JPH0911508A - Printer - Google Patents

Abstract

PURPOSE: To properly correct the density irregularity of a specific color other than a reference color by using the image reading systems adapted to the reference values of Y, M, C, Bk in an ink jet printer. CONSTITUTION: When a test image of a specific color is read by a reading means 31, the color thereof is judged by a hue judging means 601. The optimum one among brightness signals passed through R, G, B filters is selected on the basis of this judgment to be converted to a density value (density formation 603). By the function f(x) corresponding to the color judged with respect to this density value, the density value corresponding to the judged color is set (correction value formation 604, conversion table formation 605) and the correction value corresponding to each emitting orifice is calculated on the basis of the density value and density irregularity is corrected (608).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing device,
More specifically, the present invention relates to correction of density unevenness and the like using a reading system when printing is performed using a color other than the reference color normally used for printing.

[0002]

2. Description of the Related Art In recent years, a printing apparatus used in a printer, a copying machine, a facsimile or the like, or an inkjet printing apparatus (hereinafter referred to as an inkjet printing apparatus) as an information output apparatus of a composite electronic apparatus such as a computer or a word processor or a workstation ) Is becoming popular. An inkjet printing apparatus prints by ejecting ink from an inkjet head onto a printing material. According to this method, it is easy to reduce the size of the head and the structure associated with it, and to print high-definition images. High-speed recording, low running cost, low noise due to non-impact method, and easy recording of color images using multicolor inks. Have advantages.

In particular, an ink jet head of a type which ejects ink by utilizing thermal energy is provided with an electrothermal conversion element, an electrode, a liquid path and the like on a substrate such as silicon by a semiconductor manufacturing process such as etching, vapor deposition and sputtering. By forming and further attaching a top plate or the like, it is possible to easily manufacture a device having a high-density liquid passage arrangement (ejection outlet arrangement), and further downsize.

As one printing method of an ink jet printing apparatus in which such a head can be used, a direction (hereinafter, referred to as a main scanning direction) intersecting a conveyance direction of a material to be printed (hereinafter also referred to as a sub scanning direction) is used. A serial scan method in which a head is scanned to perform printing is known. In this method, one line is formed by ejecting ink from an inkjet head mounted on a carriage that moves in the main scanning direction along a recording material. Minute image is printed, and after the printing of one line is completed, a predetermined amount of paper is fed (pitch conveyance) in the sub-scanning direction, and then the image of the next line is fed to the recording material that has stopped again. By repeating the operation of printing, the entire printing material is printed. In this way, by using an inkjet head capable of arranging a plurality of ejection openings in the print material conveyance direction, the array length of the ejection openings can directly correspond to the print width for one line, that is, the pitch feed amount. This makes it possible to further speed up printing.

However, there may be variations in the amount of ink ejected from each ejection port of the ink jet head and in the ejection direction, so that the variations cause density unevenness and periodic streaks in the entire printed image. However, there is a problem that the image quality is deteriorated. There is also a problem that density unevenness and the like change with time when printing for a long time.

In response to the above problems, a predetermined head ejection state check test image is printed on a print material other than the print material to be printed, and the print head is read based on the read result of the test image. It has been proposed to control the drive of the.

As a test image reading means used in this control, a scanner having a color sensor is used.
It is conventionally known to obtain a density signal value through a complementary color filter of each hue provided in the sensor. Then, the ejection state of the inkjet head is detected based on the density signal value, the drive signal is corrected according to the detection result, and an image with reduced density unevenness is printed.

By the way, as one of the materials to be printed in the ink jet printing apparatus, a cloth is attracting attention, and as a method for forming an image on the cloth, a printing method has been conventionally known, and a typical one of them is known. As such, there is a screen printing method in which a silk screen plate is used to directly print on a fabric or the like. The screen printing method is a method in which an original image to be printed is made into a screen plate for each color used in the original image, and the ink is directly transferred to the cloth through the eyes of silk for dyeing.

However, such a screen printing method requires a great number of man-hours and days for producing the screen plate, and also requires a lot of work such as preparation of ink of each color required for printing, alignment of the screen plate, and the like. To do. Further, the device is relatively large, and the size is further increased in proportion to the number of colors to be used, thus requiring an installation space and also a storage space for the screen plate.

In contrast to such a conventional printing method, the above-mentioned ink jet type printing apparatus can directly print an image on a cloth or the like, whereby a screen plate is not required and the steps up to printing on the cloth, The number of days can be greatly shortened, and downsizing of the device can be achieved. However, when the cloth is used as the printing material, the color developability tends to be lower than when printing is performed on paper. For this reason, four colors (cyan,
In the case of cloth, color reproduction may not be possible in a sufficient range with only the reference colors (magenta, yellow, and black). Ink of colors other than these four reference colors is used as a special color and this special color ink is used in combination with the reference color ink. The technology to
Proposed.

[0011]

However, as described above, the reading system for reading the test image for reducing the density unevenness is configured to be adapted only to the above four reference colors. When a spot color is used, there is a problem in that even if a test image is printed with these inks and the reading is performed, the reading result does not reflect the accurate ejection status of the head.

That is, conventionally, a color sensor is used in the reading system, and C (cyan), M (magenta), and Y (yellow) are detected through complementary color filters of respective colors. Density unevenness and the like are corrected based on the density and for the achromatic color BK (black) based on the main density measured by one of the complementary color filters. Therefore, the density of the test image printed by the spot color cannot be accurately read in the conventional example in which the filter is set and the reading through the filter is performed as described above, and the inkjet head is controlled based on the read result. However, it was not possible to satisfactorily reduce streaks and unevenness.

The present invention has been made to solve such a problem, and an object thereof is to use a color other than the reference color even if a reading system adapted to a predetermined reference color is used. It is an object of the present invention to provide a printing apparatus that can appropriately read an existing image and correct good density unevenness and the like accordingly.

[0014]

According to the present invention, there is provided:
In a printing apparatus that uses a print head to perform color printing on a printing material, a reading unit that can read a color image printed using the print head and can generate a plurality of read signals for the reading, A determination unit that determines the color read by the reading unit, a selection unit that selects at least one of the plurality of read signals generated by the reading unit based on the color determined by the determination unit, and the selection unit selects Based on at least one signal, the correction value creating means for obtaining the correction value of the color according to the color judged by the judging means, and the correcting means for carrying out the density unevenness correction by the correction value found by the correction value generating means It is characterized by having and.

[0015]

According to the above construction, the reading signal is selected and the correction value is created based on the selected signal in accordance with the color judged by the judging means. Even if it is not the adapted standard color,
It is possible to create a correction value according to the color.

[0016]

An embodiment of the present invention will be described below in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a sectional view showing the outline of an ink jet printing apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 is a main body of an ink jet printing apparatus, 2 is a long roll of paper as a printing material, 4 is a cutter for cutting the printing material to a predetermined length, and 3 and 5 are respectively. A pair of transport rollers for transporting the print material upward in the drawing, and 6 are sub-scanning rollers for accurately transporting and positioning the print material by an amount corresponding to a print width of an inkjet head (hereinafter, simply referred to as a head) described later. is there. With the above configuration, the roll 2
A transport path for the print material supplied from the printer is formed.

Further, in FIG. 1, reference numeral 9 is a carriage for supporting the head, which is constituted by a pair of main scanning rails 9a.
It is movably supported in a vertical direction (horizontal direction in an actual printing apparatus) with respect to the drawing. A platen 10 is provided at a position facing the carriage 9 and the material to be printed. The platen keeps its printing surface flat and conveys the material to the head as the material to be printed is conveyed. In order to prevent this, for example, suction by air, or a suction suction means such as an electrostatic suction plate is provided.

Next, the area around the ink jet head is shown in FIG.
This will be described with reference to FIG.

The carriage 9 has ink jet heads 9C, 9M and 9 corresponding to standard colors of cyan, magenta, yellow and black and special colors of orange and blue.
Equipped with Y, 9Bk, 9OR, and 9BL. Reference numeral 11 denotes an ink supply system that supplies ink to these heads 9C, 9M, 9Y, 9Bk, 9OR, 9BL, and ink cartridges 11C, 11M, 11Y, 11Bk, 11OR, 11B corresponding to cyan, magenta, yellow, and black.
With L. From each ink cartridge, a tube 12C, 12M, 12Y,
The corresponding heads 9C, 9M, 9Y, 9Bk, 9OR and 9BL via 12Bk, 12OR and 12BL, respectively.
Ink is supplied to. Reference numeral 13 denotes a motor for scanning and driving the carriage 9 in the main scanning direction (longitudinal direction in the drawing). Via a pulley 14 fixed to the motor 13, a pulley 15 on the other end side, and a belt 16 stretched by these pulleys. Then, the driving force is transmitted to the carriage 9.
Reference numeral 17 denotes a motor for scanning and driving the ink supply system 11 in the main scanning direction (the horizontal direction in the drawing) in synchronization with the carriage 9, and includes a drive pulley 18 and the other pulley 19 fixed to the motor 17, and these pulleys. The ink supply system 11 is driven via the stretched belt 20.

Reference numeral 22 denotes the above-mentioned roll-shaped printing material, which is conveyed upward by the conveying roller 5 and the sub-scanning roller 6. This printed material is used for image printing and is distinguished from the one for performing the test image printing described later, and hereinafter this is referred to as the first printed material.
A cap member 23 is provided to perform a process for removing a factor that deteriorates the image quality (hereinafter, referred to as “ejection recovery process”). Heads 9C, 9M, 9Y,
9Bk, 9OR, 9BL discharge port surface cap member 23
In this state, the ink is discharged from the head ejection port by suction or pressure. Further, in the cap member 23, a high-speed airflow is introduced to the head ejection port surface, and the residual ink, dust, fluff, etc. accompanying the ink ejection is blown off from the ejection port surface by the airflow, thereby cleaning the ejection failure. Prevent.

As described above, the control of the entire printing apparatus of this embodiment shown in FIGS. 1 and 2 is executed under the control of the control section (not shown). This control unit is a C such as a microprocessor.
RO that stores PU, control program and various data
M, a RAM used as a work area for the CPU, and the like.

Next, the print sequence in the apparatus of this embodiment will be described with reference to FIGS.

In FIG. 1, when the print material fed out from the roll 2 is detected by a detection sensor (not shown) provided immediately in front of the transport roller 5 as it is transported, the transport roller 5 moves a predetermined amount, That is, the leading edge of the printing material is driven to reach the sub-scanning roller 6.

The tip of the material 22 to be printed is the sub-scanning roller 6
2, the carriage 9 and the ink supply system 11 are driven in the scanning direction (right side in the drawing) by motors 13 and 17, respectively. Along with this, heads 9C, 9M, 9Y, 9Bk, 9OR, 9BL
Is 1 in the print width shown by 1 in the figure based on the image signal.
Print lines.

After the printing of one line is completed, the carriage 9 and the ink supply system 11 are driven to return to a predetermined position on the left side of the drawing, and the material 22 to be printed is the motor 2.
By driving No. 1, the sheet is accurately conveyed in correspondence with the print width 1. After performing the above-described sequence of printing and carrying of the printing material for a predetermined number of cycles, the printing material 22 is discharged to the outside of the machine.

Reference numeral 31 denotes a monitor for detecting the ejection state of the ink jet head, which is a test image printed at a predetermined interval on a second print target material 41 dedicated to the monitor provided at one end of the platen 10. A certain predetermined test pattern (uniform density pattern) 32 is monitored. The printed material 41 dedicated to the monitor has a predetermined pattern 3
When the second printing is performed, it is supplied onto the platen 10 by the supply roll 42, and after printing, it is taken up by the take-up roll 43 via the monitor 31.

The predetermined pattern 32 is printed,
The interval at which the print signal is corrected based on this is, for example, when a roll-shaped cloth is used as the printing material,
Since printing is often performed by repeating unit designs, the inkjet head is performed when printing of one unit of the design is completed, that is, when printing of a width in the sub-scanning direction corresponding to one unit of the design is completed. It is possible to suppress the occurrence of defective factors of the printed product such as the occurrence of uneven density due to the defective ejection state. Further, the printing of the predetermined pattern 32 and the accompanying correction, etc. may be performed every time when the printing of a predetermined number of lines is completed. In this case, the predetermined number of lines is appropriately determined depending on the likelihood of non-ejection of the inkjet head, the surface condition of the cloth, and the like. Further, if the above-mentioned processing relating to the ejection state detection is performed every line, the ejection state abnormality detection can be performed in real time, while if it is performed every predetermined row, printing can be performed without lowering the printing speed. .

The ejection state detection interval may be increased or decreased as necessary because there is a difference in the likelihood of ejection failure depending on the type of ink used for printing. The predetermined pattern 32 is, for example, a solid pattern in which the print frequency is set to 50% of the normal frequency or 30, 6
It may be a single pattern or a combination of a plurality of patterns such as a plurality of patterns of 0,75%.

Next, referring to FIG. 4, the above-mentioned predetermined pattern is read by the monitor 31 equipped with a scanner or the like, and the density signal value obtained as a result is used to explain in detail the correction method for correcting density unevenness. .

FIG. 4 is a diagram typically showing the sensor output in the monitor 31, and FIG. 5 is a diagram in which the sensor output value in FIG. 4 is converted into a density signal by a conversion formula.

In FIG. 5, if there is at least one output smaller than the value b, which is smaller than the average value a of each pixel output by a predetermined amount, it is determined that the ejection is not performed. Further, if there is an output that exceeds a value c that is a predetermined amount larger than the average value a or falls below a value d that is smaller than the average value a, it is determined that the density unevenness is large.

The determination of the density unevenness is not limited to the above-mentioned configuration, and for example, another method such as obtaining the standard deviation of the output value of the density signal of each pixel and making the determination based on its magnitude is used. May be. Further, the output value of the density signal of each pixel may be used as it is as the value corresponding to each ejection port of the head used for correcting the density unevenness, but the influence of noise, reading error, etc. is reduced. Therefore, an average value of adjacent pixels of each pixel output, for example, three pixels before and after, may be used as the pixel output.

In this embodiment, a cloth is used as the first printed material, and a sheet dedicated to ink jet printing is used as the second printed material for the test image. As a sheet for exclusive use in ink jet printing, there is, for example, a sheet obtained by mixing silica powder or alumina particles in an aqueous polyvinyl alcohol solution, coating the surface of the sheet and drying. The paper that has been subjected to such a treatment has less ink bleeding than a normal paper that is not subjected to such treatment, and is suitable for use as the second print material. That is, when a test image is printed, the test image is read, and the ejection status of the head is detected based on the read result, the influence of ink bleeding on the detected density can be reduced, which is optimal.

To correct the density unevenness, the difference between the average value a of each pixel output in FIG. 5 and the output value of each ejection port is obtained, and the correction value is determined so that each output value matches the average value a (hereinafter referred to as “correction value”). , The correction value of the paper) is used to correct the drive signal for each ejection port.

FIG. 3 is a diagram showing the monitor 31 in detail.

In the figure, reference numeral 32 is a pattern of a test image printed on the printed material 41 dedicated to the monitor, which is a single color for each of the four reference colors of cyan, magenta, yellow and black and each of orange and blue as special colors. One line width is printed with uniform density.
33 is a pair of illumination lamps for illuminating the pattern 32,
34 is the pattern 3 illuminated by these illumination lamps 33.
2 is a projection lens for projecting 2 and 35 is a projection lens 34
It is a color sensor such as a CCD for photoelectrically converting the pattern 32 projected by. The number of elements is preferably equal to or larger than the number of ejection ports of the inkjet head.

The test image 32 printed on the second printed material 22 is read by the monitor 31 for detecting the ejection state of the ink jet head.
That is, the color sensor 35 uses the test image pattern 35.
Is read and an RGB signal is output. Since this signal is a luminance signal, it is converted into a density signal by a conversion formula according to the characteristics of the sensor that has read it. This converted signal value corresponds to each ejection port of the inkjet head,
This makes it possible to measure the density of the image generated by the ejection for each ejection port.

In the present embodiment, the four standard colors C (cyan), M (magenta), Y (yellow), and Bk (black) used in the conventional full-color recording, and the special color OR (orange), BL (blue) is used. In this case, as described above, even if the special colors orange and blue are directly read by the monitor 31 adapted to the four reference colors, the result may be inappropriate. Therefore, in this embodiment, the following processing is performed.

That is, in the present embodiment, the hue judging means judges the hue of the color material of the test image printed on the paper which is the second print material, and the optimum R, G, B filter is judged based on the judgment. One of the two is selected, and the density value x calculated based on the luminance signal obtained from the transmitted light of the selected one filter is calculated by a function f (x) defined according to the hue of the spot color. To do. Then, using the calculation result, the drive signal for each ejection port of the inkjet head relating to the spot color is corrected.

FIG. 6 is a block diagram showing a configuration of the above-described processing relating to the correction of the density unevenness according to the present embodiment together with the flow of the processing.

In FIG. 6, the reading means including the monitor 31 described above is used as the ink jet heads 9Y and 9Y for the respective colors.
The hue determination unit 601 determines the hue of each pixel based on the result of reading for each pixel formed by each of the C, 9M, 9Bk, 9OR, and 9BL ink ejection ports.

As a concrete configuration of the hue judging means 601, a combination of R, G and B luminance signals for representative colors is stored in advance, and the R, G detected by the reading means 31 is detected.
The color corresponding to the RGB combination closest to the G and B data is determined as the hue.

As another constitution of the hue judging means,
For example, the color of the color material may be judged by the operator's visual sense, and a filter determined for each color in advance is selected based on this judgment. Further, the RGB data obtained by the reading means for each color is stored as a data file, and the RGB data detected by the reading means 31 is an extension (file name) of the data file.
Alternatively, the color of the data may be determined by.

The RGB filter selection unit 602 selects the optimum filter among the R, G, and B filters according to the hue determined by the hue determination unit 601. Specifically, only the luminance signal obtained through the filter to be selected is made valid according to the judgment hue. Next, the density creating unit 603 converts the selected (validated) luminance signal into the value x of the density signal.

The correction value creating section 604 performs an operation on the density signal x using a predetermined function f (x) suitable for the hue judged by the hue judging means 601, and obtains a density value (absolute value) suitable for the hue. ) (This value is x '). From the value x'for each pixel corresponding to each ejection port of the head, the average value of the entire ejection port of the head is obtained, and the difference Δx 'between the value x'of each pixel and the average value is calculated, and this is calculated. This is a correction value for uneven density. Then, the correction value Δ obtained in this way
x'is stored as a table for each pixel (conversion table creating unit 605).

On the other hand, the image data to be printed is stored in the image memory 606 as the density data of the pixel corresponding to each ejection port of each head, and these data are palette-converted by the palette converter 607. Then, the density unevenness correction unit 608 adds the correction value Δx ′ stored as the above table for each corresponding pixel to this palette-converted density data, thereby corresponding to each ejection port of each inkjet head. Correct density unevenness.

After that, the γ conversion unit 609 performs γ conversion of the density value in which the density unevenness is corrected, and then performs binarization processing (binarization processing unit 610) to obtain ejection data of each ink jet head.

According to the structure of the present embodiment described above, for example, in the case of a special color OR, four reference colors (C, M, Y, B) are used.
In k), the B filter that is the complementary color of Y and has the optical characteristics most similar to the optical characteristics of OR is selected as the optimum filter, and f (x) = 0.7x is used as the function f (x).

In this way, according to the hue of the color material used for printing, the density value obtained by selecting one optimum filter is further calculated by a predetermined function f (x) to obtain the hue. By obtaining an appropriate density value and performing density unevenness correction based on the correction value obtained based on the density value and printing, an image in which density unevenness is satisfactorily reduced is obtained not only for the above-described four standard colors but also for an image with a special color. be able to.

(Second Embodiment) In the second embodiment of the present invention, as shown in FIG.
The hue of the color material of the image printed on the target print material (coated paper) is determined, and based on this, the RGB filter selection unit 7
In 02, the optimum combination of two filters is selected. The density creating unit 703 performs an operation on the luminance signal value obtained by using the two selected filters with a function g (y) defined according to each color similarity, and obtains the resulting density signal value. The density unevenness correction of the spot color is performed by using this.

According to the above configuration, for example, in the case of the special color OR, the G filter and the B filter which are complementary colors of M and Y are used, and the luminance signal values y _g and y _b obtained by the respective filters are obtained. As a function g (y) for performing a pair operation, g
(Y) = 0.3y _g + 0.7y _b is used. In this way, select the two optimum filters for each hue,
If unevenness correction is performed using the density signal value calculated by the function g (y) and printing is performed, a high-quality image with less density unevenness can be obtained even when a conventional reading unit is used.

(Third Embodiment) In the present embodiment, FIG.
As shown in FIG. 3, three filters are selected according to each hue, the brightness signal values obtained by using the R, G, and B filters are calculated by the function h (y), and the calculated brightness signal values are obtained. Is used to correct the density unevenness of the spot color.

In this embodiment, for example, in the case of a special color OR,
Luminance signal values y _r obtained from the R, G, and B filters,
As a function h (x) that performs an operation on y _g and y _b , h
(X) = 0.1y _r + 0.3y _g + 0.6y _b is used. In this way, for the special color, the brightness signal values of the R, G, and B kernel filters are calculated by the function h (y) appropriate for each hue, and the unevenness correction is performed with the calculated brightness signal value to perform printing. By using the conventional reading means,
It is possible to obtain a high-quality image with less density unevenness that has been appropriately corrected.

(Fourth Embodiment) In the present embodiment, as shown in FIG. 9, when the hue judging means 901 judges that it is a spot color, one of the above-mentioned first, second and third embodiments is executed. A correction value for density unevenness is obtained by the spot color processing unit 911 according to the above method. On the other hand, for the reference four colors, the reference four-color processing unit 912 applies the above RGB values to C, M, and Y for the complementary color filters of the respective complementary color filters and Bk which is an achromatic color.
Density unevenness correction is performed using the luminance signal obtained by the transmitted light of any one of the filters.

As described above, the hue determining means discriminates the reference four colors from the spot colors and processes the reference four colors and the spot colors separately, so that not only the image data including the spot colors but also the reference four colors are processed. Appropriate density unevenness correction can be performed on image data with a simpler sequence.

In the description of each of the above embodiments, the ink jet type printing apparatus has been described as an example, but it is apparent from the above description that the present invention can be applied to a thermal transfer type printing apparatus. Further, using a print head in which a plurality of recording elements are arranged, each recording element is caused to print a predetermined color, or a block composed of a plurality of recording elements is divided and a predetermined color is printed for each block. It may be configured so that color printing is performed.

(Others) It should be noted that the present invention includes a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for performing ink ejection, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full line type recording head having a length corresponding to the maximum width of a recording medium which can be recorded by the recording apparatus. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type as described above, the recording head fixed to the apparatus main body or the electric connection with the apparatus main body or the ink from the apparatus main body is attached to the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

Further, it is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

The type and number of recording heads to be mounted are, for example, not only one provided for single color ink, but also a plurality of inks having different recording colors and densities. A plurality may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change from the solid state of the ink to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying heat energy such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not limited to those used as image output terminals of information processing equipment such as computers, copying apparatuses combined with readers and the like, and facsimile apparatuses having a transmission / reception function. It may take a form.

[0068]

As is apparent from the above description, according to the present invention, the reading signal is selected and the correction value is created based on the selected signal according to the color judged by the judging means. Even if the color related to the reading is other than the reference color that is previously adapted to the reading means, it is possible to create the correction value according to the color.

As a result, by using the above correction values, it is possible to perform optimum density unevenness correction for each color and obtain a high-quality printed image.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an inkjet printing apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing details around a print unit of the apparatus shown in FIG.

3 is a perspective view showing a detailed configuration of a test image monitor in the apparatus shown in FIGS. 1 and 2. FIG.

FIG. 4 is a diagram showing an output of an image reading sensor.

FIG. 5 is a diagram showing a density signal obtained by converting the sensor output.

FIG. 6 is a block diagram showing a configuration of density unevenness correction processing according to the first embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of density unevenness correction processing according to a second embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of density unevenness correction processing according to a third embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of density unevenness correction processing according to a fourth embodiment of the present invention.

[Explanation of symbols]

9Bk, 9Y, 9M, 9C, 9OR, 9BL Inkjet head 11Bk, 11Y, 11M, 11C, 11OR, 11B
L Ink tank 31 Monitor (reading means) 32 Test image 35 Color sensor 601, 701, 801, 901 Hue judging means 602, 702, 802 RGB filter selecting section 603, 703, 803 Density creating section 604, 704, 804 Correction value creation Part 605, 705, 805, 905 Conversion table creation part 606, 706, 806, 906 Image memory 607, 707, 807, 907 Palette conversion part 608, 708, 808, 908 Density unevenness correction part 609, 709, 809, 909 γ Conversion unit 610, 710, 810, 910 Binarization processing unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H04N 1/46 H04N 1/46 Z

Claims (4)

[Claims] 1. A printing apparatus for performing color printing on a printing material using a print head, which can read a color image printed by using the print head and can generate a plurality of read signals for the reading. A reading unit; a determining unit for determining the color read by the reading unit; and a selecting unit for selecting at least one of a plurality of read signals generated by the reading unit based on the color determined by the determining unit, Based on at least one signal selected by the selection means,
A correction value creating unit that obtains a correction value of the color according to the color determined by the determination unit; and a correction unit that performs density unevenness correction based on the correction value obtained by the correction value generating unit. And printing device. 2. Further comprising a test image printing means for printing a test image using the print head,
The printing device according to claim 1, wherein the reading unit generates the plurality of read signals by reading the test image. 3. The print according to claim 1, wherein the test image is printed on a paper as a material to be printed, and the color image is printed on a cloth as a material to be printed. apparatus. 4. The printing apparatus according to claim 1, wherein the print head is a head that ejects ink, and ejects the ink by utilizing thermal energy.