a control circuit, 1700 is an interface for inputting a recording signal, 1701 is an MPU, 1702 is a ROM for storing a control program executed by the MPU 1701, and 1703 is various data (the recording signal and the recording data supplied to the head). Etc.) are stored in the DRAM. A gate array (GA) 1704 controls supply of print data to the print head IJH, and also controls data transfer between the interface 1700, the MPU 1701, and the RAM 1703. Reference numeral 1710 denotes a carrier motor for transporting the recording head IJH, and reference numeral 1709 denotes a transport motor for transporting the recording paper. Reference numeral 1705 denotes a head driver for driving the recording head, and 1706 and 1707 denote motor drivers for driving the transport motor 1709 and the carrier motor 1710, respectively.
[0037]
The operation of the above control configuration will be described. When a print signal enters the interface 1700, the print signal is converted into print data between the gate array 1704 and the MPU 1701. Then, the motor drivers 1706 and 1707 are driven, and the recording head is driven in accordance with the recording data sent to the head driver 1705 to perform recording.
[0038]
In this example, the control program executed by the MPU 1701 is stored in the ROM 1702. However, an erasable / writable storage medium such as an EEPROM is further added, and the control program is changed from a host computer connected to the inkjet printer IJRA. It can be configured to be able to do so.
[0039]
As described above, the ink tank IT and the recording head IJH may be integrally formed to constitute a replaceable ink cartridge IJC. However, the ink tank IT and the recording head IJH may be configured to be separable. Then, when the ink runs out, only the ink tank IT may be replaced.
[0040]
FIG. 13 is an external perspective view showing a configuration of an ink cartridge IJC in which an ink tank and a head can be separated. In the ink cartridge IJC, as shown in FIG. 13, the ink tank IT and the recording head IJH can be separated at the position of the boundary line K. When the ink cartridge IJC is mounted on the carriage HC, the ink cartridge IJC is provided with an electrode (not shown) for receiving an electric signal supplied from the carriage HC side. Is driven to eject ink.
[0041]
In FIG. 13, reference numeral 500 denotes an ink ejection port array. Further, the ink tank IT is provided with a fibrous or porous ink absorber for holding ink.
[0042]
[First Embodiment]
FIG. 1 is a functional block diagram showing a configuration example of the first embodiment of the present invention.
[0043]
In this embodiment, a processing device 101 that controls error calculation, data reading / writing, and the like, a processing procedure storage unit 102 that stores constants such as diffusion coefficients and programs, and diffuses the effects of error diffusion and the amount of implantation. It comprises a data storage means 103 for temporarily storing information and the like, a data input means 104 for receiving image data to be recorded, and an image output means 105 for transmitting recording data.
[0044]
Correspondence with the control configuration shown in FIG. 12 is as follows: the processing device 101 is an MPU 1701 and a gate array 1704; the processing procedure storage means 102 is a ROM 1702; the data storage means 103 is a DRAM 1703; the data input means 104 is an interface 1700; Each corresponds to a head driver 1705.
[0045]
FIG. 2 is a diagram illustrating a schematic process of creating print data in the present embodiment.
[0046]
First, binarization processing is performed on input image data (201). Further, a limit value for the number of ejection dots per unit area is calculated in advance from parameters such as the type of output medium (202). Then, it is determined whether or not ejection can be performed according to the output value of the binarization processing 201. If the ejection cannot be performed, information for restricting ejection dots is fed back to the binarization processing (203). When the information for restricting the ejection dots is received, the binarization process 201 performs a process in a case where the ejection dots are not placed at the position. If it is determined in the ejection dot restriction process 203 that the output can be performed as it is, the corresponding dot pattern is output (204).
[0047]
FIG. 3 is a flowchart showing the basic processing of print data creation in the present embodiment.
[0048]
When the process is started, an initialization process of the entire image processing is executed (step S1), and a discharge amount limit value is calculated according to a type of a recording medium to be used (step S2). Thereafter, the input image is read in units of pixels (step S3), and binarization processing is performed (step S4).
[0049]
As a result of the binarization processing in step S4, it is determined whether or not there is an ejection dot for the pixel (step S5). If there is no ejection dot, there is no need to limit the ejection amount, so the next The process returns to step S3 in order to read the pixels of the image. On the other hand, if there are ejection dots, it is checked whether or not it is necessary to perform ejection dot restriction processing (step S6).
[0050]
If the result of the check in step S6 indicates that ejection cannot be performed for the pixel, the set ejection dot is cleared (step S8), and the process returns to step 4 to perform the ejection dot again in the binarization process. Is restricted so as not to be set, and the binarization process is performed again.
[0051]
As a result of the check in step S6, if there is no ejection restriction for the pixel, a process of outputting dot data is performed, and a process of diffusing the influence on surrounding pixels by outputting the dot data is performed (step S9). ). Thereafter, it is determined whether or not the processing for all the input images has been completed (step S10). If not, the process returns to step S4 to repeat the processing for the next image pixel.
[0052]
When the processing for all the images is completed as described above, the end processing is performed (step S11), and the recording data creation processing ends.
[0053]
FIG. 4 is a diagram illustrating the concept of ejection dot restriction in the present embodiment. Here, when a dot is ejected at the upper left position in a 2 × 2 pixel matrix, the dischargeable positions when ejection restrictions of 50%, 25%, and 75% are applied are (a), (b) and (C) shows each.
[0054]
For example, in (a), if a limit of 50% is applied to a 2 × 2 area, and a dot is hit at the upper left position, it is possible to hit within this 2 × 2 area. The position is only one diagonal position. Similarly, in the case where the limit of the hit amount shown in (b) is 25%, if a dot is hit in the upper left position, there is no more hit position in this 2 × 2 area, and (c) In the case where the limit of the driving amount is 75%, the positions where the driving can be performed in this 2 × 2 area are two places, the upper right and the lower left.
[0055]
FIG. 5 is a flowchart of the error diffusion process including the driving amount limiting process. First, an image reading position and buffer initialization process are performed (step S51), density data of the pixel at the current position is read (step S52), and this density is compared with a binarization threshold (step S53).
[0056]
If the density data is larger than the threshold value, the driving amount diffusion processing is reflected (step S55). Specifically, the dot level is set to 1 (step S551), the ejection amount limitation process is performed (step S552), and the determination process regarding the limitation is performed (step S553).
[0057]
In the process of step S55, it is determined whether or not the data of the pixel can be hit as it is. If the data cannot be hit, the dot level is set to 0 (step S56), and the difference between the density data and the density data previously read is determined. Error diffusion is performed by error diffusion processing (step S57).
[0058]
On the other hand, if the density data is not larger than the threshold, the dot level is set to 0 (step S56), and the process proceeds to step S57.
[0059]
Finally, it is determined whether or not the currently processed pixel is the end of the image (step S58). If not, the process moves to the next pixel position (step S59) and returns to step S52 to repeat the processing.
[0060]
FIG. 6 is a flowchart showing the details of the processing in S552 and S553 of S55 (implantation amount diffusion processing) in FIG.
[0061]
First, when the process starts, it is determined whether or not the hit amount of the currently hitting pattern is 0 (step S61). To end. If the value is not 0, the driving amount limit value at the pixel position to be driven is read from the driving amount diffusion memory (step S62).
[0062]
Next, the read limit value and the driving amount of the pattern to be hit are added, and it is determined whether or not it exceeds 100% (step S63). If it exceeds 100%, it is determined that the shot cannot be made, and the process ends with a shot NG. If the added value does not exceed 100%, the basic implantation amount limit value L for the remaining portion (3 pixels) of the 2 × 2 pixel area is set according to the following equation in order to spread the limitation amount of the implantation amount. The calculation is performed (step S64).
[0063]
Here, as for the basic driving amount limit value L, assuming that the driving amount limit value for the region is X and the ejection amount for the pixel data is Id,
・ If the driving amount exceeds the limit,
L (%) = (number of diffusion destination pixels) × (100−X) + (Id−X)
・ If the driving amount is less than the limit value,
L (%) = 0
It becomes. In the present embodiment, the number of diffusion destination pixels is three.
[0064]
In subsequent steps S65 to S67, a value obtained by multiplying the limit value by the distribution coefficient as shown in FIG. 4 is assigned to the right, lower right, and lower pixels, and the process ends with OK.
[0065]
FIG. 7 is a diagram showing a configuration of a memory used for error diffusion in step S57 and diffusion processing of the ejection amount limitation value (effect on ejection amount limitation) in steps S65 to S67 in the present embodiment.
[0066]
In the present embodiment, two diffusion memories 701 and 702 are provided in the data storage means 103 for each dot position in order to perform error diffusion relating to density and diffusion processing of the influence relating to ejection amount limitation in parallel. . Each of the diffusion memories 701 and 702 is configured to be able to store data corresponding to each pixel in two lines.
[0067]
In the diffusion processing of the influence on the ejection amount restriction, when a dot is hit at a certain point, it is recognized that 100% of the ink amount has been hit at that point, and this 100% is regarded as the restriction information of the adjacent dot position and the surrounding information is set. Spread to pixels.
[0068]
The example shown in FIG. 7 is a case where the hit amount limit value is 50% and information on whether or not a dot has been hit on the upper left pixel is diffused in three directions of right, lower right, and lower.
[0069]
When a dot is hit, as shown in the lower left side of the figure, 100% information indicating that the dot has been hit is diffused by multiplying the right, lower right, and lower pixels by different coefficients, respectively, and is diffused. Is stored as restriction information in a portion corresponding to each pixel. In this case, since the hit amount limit value is 50%, as shown in FIG. 4A, 100% is set as the limit information so that dots are not hit at two pixels other than the lower right. Spread and stored. In the lower right pixel where dots can be formed, 0% is diffused and stored as restriction information.
[0070]
On the other hand, when no dot is formed at the upper left position, 0% information indicating that no dot is formed is provided in a portion corresponding to the other three pixels, as shown at the lower right of FIG. Spread and stored.
[0071]
In the error diffusion process relating to density, as shown in the upper part of the figure, a difference between a density value to be originally recorded at a target position and an actually recorded density value is obtained, and the difference is diffused to surrounding pixels. . In the present embodiment, the difference value is spread to four pixels of right, lower right, lower, and lower left by 1/4.
[0072]
In the error diffusion process relating to the density, if no dot is formed at the target position, the error is further accumulated and propagated to the process for the next pixel.
[0073]
In this way, the error diffusion process and the hit amount limiting diffusion process for the upper left target pixel are completed. Next, when performing diffusion processing on a pixel at the right position to be processed, it is determined whether or not dots can be formed on the target pixel by referring to the restriction information stored in the previous processing.
[0074]
As described above, according to the present embodiment, it is possible to control the ink ejection amount in a predetermined area unit so as not to exceed the limit value, while taking into account the amount of ink that the recording medium can absorb per unit area. The density of the image to be recorded can be reproduced.
[0075]
[Second embodiment]
In the first embodiment, each pixel is composed of one dot, but the present invention can be applied to other cases, for example, when each pixel is composed of a plurality of dots. Hereinafter, a case where each pixel is formed of 4 × 4 dots will be described as a second embodiment.
[0076]
FIG. 8 is a diagram showing an outline of the processing in a case where each pixel is composed of 4 × 4 dots and the area of 2 × 2 pixels is limited to a discharge amount of 50%. In the figure, (a) is the initial state, (b) is the distribution of the limit value to the other three pixels when the ejection amount corresponding to 100% is injected into the upper left pixel, and (c) is the distributed limit value. , (D) and (e) show the determination as to whether or not it is possible to hit the upper right pixel.
[0077]
In the initial state shown in (a), no limitation is imposed on any of the four pixels. Therefore, any dot pattern up to 100% can be printed in a pixel consisting of 4 × 4 dots at the upper left.
[0078]
For example, if an 8-dot pattern is to be printed here, 50% of this pixel is to be printed. Then, since the amount of shot of the pixel (50%) does not exceed the entire limit (50%), it is not necessary to propagate the limit by the amount of shot to the surroundings. However, assuming that a 100% pattern of 16 dots is applied to this pixel, which exceeds the limit for the area by 50%, this excess is distributed to the three surrounding pixels by an appropriate coefficient. .
[0079]
This will be described in detail. First, a basic limit value L is defined. The basic limit value L is the sum of the limits for the maximum shot amount 300% that can be shot in the remaining three pixels that have not yet been shot in the 2 × 2 area. Therefore, when L = 300%, it means that the remaining three pixels cannot be shot at all.
[0080]
On the other hand, when L = 100%, since 300% −100% = 200%, a 100% pattern can be printed on two pixels. This basic limit value is multiplied by an appropriate diffusion coefficient that sums up to 1, distributed to the remaining three pixel positions and substituted, and used as a reference for determining whether or not a desired pattern can be formed on that pixel. , The amount of driving is limited.
[0081]
The relationship between the percentage of the ejection amount Id of the pattern corresponding to the pixel data and the basic limit value L is obtained from the above-described formula using the ejection amount limit value X.
[0082]
That is, in the example shown in FIG. 8, since Id = 100 (%) and X = 50 (%),
L = 3 × (100-50) + (100-50) = 200 (%)
It becomes. That is, if a 50% ejection limit is applied to the maximum ejection amount of 400% that can be hit in 2 × 2 pixels, the ejection amount that can be hit in this area is 200%, and 100% of the shot amount has been hit. The hit amount that can be hit on the remaining three pixels is 100%. Since the limit of 200% applied by the above equation is applied to the maximum ejection amount of 300% of the area of 3 pixels that have not yet been hit in 2 × 2, 300% −200% = 100%, and the limit is correctly set. Will be
[0083]
As shown in FIG. 8 (b), the value of L is substituted by multiplying by an appropriate diffusion coefficient as an ejection amount limiting value of the three pixels on the right, lower right, and lower and distributed and stored in the corresponding line buffer. And consider when hitting the pixel at that position.
[0084]
For example, as shown in (a), when the basic limit value of the pixel position to be hit at present is 0, and the hit amount Id to hit is 100%, the basic limit value is 0 (%) and the hit amount is 100 (%). ) Does not exceed 100%, so it is possible to hit this pattern. At the same time, the basic limit value L is obtained by the above equation, and is distributed to the right, lower right, and lower by predetermined coefficients. (C) shows an example in which the basal amount limit value L is distributed to the other three pixels by such diffusion.
[0085]
If the driving amount Id is equal to or less than the driving amount limit value X, there is no influence. Therefore, if the driving amount Id of the pattern is equal to or lower than the limit value X, there is no restriction on surrounding pixels. Therefore, as shown in the above equation, the basic limit value L becomes 0, and therefore it is not necessary to perform the driving amount limiting process.
[0086]
Next, as shown in (d), if it is attempted to hit a 100% pattern on the upper right pixel where the basic limit value L is 50%, then adding 100% to the 50% limit value gives 150%> It becomes 100%, and it is determined that the shot cannot be performed because it exceeds 100%. On the other hand, when a 50% pattern is to be hit at this position as shown in (e), it is determined that a hit can be made because the basic limit value 50% + the driving amount 50% = 100%.
[0087]
Therefore, it is determined that a pattern other than a pattern having no dot cannot be hit at a pixel position where the basic limit value is 100%.
[0088]
FIG. 9 is a flowchart illustrating an error diffusion process including the driving amount limiting process according to the present embodiment. First, an initialization process is performed (step S91), density data of the pixel at the current position is read out (step S92), and subsequently, a gradation rank to be compared is initialized (step S93) and compared with a gradation rank value (step S93). S94, 95).
[0089]
As a result of the comparison in step S95, when the density data is larger than the gradation rank, the gradation level is increased by one (step S96), and the process returns to step S94. If the gradation level exceeds the density data in step S95, a limitation process relating to the amount of ejection and its diffusion process are performed on the obtained gradation level (step S97).
[0090]
More specifically, the processing for limiting the amount of shot is performed (step S971), and it is determined whether or not the pixel data can be shot as it is (step S972). If not, the tone rank is lowered by one (step S973). In step S972, it is checked whether or not the player can hit again. This process is repeated until the tone rank is reached.
[0091]
When a tone that can be finally implanted is determined, the difference between the tone and the previously read density data is error-diffused by density error diffusion processing (step S98). Finally, it is determined whether or not the currently processed pixel is the end of the image (step S99). If it is not the end, the pixel is moved to the next pixel position (step S100), and the process returns to step S92 to repeat the processing.
[0092]
The detailed processing of step S971 and step S972 performed in step S97 is the same as the flowchart of FIG. 6 described for the first embodiment, and a description thereof will not be repeated.
[0093]
As described above, according to the present embodiment, even when each pixel is composed of a plurality of dot patterns, it is possible to control the ink ejection amount in a predetermined area unit so as not to exceed the limit value, and to perform printing. The density of an image to be recorded can be reproduced while considering the volume of ink that the medium can absorb per unit area.
[0094]
[Third Embodiment]
In the above-described embodiment, the range in which the influence of the implantation amount is diffused is a 2 × 2 square, but this range does not need to be a constant shape. For example, even when the range affected by the implantation amount of a certain pixel is an irregular pixel unit area, the number of affected pixels is substituted into the above equation for calculating L as the number of pixels included in the area minus one. Thus, a similar effect can be obtained.
[0095]
In the third embodiment, the range in which the influence (limit value) of the driving amount is diffused is set to an arbitrary shape. The processing will be described below with reference to the flowchart of FIG.
[0096]
First, when the process starts, it is determined whether or not the driving amount of the pattern currently being hit is 0 (step S101). The processing ends. On the other hand, if it is other than 0, the driving amount limit value at the pixel position to be driven is read from the driving amount diffusion memory (step S102). Next, the read limit value and the driving amount of the pattern to be hit are added, and it is determined whether or not it exceeds 100% (step S103).
[0097]
If the total value exceeds 100% in step S103, it is determined that no hit is made, and the process is terminated. On the other hand, if it does not exceed 100%, the basic driving amount limit value L is calculated according to the above formula for obtaining L in order to diffuse the driving amount limit value (step S104). The limit value is substituted by a predetermined coefficient (step S105). Subsequently, the next reflection position is searched (step S106), and it is determined whether or not the reflection position still exists (step S107). If there is another reflection position, the process returns to step S105 to set the limit value for the next reflection position. Perform substitution processing. In this manner, the process is repeated until there is no more reflection position. When this process ends, the process ends with OK.
[0098]
As described above, according to the present embodiment, even when the range in which the influence of the ejection amount is diffused is an arbitrary shape, control can be performed so that the ink ejection amount does not exceed the limit value in a predetermined area unit. Thus, the density of an image to be recorded can be reproduced while taking into account the volume of ink that the recording medium can absorb per unit area.
[0099]
[Modification]
The present invention can be applied to a case where each pixel is represented by a method other than the embodiment described above.
[0100]
For example, for a method using a plurality of types of dots having different capacities, if the total volume of the dots forming the pattern corresponding to the pixel data is converted into the amount of ejection, the same processing as in the above embodiment can be performed. It is possible to get the effect.
[0101]
In addition, even in a method in which a plurality of dots are ejected at the same dot position, the above-described embodiment can be implemented by using a formula or table for converting the total number of dots used in the pattern corresponding to the pixel data into the ejection amount. The same effect can be obtained by the same processing as.
[0102]
Furthermore, even for a method using a plurality of types of inks having different densities, if the dots used in the pattern corresponding to the pixel data are converted into the standard ink ejection amount, the same configuration as in the above embodiment is obtained. A similar effect can be obtained.
[0103]
Similarly, the present invention can be applied to a method in which a pattern is formed using a plurality of dots having different ejection amounts and densities, such as large and small dots having different volumes and dark and light dots having different densities.
[0104]
Even when the dot pattern corresponding to one pixel is not a 4 × 4 size but a square such as n dots × m dots, the amount of ink that can be applied to the area occupied by the pattern corresponding to that pixel By converting to a ratio to the same, the same effect can be obtained by the same processing as in the second embodiment.
[0105]
In addition, the shape of the area occupied by the dot pattern assigned to one pixel is not limited to a certain shape. For example, even if the area for one pixel is assigned to the area of the irregular shape, the amount of ejection for the area of the irregular shape and the number of dots assigned to the area of the irregular shape By using the relational expression or table of the driving amount, the same effect can be obtained with the same configuration.
[0106]
Further, the range in which the influence of the implantation amount is diffused is not limited to the 2 × 2 region. For example, even when the range affected by the amount of hit of a certain pixel is an area of n × m pixels, the number of affected pixels is set to n × m−1 pixels and substituted into the above equation for obtaining L. The same effect can be obtained by the same processing as in the embodiment.
[0107]
The limit value for the entire amount of shot does not need to be fixed in an image or a system. For example, the limit value of the driving amount may be changed at any time according to the value of the pixel of the input image. In that case, the value of X in the above equation for obtaining L is a function for the value of the target pixel of the input image. By doing so, it is possible to relax the limitation on the ejection amount in the solid recording portion and impose a practical limitation such as a tighter limitation on the ejection amount in the low density band.
[0108]
[Other embodiments]
The above-described embodiment includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for causing ink to be ejected, particularly in an ink jet recording system. By using a method that causes a change in the state, it is possible to achieve higher density and higher definition of recording.
[0109]
Regarding the typical configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). Applying at least one drive signal corresponding to the recording information and providing a rapid temperature rise exceeding the nucleate boiling, to generate heat energy in the electrothermal transducer, thereby causing the recording head to emit heat energy. This is effective in that film boiling occurs on the heat-acting surface of the liquid, and as a result, air bubbles in the liquid (ink) corresponding to the drive signal on a one-to-one basis can be formed.
[0110]
By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is in a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.
[0111]
As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.
[0112]
As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (the linear liquid flow path or the right-angled liquid flow path) as disclosed in each of the above-mentioned specifications, a heat acting surface The configurations described in U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose the configuration in which the is bent, are also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slot is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, or an opening for absorbing a pressure wave of thermal energy is discharged. A configuration based on JP-A-59-138461, which discloses a configuration corresponding to each unit, may be adopted.
[0113]
Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is satisfied by a combination of a plurality of recording heads as disclosed in the above specification. Either the configuration or the configuration as one recording head integrally formed may be used.
[0114]
In addition, not only the cartridge-type recording head in which the ink tank is provided integrally with the recording head itself described in the above embodiment, but also the electric connection with the apparatus main body by being attached to the apparatus main body. A replaceable chip-type recording head that can supply ink from the apparatus main body may be used.
[0115]
Further, it is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like to the configuration of the printing apparatus described above, since the printing operation can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or sucking means, preheating means using an electrothermal transducer or another heating element or a combination thereof. It is also effective to provide a preliminary ejection mode for performing ejection that is different from printing, in order to perform stable printing.
[0116]
Further, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, and may be a printing head integrally formed or a combination of a plurality of printing heads. The device may be provided with at least one of the full colors.
[0117]
In the above-described embodiment, the description has been made on the assumption that the ink is a liquid.However, even if the ink solidifies at room temperature or below, an ink that softens or liquefies at room temperature may be used. Alternatively, in the ink jet system, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. It is sufficient if the ink is sometimes in a liquid state.
[0118]
In addition, to prevent the temperature rise due to thermal energy from being used as the energy of the state change of the ink from the solid state to the liquid state, or to prevent the ink from evaporating, the ink solidifies in a standing state. Alternatively, ink that liquefies by heating may be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used.
[0119]
In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held in a liquid state or a solid state in the concave portion or through hole of the porous sheet. It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.
[0120]
The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but can be applied to a device including one device (for example, a copier, a facsimile machine, etc.). May be applied.
[0121]
Further, an object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and a computer (or a CPU or a CPU) of the system or the apparatus. Needless to say, the present invention can also be achieved by an MPU) reading and executing a program code stored in a storage medium. In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instruction of the program code. It goes without saying that a part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.
[0122]
Further, after the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is executed based on the instruction of the program code. It goes without saying that the CPU included in the expansion card or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0123]
When the present invention is applied to the storage medium, the storage medium stores program codes corresponding to the flowcharts (shown in FIGS. 3, 5, 6, 9, and / or 10) described above. Will be.
[0124]
【The invention's effect】
As described above, according to the present invention, when there is a pixel that ejects ink, information for restricting the ejection of ink is sequentially transmitted, and the amount of ink ejected in a predetermined area unit is the amount that the recording medium can absorb. , And macroscopic (macro) density of an image to be recorded can be reproduced.
[Brief description of the drawings]
FIG. 1 is a functional block diagram illustrating a configuration example of a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a schematic process of creating print data according to the first embodiment;
FIG. 3 is a flowchart illustrating a basic process of creating print data according to the first embodiment.
FIG. 4 is a diagram illustrating the concept of ejection dot restriction in the first embodiment.
FIG. 5 is a flowchart of an error diffusion process including a driving amount limiting process.
FIG. 6 is a flowchart showing details of a driving amount diffusion process.
FIG. 7 is a diagram illustrating a configuration of a memory used for a diffusion process of a driving amount limit value.
FIG. 8 is a diagram illustrating an outline of a process according to a second embodiment.
FIG. 9 is a flowchart of an error diffusion process according to the second embodiment.
FIG. 10 is a flowchart of a process according to the third embodiment.
FIG. 11 is a diagram illustrating an appearance of a printer according to a preferred embodiment of the present invention.
FIG. 12 is a block diagram illustrating a control configuration of the printer in FIG. 11;
FIG. 13 is a diagram illustrating an ink jet cartridge of the printer in FIG. 11;
[Explanation of symbols]
101 processing unit
102 Processing procedure storage means
103 Data storage means
104 Data input means
105 Data output means
201 Binarization processing
202 Ejection dot limit calculation process
203 ejection dot restriction processing
204 dot pattern output processing

Claims (10)

An inkjet recording apparatus that performs recording by discharging ink droplets from an inkjet recording head to a recording medium,
Reading means for reading out the value of each pixel of the image data to be recorded in a predetermined order,
A binarizing unit that outputs binary data indicating whether or not to eject an ink droplet in accordance with the value of the pixel read by the reading unit;
Storage means for storing, for each pixel, restriction information indicating whether or not ejection of ink droplets is possible;
The binary data is output when binary data indicating ejection of ink droplets is output from the binarization unit and the corresponding restriction information stored in the storage unit indicates that ink droplets can be ejected. Determination output means for performing
An ink jet recording apparatus comprising: a limit changing unit that changes the limit information for a pixel that is read later by the reading unit when binary data indicating ejection of an ink droplet is output from the determination output unit. apparatus. 2. The ink jet recording apparatus according to claim 1, wherein the restriction information is determined in consideration of an amount of ink droplets that can be absorbed in a predetermined recording area including a plurality of pixels. 3. The ink jet recording apparatus according to claim 2, wherein the change unit changes restriction information of each pixel in the recording area excluding the read pixel at a predetermined rate. 4. The apparatus according to claim 1, further comprising an error diffusion unit configured to perform an error diffusion process on a value of a pixel to be read later by referring to the binary data output from the determination output unit. 5. Ink jet recording device. An inkjet recording apparatus that performs multi-tone recording by discharging a plurality of ink droplets and ink droplets having different densities from an inkjet recording head according to pixel values,
Reading means for reading out the value of each pixel of the image data to be recorded in a predetermined order,
Multi-gradation means for outputting gradation data indicating the number or density of ink droplets to be ejected in accordance with the value of the pixel read by the reading means;
Storage means for storing, for each pixel, restriction information corresponding to an acceptable amount of ink droplets;
A gradation changing unit for changing the gradation data with reference to the restriction information;
An ink jet recording apparatus, comprising: a limit changing unit that changes the limit information for a pixel that is read later by the reading unit in accordance with the gray scale data output from the gray scale changing unit. 6. The recording head according to claim 1, wherein the recording head is a recording head that discharges ink using thermal energy, and includes a thermal energy converter for generating thermal energy to be applied to the ink. The inkjet recording device according to any one of the above. An inkjet recording method for performing recording by discharging ink droplets from an inkjet recording head to a recording medium,
A reading step of reading the value of each pixel of the image data to be recorded in a predetermined order,
A binarization step of outputting binary data indicating whether or not to eject an ink droplet in accordance with the value of the pixel read in the reading step;
A storing step of storing, in each of the pixels, restriction information indicating whether or not ejection of ink droplets is possible in a storage unit;
Outputting binary data when the binary data indicating the ejection of ink droplets is output in the binarization step and the corresponding restriction information stored in the storage means indicates that ink droplets can be ejected; Judgment output step to be performed;
An ink jet recording method comprising: when binary data indicating ejection of ink droplets is output in the determination output step, a limit changing step of changing the limit information for a pixel to be read later in the reading step. Method. An ink jet recording method for performing multi-tone recording by discharging a plurality of ink droplets or ink droplets having different densities from an ink jet recording head according to the value of a pixel,
A reading step of reading the value of each pixel of the image data to be recorded in a predetermined order,
A multi-gradation step of outputting gradation data indicating the number or density of ink droplets to be ejected in accordance with the value of the pixel read in the reading step;
A storing step of storing limiting information corresponding to the amount of ink droplets that can be received in a storing unit for each pixel;
A gradation changing step of changing the gradation data with reference to the restriction information;
An ink-jet recording method, comprising: changing the limit information for a pixel to be read later in the readout step in accordance with the grayscale data output in the grayscale change step. A storage medium storing an inkjet recording method for performing recording by discharging ink droplets from an inkjet recording head to a recording medium,
A reading step of reading the value of each pixel of the image data to be recorded in a predetermined order,
A binarization step of outputting binary data indicating whether or not to eject an ink droplet in accordance with the value of the pixel read in the reading step;
A storing step of storing, in each of the pixels, restriction information indicating whether or not ejection of ink droplets is possible in a storage unit;
Outputting binary data when the binary data indicating the ejection of ink droplets is output in the binarization step and the corresponding restriction information stored in the storage means indicates that ink droplets can be ejected; Judgment output step to be performed;
When binary data indicating ejection of ink droplets is output in the determination output step, a program code for executing a restriction change step of changing the restriction information for a pixel read out later in the readout step is stored. A storage medium characterized by the above-mentioned. A storage medium storing an ink jet recording method for performing multi-gradation recording by discharging a plurality of ink droplets and ink droplets having different densities from an ink jet recording head according to pixel values,
A reading step of reading the value of each pixel of the image data to be recorded in a predetermined order,
A multi-gradation step of outputting gradation data indicating the number or density of ink droplets to be ejected in accordance with the value of the pixel read in the reading step;
A storing step of storing limiting information corresponding to the amount of ink droplets that can be received in a storing unit for each pixel;
A gradation changing step of changing the gradation data with reference to the restriction information;
Storing a program code for performing, in accordance with the gradation data output in the gradation changing step, a restriction changing step of changing the restriction information for a pixel to be read later in the reading step. Medium.

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