JPH1134359A - Print data corrector, print system, print data correcting method, and software recording medium having print data correction program recorde therein - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a constant print result even when the use period of ink is prolonged by correcting a print data based on a detected use period such that the fluctuation of print density due to the viscosity of ink variable with the use period is canceled. SOLUTION: In the process of a print system for generating a print data, a print data corrector 30a receives a generated print data and outputs a data corrected as specified. A use period detecting means 30a1 determines the use period of ink in a printer 30 directly or indirectly. Since the ink is replaced in units of cartridge in case of an ink jet printer, the period after loading an ink cartridge is measured. A print data correction means 30a2 corrects the print data with reference to a conversion table corresponding to the loading period quantity of ink thus obtaining constant print results at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a print data correction device, a print system, a print data correction method, and a software recording medium on which a print data correction program is recorded.

[0002]

2. Description of the Related Art In recent years, the definition of a color ink jet printer has been advanced, and the color ink jet printer has been called a so-called photographic image quality. In such an ink jet printer, a predetermined color dot is attached to a desired position by discharging a predetermined color ink in a granular form, and an image is expressed in a dot matrix form. In this case, a color image is reproduced using three color inks of cyan (C), magenta (M) and yellow (Y) or four color inks obtained by adding black (K) thereto.

[0003] In order to be referred to as photographic image quality, it is important to reduce the size of dots, but color reproducibility is also extremely important. In spite of the fact that colors are represented by red, green and blue (RGB) multi-gradation data inside the computer, the printer can only support CMYK two-gradation data. Have been done. In other words, it is realized by CMYK two-gradation display while maintaining the color represented by RGB multi-gradation. Of course,
Here, it is assumed that each dot is colored at a prescribed density.

However, although the print data is output while maintaining color reproducibility, the weight of the color ink particles ejected by the print head differs depending on the ink viscosity, and as a result, each dot becomes It may not be said that the color is developed at the original density.

[0005]

In the above-described conventional color ink jet printer, ink is supplied from an ink cartridge to a nozzle through a liquid supply line, but the viscosity of the ink is changed by aging. Get higher. That is, the viscosity of the ink gradually increases with time, so that it becomes difficult for the ink to flow through the liquid supply pipe, and the weight of the ejected ink particles gradually decreases. Then, it cannot be said that each dot is colored at the original density, and as a result, there is a problem that color reproducibility may be deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an object to provide a print data correction apparatus, a print system, and a print data correction method capable of obtaining a fixed print result even when the period of using ink is prolonged. It is an object of the present invention to provide a print data correction method and a software recording medium on which a print data correction program is recorded.

[0007]

According to a first aspect of the present invention, there is provided a print head for discharging ink supplied via a liquid supply pipe from a nozzle in a granular manner. In a printing device that prints a dot matrix image by attaching the ink of the present invention onto a recording medium, halftone processing is performed on multi-gradation print data to convert it into two-gradation print data and output it.
What is claimed is: 1. A print data correcting apparatus for correcting a print density based on the print data, comprising: a use period detecting means for detecting a use period of the ink; Print data correcting means for correcting the print data based on the detected use period so as to cancel the print data.

[0008] In the invention according to claim 1 configured as described above, the print head of the printing apparatus has a nozzle for supplying ink through a liquid supply pipe, and ink droplets are discharged from the nozzle. Discharge. Therefore, the amount of ejected ink particles changes depending on the viscosity of the ink. When a dot matrix image is printed by attaching the same ink particles to a recording medium, the size of the dots changes depending on the amount of the ink particles, and the print density per dot changes.

On the other hand, the use period detecting means detects the use period of the ink, and the print data correcting means detects that the print density is reduced by the amount of ink particles which changes according to the ink viscosity corresponding to the detected use period. The print data is corrected based on the detected liquid level so as to cancel. On this premise, the multi-gradation print data is converted into two-gradation print data by halftone processing and output. However, in this process, the print data contains print density information. The print data is corrected so as to change the print density as described above. In other words, the print density is made constant by correcting the print data according to the ink usage period.

[0010] A printing apparatus is a device in which ink particles are deposited on a recording medium by a print head supplied through a liquid supply pipe, and has a correlation with the amount of ink particles with respect to a period of use of the ink. Should be fine. In this case, the method of discharging the ink particles is not particularly limited, and
It can be applied to various types such as a micro pump type and a bubble jet type.

The use period detecting means only needs to be able to substantially detect the use period of the ink, and various detection methods can be adopted. For example, if only the ink is to be refilled into the ink tank, the usage period may be measured from the ink replenishment timing. However, many ink jet printers use ink cartridges. As a preferred example in such a case, the invention according to claim 2 is the print data correction device according to claim 1, wherein the ink is an ink cartridge. And the liquid is supplied to the nozzles from the liquid supply conduit, and the use period is set to a period for loading the ink cartridge.

In the invention according to claim 2 configured as described above, the ink is additionally replenished for each ink cartridge, and the ink is supplied from the ink cartridge to the nozzle via the liquid supply conduit. Therefore, the loading period of the ink cartridge is the use period, and the loading period is counted.

Needless to say, the loading period and the use period may be timed on the printing apparatus side, or may be changed as appropriate, such as timed on the printing data correction apparatus side.

By the way, the print data correcting device for correcting the print data in this way does not necessarily have to be an integrated device, and various modifications are possible. As an example, the invention according to claim 3 is a printing system including a printing device and a printing control device, wherein the printing device discharges ink supplied through a liquid supply pipe from a nozzle in a granular manner. A print head that prints a dot matrix image by attaching the same granular ink onto a recording medium, and a use period detection unit that detects a use period of the ink. The apparatus includes a print data conversion unit that converts multi-gradation print data into two-gradation print data by performing halftone processing, and cancels a change in print density due to an ink viscosity that changes according to the usage period. And print data correction means for correcting the print data based on the detected use period.

According to the third aspect of the present invention, as described above, the use period detecting means of the printing apparatus provided with the printing means having a correlation between the use period of the ink and the amount of the ink particles is provided. The print data correction means of the print control device, which converts the print data from multi-gradation to two-gradation and outputs the data to such a printing apparatus, is based on the detected use period of the ink. The print data is corrected to cancel the change in print density due to the amount of ink particles changing according to the usage period.

In this case, the use period detecting means is provided in the printing apparatus, but a specific configuration example of the printing system is not limited to this. For example, the use period detecting means may be called a print data correcting apparatus. It is not something to be done. In addition, since the use period can be detected as long as the start of use of the ink can be grasped, the detection may be performed on either the printing apparatus side or the print control apparatus side.

Further, the invention is not necessarily limited to a form-shaped device, and as an example, the invention according to claim 4 is a device for ejecting ink supplied through a liquid supply pipe from a nozzle in a granular manner. For a printing device that prints a dot matrix image by attaching the same granular ink on a recording medium and printing it, it converts the multi-gradation print data into two-gradation print data by halftone processing and outputs it A print data correction method for correcting a print density based on the print data, wherein the print data correction method detects a use period of the ink and cancels a change in print density due to an ink viscosity that changes according to the use period. Thus, the print data is corrected based on the detected use period.

That is, there is no difference that the method is not necessarily limited to the work of correcting with a substantial device, and is effective as a method.

Incidentally, as described above, a print data correcting apparatus for correcting 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 appropriately changed, for example, by hardware or software.

In the case of software for correcting colors as an embodiment of the idea of the present invention, the software naturally exists on a software recording medium on which such software is recorded.
I have to say that it is used.

As one example, the invention according to claim 5 is provided with a print head that discharges ink supplied through a liquid supply pipe from a nozzle in a granular manner, and causes the same granular ink to adhere to a recording medium. In a printing apparatus that prints an image in the form of a dot matrix, halftone processing is performed on multi-gradation print data to convert it into two-gradation print data, and when outputting the data, the print density based on the print data is corrected. A software recording medium on which a print data correction program is recorded, wherein the use period of the ink is detected, and the detected use period is changed so as to cancel a change in print density due to an ink viscosity that changes according to the use period. The configuration is such that the print data is corrected based on a period.

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. Also, the duplication stages of the primary duplicated product, the secondary duplicated product, and the like are equivalent without any question. In addition, the present invention is still used even when the supply method is performed using a communication line, and the same applies to a case where the information is written on a semiconductor chip.

Further, even when a part is implemented by software and a part is implemented by hardware, there is no difference in the concept of the invention, and it is necessary to store a part on a software recording medium. May be in a form that is read as appropriate in accordance with.

[0024]

As described above, according to the present invention, even when the amount of ink to be ejected is reduced as a result of a prolonged period of use of the ink and an increase in the viscosity of the ink, printing is performed in accordance with the changing amount of ink. Since the print data is modified so as to change the density, it is possible to provide a print data modifying apparatus capable of keeping the print result constant by an easy method.

According to the second aspect of the present invention, since the use period of the ink is detected during the loading period of the ink cartridge, the time can be easily measured.

Further, according to the invention of claim 3,
Similarly, it is possible to provide a printing system capable of keeping a printing result constant by an easier method, and according to the invention according to claim 4, it is possible to provide a similar print data correction method. According to the fifth aspect, it is possible to provide a software recording medium on which a similar print data correction program is recorded.

[0027]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a print data correcting apparatus according to an embodiment of the present invention in a claim correspondence diagram. FIG. 2 is a block diagram showing an example of a hardware configuration of a printing system to which the print data correcting apparatus is applied. Is shown.

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, and a CD-R.
The OM drive 24, the floppy disk drive 25, the modem 26, the display 27, and the like correspond thereto, and a specific example of the printing device 30 corresponds to the ink jet printer 31 or the like. The modem 26 is connected to a public communication line, is connected to an external network via the public communication line, and can download and install software and data.

Here, the scanner 11 and the digital still camera 12 as the image input device 10 output image data of 256 gradations of RGB (green, blue, red) as image data, and the ink jet printer 31 as the printing device 30.
Is CMYK (cyan, magenta, yellow, black)
Is required as input. Therefore, in the computer 21 as the image processing device 20, the image data of 256 gradations is inputted, predetermined image processing and printing processing are performed, and the image data is output as image data of two gradations.

FIG. 3 shows the flow of this image data. The image input device 10 outputs to the image processing device 20 the RGB multi-tone (256 tones) image data represented as pixels in a dot matrix. The image 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). The image processing device 20 performs a color conversion process from the RGB color space to the CMYK color space, and in this process, the RGB 256-gradation image data is converted into the CMYK 256-gradation image data. Thereafter, the data that can be input by the printing device 30 is 2
In consideration of the gradation, halftone processing for converting image data of 256 gradations into image data of 2 gradations 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 since it is substantially the same image data even in a process before that. The print data correction device 30a can correct the print data at any stage in principle. In the present embodiment, the print data correction device 30a converts the CMYK image data of 256 tones simultaneously with the color conversion process. It is to be done.

In the computer 21, an operating system 21a is running, and a printer driver 21b and a display driver 21c corresponding to the ink jet printer 31 and the display 27 are installed. The application 21d is processed by the operating system 21a. Is controlled, and the display 27 is operated in cooperation with the display driver 21c.
, And print processing is executed in cooperation with the printer driver 21b as necessary. Therefore,
The printer driver 21b mainly forms the print data correction device 30a.

In the present embodiment, in the process of generating print data in such a printing system, the print data correcting device 30a inputs the generated print data, corrects the data, and outputs it. in this case,
The use period detecting unit 30a1 directly or indirectly determines the use period of the ink in the printing apparatus 30, and obtains the ink cartridge loading period as described later. Correct the print data with reference to the corresponding conversion table. In the process of generating print data, a print data conversion process 30a3 for converting the above-described multi-gradation print data into two-gradation print data is also interposed. Hereinafter, these steps will be described in detail. However, the print data conversion processing 30a3 for converting the multi-gradation print data into the two-gradation print data employs an ordinary well-known method and will not be described in detail.

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, a print head 31a including three print head units, a print head controller 31b for controlling the print head 31a, and printing for moving the print head 31a in the digit direction. A head girder moving motor 31c, a paper feed motor 31d for feeding printing paper in the row direction, and a printer controller 31e which is an interface between the print head controller 31b, the print head girder moving motor 31c, and the paper feed motor 31d to an external device. Dot printing mechanism, and can print an image according to print data.

FIG. 5 shows a more specific configuration of the print head 31a, and FIG. 6 shows an operation at the time of ink ejection. A detachable ink cartridge 31a1 is provided for supplying ink to the print head 31a. A fine conduit 31a3 from the ink cartridge 31a1 to the nozzle 31a2 is formed, and an end portion of the conduit 31a3. Is formed with an ink chamber 31a4. The wall surface of the ink chamber 31a4 is formed of a material having flexibility, and the wall surface of the ink chamber 31a4 is a piezoelectric element 3 which is an electrostrictive element.
1a5 is provided. The piezo element 31a5 has a crystal structure that is distorted by applying a voltage and performs high-speed electrical-mechanical energy conversion. The distortion operation of the crystal structure pushes the wall surface of the ink chamber 31a4, and the ink chamber 31a4 is pressed. Decrease the volume of Then, a predetermined amount of color ink particles is vigorously ejected from the nozzle 31a2 communicating with the ink chamber 31a4. This pump structure is called a micro pump mechanism.

A cartridge sensor 31f for detecting the presence or absence of each ink cartridge 31a1 is also provided. The cartridge sensor 31f is connected to a printer controller 31e so that the printer controller 31e can detect the presence or absence of each ink cartridge 31a1. I have.

It should be noted that two independent rows of nozzles 31a2 are formed in one print head unit, and color ink is supplied to each row of nozzles 31a2 independently. Therefore, each of the three print head units is provided with two rows of nozzles 31a2, and it is possible to use the six color inks to the maximum extent. 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 The left and right two rows are used for magenta ink and yellow ink, respectively.

As described above, in this embodiment, the ink jet printer 31 employing the micropump mechanism is used.
Has been applied. In the inkjet printer 31, printing is performed by discharging one ink particle for one dot from the above-described print head 31a. However, since the amount of ink droplets changes according to the ink viscosity, and the amount of ink droplets corresponds to the size of the dots, the size of one dot eventually changes according to the ink viscosity. Will be. If the printing density does not change much due to overprinting, the size of the dot has an effect on the printing density. Therefore, if the size of the dot changes in accordance with the ink viscosity, the print density changes, and the color balance and lightness become uncertain in color, and the gray density becomes inconsistent in monochrome.

In the present embodiment, the ink jet printer 31 employing the micropump mechanism has been described. However, if the difference in the ink particles depending on the ink viscosity causes the print density to be affected, other ink jet printers may be used. The present invention is also applicable to a printer having an ink ejection mechanism.

For example, as shown in FIG.
A heater 31a8 is provided on the wall surface of the nearby conduit 31a7, and a bubble jet type pump mechanism that heats the heater 31a8 to generate bubbles and discharges color ink at the pressure is also in practical use. Even in this case, if the ink usage period is prolonged and the ink viscosity changes, it is inevitable that the amount of ink droplets ejected from the nozzle 31a6 will be affected.

In the present embodiment, a computer system is incorporated between the image input device 10 and the printing device 30 to perform the printing process. However, such a computer system is not always required. For example, as shown in FIG. 8, in a printer 32 that inputs and prints image data without passing through a computer system, an image as print data input through a scanner 11b, a digital still camera 12b, a modem 26b, or the like. It is also possible to configure so as to input data and make a correction to eliminate the machine difference.

By the way, the use period detecting means 30a1 detects the use period of the ink in the ink jet printer 31 having such a configuration. In the present embodiment, since the ink is exchanged in units of the ink cartridge 31a1, the charging period from when the ink cartridge 31a1 is mounted to the present is substantially measured and detected.

Although it is possible to detect the replacement of the ink cartridge 31a1 by the cartridge sensor 31f and measure the time in the ink jet printer 31,
Originally, it is normal that it does not have a timing function,
For that purpose, it is necessary to provide timekeeping means. On the other hand, in the computer 21 that causes the inkjet printer 31 to perform printing, the printer driver 21b exchanges various information including a paper jam of the inkjet printer 31 via the printer controller 31e. Therefore, the printer driver 21b
If the replacement timing of the ink cartridge 31a1 is acquired on the side of and the information is stored in the hard disk 22 or the like, the use period can be easily detected by using the timekeeping means provided in the computer 21. In the present embodiment, in consideration of such a background, the use period is mainly detected on the computer 21 side while using the cartridge sensor 31f in the inkjet printer 31.

FIG. 9 shows a flowchart of the firmware executed by the printer controller 31e. The printer controller 31e monitors whether or not the ink cartridge 31a1 has been replaced during execution of the firmware.

Step S100 is a buffer process for writing the print data output from the computer 21 to the buffer or reading the print data from the buffer.
Is print data generation processing for generating print data for discharging from each nozzle 31a2 based on print data read from the buffer. Thereafter, in S120, the detection status of the cartridge sensor 31f is checked, and a change point from the state where it is determined that there is no ink cartridge 31a1 to the state where it is determined that there is an ink cartridge 31a1 is monitored. Then, when this change point is detected, it can be determined that the ink cartridge 31a1 has been replaced. Therefore, the printer controller 31e notifies the printer driver 21b that the ink cartridge has been replaced. In the next 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 based on the above-described print data is executed. Step S
At 150, a process corresponding to an operation of an operation panel or the like provided on the inkjet printer 31 is executed, or an external operation corresponding process in response to another control from the computer 21 is executed. In the above description, the printer driver 21b is notified that the ink cartridge 31a1 has been replaced in step S120. For example, in step S120, only the detection result of the cartridge sensor 31f is monitored, At S150, it may be notified that the ink cartridge 31a1 has been replaced in response to an inquiry from the computer 21.

Therefore, the ink jet printer 31
As shown in FIG. 10, in the printing system employing the printer, a use period detecting unit 30a1 using a cartridge sensor 31f on the side of the ink jet printer 31, a print data correcting unit 30a2, and a print data converting unit 30a.
3 is included on the computer 21 side. In this case, the replacement timing of the ink cartridge 31a1 does not necessarily have to be detected on the ink jet printer 31 side.
When the a1 is replaced, the printer driver 21b may directly monitor via the GUI as shown in FIG.

On the other hand, the use period of the ink cartridge 31a1 does not necessarily have to be timed on the computer 21 side, but may be detected by providing the ink jet printer 31 with a time measuring means as described above. FIG. 12 shows a printing system in this case.

Next, a description will be given of the print data correcting means 30a2 for correcting the print data output to the ink jet printer 31 as described above. As described above, the printer driver 21b uses the usage period detecting unit 30a1.
The correction look-up table for print data is created so that the influence of the ink viscosity, which varies according to the usage period, on the print density can be canceled. In order to reduce the frequency of creating the correction look-up table, save the table update date of updating the correction look-up table, and re-create the correction look-up table only when a predetermined period or more has elapsed. To

FIG. 13 shows the processing of the printer driver. When the printer driver 21b is started, it is inquired in step S200 whether or not the ink cartridge has just been replaced with the ink jet printer 31, and if it is immediately after the replacement, in step S205 the current date is set as the ink cartridge replacement date. The data is written and stored in the hard disk 22 or the like. This date is managed by the operating system 21a, and thereafter, by referring to the hard disk 22, it is always possible to know when the currently used ink cartridge 31a1 has been used. The ink cartridge 31
When a1 is replaced, it is necessary to update the correction look-up table, and the table update date is changed to a predetermined old date.

Next, in step S210, the interval from the update of the correction look-up table to today is calculated. The table update date was written to the hard disk 22 when the correction lookup table was updated last time, and the latest update date is read and compared. And
In step S215, it is determined whether the update interval is large,
If a predetermined period (for example, 10 days) has elapsed, the correction look-up table will be created again.
Of course, if the period is less than this period, the color conversion process is executed in step S240 without creating a new correction lookup table, and the 256th gradation of RGB is used for CMYK.
After performing halftone processing in step S245 to convert to CMYK two gradations, the created print data is output to the inkjet printer 31 and printed in step S250. become.

On the other hand, if a predetermined period or more has elapsed since the last update date, that is, if it is determined that the ink viscosity has increased to some extent since the last time the correction look-up table was created, the size of the ejected ink particles Since the amount begins to be affected, the use period from the date of ink cartridge replacement to today is calculated in step S220.
At 225, a correction look-up table based on the usage period is created. FIG. 14 shows the relationship between the usage period and the ink droplets to be ejected. The horizontal axis indicates the usage period in days, and the vertical axis indicates the ink ejection weight in%. The amount of ink used tends to decrease linearly in proportion to the number of days. It should be noted that there is a variation in the ink ejection weight for each print head 31a, and a graph in FIG. 15 shows whether or not the downward tendency changes depending on the variation. As shown in the figure, the variation in the original ink ejection weight does not significantly affect the downward tendency.

To correct such a downward tendency, a correction look-up table is created so as to achieve the input / output relationship shown in FIG. That is, assuming that the input and output are 256 gradations, a correspondence relationship of the γ curve in which the output value is larger than the input value is formed. Of course, the value of γ is set according to the usage period, and the γ curve need not always be used at this time. The value of γ is obtained in advance by an experiment.

When correcting the print data,
Although it is not impossible to refer to the correction look-up table, in any case, since the color conversion table is referred to, the color conversion table is rewritten in step S230 to incorporate the contents of the correction look-up table. By doing so, the optimum correction will be executed only by color conversion without referring to the correction lookup table. When the correction look-up table is created in this way, the date of today is written as a table update date in a predetermined area of the hard disk 22 in step S235 as described above.

Although this flowchart corresponds to the printing system configuration shown in FIG. 10, when the printer is provided with the use period detecting means as shown in FIG.
The printer driver 21b may execute a flowchart as shown in FIG. In this case, when the printer driver 21b is activated, the use period is input via the printer controller 31e in step S300. next,
In step S305, the old usage period previously written by the printer driver 21b itself is read. The old use period indicates the use period when the correction lookup table is created. In step S310, an interval is obtained based on the difference between the old use period and the new use period. It is determined whether it is greater than.

As described above, it takes time to re-create the correction look-up table, so that the update interval is also reduced in this example. If the interval is large, the content of the current correction look-up table begins to affect the amount of ejected ink droplets.
In step S320, a correction look-up table based on the new use period is created, the color conversion table is rewritten to incorporate the contents of the correction look-up table, and in step S325, the current use period can be read as the old use period. It is written on the hard disk 22. Therefore, when the printer driver 21b is started up from the next time, the same use period is read as the old use period in step S305, and compared with the new use period as described above.

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 separately performed.

Next, the printer driver 21 shown in FIG.
The operation of this embodiment having the above configuration will be described with reference to the flowchart of FIG.

Assuming that the image data read by the scanner 11 is to be printed by the ink jet printer 31, first, the application 2 is executed on the computer 21 while the operating system 21 a is running.
1d is started, and the scanner 11 starts reading. When the read image data is captured by the application 21d via the operating system 21a, predetermined image processing is performed, and print processing is selected.

When the printing process is selected, the operating system 21a activates the printer driver 21b. After startup, the printer driver 21b inquires of the inkjet printer 31 in the first step S200 as to whether or not the ink cartridge has just been replaced. When printing is performed for the first time, since the ink cartridge has just been replaced, the date of the day managed by the operating system 21a is stored as the ink cartridge replacement date in step S205, and the table update date is changed to a predetermined old date. In order to save the table update date. Thereafter, in step S210, the date of updating the table is read and compared with the date of the current day.
The table update interval is calculated, but since the table update date has been rewritten immediately before that to be the old date, the table update interval is large. Then, in step S215, it is also determined that the table update interval is equal to or greater than the threshold value, and the stored ink cartridge replacement date is read in step S220 and subtracted from the current date to calculate the use period. In step S225, a correction look-up table is created based on the usage period thus calculated. However, at the beginning, since the ink viscosity is in the initial state, there is substantially no difference between the input and output in the correction look-up table. In step S230, the color conversion table is rewritten based on the correction look-up table. In step S235, the updated table update date is written to the hard disk 22.

Thereafter, color conversion is performed in step S240.
After performing the halftone processing in step S245, the print data is output to the inkjet printer 31 in step S250.

On the other hand, the printer driver 21b is also started at the time of the next printing. At this time, it is determined that the ink cartridge has not been replaced immediately. Then, printing is performed without creating a correction look-up table in steps S240 to S250.

However, the ink viscosity should increase as the period elapses, and occasionally it is determined that the table update interval is larger than the threshold, and a correction look-up table corresponding to the ink usage period is created. I do.

Of course, when the print data is corrected in this way, the print data becomes data to be printed darker than before the correction. However, as the viscosity of the ink increases, the weight of the ejected ink particles decreases, which means that the dot size decreases and the print density decreases. In this case, the correction of the print data to a slightly higher density is offset by the smaller dots resulting in a smaller print density, and a 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.

As described above, when the ink is ejected while supplying the ink through the liquid supply line as in the ink jet printer 31, the viscosity of the ink increases as the use period of the ink becomes longer, and the ejected ink is increased. Since the amount of ink drops is also reduced, the amount of ink drops ejected is estimated by detecting the ink usage period, and the print data is modified so as to compensate for the change in the amount of ink drops. It is possible to always maintain good printing results regardless of the ink usage period.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to a claim of a print data correcting apparatus of 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 device is applied.

FIG. 3 is a block diagram illustrating a specific procedure of a printing process.

FIG. 4 is a schematic block diagram of a printer.

FIG. 5 is a more detailed schematic explanatory view of a print head unit in the printer.

FIG. 6 is a schematic explanatory view showing a situation in which color ink is ejected by the print head unit.

FIG. 7 is a schematic explanatory view showing a situation in which color ink is ejected by a print head of a bubble jet system.

FIG. 8 is a schematic block diagram showing another application example of the print data correction device of the present invention.

FIG. 9 is a flowchart of firmware in the inkjet printer.

FIG. 10 is a diagram illustrating a functional configuration according to the embodiment;

FIG. 11 is a diagram illustrating a GUI screen of a printer driver.

FIG. 12 is a diagram showing a functional configuration in another application example.

FIG. 13 is a flowchart of a printer driver.

FIG. 14 is a graph showing a relationship between an ink usage period and an ink ejection weight.

FIG. 15 is a graph showing a change state of an ink ejection weight in a print head having variations.

FIG. 16 is a graph showing an input / output relationship in a correction lookup table.

FIG. 17 is a flowchart of a printer driver according to a modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Image input device 20 ... Image processing device 21 ... Computer 23 ... Keyboard 30 ... Printing device 31-32 ... Printer

Claims (5)

[Claims] 1. A printing method comprising: providing a print head for discharging ink supplied via a liquid supply pipe from a nozzle in a granular manner; and attaching the same granular ink onto a recording medium to print a dot matrix image. A print data correction device that corrects a print density based on the print data by converting the multi-gradation print data into two-tone print data by halftone processing and outputting the print data to the device. A use period detecting means for detecting a use period of the print data, and print data for correcting the print data based on the detected use period so as to cancel the change in print density due to the ink viscosity changing according to the use period. A print data correction apparatus, comprising: correction means. 2. The print data correcting apparatus according to claim 1, wherein the ink is loaded via an ink cartridge and supplied from the liquid supply pipe to the nozzle, and the ink is used for a period of time. A print data correction apparatus, which is a loading period of the ink cartridge. 3. A printing system comprising a printing device and a printing control device, wherein the printing device includes a print head that discharges ink supplied via a liquid supply pipe from a nozzle in a granular manner. A printing unit that prints a dot matrix image by adhering granular ink onto a recording medium; and a use period detection unit that detects a use period of the ink. Print data conversion means for converting print data into two-gradation print data by performing halftone processing; and a use period detected so as to cancel a change in print density due to an ink viscosity that varies according to the use period. A print data correction unit for correcting the print data based on the print data. 4. A printing method comprising a print head for discharging ink supplied via a liquid supply pipe from a nozzle in a granular manner, and printing a dot matrix image by depositing the same granular ink on a recording medium. A print data correction method for correcting print density based on the print data when converting and outputting two-tone print data by performing halftone processing on the multi-gradation print data for the apparatus,
Detecting the use period of the ink, and correcting the print data based on the detected use period so as to cancel the change in print density due to the ink viscosity that changes according to the use period. Print data correction method. 5. A printing method comprising: providing a print head for discharging ink supplied via a liquid supply pipe from a nozzle in a granular manner; and attaching the same granular ink onto a recording medium to print a dot matrix image. A software recording medium storing a print data correction program for correcting a print density based on the multi-gradation print data based on the multi-gradation print data when the multi-gradation print data is converted into two-gradation print data by outputting the data to the device. Detecting a use period of the ink and correcting the print data based on the detected use period so as to cancel a change in print density due to an ink viscosity that changes according to the use period. A software recording medium on which a print data correction program is recorded.