JP3620621B2 - Print data correction apparatus, print system, print data correction method, and software recording medium recording print data correction program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a print data correction apparatus, a printing system, a print data correction method, and a software recording medium on which a print data correction program is recorded.
[0002]
[Prior art]
In recent years, high-definition color ink-jet printers have advanced, and so-called photographic image quality has been reached. In such an ink jet printer, predetermined color inks are ejected in granular form, dots of a predetermined color are added to desired positions, and the image is expressed in a dot matrix. In this case, a color image is reproduced using three colors of cyan (C), magenta (M), and yellow (Y), or four color inks obtained by adding black (K) thereto.
[0003]
By the way, in order to come to be called photographic image quality, it is important to make the dots minute, but color reproducibility is also extremely important. Despite the fact that colors are expressed in multi-tone data of red, green and blue (RGB) inside the computer, the printer can only handle CMYK two-tone data, so color space conversion and gradation conversion are performed. It has been broken. That is, two-tone display of CMYK is realized while maintaining colors expressed by RGB multi-tones. Of course, it is assumed here that each dot is colored at a specified density.
[0004]
However, although the print data is output while maintaining the color reproducibility, the weight of the color ink particles ejected by the print head actually differs depending on the remaining amount of ink. It may not be said that the color is developed at the density.
[0005]
[Problems to be solved by the invention]
In the conventional color ink jet printer described above, since the weight of the ejected ink particles gradually decreases as the remaining amount of ink decreases as printing is performed, it can be said that each dot is colored at its original density. As a result, there is a problem that color reproducibility may deteriorate.
[0006]
One of the possible causes of this is the liquid level of the ink tank in which the color ink is stored. This is because the weight increases, and if the liquid level is low, the pressure is reduced by that amount and the weight of the discharged color ink particles is also reduced. In this case, it is possible to adopt a mechanical configuration in which the liquid level is constant, but the structure becomes complicated and the manufacturing cost must be increased.
[0007]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a print data correction device, a printing system, and a print data correction method capable of obtaining a constant print result regardless of the remaining amount of ink by an easier method. Another object of the present invention is to provide a software recording medium on which a print data correction program is recorded.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is provided with a print head which is supplied with liquid from an ink tank and ejects ink particles from a nozzle, and the ink particles are adhered to a recording medium to form a dot matrix image. A print data correction device for correcting the print density based on the print data when the multi-tone print data is halftone processed to be converted into print data and output. Ink remaining amount detecting means for detecting the liquid level in the tank and canceling the change in the printing density due to the amount of ink particles changing according to the liquid level.The multi-tone print data is converted according to the detected liquid level according to the input / output relationship in which the correspondence before and after the correction is made for the multi-tone print data.And a print data correction means for correcting.
[0009]
In the invention according to claim 1 configured as described above, the print head of the printing apparatus has a nozzle supplied from an ink tank, and ejects ink particles from the nozzle. Accordingly, the amount of ejected ink particles changes depending on the liquid level in the ink tank. When a dot matrix image is printed by attaching the ink particles on the recording medium, the size of the dots changes depending on the amount of ink particles, and the printing density per dot changes.
[0010]
On the other hand, the remaining ink level detecting means detects the liquid level of the ink tank, and the print data correcting means detects the liquid level detected so as to cancel the change in the printing density due to the amount of ink particles changing according to the liquid level. Above based on rankMulti-toneCorrect the print data. As a premise of this, halftone processing is performed on multi-tone print data, for example, converted into two-tone print data and output. However, since the print data includes print density information in this process, this is necessary. Same as changing the print density as described above.Multi-toneCorrect the print data.
[0011]
That is, depending on the liquid level of the ink tankMulti-toneThe print density is fixed by correcting the print data.
[0012]
In the printing apparatus, ink particles are deposited on a recording medium by a print head supplied from an ink tank, and any ink particles may be correlated with the liquid level of the ink tank. In this case, the method for specifically ejecting ink particles is not particularly limited, and may be a micropump system or a bubble jet.(R)It can be used for various types of systems.
[0013]
The ink remaining amount detecting means only needs to be able to substantially detect the liquid level in the ink tank, and various detection methods can be adopted. For example, a liquid level sensor that directly detects the liquid level may be used, or a liquid level may be indirectly detected from the amount of ink used. As an example of the latter, the invention according to claim 2 is the print data correction apparatus according to claim 1, wherein the ink remaining amount detecting means includes a counting means for counting the total amount of ejected ink particles, and a result of the counting. And a liquid level estimating means for estimating the amount of decrease in the liquid level based on the configuration.
[0014]
In the invention according to claim 2 configured as described above, the total amount of ink particles ejected by the counting means is counted, and the ink amount used can be calculated by this total count amount × ink particle amount. Then, the liquid level estimation means performs such calculation based on the count result and estimates the amount of decrease in the liquid level. Of course, the specific calculation formula can be variously modified, and the calculation of the liquid level also changes depending on the shape of the ink tank.
The invention according to claim 3 is the above claim 1 or claim.2In the print data correction apparatus described above, the print data correction means includes:Refer to the correction lookup table in which the correspondence relationship before and after correction for the multi-tone print data is formed according to the gradation so as to cancel the change in the print density due to the ink particle amount that changes according to the liquid level. Then, the multi-tone print data is corrected by reading out the multi-tone print data after correction corresponding to the detected liquid level corresponding to the multi-tone print data before correction.As a configuration.
In the invention according to claim 3 configured as described above, a correction lookup table for achieving a predetermined input / output relationship is provided.Multi-toneWhen the correction lookup table is referenced in the print data, the correctedMulti-toneThe print data is read and theMulti-toneThe print data can be corrected.
The invention according to claim 4 is the aboveAny one of claims 1 to 3In the print data correction apparatus according to claim 1, the print data correction means includes the detected liquid level.Sought fromWhen the change of the same liquid level becomes larger than the predetermined amountInput / output relationship aboveAs a configuration to create.
In the invention according to claim 4 configured as described above, the ink is not regenerated every time printing is performed, but only when the ink is reduced to some extent by obtaining the ink reduction.Input / output relationship aboveCreate
The invention according to claim 5 is the aboveClaim 4In the print data correction device described in the above, the print data correction means stores the detected liquid level as an old ink remaining amount, and when the ink tank is replaced, an ink reduction amount as a value of the old ink remaining amount. Set a value that increasesDoAs a configuration.
In the invention according to claim 5 configured as described above, when it is found that the ink tank has been replaced, a value that increases the ink reduction amount is set to the remaining amount of the old ink. As a result, when the next remaining ink amount is compared, the change in the liquid level is surely increased and a correction lookup table is created.
Note that the old ink remaining amount is not stored when printing is started for the first time, but if the value is set to “0”, the ink reduction amount becomes a large value regardless of the new ink remaining amount. In this case, the amount is not reduced, but if the difference is large, the old correction look-up table is judged to be useless and remade.
The invention according to claim 6 is the aboveClaim 1The print data correction device according to claim 5, wherein the print data correction means includes:Referenced when color-converting the multi-tone print dataThe contents of the color conversion tableAccording to the above input / output relationshipThe configuration is rewritten.
Configured as aboveClaim 6In the invention according to the present invention, the color conversion table is rewrittenInput / output relationship aboveIncorporate the contents of.
[0015]
By the way, the print data correction device for correcting the print data in this way is not necessarily an integrated device, and various modifications are possible. As an example, the invention according to claim 7 is a printing system including a printing device and a printing control device, and the printing device includes a print head that is supplied from an ink tank and ejects ink particles from a nozzle. And a printing unit that prints a dot matrix image by depositing the same ink particles on a recording medium, and a remaining ink level detecting unit that detects a liquid level in the ink tank. Print data conversion means for converting gradation print data into half-tone processed print data, and canceling the change in print density due to the amount of ink particles changing according to the liquid levelThe multi-tone print data is converted according to the detected liquid level according to the input / output relationship in which the correspondence before and after the correction is made for the multi-tone print data.And a print data correction means for correcting.
[0016]
In the invention according to claim 7 configured as described above, the ink remaining amount detecting means of the printing apparatus provided with the printing means having the correlation between the liquid level of the ink tank and the ink particle amount as described above is the same ink. The print data correction means of the print control device that detects the liquid level of the tank and outputs halftone processed multi-tone print data to such a printing device is the amount of ink particles that changes according to the liquid level. To cancel the change in print density due toThe multi-tone print data is converted according to the detected liquid level according to the input / output relationship in which the correspondence before and after the correction is made for the multi-tone print data.The correction is made to cancel the change in the print density due to the amount of ink particles changing according to the liquid level.
[0017]
In this case, the ink remaining amount detecting means is provided in the printing apparatus, but it can also be called a print data correction apparatus including this, and moreover, when the print data is output to the printing apparatus, it is described above. If the total amount of the ink particles is counted, the liquid level can be detected outside the printing apparatus.
[0018]
In addition, the present invention is not necessarily limited to a certain device, and as an example, the invention according to claim 8 includes a print head that is supplied from an ink tank and ejects ink particles from a nozzle, and the ink particles are recorded on the recording medium. When printing multi-tone print data by halftone processing and printing it to a printing device that prints a dot matrix image attached to the top, the print density based on the print data is corrected. In doing so, the liquid level in the ink tank is detected, and the change in print density due to the amount of ink particles that changes in accordance with the liquid level is canceled out.The multi-tone print data is converted according to the detected liquid level according to the input / output relationship in which the correspondence before and after the correction is made for the multi-tone print data.As a configuration to be corrected.
The invention according to claim 9 is the print data correction method according to claim 8, wherein the input / output is performed when a change in the liquid level obtained from the detected liquid level is larger than a predetermined amount. It is configured to create a relationship.
Furthermore, the invention according to claim 10 is the print data correction method according to claim 8 or 9, wherein the content of the color conversion table referred to when the multi-tone print data is color-converted is increased. It is configured to rewrite in accordance with the entry / output relationship.
[0019]
That is, there is no difference in that the method is not limited to the work to be corrected by a substantial apparatus, and is effective as a method.
[0020]
By the way, as described above, the print data correction apparatus for correcting the print data may exist alone or may be used in a state of being incorporated in a certain device. Is included. Further, it can be changed as appropriate, for example, by hardware or by software.
[0021]
In the case of software for color correction as an embodiment of the idea of the present invention, it naturally exists on a software recording medium in which such software is recorded, and it must be used.
[0022]
As an example,Claim 11The present invention relates to a printing apparatus that includes a print head that is supplied from an ink tank and ejects ink particles from nozzles, and that deposits the ink particles on a recording medium to print a dot matrix image. When halftone processing is performed on the tonal print data and converted to print data for output, the print density based on the print data is corrected.Bringing functions to a computerA software recording medium on which a print data correction program is recorded, wherein the liquid level of the ink tank is detected, and the change in print density due to the amount of ink particles that changes in accordance with the liquid level is canceled out.The function of correcting the multi-gradation print data according to the detected liquid level according to the input / output relationship in which the correspondence before and after the correction for the multi-gradation print data is formed according to the gradation is realized.As a configuration.
According to a twelfth aspect of the present invention, in the software recording medium on which the print data correction program according to the eleventh aspect is recorded, the change in the liquid level obtained from the detected liquid level is larger than a predetermined amount. The above input / output relationship is created when
Further, according to a thirteenth aspect of the present invention, in the software recording medium on which the print data correction program according to the eleventh or twelfth aspect of the present invention is recorded, a color referred to when the multi-tone print data is color-converted. The contents of the conversion table are rewritten according to the input / output relationship.
[0023]
Of course, the software recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any software recording medium to be developed in the future. In addition, the duplication stages such as the primary duplication product and the secondary duplication product are equivalent without any question. In addition, even if the supply method is written on a semiconductor chip, the present invention is still used.
[0024]
Furthermore, even when a part is software and a part is realized by hardware, there is no difference in the idea of the invention, and a part is stored on a software recording medium as needed. It may be in a form that is read appropriately.
[0025]
【The invention's effect】
As described above, the present invention does not mechanically make the liquid level constant, but changes the printing density according to the changing liquid level.Multi-tone print data can be converted to multi-tone print data according to the input / output relationship formed before and after correction.Since the correction is made, it is possible to provide a print data correction apparatus capable of making the printing result constant by an easier method.
[0026]
According to the second aspect of the present invention, since the total amount of ejected ink particles is counted to detect the remaining amount of ink, a sensor for detecting the liquid level is not required, and the configuration can be made easily. it can.
Furthermore, according to the third aspect of the present invention, the print data can be corrected using the correction lookup table.
Furthermore, claim 4, Claim 9 and Claim 12According to the invention, when the change in the liquid level becomes larger than the predetermined amountInput / output relationship in which the correspondence before and after correction for the multi-tone print data is formed according to the toneBy creating this, it is possible to reduce the work that takes time to re-create.
According to the fifth aspect of the present invention, when the ink tank is replaced, a value that increases the ink loss is set as the value of the old ink remaining amount.Input / output relationship aboveWill be able to create.
Furthermore, claim 6, Claim 10, claim 13According to the invention, the color conversion table referred to in any caseInput / output relationship aboveWill be incorporated only for correctionInput / output relationship aboveThere is no need to refer to
[0027]
Further, according to the invention according to claim 7, it is possible to provide a printing system capable of making the printing result constant in the same easy manner, and according to the invention according to claim 8, the print data correction is possible. Can provide a way,Claim 11According to the invention, a software recording medium in which a print data correction program is recorded can be provided.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0029]
FIG. 1 shows a print data correction apparatus according to an embodiment of the present invention by a claim correspondence diagram. FIG. 2 shows a hardware configuration example of a printing system to which the print data correction apparatus is applied. .
[0030]
This printing system can be roughly classified into an image input device 10, an image processing device 20, and a printing device 30. The image input device 10 corresponds to a scanner 11, a digital still camera 12, or a video camera 14, and the image processing device 20 includes a computer 21, a hard disk 22, a keyboard 23, a CD-ROM drive 24, and a floppy.(R)A disk drive 25, a modem 26, a display 27, and the like are applicable, and a specific example of the printing apparatus 30 is an ink jet printer 31 and the like. The modem 26 is connected to a public communication line, connected to an external network via the public communication line, and can be installed by downloading software and data.
[0031]
Here, the scanner 11 and the digital still camera 12 as the image input device 10 output RGB (green, blue, red) 256-gradation image data as image data, and the ink-jet printer 31 as the printing device 30 receives CMYK ( Cyan, magenta, yellow and black) are required as input. Therefore, in the computer 21 as the image processing apparatus 20, the 256-gradation image data is input, predetermined image processing and printing processing are performed, and output as 2-gradation image data.
[0032]
FIG. 3 shows the flow of this image data. The image input device 10 outputs RGB multi-gradation (256 gradations) image data represented as dot-matrix pixels to the image processing device 20, and The processing device 20 performs predetermined image processing and outputs the image data to the printing device 30 as CMYK two-gradation image data (binary data). In the image processing apparatus 20, a color conversion process from the RGB color space to the CMYK color space is performed, and the RGB 256 gradation image data is converted into CMYK 256 gradation image data. Thereafter, considering that the data that can be input by the printing apparatus 30 has two gradations, a halftone process for converting 256 gradation image data into two gradation image data is executed. The image data is output to the printing apparatus 30 as print data through such a process, but can be called print data in a broad sense because it is data about the same image in the previous process. In principle, the print data correction device 30a can perform correction processing on any level of print data. In the present embodiment, the color conversion processing and the CMYK 256-gradation image data are simultaneously performed. It shall be performed against.
[0033]
Note that an operating system 21a is operating in the computer 21, a printer driver 21b and a display driver 21c corresponding to the ink jet printer 31 and the display 27 are incorporated, and the application 21d executes processing in the operating system 21a. Controlled, display is performed on the display 27 in cooperation with the display driver 21c, and printing processing is executed in cooperation with the printer driver 21b as necessary. Therefore, the printer driver 21b mainly constitutes the print data correction device 30a.
[0034]
In the present embodiment, in the process of generating print data in such a printing system, the print data correction device 30a inputs the generated print data, performs predetermined data correction, and outputs it. In this case, the ink remaining amount detecting means 30a1 obtains the ink remaining amount or the ink liquid amount in the printing apparatus 30 directly or indirectly, acquires the ink remaining amount as will be described later, and print data correcting means 30a2. Refers to the conversion table corresponding to the ink remaining amount to correct the print data. In the process of generating print data, the above-described print data conversion process 30a3 for converting the multi-tone print data into the two-tone print data is also interposed. Hereinafter, these steps will be described in detail. However, the print data conversion process 30a3 for converting the multi-tone print data into the two-tone print data employs a commonly known method and will not be described in detail.
[0035]
First, the ink jet printer 31 that performs printing based on the corrected print data will be described. FIG. 4 shows a schematic configuration of the ink jet printer 31. The print head 31a includes three print head units, the print head controller 31b that controls the print head 31a, and the print that moves the print head 31a in the digit direction. From a head digit moving motor 31c, a paper feed motor 31d for feeding printing paper in the line direction, and a printer controller 31e corresponding to an interface between these print head controller 31b, the print head digit moving motor 31c, and the paper feed motor 31d. The dot printing mechanism is provided, and an image can be printed according to the print data.
[0036]
FIG. 5 shows a more specific configuration of the print head 31a, and FIG. 6 shows an operation during ink ejection. A fine pipe line 31a3 extending from the color ink tank 31a1 to the nozzle 31a2 is formed in the print head 31a, and an ink chamber 31a4 is formed at a terminal portion of the pipe line 31a3. The wall surface of the ink chamber 31a4 is formed of a flexible material, and a piezoelectric element 31a5 that is an electrostrictive element is provided on the wall surface. The piezo element 31a5 has a crystal structure that is distorted by applying a voltage and performs high-speed electro-mechanical energy conversion. The distorted operation of the crystal structure pushes the wall surface of the ink chamber 31a4, thereby the ink chamber 31a4. Reduce the volume of the. Then, a predetermined amount of color ink particles are ejected vigorously from the nozzle 31a2 communicating with the ink chamber 31a4. This pump structure is called a micro pump mechanism.
[0037]
Note that two independent rows of nozzles 31a2 are formed in one print head unit, and color ink is supplied independently to the nozzles 31a2 in each row. Accordingly, the three print head units are each provided with two rows of nozzles 31a2, and it is possible to use six color inks to the maximum. In the example shown in FIG. 4, two rows in the left print head unit are used for black ink, only one row in the middle print head unit is used for cyan ink, and in the right print head unit. The left and right two rows are used for magenta ink and yellow ink, respectively.
[0038]
Thus, in the present embodiment, the present invention is applied to the inkjet printer 31 that employs a micropump mechanism. In the inkjet printer 31, printing is performed by ejecting one ink particle for one dot from the print head 31 a described above. However, the amount of ink particles changes according to the liquid level of the ink tank 31a1, and the amount of ink particles corresponds to the size of the dots. Therefore, the size of one dot is the size of the ink tank 31a1 after all. It changes depending on the liquid level. In the case where the print density does not change significantly by overstrike, the dot size affects the print density. Therefore, if the dot size changes according to the liquid level in the ink tank 31a1, the print density changes, and the color balance and lightness in color and the gray density in monochrome are not constant. It will be.
[0039]
In the present embodiment, the ink jet printer 31 that employs the micropump mechanism has been described. However, as long as the ink particle has a difference depending on the liquid level of the ink tank, and the print density is affected, other ink jet printers 31 may be used. The present invention can also be applied to a printer having an ink ejection mechanism.
[0040]
For example, as shown in FIG. 7, a bubble jet is provided in which a heater 31a8 is provided on the wall surface of a pipe line 31a7 in the vicinity of the nozzle 31a6, bubbles are generated by heating the heater 31a8, and color ink is discharged at that pressure.(R)A pump mechanism of the type has also been put into practical use. Even in this case, it is inevitable that the pressure state at the nozzle 31a6 differs depending on the liquid level of an ink tank (not shown) and affects the amount of ink particles.
[0041]
In this embodiment, a computer system is incorporated between the image input apparatus 10 and the printing apparatus 30 to perform printing processing. However, such a computer system is not necessarily required. For example, as shown in FIG. 8, in a printer 32 that inputs and prints image data without going through a computer system, an image as print data inputted through a scanner 11b, a digital still camera 12b, a modem 26b, or the like. It is also possible to input data and make corrections to eliminate the machine difference.
[0042]
By the way, the ink remaining amount detecting means 30a1 detects the liquid level of the ink tank 31a1 in the ink jet printer 31 having such a configuration. There are two methods for detecting the same liquid level, that is, a method for actually detecting the liquid level in the ink tank and a method for estimating the decrease in the liquid level from the amount of ink used based on the print data. Of course, the former is more reliable, but if the cartridge-type ink tank 31a1 is provided with a sensor for measuring the liquid level, the cost increases. For this reason, in the present embodiment, the latter method, which is advantageous in terms of cost, is adopted.
[0043]
FIG. 9 shows a flowchart of firmware executed by the printer controller 31e. The printer controller 31e measures the liquid level in the ink tank 31a1 by executing this firmware.
[0044]
Step S100 is a buffer process in which print data output from the computer 21 is written into or read from the buffer. Step 110 generates print data to be ejected from each nozzle 31a2 based on the print data read from the buffer. This is print data generation processing. Since it is known how many nozzles 31a2 eject ink droplets at this time, in step S120, ink particle counting processing for counting the ejected ink particles is executed. In subsequent step S130, a head moving process for moving the print head 31a to a predetermined position is executed. In step S140, a print head driving process for applying a voltage to the piezo element 31a5 of each nozzle 31a2 is executed based on the print data described above. In step S150, a process corresponding to an operation on an operation panel or the like provided in the inkjet printer 31 is executed, or a process in response to other control from the computer 21 is executed. For example, if an instruction to output the above-described ink particle count result is input from the computer 21, the output process is executed.
[0045]
Accordingly, in the printing system employing the ink jet printer 31, as shown in FIG. 10, the printer side includes the ink remaining amount detection means 30a1 together with the printing means, and the computer side includes the print data conversion means 30a3 and the print data correction. Means 30a2 will be included. On the other hand, the method for estimating the ink tank 31a1 liquid level by counting the ejected ink particles as described above is not necessarily performed on the printer side. FIG. 11 shows a block diagram when such estimation is executed on the computer side. If the ink particles are counted by a similar method when the print data is generated by the printer driver 21b of the computer 21, the remaining amount of ink can be detected. In this case, since it is necessary to reset the ink particle count when the ink tank 31a1 is replaced, in this embodiment, when the ink tank 31a1 is replaced, it can be designated by the GUI of the printer driver 21b as shown in FIG. It is like that.
[0046]
Next, the print data correction unit 30a2 that corrects the print data output to the ink jet printer 31 as described above will be described. As shown in FIG. 13, the ink remaining amount is detected on the ink jet printer 31 side, and this is acquired by the printer driver 21b on the computer 21 side, and the change in the amount of ink particles due to the ink remaining amount can be canceled. A correction lookup table for the print data is created.
[0047]
FIG. 14 shows the processing of this printer driver. When the printer driver 21b is activated, the (new) ink remaining amount based on the ink particle counter is input via the printer controller 31e in step S200. In this case, since the liquid level of the ink tank 31a1 can be calculated from the count value of the ink particles after all, it may be the remaining amount of ink or the count of ink particles. In step S210, the printer driver 21b itself reads the (old) ink remaining amount previously written. This old ink remaining amount indicates the ink remaining amount when the correction lookup table is created as will be described later. In step S220, the ink reduction is performed based on the difference between the old ink remaining amount and the new ink remaining amount. Then, it is determined whether or not this value is larger than a predetermined threshold value. Since it takes time to recreate the correction lookup table, it is not necessary to recreate the correction look-up table every time printing is performed, but to create the correction look-up table only when the amount of ink has been reduced to some extent by obtaining the ink reduction amount. It should be noted that the amount of new ink remaining after the ink replacement is larger, so the amount is not necessarily reduced.
[0048]
Therefore, if the ink reduction is not large, the color conversion process is executed in step S260 without creating a new correction lookup table to convert from 256 RGB gradations to 256 CMYK gradations, and half in step S270. After the tone processing is executed and converted into CMYK two gradations, the created print data is output to the inkjet printer 31 for printing in step S280.
[0049]
On the other hand, when the ink reduction amount is large, that is, when it is determined that the liquid level in the ink tank 31a1 has dropped to some extent since the last time the correction lookup table was created, the amount of ejected ink particles begins to affect. In step S230, a correction lookup table based on the new ink remaining amount is created. FIG. 15 shows the relationship between the remaining amount of ink and the ejected ink particles. The horizontal axis indicates the ink usage in%, and the vertical axis indicates the ink discharge weight in%. When the ink use amount is between 0% and 60%, the ink discharge weight decreases linearly, and the decrease amount tends to increase when the ink use amount exceeds 60%. Note that there is a variation in the ink discharge weight for each print head 31a, and the graph of FIG. 16 shows whether or not this downward tendency changes due to the difference in the variation. As shown in the figure, the variation in the original ink discharge weight does not greatly affect the downward trend.
[0050]
In order to correct such a downward trend, the correction lookup table is created so as to achieve the input / output relationship shown in FIG. That is, on the premise that the input / output is 256 gradations, the correspondence relationship of the γ curve is formed in which the output value is larger than the input value. Of course, the value of γ is set according to the remaining amount of ink, and at this time, it is not always necessary to use the γ curve. The value of γ is obtained in advance by experiments.
[0051]
In correcting the print data, it is not impossible to refer to the correction lookup table every time, but since the color conversion table is referred to in any case, the color conversion table is rewritten in step S250 to correct the correction lookup table. Incorporate the contents of. By doing so, the optimum correction can be performed only by performing color conversion without referring to the correction lookup table. It should be noted that the ink remaining amount when the correction lookup table is created in this way is written in a predetermined area in step S250, and when the printer driver 21b is started next time, the same ink remaining amount is obtained in step S210. Is read as the old ink remaining amount and compared with the new ink remaining amount as described above.
[0052]
FIG. 18 shows a flowchart for managing the remaining ink amount only on the printer driver 21b side. In general, the correction lookup table is created only when the amount of ink reduction is large. When it is found that the ink tank has been replaced by the GUI, the new ink remaining amount and the old ink are determined in steps S300 and S305. Reset the remaining amount. Here, the old ink remaining amount is set to a value that increases the ink reduction amount. By doing so, if the ink reduction is calculated in step S310 when the ink tank is replaced, the correction lookup is performed in steps S320 to S330 in the same manner as when it is determined that the ink reduction is large in a normal case. A table is created and the remaining ink level at that time is rewritten as the old ink level. On the other hand, since the amount of ink used cannot be determined unless the print data to be output to the ink jet printer 31 is created, after the print processing is performed in steps S335 to S345, the new ink remaining amount is obtained and written in step S350. The calculation of the ink reduction in step S310 is to calculate the difference between the new ink remaining amount and the old ink remaining amount written to each other.
[0053]
Of course, temporary storage of these various data may be performed using the hard disk 22 or the like connected to the computer 21.
[0054]
Note that, as described above, the difference in the amount of ink used for each print head 31a also affects the print density, but this correction is performed separately.
[0055]
Next, the operation of the present embodiment configured as described above will be described with reference to the flowchart of the printer driver 21b shown in FIG.
[0056]
Assuming that the image data read by the scanner 11 is printed by the printer 31, first, the application 21d is started and the scanner 11 starts reading while the operating system 21a is running on the computer 21. Let When the read image data is taken into the application 21d via the operating system 21a, predetermined image processing is performed and printing processing is selected.
[0057]
When the printing process is selected, the operating system 21a activates the printer driver 21b. The printer driver 21b instructs the inkjet printer 31 to output the ink particle count value in the first step S200 after the activation, and inputs the value counted by the firmware via the printer controller 31e. In step S210, the old ink remaining amount stored in the hard disk 22 or the like is read, and in step S220, the ink reduction amount is calculated.
[0058]
When printing is started for the first time, the old ink remaining amount is not stored and becomes “0”, and the ink reduction amount becomes a large value regardless of the new ink remaining amount. In this case, the amount is not reduced, but if the difference is large, the old correction look-up table is judged to be useless and remade. When the ink tank 31a1 is replaced, the counter is cleared and the new ink remaining amount becomes larger than the old ink remaining amount.
[0059]
In any case, it is initially determined that the ink reduction is large, and in step S230, a correction lookup table is created based on a γ value that provides a print density corresponding to the ink particles with the new ink remaining amount. However, since the ink remaining amount is close to 100% at the beginning (the amount of ink used is close to 0%), the correction look-up table has substantially no difference between input and output. In step S240, the color conversion table is rewritten based on the correction lookup table, and in step S250, the remaining ink amount to be used in the current color conversion table is written in the hard disk.
[0060]
Thereafter, color conversion is performed in step S260, halftone processing is performed in step S270, and print data is output to the inkjet printer 31 in step S280.
[0061]
On the other hand, the printer driver 21b is activated at the next printing, but if the remaining amount of ink has not changed much, printing is performed without creating a correction lookup table in steps S230 to S250. However, since the new ink remaining amount decreases each time printing is repeated, it is sometimes determined that the ink reduction amount is large, and the correction lookup table according to the ink particle amount at the new ink remaining amount as described above. Create Further, as described above, since the ink particle amount tends to decrease as the ink usage exceeds 60%, the correction amount in the correction lookup table increases accordingly.
[0062]
Of course, when the print data is corrected in this way, the print data becomes data that is printed darker than before the correction. However, as the liquid level in the ink tank 31a1 decreases, the weight of the ejected ink particles decreases, which means that the dot size decreases and the print density decreases. Then, correcting the print data to be slightly darker offsets that the dots become smaller and lighter as a result, and the print density as the original print data can be obtained. Further, the balance between the color inks is maintained, and good color reproducibility can be obtained.
[0063]
In this way, when the amount of ink particles to be discharged decreases as the liquid level of the ink tank 31a1 such as the ink jet printer 31 decreases, by detecting the ink remaining amount directly or indirectly, The amount of ink particles ejected according to the liquid level is known, and the print data has been modified to compensate for the change in the amount of ink particles, so the print results are always good regardless of the ink tank liquid level. Can be maintained.
[Brief description of the drawings]
FIG. 1 is a diagram corresponding to claims of a print data correction apparatus according to the present invention.
FIG. 2 is a block diagram illustrating a specific hardware configuration example of a printing system to which the print data correction apparatus is applied.
FIG. 3 is a block diagram illustrating a specific procedure of print processing.
FIG. 4 is a schematic block diagram of a printer.
FIG. 5 is a more detailed schematic explanatory diagram of a print head unit in the printer.
FIG. 6 is a schematic explanatory diagram illustrating a situation in which color ink is ejected by the print head unit.
FIG. 7: Bubble jet(R)It is a schematic explanatory drawing which shows the condition which discharges color ink with a printing head of a system.
FIG. 8 is a schematic block diagram illustrating another application example of the print data correction apparatus of the present invention.
FIG. 9 is a flowchart of firmware in the inkjet printer.
FIG. 10 is a diagram showing a functional configuration in the present embodiment.
FIG. 11 is a diagram illustrating a functional configuration in another application example.
FIG. 12 is a diagram showing a GUI screen of a printer driver in the application example.
FIG. 13 is a diagram illustrating a flow of a procedure in hardware indicating ink remaining amount detection and print data correction.
FIG. 14 is a flowchart of a printer driver.
FIG. 15 is a graph showing the relationship between ink usage and ink discharge weight.
FIG. 16 is a graph showing a change state of an ink discharge weight in a print head having variations.
FIG. 17 is a graph showing an input / output relationship in a correction lookup table.
FIG. 18 is a flowchart of a printer driver according to a modified example.
[Explanation of symbols]
10. Image input device
20 Image processing apparatus
21 ... Computer
23 ... Keyboard
30 ... Printing device
31-32 ... Printer

Claims (13)

Multi-tone print data is provided to a printing device that has a print head that is supplied from an ink tank and ejects ink particles from nozzles, and that prints a dot matrix image by attaching the ink particles onto a recording medium. A print data correction device for correcting a print density based on the print data when the halftone process is performed and converted into print data, the ink remaining amount detecting means for detecting the liquid level of the ink tank, The correspondence before and after the correction for the multi-tone print data is detected according to the input / output relationship formed according to the gradation so as to cancel the change in the printing density due to the amount of ink particles that changes according to the liquid level. And a print data correcting means for correcting the multi-gradation print data according to the liquid level . 2. The print data correction apparatus according to claim 1, wherein the ink remaining amount detecting means counts the total amount of ejected ink particles, and the liquid level for estimating the liquid level reduction amount based on the counting result. And a print data correction apparatus. In the print data correction apparatus according to claim 1 or 2 ,
In the print data correction means, a correspondence relationship before and after the correction for the multi-tone print data is formed in accordance with the gradation so as to cancel the change in the print density due to the amount of ink particles changing in accordance with the liquid level. By reading the corrected multi-tone print data corresponding to the detected liquid level corresponding to the multi-tone print data before correction with reference to the corrected lookup table, print data correction device, characterized by modifying the print data. In the print data correction apparatus according to any one of claims 1 to 3 ,
The print data correction device, wherein the print data correction means creates the input / output relationship when a change in the liquid level obtained from the detected liquid level becomes larger than a predetermined amount. In the print data correction apparatus according to claim 4 ,
The print data correction means stores the detected liquid level as an old ink remaining amount, and sets a value that increases the ink reduction as the old ink remaining amount when the ink tank is replaced. A print data correction apparatus characterized by the above. In the print data correction device according to any one of claims 1 to 5,
The print data correction device, wherein the print data correction means rewrites the content of a color conversion table referred to when the multi-tone print data is color-converted according to the input / output relationship . A printing system comprising a printing device and a printing control device, wherein the printing device includes a print head that is supplied from an ink tank and ejects ink particles from a nozzle, and the ink particles are adhered to a recording medium. A printing unit that prints a dot matrix image; and a remaining ink amount detecting unit that detects a liquid level in the ink tank. The correspondence between the print data conversion means for converting to data and the correction before and after the correction for the multi-tone print data so as to cancel the change in the print density due to the ink particle amount changing according to the liquid level depends on the tone. It is characterized by comprising a print data correction means for correcting the print data of the multi-tone in response to the detected liquid level according to the input-output relationship formed Te Printing system. Multi-tone print data is provided to a printing device that has a print head that is supplied from an ink tank and ejects ink particles from nozzles, and that prints a dot matrix image by attaching the ink particles onto a recording medium. When correcting the print density based on the print data when it is converted to print data by halftone processing and output, the ink level that detects the liquid level in the ink tank and changes according to the liquid level In order to cancel the change in print density due to the multi-tone print data, the multi-tone print data has a correspondence relationship before and after correction according to the input / output relationship formed according to the tone, and the multi-tone according to the detected liquid level. A print data correction method comprising correcting the print data. In the print data correction method according to claim 8,
  A printing data correction method, wherein the input / output relationship is created when a change in the liquid level obtained from the detected liquid level becomes larger than a predetermined amount. In the print data correction method according to claim 8 or 9,
  A method of correcting print data, comprising: rewriting the contents of a color conversion table referred to when color-converting the multi-tone print data according to the input / output relationship. Multi-tone print data is provided to a printing device that has a print head that is supplied from an ink tank and ejects ink particles from nozzles, and that prints a dot matrix image by attaching the ink particles onto a recording medium. A software recording medium having recorded thereon a print data correction program for causing a computer to realize a function of correcting a print density based on the print data when halftone processing is performed and converted into print data. The correspondence before and after the correction for the multi-tone print data was formed according to the gradation so as to cancel the change in the print density due to the amount of ink particles changing according to the liquid level . depending on the detected liquid level according to the input-output relationship that to realize the function of correcting the print data of the multi-tone Recorded software recording medium the print data modification program to symptoms. A software recording medium recording the print data correction program according to claim 11,
  A software recording medium on which a print data correction program is recorded, wherein the input / output relationship is created when a change in the liquid level obtained from the detected liquid level exceeds a predetermined amount. In a software recording medium on which the print data correction program according to claim 11 or 12 is recorded,
  A software recording medium having a print data correction program recorded thereon, wherein the contents of a color conversion table referred to when performing color conversion on the multi-tone print data are rewritten according to the input / output relationship.

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