JP3295226B2 - Image forming method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording method and apparatus, for example, a multi-head in which a plurality of image recording elements are arranged in a predetermined direction. In particular, an image is formed by discharging ink droplets. The present invention relates to an image recording method and an apparatus using an inkjet type recording head to be formed.

[0002]

2. Description of the Related Art An ink jet recording method is a method in which ink is ejected onto a recording medium in accordance with a recording signal to perform recording, and is widely used because of a low running cost and a quiet recording method. In this method, by using a head in which many nozzles are formed on a straight line perpendicular to the direction of relative movement of the head with respect to the recording medium, the width corresponding to the number of nozzles can be reduced by one relative scan in one head scan. Can be recorded every time, and speeding up can be achieved relatively easily.

[0003]

However, it is difficult to uniformly manufacture an image recording element comprising a multi-head, and the characteristics of the image recording element vary to some extent. For example, in an ink jet multi-head, variations occur in the shape and the like of nozzles, and such non-uniformity in characteristics between image recording elements results in non-uniformity in the size and density of dots recorded by each image recording element. This causes density unevenness in the recorded image.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and an image recording method and an apparatus for recording a stable and high-quality image by correcting variations in print density by an image recording element comprising a multi-head. The purpose is to provide.

[0005]

In order to achieve the above object, an image recording apparatus according to the present invention has the following arrangement. That is, using a recording head in which a plurality of image recording elements are arranged ,
Image data corresponding to each of the plurality of image recording elements
An image forming apparatus for forming an image based on a plurality of image recording elements, wherein the density of an image formed by the plurality of image recording elements varies.
Each of the plurality of image recording elements for correcting luck
Using the first correction data corresponding to
A correcting unit that corrects image data corresponding to each of the plurality of recording elements, an image forming unit that forms an image by the recording head based on the image data corrected by the correcting unit, and an image forming unit that is arranged on the recording head. All images
Of the recording elements, some continuous image recording elements
An image is formed using a partial image recording element array comprising
Control means for performing control by the control means.
When forming an image using the partial image recording element array,
The correction unit may include the partial image recording element array used for recording.
Corresponding to a predetermined number of image recording elements located at the end of the array
Second correction data for correcting image data
Using the first correction data, the partial image recording element array
Image data corresponding to each of the image recording elements
The image forming means is configured to perform the correction based on the corrected image data.
Then, an image is formed using the partial image recording element array .

[0006] Further, another invention is to provide a plurality of image recording elements.
Using an array of recording heads, the plurality of image recording elements and
Form an image based on the corresponding image data
An image forming method, wherein the plurality of image recording elements
The method for correcting variations in density of an image to be formed.
First correction data corresponding to each of the plurality of image recording elements
A plurality of recording elements of the recording head using
Correction step means for correcting corresponding image data;
Based on the image data corrected in the correct process,
An image forming step of forming an image by a recording head;
Of the image recording elements arranged in the recording head.
Of which, a part consisting of a plurality of continuous image recording elements
Partial image formation for forming an image using an image recording element array
In the image formation in the mode, the correction step includes recording
At the end of the array of the partial image recording element rows used for
Image data corresponding to a predetermined number of image recording elements
And second correction data for
Each of the image recording elements of the partial image recording element row
Correcting the image data corresponding to the
The partial image recording based on the corrected image data
An image is formed using the element array .

[0007]

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention for solving the above-mentioned problems will be described below. As the overall configuration of the embodiment, in Embodiment 1, a method and apparatus for correcting the print density in the case of forming an image using all the nozzles of the inkjet multi-head will be described. In Embodiments 2 to 5,
A description will be given of a print density correction method and apparatus in a case where a mode for forming an image using all the nozzles of the inkjet multi-head and a mode for forming an image using only one nozzle of the inkjet multi-head are simultaneously provided. In Examples 6 to 8, a mode in which an image is formed using all the nozzles of the inkjet multi-head, a mode in which an image is formed using only one nozzle of the inkjet multi-head, A description will be given of a print density correction method and apparatus in a case where a mode for forming an image using only the central nozzle is provided at the same time. (Embodiment 1) In Embodiment 1, a method and an apparatus for correcting a print density when an image is formed using all nozzles of an ink jet multi-head will be described in detail below.

To explain the first embodiment according to the present invention,
For example, first, a printing element of 256 nozzles will be summarized with reference to FIG. 4 in terms of the configuration of the first embodiment according to the present invention.

To achieve the above object, the image forming apparatus of the present embodiment includes a multi-head (10a, 10b, 10c) in which a plurality of image recording elements are arranged in a predetermined direction. In the multi-head, the image density varies at the time of image formation due to the following two factors, and the image quality deteriorates.

One of the factors will be described below.

Each nozzle of the multi-head (hereinafter also referred to as a recording head) generally has different printing characteristics mainly due to manufacturing variations. One example is shown in FIG.
5 shows image density characteristics when the input signal level to each nozzle is made uniform. Here, the horizontal axis indicates the nozzle number, and the vertical axis indicates the corresponding image density. It can be seen that density unevenness corresponding to each nozzle occurs.

Another factor will be described below.

Since there is a non-uniform temperature distribution depending on the arrangement position of the nozzles, the printing characteristics are also non-uniform.

FIG. 13 is a diagram showing the correlation characteristic of the temperature corresponding to each nozzle when the input signal level to each nozzle is made uniform when the number of nozzles is 256. Where 5
The horizontal axis for the curve 000 is the nozzle number, and the vertical axis is the printhead temperature.

The horizontal axis of the curve 5001 is the nozzle number, and the vertical axis is the image recording density. FIG.
As shown at 5000, the head temperature T2 at both ends of the recording head is the head temperature T2 in the central region of the recording head.
1 (T1> T2). As a result,
The problem is that the amount of ink droplets ejected from the recording nozzles at both ends of the multi-nozzle recording head decreases, the recording dot diameter decreases, and the recording density decreases at both ends of the multi-nozzle recording head. appear.

Therefore, the density of the image data corresponding to both ends of the multi-nozzle recording head is corrected. The image density corresponding to each nozzle as an expected result of the correction is shown by 5001, and the output densities from all the nozzles are uniformly corrected.

As described above, variations in image density occur mainly due to the two factors described above. The points of the configuration of the image forming apparatus for solving this problem will be described below.

The reading unit 30 reads a test pattern formed by the image recording elements (nozzles) of the multi-head. Then, from the read values, the density unevenness calculation unit (the CPU 100 executes the density unevenness calculation program stored in the ROM 50) calculates the density unevenness amount depending on the manufacturing variation of each image recording element of the multi-head. Then, based on the density unevenness amount, the first density unevenness correction units (34a, 34b, 34c, 34d, 37a, 37
b, 37c, and 37d) correct image data composed of input luminance data or density data. The corrected image data is supplied to a gradation correction unit (39a, 39b, 39c,
39d), and then binarization processing (40a,
After performing 40b, 40c, and 40d), printing is performed with the multi-head (10a, 10b, 10c, and 10d).

By the processing based on the above configuration, a high-quality image with little variation can be formed.

Hereinafter, Embodiment 1 of the present invention will be described in more detail and specifically with reference to the drawings.

FIG. 1 is a schematic diagram for explaining the entire image forming apparatus of the present embodiment.
A color image scanner unit (hereinafter abbreviated as “reader unit”) 1 for outputting digital color image data, and a recording paper 4 for outputting digital color image data output from the reader unit 1
The image forming apparatus according to the present embodiment includes a printer unit 2 for recording the image on the printer.

The reader unit 1 includes an exposure lamp (not shown), a lens, and an image sensor 3 (C in this embodiment) capable of reading a full-color line image.
The image of the document placed on the platen glass is read by a CD sensor), and the control of the entire apparatus is controlled by the main CPU 100. Also, the main CPU
Reference numeral 100 denotes a printer control 102 for controlling the control operation of the printer unit 2 and a reader control CP for controlling the reading control operation.
U104, Main image processing unit 1 for processing image processing operation
06, an operation unit 108 as an input unit by an operator is connected.

The main image processing unit 106 includes a masking unit,
Image processing such as black extraction, binarization, and γ correction is performed. Further, a synchronous memory 110 is connected to the printer control CPU 102 and the main image processing unit 106. This synchronous memory 1
Numeral 10 is for absorbing the time variation of the input operation and correcting the delay due to the arrangement of the recording heads described above. And the output of this synchronous memory 110 is
The head driver 115 is controlled by the printer control CPU 102.
Is output to the recording head 10.

The printer control CPU 102 is connected to a printer drive system 114 for controlling input drive of the printer.

The reader control CPU 104 includes an input system image processing unit 116 for performing necessary correction processing in a reading system such as shading correction, color correction, and γ correction, and a reader unit driving system 118 for controlling input driving of the reader. And connected to.

Further, the input system image processing unit 116
D sensor 3 is connected to the input system image processing unit 1
Reference numeral 16 is connected to the main image processing unit 106.

FIG. 2 is a schematic view for explaining the printer section 2 of the image forming apparatus of the present embodiment, and is roughly divided into two guide rails 15a and 15b, an ink jet head 10 and a head carriage 11, and ink feeding. Part 14 (14Y, 1
4M, 14C, 14B), a head recovery unit 20, and an electrical system (not shown).

The ink supply unit 14 stores ink and supplies a required amount of ink to the head 10, and includes an ink tank 14, an ink pump 13, and the like. The ink supply section 14 and the head 10 are connected by an ink supply tube 12, and usually, the ink is automatically supplied to the head 10 by an amount discharged from the head by capillary action. Further, at the time of a head recovery operation as described later, the ink pump 1
3, the ink is forcibly supplied to the head 10.

The head 10 and the ink supply unit 14 are mounted on a head carriage 11 and an ink carriage (not shown), respectively. A belt 16 provided between pulleys 17a and 17b is connected to a shaft 18 of a motor 19, 19
Along the guide rails 15a and 15b according to the rotation of
It is configured to reciprocate in the direction of arrow S.

In order to maintain the stability of the head, the head recovery section 20 controls the head 1 at the home position HP.
0, and specifically performs the operation described below. At the time of operation, the head 10 is moved forward in the direction of arrow f to cap the head 10 at the home position in order to prevent evaporation of ink from inside the head nozzle (capping operation), or before starting image recording, bubbles or dust in the nozzle. In order to discharge the ink, it is necessary to press the ink flow path in the head using an ink pump to forcibly discharge the ink from the nozzles (pressure recovery operation). Performs functions such as collecting.

FIG. 3 is a perspective view showing a schematic configuration of the ink jet recording head 10. This head is an electrothermal conversion film formed on a substrate 21 through semiconductor manufacturing process steps such as etching, vapor deposition and sputtering. It comprises a body 22, electrodes 23, nozzle walls 24, and a top plate 25.

The recording ink is stored in the ink tank 14 (FIG. 2).
) Through the ink supply tube 12 and into the common liquid chamber 26 of the recording head 10. 27 is a supply pipe connector.

The ink supplied into the common liquid chamber 26 is supplied into the nozzle 28 by capillary action, and is stably held by forming a meniscus on the discharge port surface at the tip of the nozzle.

Here, when electricity is supplied to the electrothermal converter 22, the ink on the electrothermal converter surface is heated, and a bubbling phenomenon occurs.
Ejects ink droplets.

With the above configuration, the nozzle density 1
With a high-density nozzle arrangement such as 6 nozzles / mm, 128
It becomes possible to manufacture a multi-nozzle ink jet recording head of nozzles or 256 nozzles.

FIG. 4 is a block diagram of the image forming apparatus of the first embodiment. Reference numerals 36a, 36b, 36c, and 36d denote four color image signals of cyan, magenta, yellow, and black, respectively, and 37a, 37b, and 37c. , 37d are non-uniformity correction tables for the respective colors, 38a, 38b, 38
c, 38d are tables 37a, 37b, 37c, 3
The non-uniformity-corrected image signals 39a, 39b, 39c, and 39d for the respective colors output from 7d are the non-uniformity-corrected image signals 38a, 38b, 38c, and 38 for the respective colors.
tone correction table for inputting d, 40a, 40b, 40
c and 40d denote binarization circuits, 10a, 10b and 10 for inputting output signals of the respective tables 37a, 37b and 37c.
c, 10d are the respective binarization circuits 40a, 40b, 40c,
Inputting a 40d output signal 25 for each color
A 6-nozzle inkjet head, a reading unit 30 including a photoelectric conversion element (CCD) having filters of three colors of m red (R), green (G), and blue (B), and photoelectrically converting and reading an image; 31a, 31b, 31c, 3
1d is a signal read by the reading unit 30; R, G, B read signals; 32, a RAM for temporarily storing R, G, B signals from the reading unit 30;
CPUs 33a, 33b, 33c, 33d for calculating unevenness correction data based on the R, G, B signals from M32
Are non-uniformity correction data lines 34a, 34b, 34c, 34d for transferring non-uniformity correction data for cyan, magenta, yellow, and black from the CPU 100, respectively.
Are non-uniformity correction RAMs for inputting and storing the non-uniformity correction data for each color, 35a, 35b, 35c, 35d
Are output from the unevenness correction RAMs 34a, 34b, 34c, and 34d, and are output from the unevenness correction tables 37a, 37b, and 37d.
Unevenness correction signals for each color input to c and 37d.

Image signals 36a, 36b, 36c, 36d
Are the unevenness correction tables 37a, 37b, 37c, and 3 controlled by the unevenness correction signals 35a, 35b, 35c, and 35d.
7d is converted so as to correct the unevenness of the heads 10a, 10b, 10c and 10d. The unevenness correction table
As shown in FIG. 12, there are 61 correction (γ) straight lines whose inclinations from Y = 0.70x to Y = 1.30x are different by 0.01, and the unevenness correction signals 35a, 35b, 35c, 3
A correction straight line is selected according to 5d. For example, when a signal of a pixel to be printed by a nozzle having a large dot system is input, a correction straight line having a small inclination is selected, and a correction straight line having a large inclination is selected for a nozzle having a small dot system to correct an image signal.

The unevenness correction RAM stores correction straight line selection signals necessary for correcting unevenness of each head. That is, 256 non-uniformity correction signals having 61 types of values from 0 to 60 are stored, and the non-uniformity correction signals 35a, 35b, 35c, and 3 are synchronized with the input image signal.
5d is output. Signals 38a, 38b, 38 whose unevenness has been corrected by the gamma straight line selected by the unevenness correction signal
c and 38d are gradation correction tables 39a, 39b and 39
c, 39d, where the gradation characteristics of each head are corrected and output.

After that, the signals are converted to the binarization circuits 40a and 40a.
b, 40c, and 40d are binarized, and the heads 10a,
10b, 10c and 10d are driven to form a color image.

Next, a method of creating the first density unevenness correction data of this embodiment will be described.

First, all the non-uniformity correction tables 37a, 37b, 37c, and 37d are set to straight lines having a slope of 1.0 by a control signal (not shown), so that no non-uniformity correction is performed. Subsequently, an unevenness correction pattern is output from an unillustrated signal source to an unevenness correction table, and the heads 10a, 10b,
These are recorded (printed out) on paper or the like by 10c and 10d. The unevenness correction pattern may be a uniform pattern with an arbitrary print duty, but a duty of about 30 to 75% is appropriate. Here, a uniform halftone having a 50% duty is recorded in cyan, magenta, yellow, and yellow.

The output pattern is read by the reading section 30, and the read signals 31a, 31b, 3
1c is stored in the RAM 32. C of the reading unit 32
The CD has the same reading density as the recording density of the head, and is 400 dpi in this embodiment. The number of pixels of the CCD is larger than at least the number of nozzles 256 of the head. Red (R) obtained by this reading,
Among the green (G) and blue (B) signals, the red signal shows the cyan head uneven distribution, the green signal shows the magenta head uneven distribution, the blue signal shows the yellow head uneven distribution data, and the red signal, green signal, and blue signal. The distribution of the black head is obtained from the signal obtained by performing the arithmetic processing on the signal. Here, for the sake of simplicity, a case will be described in which the unevenness distribution of the cyan head is obtained, the first density unevenness correction data is created by the first correction data calculation unit, and the unevenness correction is performed.

First, let the red signal obtained for each nozzle of the cyan head be Rn (n = 1 to 256).

On the other hand, Cn = −log Rn / R0 where R0 is a constant satisfying Rn ≧ R0. By performing the following calculation, the density signal is converted into a cyan density signal Cn, and a density unevenness distribution is obtained.

Next, the average density of cyan Is calculated.

Next, how much the density of each nozzle deviates from the average density is calculated as follows.

[0053] Next, the signal correction (ΔS) n according to (ΔC) n is given by: ΔSn = KxΔCn where K is a coefficient. Ask for.

Subsequently, a selection signal of a correction straight line to be selected is obtained in accordance with ΔSn, and an unevenness correction signal having 61 values from 0 to 60 is stored in the unevenness correction RAM 34a for 256 nozzles.

In this way, a different γ straight line is selected for each nozzle based on the first unevenness correction data created by the first correction data calculation unit, and the unevenness in density is corrected.

By the processing based on the above configuration, a high-quality image with little variation can be formed.

In this embodiment, the operation of reading the printed correction pattern may be performed by a user or a service person scanning the output sample in the reading section.

Further, the machine may be configured to automatically read the printed sample.

(Embodiment 2) In Embodiment 1, the configuration of the image forming apparatus for printing by using all the nozzles of the multi-head is shown. However, a mode for printing by using some of the nozzles among all the nozzles is further provided. The image forming apparatus according to the second embodiment will be described in detail below.

When the recording operation mode is not a recording operation mode using all the recording nozzles of the multi-nozzle recording head (hereinafter, referred to as an all-nozzle recording mode) but has a reduced recording mode, for example, as shown in 2001 in FIG. ,
In the case where printing is performed only for the printing width L / 2 by 128 nozzles, which is half of the 256 nozzles, printing is performed only by the printing nozzle areas of the printing head nozzle numbers 1 to 128 of the printing head. The recording head temperature T2 in the central nozzle region M decreases (T1
> T2), the recording density D2 for a uniform input image signal in the recording nozzle area M decreases (curve 2000 in FIG. 14), and a problem occurs (D1> D2). The problem is that the configuration shown in the first embodiment basically corrects the temperature characteristics for all the nozzles as shown by 5000 in FIG. 13, and when an image is formed in the all-nozzle recording mode. In the case where the image quality is good, but printing is performed by switching to the reduced recording mode, printing with poor image quality is performed because the temperature characteristics shown in FIG. 14 are not compensated. Reference numeral 5001 in FIG. 13 indicates an ideal image density for each nozzle and is uniform. That is, it is necessary to correct the output from each nozzle so that the image density becomes uniform.

In FIG. 14, reference numeral 2000 denotes all nozzles (256
FIG. 9 shows temperature characteristics when half of the nozzles (nozzle numbers 1 to 128) are used. The horizontal axis represents each nozzle number, and the vertical axis represents the corresponding image density. 2001 is
5 shows image density characteristics when printing is performed with half the nozzles (nozzle numbers 1 to 128). As is clear from the curve shape of 2001, the nozzle temperature T2 at both ends of the half nozzles (nozzle numbers 1 to 128) is lower than the nozzle temperature T1 in the central region (T1> T2). In this case, the amount of ink droplets ejected from the recording nozzles at both ends decreases, and the diameter of the recording dot decreases, resulting in a problem that the recording density decreases at both ends.

On the other hand, 2000 (see FIG. 14) shows image density characteristics when an image is formed in the reduced recording mode using the image forming apparatus of the first embodiment. As is apparent from the curve shape of 2000, half of the nozzles (nozzle numbers 1 to 12)
8) The nozzle temperature T2 at the right end becomes lower than the nozzle temperature T1 in the center region (T1> T2). As a result, the amount of ink droplets ejected from the recording nozzles at both ends is reduced. As a result, there arises a problem that the recording dot diameter becomes small and the recording density decreases at the right end. On the other hand, half of the nozzles (nozzle numbers 1 to 12)
At the left end of 8), since the image data is corrected, the recording density does not decrease.

That is, as shown in FIG. 15A, after the density unevenness of the multi-nozzle recording head 10 having the number N of nozzles is corrected by the above-described method, the recording paper 4 is adjusted by the total nozzle width L of the multi-nozzle recording head. Above recording width pitch L
When recording is performed by using the image density correction method, an image having a uniform density can be recorded over the front surface of the recorded image by correcting the image signal using the density unevenness correction data.
As shown in the figure, a multi-nozzle recording head 1 having N nozzles
In the case where recording is performed at a recording width pitch L / 2 for every N / 2 nozzles, the recording head temperature in the central nozzle region M of the recording head 10 decreases, and the recording density decreases. will be reduced, as a result, the recorded image would be low density unevenness density width 2M per pitch L is generated, the recording image quality even would not significantly deteriorate.

For example, as shown in FIG. 6, of the 256 nozzle print head, nozzle No. 1 to nozzle No. 1 (l
= 128), the recording operation is performed with the recording nozzle width of the first half of 128 nozzles, and the second correction data calculation unit prevents a decrease in recording density due to a decrease in head temperature in the central region of the recording head. For this purpose, the following correction processing is performed.

FIG. 5 is a diagram showing the principle of a correction process for preventing a decrease in recording density due to a decrease in head temperature. Here, the horizontal axis indicates the nozzle number of each recording head, and the vertical axis indicates
The correction coefficient F of the image data corresponding to the nozzle number of each recording head is shown. As can be easily understood from FIG. 5, a predetermined number of n nozzles (nozzle No. in the present embodiment) at the end of the central area of the print head corresponding to the density reduction nozzle area M where the print density of the print head decreases. The correction is performed on the image data corresponding to 124 to 128 (5 nozzles in total).

FIG. 16 is a diagram showing the configuration of the image forming apparatus according to the second embodiment. Referring to this figure, the point different from the configuration of the first embodiment (see FIG. 4) is mainly the multiplier (6).
0a, 60b, 60c, and 60d), a second unevenness correction table 1000, and a print element (nozzle) number control unit 41. The configuration of the other blocks is basically the same, and a description of those operations will be omitted.

Second unevenness correction table 1000 (FIG. 4)
Stores the corresponding values of the nozzle number and the correction coefficient F shown in FIG. 5, and when the CPU 100 specifies the nozzle number to be used for printing, the second unevenness correction table 10
From 00, the corresponding correction coefficient F value is output. The outputs include Fa, Fb, Fc, and Fd. In the present embodiment, the same correction coefficient F value is output.

The Fa, Fb, Fc, and Fd are input to the multiplier 60a, the multiplier 60b, and the multiplier 60c, respectively. And multiplier 6
0a, multiplier 60b, multiplier 60c,
The multipliers 60d are also provided with the irregularity correction RA, respectively.
M34a, unevenness correction RAM 34b, unevenness correction RAM 34
c) Multiply each unevenness correction signal from the unevenness correction RAM 34d. That is, the non-uniformity correction RAMs 34a, 34b, and 34 tuned for correction in the all-nozzle recording mode
c and 34d are corrected in the reduced recording mode by the correction coefficient F value from the second non-uniformity correction table, and the resulting signals are output to the non-uniformity correction tables 37a, 37b and 37c. , 37d. Unevenness correction tables 37a, 37b, 37c, 37d
Subsequent processing is the same as in the first embodiment.

Incidentally, the second unevenness correction table 1000
For example, it can be realized by a ROM or a RAM.

The recording element (nozzle) number control unit 41 sends a selection signal of the all-nozzle recording mode and the reduced recording mode to the CPU 1.
00 is output to specify the nozzle to be used.

The CPU 100 receives this selection signal, and in the case of the all-nozzle recording mode, the second unevenness correction table 1
000, an instruction signal for outputting a correction coefficient of 1.0 is given,
The second unevenness correction table 1000 outputs a correction coefficient of 1.0 to the multipliers 60a, 60b, 60c, and 60d. That is, it is equivalent to not performing correction. Also,
In the case of the reduced recording mode, the CPU 100 gives a nozzle number to the second unevenness correction table 1000 and gives an instruction signal for outputting a correction coefficient value according to the table of FIG. 5, and the second unevenness correction table 1000 The correction coefficient to be output is output to the multipliers 60a, 60b, 60c, and 60d.

With the above configuration, a high-quality image can be formed using either the all-nozzle printing mode or the reduced printing mode.

As described above, the first density non-uniformity correction data, that is, the correction data for the all-nozzle print mode, is applied to the area of the number of nozzles n corresponding to the nozzle area M (FIG. 14) where the print density decreases. The second density unevenness correction data,
That is, the image data is corrected by the correction data in which the correction data for the reduced print mode is superimposed, and the print density reduction due to the temperature drop in the central region of the print head is canceled to make the density unevenness uniform. it can.

In this embodiment, of the 256 nozzles,
The correction method when the first 128 are used is shown. However, the same method is used even when the second 128 is used, that is, the second unevenness correction table corresponds to the temperature characteristics of the second 128. Needless to say, this can be realized by storing the input / output relationship thus obtained.

The second unevenness correction table stores the step-like input / output relationship between the nozzle number and the image data correction coefficient F shown in FIG. 5, but is specified by this step-like input / output relationship. Needless to say, the input / output relationship may be any as long as it is an input / output relationship that compensates for print density due to the temperature characteristics of each nozzle.

Therefore, for example, when performing a recording operation,
Even if the distribution of the number of recording nozzles is changed, the input / output relationship of the second non-uniformity correction table can be rewritten so that the recording density non-uniformity due to the change in the distribution of the temperature gradient of the recording head does not occur. It is possible to easily and always record high-quality images. Example 3 In Example 2, in order to realize the correction of the reduced recording mode, the nozzle numbers shown in FIG. 5 - has been stored stepped input-output relationship of the image data correction factor F, Example 3 In the following, a method of performing density unevenness correction using the input / output relationship between the nozzle number and the correction coefficient F shown in FIG. 7 will be described.

FIG. 7 is a diagram showing the principle of a correction process for preventing a decrease in recording density due to a decrease in head temperature in the image forming apparatus according to the second embodiment. Here, the horizontal axis indicates the nozzle number of each recording head, and the vertical axis indicates the correction coefficient F of the image data corresponding to the nozzle number of each recording head. As can be easily understood from FIG. 7, a predetermined number of n nozzles at the end of the central region of the recording head (corresponding to the nozzle
The image data corresponding to No. 124 to 128 (5 nozzles in total) is corrected. Second unevenness correction table 100
0 (FIG. 16) stores the corresponding value of the nozzle number and the correction coefficient F shown in FIG. 5, and when the CPU 100 specifies the nozzle number to be used for printing, the second unevenness correction is performed. from the table 1000, the corresponding correction factor F value is output.

For example, of the print heads having a print width L and all print nozzles of 256 nozzles, nozzle No. 1 to nozzle No. 1
When printing is performed with a printing width of L / 2 using half of the 128 printing nozzles up to (l = 128), when performing density unevenness correction on each printing nozzle, a second density unevenness correction coefficient F The density unevenness correction amount for each recording nozzle is provided with a gradient corresponding to the head temperature gradient.

That is, as shown in 2001 in FIG. 14, the temperature distribution of the print head is such that the temperature drop due to heat radiation becomes larger at the end of the print nozzle that performs the print operation. The magnitude of the density non-uniformity data correction amount for each recording nozzle is corrected according to the magnitude of the temperature gradient of each recording nozzle. By making the second density unevenness data correction amount small for a print nozzle with a small decrease,
It is possible to more uniformly correct density unevenness.

In the second embodiment, the correction having the step-like input / output relationship was performed. However, if the image density gradient on the end side shown in 2001 in FIG. 14 is viewed, the correction having the gradient shown in FIG. 7 was performed. The correction accuracy can be more improved. (Embodiment 4) In Embodiments 2 and 3 , the temperature characteristics of each multi-nozzle recording head were treated as static, but actually, due to changes in the surrounding environment and heat generation of the image forming apparatus itself. Since the temperature fluctuates with respect to time, in the fourth embodiment, this temperature fluctuation is also introduced as one parameter of correction, and even when the temperature of the recording head is changed for each recording head. And a correction method capable of forming a higher quality image.

In the present image forming apparatus, as in the second and third embodiments, the all-nozzle recording mode and the reduced recording mode are simultaneously provided.

FIG. 8 is a diagram showing the principle of a correction process for preventing a decrease in recording density due to a decrease in head temperature in the image forming apparatus of the fourth embodiment. Here, the horizontal axis indicates the nozzle number of each recording head, and the vertical axis indicates the correction coefficient F of the image data corresponding to the nozzle number corresponding to each temperature of each recording head.

Based on the input / output characteristics at each temperature shown in FIG. 8, a predetermined number of n nozzles (the number of nozzles at the end of the central area of the recording head corresponding to the density decreasing nozzle area M where the recording density of the recording head decreases) are determined. In the embodiment, the nozzle Nos.
The correction is performed on the image data output by 28 (5 nozzles in total).

The input / output characteristic data at each temperature shown in FIG. 8, that is, the corresponding values of the nozzle number and the correction coefficient F shown in FIG. 8 are stored in the second unevenness correction table 1000 (FIG. 17) for each temperature. ) Are stored in the CPU 100, and the CPU 100 uses the nozzle number (via the nozzle number designation line 70) for printing and the temperature value (71 temperature designation line 71) of each head (10a, 10b, 10c, 10d). Is specified, the corresponding correction coefficient F value is output from the second unevenness correction table 1000 to the corresponding print head.

This temperature is determined by the temperature sensors 80a, 80b, and 8 attached to the respective color output heads, that is, the recording heads 10a, 10b, 10c, and 10d.
The temperature is sensed by 0c and 80d, and the temperature value is transferred to the CPU 100. The CPU 100 quantizes the temperature to any one of the temperatures T1, T2, T3, T4, and T5 shown in FIG. Transfer to 1000.

The generated correction coefficient F value (Fa, Fb, F
Subsequent processing relating to c, Fd) is the same as in the third embodiment, and a description thereof will be omitted.

As described above, in the fourth embodiment, a recording head temperature detection sensor for detecting the value of the temperature of each recording head is provided on each recording head 10, and the second non-uniformity correction table is used. The magnitude of the density unevenness correction coefficient F (T) is switched according to the magnitude of the value of the recording head temperature detected from each recording head temperature sensor.

That is, the value of the temperature of each recording head differs depending on the state of the history of the recording operation by each recording head, the installation / operation conditions of the image forming apparatus, or the installation environment conditions. Since the degree of temperature decrease and the temperature gradient state at the end of the recording nozzle differ depending on the temperature state of each recording head, in this embodiment, each recording is performed using the second unevenness correction table. The density unevenness correction coefficient F (T) is made different in accordance with the magnitude of the value of the temperature of the recording head detected from the head temperature sensor, and the recording nozzle at the end when the recording head temperature is high (T5). Density unevenness data correction coefficient F for
(T5) is increased, and the second density unevenness data correction coefficient F (T1) for the recording nozzle at the end when the recording head temperature is low (T1, T1 <T5) is decreased. In addition, even when the temperature of the recording head changes for each recording head, more accurate density unevenness correction can be realized. [Fifth Embodiment] In the fourth embodiment, the input / output relationship between the nozzle number and the image data correction coefficient F shown in FIG. 8 is stored in order to realize the correction in the reduced recording mode. A method of performing density unevenness correction using the input / output relationship between the nozzle number and the correction coefficient F shown in FIG.

In general, the nozzle numbers shown in FIG.
The input / output relationship of the correction coefficient F corresponds closer to the actual temperature characteristics of each head, and the range of nozzles to be corrected differs depending on the difference in each temperature.

FIG. 9B shows the relationship between the head temperature T (horizontal axis) and the number of nozzles that need to be corrected. That is, it means that the number of nozzles to be corrected increases as the temperature increases.

This relationship is reflected in the input / output relationship between the nozzle number and the correction coefficient F shown in FIG. If the image data is corrected using the input / output relationship between the nozzle number and the correction coefficient F, a higher quality image can be formed.

The configuration of the image forming apparatus of the present embodiment is the same as the configuration shown in FIG. 17, except that the input / output relation data stored in the second unevenness correction table is different.

In the fifth embodiment, a printhead temperature sensor for detecting the value of the printhead temperature is provided on each printhead 10, and the printhead temperature sensor detects the printhead temperature using the second unevenness correction table. In accordance with the magnitude of the value of each print head temperature, the number of print nozzles for which density unevenness correction is performed and the density unevenness correction coefficient F (T) corresponding to each print nozzle are given a size.

That is, the temperature value of each recording head differs depending on the state of the history of the recording operation by each recording head, the installation / operation conditions of the image forming apparatus, or the installation environment conditions. In this embodiment, the second unevenness correction table is used, because the degree of distribution of the temperature drop at the end of the recording nozzle and the state of the temperature gradient vary depending on the temperature state of each recording head. The number n of print nozzles for performing density unevenness correction and the density unevenness correction coefficient F corresponding to each print nozzle in accordance with the magnitude of the printhead temperature value detected from each printhead temperature sensor.
As shown in FIG. 9B, the number of recording nozzles for which density unevenness correction is performed on the recording nozzles at the end when the recording head temperature is high (T5), as shown in FIG. (Nozzle Nos. 122 to 128 in this embodiment),
Further, as shown in FIG. 9A, the density unevenness correction coefficient F (T) corresponding to each of these print nozzles is also increased. Conversely, when the recording head temperature is low (T1, T
1 <T5), the number n of print nozzles for performing density unevenness correction is smaller than that when the print head temperature is high (nozzle numbers 126 to 12 in this embodiment).
8; n = 4), so that the density unevenness correction coefficient F (T) corresponding to each of these print nozzles also becomes smaller than when the print head temperature is high, corresponding to the temperature distribution and gradient of the print head. Corrects density unevenness with high accuracy. (Embodiment 6) In Embodiments 2 to 5, an image forming apparatus capable of forming a high-quality image using either the all-nozzle printing mode or the reduced printing mode has been described. Is related to a method of correcting image data when an image is formed using a plurality of nozzles at either end of the nozzle array.

In the sixth embodiment, as a method of using the nozzles in the reduced recording mode, an image forming apparatus having a method of correcting image data when forming an image using a plurality of nozzles at the center of the nozzle array will be described in detail. Will be described.

The configuration of the image forming apparatus according to the sixth embodiment is substantially the same as the configuration shown in FIG. 16, and is different in that the input / output characteristic data stored in the second non-uniformity correction table is different and the recording element ( In the case where the nozzle number control unit 41 designates the reduced recording mode in addition to the designation of the all-nozzle recording mode and the reduced recording mode, it further designates which part of the head to use, that is, whether the left nozzle or the right nozzle is used. The difference is that the nozzle designation for the center nozzle is also performed. In addition, the CPU 10
0 is obtained from the recording element (nozzle) number control unit 41.
Another difference is that these nozzle designations are further input and these nozzle designations are also made in the second unevenness correction table 1000.

Hereinafter, these different points will be described.

FIG. 18 is a diagram for explaining the characteristic of the recording density lowering due to the lowering of the head temperature of the image forming apparatus of the sixth embodiment.

FIG. 18 shows the temperature characteristics when the central nozzle (nozzle numbers 65 to 192) is used among all the nozzles (256 nozzles). The horizontal axis represents each nozzle number, and the vertical axis represents the corresponding image density. Reference numeral 9000 denotes an image density characteristic when printing is performed by the central nozzle (nozzle numbers 1 to 128) without correction in the present embodiment. As is clear from the curve shape of 9001, the nozzle temperature T2 at both ends of the half nozzle (nozzle numbers 1 to 128) is lower than the nozzle temperature T1 in the central region (T1> T2). In this case, the amount of ink droplets ejected from the recording nozzles at both ends decreases, and the diameter of the recording dot decreases, resulting in a problem that the recording density decreases at both ends.

FIG. 19 is a diagram showing the principle of a correction process for preventing a decrease in recording density due to a decrease in head temperature in the image forming apparatus of the sixth embodiment. Here, the horizontal axis indicates the nozzle number of each recording head, and the vertical axis indicates the correction coefficient F of the image data corresponding to the nozzle number of each recording head. As can be easily understood from FIG. 19, the nozzles from No. 187 to No. 192 where the print density of the print head starts to decrease,
The image data corresponding to No. 70 to No. 65 is corrected. The second unevenness correction table 1000 (FIG. 1)
6) stores the nozzle number and the corresponding value of the correction coefficient F shown in FIG. 19, and the CPU 100 specifies the center nozzle in the reduced recording mode and the nozzle number used for printing.
Is designated, the corresponding correction coefficient F value is output from the second unevenness correction table 1000.

For example, among the print heads having a print width L and all print nozzles of 256 nozzles, the nozzles No. 65 to No.
With half the 128 nozzles up to 192,
In the case where printing is performed with the printing width L / 2, when performing density non-uniformity correction for each print nozzle, the density non-uniformity correction amount for each print nozzle is used as a second density non-uniformity correction coefficient F in accordance with the head temperature gradient. To have

That is, as shown by reference numeral 9001 in FIG. 18, the temperature distribution of the print head is such that the temperature drop due to heat radiation becomes greater toward the end of the print nozzle performing the printing operation. The magnitude of the density non-uniformity data correction amount for each recording nozzle is corrected according to the magnitude of the temperature gradient of each recording nozzle. By making the second density unevenness data correction amount small for a print nozzle with a small decrease,
It is possible to more uniformly correct density unevenness. (Embodiment 7) In Embodiment 6, the temperature characteristics of each multi-nozzle recording head were treated as static, but actually, the temperature characteristics were changed with time due to changes in the surrounding environment and heat generation of the image forming apparatus itself. In Example 7, this temperature fluctuation is also introduced as one parameter of correction, and a higher quality image can be formed when forming an image using the central nozzle in the reduced recording mode. A correction method is provided.

The configuration of the image forming apparatus according to the seventh embodiment is almost the same as the configuration shown in FIG. 17, and is different in that the input / output characteristic data stored in the second non-uniformity correction table is different and the recording element ( In the case where the nozzle number control unit 41 designates the reduced recording mode in addition to the designation of the all-nozzle recording mode and the reduced recording mode, it further designates which part of the head to use, that is, whether the left nozzle or the right nozzle is used. The difference is that the nozzle designation for the center nozzle is also performed. In addition, the CPU 10
0 is obtained from the recording element (nozzle) number control unit 41.
Another difference is that these nozzle designations are further input and these nozzle designations are also made in the second unevenness correction table 1000.

The following description focuses on these different points.

FIG. 20 is a diagram showing the principle of a correction process for preventing a decrease in recording density due to a decrease in head temperature in the image forming apparatus according to the seventh embodiment. Here, the horizontal axis indicates the nozzle number of each recording head, and the vertical axis indicates the correction coefficient F of the image data corresponding to the nozzle number corresponding to each temperature of each recording head.

Based on the input / output characteristics at each temperature shown in FIG. 20, correction is performed on the image data output from the nozzles at both ends where the recording density of the recording head decreases.

The input / output characteristic data at each temperature shown in FIG. 20, that is, the corresponding value of the nozzle number and the correction coefficient F shown in FIG.
(FIG. 17), and stored in the CPU 100 from the nozzle No. used for printing (via the nozzle No. designation line 70) and the temperature value (71 temperature designation) of each head (10a, 10b, 10c). When the user designates (via a line), the corresponding correction coefficient F value is output from the second unevenness correction table 1000.

This temperature is determined by the temperature sensors 80a, 80b, 8 attached to the respective color output heads, ie, the recording heads 10a, 10b, 10c, 10d.
The temperature is sensed by 0c and 80d, and the temperature value is transferred to the CPU 100. The CPU 100 quantizes the temperature to any one of the temperatures T1, T2, T3, T4, and T5 shown in FIG. Transfer to 1000.

The generated correction coefficient F value (Fa, Fb, F
Subsequent processing relating to c, Fd) is the same as in the third embodiment, and a description thereof will be omitted.

As described above, in the fourth embodiment, a recording head temperature detecting sensor for detecting the value of the temperature of each recording head is provided on each recording head 10, and the second non-uniformity correction table is used. The magnitude of the density unevenness correction coefficient F (T) is switched according to the magnitude of the value of the recording head temperature detected from each recording head temperature sensor.

That is, the value of the temperature of each recording head differs depending on the state of the history of the recording operation by each recording head, the installation / operation conditions of the image forming apparatus, or the installation environment conditions. Since the degree of temperature decrease and the temperature gradient state at the end of the recording nozzle differ depending on the temperature state of each recording head, in this embodiment, each recording is performed using the second unevenness correction table. The density unevenness correction coefficient F (T) is made different in accordance with the magnitude of the value of the temperature of the recording head detected from the head temperature sensor, and the recording nozzle at the end when the recording head temperature is high (T5). Density unevenness data correction coefficient F for
(T5) is increased, and the second density unevenness data correction coefficient F (T1) for the recording nozzle at the end when the recording head temperature is low (T1, T1 <T5) is decreased. Thus, more accurate density unevenness correction can be realized. (Embodiment 8) In Embodiment 7, in order to realize the correction when the central nozzle is used in the reduced recording mode, FIG.
The input / output relationship between the nozzle number and the image data correction coefficient F shown in FIG. 21 is stored. In the eighth embodiment, a method for performing density unevenness correction using the input / output relationship between the nozzle number and the correction coefficient F shown in FIG. 21 is shown. .

In general, the input / output relationship between the nozzle number and the correction coefficient F shown in FIG. 21 corresponds closer to the actual temperature characteristics of each head, and the range of nozzles to be corrected differs depending on the temperature. As can be seen from FIG.
As the temperature increases, the number of nozzles to be corrected increases. If the image data is corrected using the input / output relationship between the nozzle number and the correction coefficient F, a higher quality image can be formed.

The configuration of the image forming apparatus of the present embodiment is the same as the configuration described in the seventh embodiment.
The input / output relation data stored in the non-uniformity correction table is different.

In the eighth embodiment, a printhead temperature sensor for detecting the temperature value of each printhead is provided on each printhead 10, and the printhead temperature sensor detects the temperature value of each printhead using a second unevenness correction table. In accordance with the magnitude of the value of the recording head temperature, the number of recording nozzles for which density unevenness correction is performed and the density unevenness correction coefficient F (T) corresponding to each print nozzle are given a magnitude.

That is, the value of the temperature of each recording head differs depending on the state of the history of the recording operation by each recording head, the installation / operation conditions of the image forming apparatus, or the installation environment conditions. In this embodiment, the second unevenness correction table is used, because the degree of distribution of the temperature drop at the end of the recording nozzle and the state of the temperature gradient vary depending on the temperature state of each recording head. The number n of print nozzles for performing density unevenness correction and the density unevenness correction coefficient F corresponding to each print nozzle in accordance with the magnitude of the printhead temperature value detected from each printhead temperature sensor.
As shown in FIG. 21, the number of recording nozzles for performing density non-uniformity correction is increased for the recording nozzles at the end when the recording head temperature is high (T5), as shown in FIG. In the present embodiment, nozzle numbers 122 to 128)
As shown in FIG. 9A, the density unevenness correction coefficient F (T) corresponding to each of these print nozzles is also increased. Conversely, when the recording head temperature is low (T1, T1 <T
5) For the recording nozzles on the end side, the number n of recording nozzles for performing density unevenness correction is made smaller than when the print head temperature is high, and the density unevenness correction coefficients F (T ) Also corrects the density unevenness with higher accuracy in accordance with the print head temperature distribution and gradient so that the print head temperature is lower than when the print head temperature is high. The present invention particularly provides an excellent effect in a recording apparatus having an ink jet recording head for performing recording by forming flying droplets by using thermal energy among ink jet recording methods.

The typical structure and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding the nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or the liquid path holding the Since thermal energy is generated in the electrothermal transducer and film boiling occurs on the heat-acting surface of the recording head, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis can be formed. It is valid. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. When the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface are adopted, excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, A configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600 which discloses a configuration in which the heat acting surface is arranged in a bent region may be used.

In addition, JP-A-59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, or absorbs pressure waves of thermal energy. A configuration based on JP-A-59-138461, which discloses a configuration in which an opening corresponds to a discharge unit, may also be employed.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above specification. This may be either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally.

In addition, the print head is replaceable with a print head of a replaceable chip type, which can be electrically connected to the main body of the apparatus or supplied with ink from the main body of the apparatus. Alternatively, a cartridge type recording head provided with an ink tank may be used.

It is preferable to add recovery means for the recording head, preliminary auxiliary means, and the like provided as components of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. . If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, and printing Performing a preliminary ejection mode for performing another ejection is also effective for performing stable printing.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, and may be a single recording head or a combination of plural recording heads. Alternatively, the apparatus may be provided with at least one of full colors by color mixture.

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 at room temperature, or which is liquid, In general, in the ink jet system, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. It is sufficient if the ink is in a liquid state.

In addition, the temperature rise due to the thermal energy is positively prevented by using the energy of the state change from the solid state to the liquid state of the ink, or the ink is solidified in a standing state for the purpose of preventing the evaporation of the ink. Either ink may be used, or in any case, the ink may be liquefied by application of heat energy according to the recording signal and ejected as a liquid ink, or may already start to solidify when reaching the recording medium. The use of an ink having a property of being liquefied for the first time by thermal energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or Japanese Patent Application Laid-Open No. 60-71260, in which the porous sheet is opposed to the electrothermal converter while being held in a liquid or solid state in the concave portions or through holes of the porous sheet. It may be. 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 to the above, the recording apparatus according to the present invention may be combined with a reader or the like in addition to an image output terminal of an information processing apparatus such as a word processor or a computer as described above. It may take the form of a copier, or a facsimile machine having a transmission / reception function. The present invention may be applied to a system including a plurality of devices or to an apparatus including a single device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus.

As described above, according to this embodiment,
Even when the distribution of the number of recording nozzles for performing the recording operation changes according to the recording operation mode, it is possible to print a high-quality image with no occurrence of recording density unevenness.

[0128]

As described above, according to the present invention, a stable and high-quality image can be formed by correcting a variation in print density by an image recording element comprising a multi-head.

[0129]

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining an entire image forming apparatus according to an embodiment.

FIG. 2 is a schematic diagram of an inkjet recording unit of the image forming apparatus according to the present embodiment.

FIG. 3 is a schematic diagram of an ink jet recording head.

FIG. 4 is a block diagram of the image forming apparatus according to the first exemplary embodiment.

FIG. 5 is a diagram for explaining a density unevenness correction method according to a second embodiment.

FIG. 6 is an explanatory diagram of a recording method using a recording head.

FIG. 7 is a diagram illustrating a density unevenness correction method according to a second embodiment.

FIG. 8 is a diagram illustrating a density unevenness correction method according to a third embodiment.

FIG. 9 is a diagram illustrating a density unevenness correction method according to a fourth embodiment.

FIG. 10 is an explanatory diagram of density unevenness due to a difference in nozzle characteristics of a print head.

FIG. 11 is an explanatory diagram of a density unevenness correction method.

FIG. 12 is a diagram showing a density straight line of a recording head.

FIG. 13 is a diagram illustrating a state of a print head temperature and a print image density in a print operation state in the first embodiment.

FIG. 14 is a diagram illustrating a state of a print head temperature and a print image density in a print operation state in a reduction mode in the second embodiment.

FIG. 15 is a diagram illustrating a state of density unevenness of a recorded image.

FIG. 16 is a block diagram of an image forming apparatus according to a second embodiment.

FIG. 17 is a block diagram of an image forming apparatus according to a third embodiment.

FIG. 18 is a diagram illustrating a state of a print head temperature and a print image density in a print operation state in Examples 6, 7, and 8.

FIG. 19 is a diagram illustrating a density unevenness correction method according to a sixth embodiment.

FIG. 20 is a diagram illustrating a density unevenness correction method according to a seventh embodiment.

FIG. 21 is a diagram illustrating a density unevenness correction method according to an eighth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reader part 2 Printer part 3 Image sensor 4 Recording paper 10 Recording head 11 Carriage 12 Tube 13 Pump 14 Ink tank 15 Rail 16 Belt 17 Pulley 18 Axis 19 Motor 20 Recovery part 21 Substrate 22 Electrothermal converter 23 Electrode 24 Nozzle wall 25 Top plate 26 Common liquid chamber 27 Connector 28 Nozzle 29 Discharge port 30 Reading unit 31 Read signal 32 RAM 33 Unevenness correction data 34 Unevenness correction RAM 35 Unevenness correction signal 36 Image signal 37 Unevenness correction table 38 Image signal after unevenness correction 39 Tone correction Table 40 Binarization circuit 41 Number of recording element control means 42 Number of recording element control signal 43 Recording head control signal 100 Main CPU 102 Printer control CPU 104 Reader control CPU 106 Main image processing unit 108 Operation unit 110 Period memory 114 printer unit driving meter 115 head driver 116 input system image processing unit 118 the reader unit driving system

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/01

Claims (24)

(57) [Claims] 1. A recording head having a plurality of image recording elements arranged therein, the recording head corresponding to each of the plurality of image recording elements.
An image forming apparatus that forms an image based on image data , comprising :
The plurality of image recording elements for correcting variations
Using the first correction data corresponding to each, the recording head
Correction means for correcting image data corresponding to each of the plurality of recording elements of the memory, based on the image data corrected by the correction means ,
Image forming means for forming an image by the recording head, all of the image-recording elements arranged in the recording head
That is, a partial image composed of a part of a plurality of continuous image recording elements
A system for controlling image formation using an image recording element array.
Comprising a control means, a picture by using the partial image recording element arrays by the control means
When forming an image, the correcting means is used before recording.
A predetermined number of pixels located at the end of the array of
A second image correcting means for correcting image data corresponding to the image recording element;
2 and the first correction data,
Corresponding to each of the image recording elements in the partial image recording element row.
The image forming unit corrects the corrected image data.
Using the partial image recording element array based on the image data
Image forming apparatus and forming an image Te. 2. The method according to claim 1, wherein the second correction data is used for recording.
Due to the temperature distribution characteristics of the array of image recording elements
Data to increase the image density
The image forming apparatus according to claim 1, characterized in Rukoto. Wherein the partial image recording element array, according to claim 1, wherein the array of image-recording elements of the recording head, characterized in that consists of a continuous <br/> image recording element from the end An image forming apparatus according to claim 1. 4. The recording apparatus according to claim 1, wherein the partial image recording element array is
Located on one side of the array of multiple image recording elements
Is composed of an image recording device, the second correction data is pre
Of the plurality of image recording elements arranged in the recording head,
Image data corresponding to a predetermined number of image recording elements located in the center
Data to increase the density of the formed image.
The image forming apparatus according to claim 1, wherein the correction data is correction data. 5. An image recording device according to claim 1, wherein the partial image recording element array is configured to record images at both ends of an array of a plurality of image recording elements of the recording head.
The image forming apparatus according to claim 1, characterized in that consists of the image recording elements of the central portion excluding the device. 6. The recording device according to claim 1, wherein the partial image recording element row is
Located in the center of the array of multiple image recording elements
An image recording element, wherein the second correction data is
Of the plurality of image recording elements constituting the partial image recording element row.
Images corresponding to a predetermined number of image recording elements
Correct image data to increase the density of the formed image
2. The correction data according to claim 1,
The image forming apparatus as described in the above . 7. An image reading unit for reading a test image formed by a plurality of image recording elements of the recording head, and the image reading unit reads the image.
The density of an image formed by the plurality of image recording elements;
And a calculating unit for calculating the first correction data , wherein the first correction data is for correcting the density unevenness.
The image forming apparatus according to claim 1, wherein the correction data is the correction data of: 8. The second correction data is used for recording.
A predetermined number located at the end of the array of the partial image recording element rows
The image data corresponding to the image recording element of the
This is correction data for correcting the image density to be higher.
Image recording near the end of the array of the partial image recording element rows.
2. The image forming apparatus according to claim 1 , wherein the amount by which the density increases as the recording element increases . 9. The image forming apparatus according to claim 1 , wherein the image data is luminance data or density data. 10. The recording head according to claim 1, wherein the recording head is provided with a plurality of different colors.
A plurality of correspondingly used image data, a plurality of different
The image forming apparatus according to claim 1 , wherein the image data is image data for each color corresponding to each color . Wherein said recording head, characterized in that the ink jet recording head for recording by discharging ink
The image forming apparatus according to any one of claims 1 to 10,. 12. The recording head, the heat applied to the ink
Equipped with a thermal energy converter for generating energy
In particular, the feature of discharging ink using thermal energy is
The image forming apparatus according to claim 11 , wherein: 13. A printing head in which a plurality of image printing elements are arranged, and a plurality of printing heads corresponding to the plurality of image printing elements are used.
An image forming method for forming an image based on the image data obtained , wherein the density of the image formed by the plurality of image recording elements is
The plurality of image recording elements for correcting variations
Using the first correction data corresponding to each, the recording head
A correction step of correcting image data corresponding to each of the plurality of recording elements of the memory, based on the image data corrected in the correction step ,
An image forming step of forming an image by the recording head consists of all of the image-recording elements arranged in the recording head
That is, a partial image composed of a part of a plurality of continuous image recording elements
Partial image forming mode for forming an image using an image recording element array
In the image formation by the code, the correction step includes
Located at the end of the array of the partial image recording element rows to be used
Corrects image data corresponding to a predetermined number of image recording elements
Correction data and the first correction data for
Used, each image recording element of the partial image recording element row
Correcting the image data corresponding to, the image forming step,
The partial image recording element based on the corrected image data
An image forming method, wherein an image is formed using columns . 14. The second correction data is used for recording.
Low based on the temperature distribution characteristics of the array of image recording elements
The data used to correct the image density to increase
The image forming method according to claim 13, wherein
Law . 15. The partial image recording element array, the array of image-recording elements of the recording head, consecutively from the end
Claims 1, wherein the composed image recording element
4. The image forming method according to 3 . 16. The recording apparatus according to claim 16, wherein said partial image recording element array is provided with said recording device.
The head is located on one side of the array of a plurality of image recording elements.
Wherein the second correction data comprises:
A plurality of image recording elements arranged in the recording head;
That is, the image corresponding to a predetermined number of image recording elements
Correct image data to increase the density of the formed image
14. Correction data for performing the following.
2. The image forming method according to 1., 17. The image recording device according to claim 1, wherein the partial image recording element array includes image recording elements at both ends of an array of a plurality of image recording elements of the recording head.
14. The image forming method according to claim 13 , wherein the image forming method comprises a central part of the image recording element excluding the recording element. 18. The recording apparatus according to claim 18, wherein said partial image recording element row is
The head located at the center of the array of
Wherein the second correction data comprises:
A plurality of image recording elements constituting the partial image recording element row
Corresponding to a predetermined number of image recording elements located at both ends
Correct image data to increase the density of the formed image
2. The correction data for performing correction.
4. The image forming method according to 3 . 19. The recording apparatus according to claim 19, wherein the first correction data is stored in the recording medium.
Test image formed by multiple image recording elements
The plurality of calculated based on the result of reading the image
Corrects density unevenness of the image formed by the image recording element
14. Correction data for performing the following.
2. The image forming method according to 1., 20. The method according to claim 19, wherein the second correction data is used for recording.
A predetermined position located at an end of the array of the partial image recording element rows.
Image data corresponding to the number of image recording elements are recorded.
With correction data to correct the image density
Yes, an image close to the end of the array of partial image recording element rows
The feature is to increase the amount of density increase as the printing element
The image forming method according to claim 13, wherein: 21. The image forming method according to claim 13 , wherein the image data is luminance data or density data. 22. The recording head according to claim 1, wherein the recording head is provided with a plurality of different colors.
A plurality of correspondingly used image data, a plurality of different
14. The image forming method according to claim 13 , wherein the image data is image data for each color corresponding to each color . 23. The recording head according to claim 13 , wherein the recording head is an ink jet recording head that performs recording by discharging ink.
23. The image forming method according to any one of the above items . 24. A method according to claim 24, wherein the recording head applies heat to the ink.
Equipped with a thermal energy converter for generating energy
In particular, the feature of discharging ink using thermal energy is
24. The image forming method according to claim 23 , wherein: