JPH07323613A - Image forming method and apparatus - Google Patents

Abstract

PURPOSE:To record a stable image of high quality by correcting image data on the basis of the difference between the printing density characteristics of a plurality of image recording elements and the respective temp. characteristics of a plurality of the image recording elements and forming an image on the basis of the corrected image data. CONSTITUTION:In the control device of an image forming apparatus, irregularity correction tables 37a-37d for respective colors and gradation correction tables 39a-39d subjecting image signals after the correction of irregularity for respective colors to gradation correction are provided and data subjected to gradation correction are binarized 40a-40d to be applied to ink jet heads 10a-10d. A reading part 30 reading a test pattern formed by nozzles is provided and density irregularity quantity is calculated from the read value in a CPU 100 and irregularity correction signals 35a-35b are outputted to the correction tables 37a-37d in synchronous relation to the image signals inputted from irregularity correction RAMs 34a-34d outputting correction data to respective nozzles on the basis of the density irregularity quantity.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art The 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, the running cost is low, and the recording method is quiet, and is widely used. In this method, by using a head in which a large number of nozzles are formed on a straight line perpendicular to the relative movement direction of the head with respect to the recording medium, the width corresponding to the number of nozzles is set to 1 by one relative scan of the head. It can be recorded every time, and speedup can be achieved relatively easily.

[0003]

However, it is difficult to uniformly manufacture an image recording element composed of multiple heads, and the characteristics of the image recording element vary to some extent. For example, in an inkjet multi-head, variations in the shape of nozzles and the like occur, and such non-uniformity of characteristics between image recording elements leads to non-uniformity in dot size and density recorded by each image recording element. , Causing uneven density in the recorded image.

The present invention has been made in view of the above conventional example, and provides an image recording method and apparatus for correcting a variation in print density by an image recording element including a multi-head and recording a stable and high quality image. The purpose is to provide.

[0005]

In order to achieve the above object, an image recording method and apparatus of the present invention have the following constitution. That is, in an image forming apparatus including a recording head in which a plurality of image recording elements are arranged, an image is formed based on a difference in print density characteristics of the plurality of image recording elements and each temperature characteristic of the plurality of image recording elements. A correction unit that corrects data and an image forming unit that forms an image based on the image data corrected by the correction unit are provided.

According to another aspect of the present invention, there is provided a recording head having a plurality of image recording elements arranged therein, and an image forming mode for forming an image using all the image recording elements of the recording head, and the recording head. An image forming apparatus having an image forming mode of a partial image recording element for forming an image by using a part of the image recording element, wherein temperature characteristics of all image recording elements of the recording head and partial image recording of the recording head are performed. Correction means for correcting the image data based on the temperature characteristic of the element, and image forming means for forming an image using the partial image recording element of the recording head based on the image data corrected by the correction means. Equipped with.

Another aspect of the present invention is an image forming method including a recording head in which a plurality of image recording elements are arranged, wherein the difference in print density characteristics of the plurality of image recording elements and the plurality of image recording elements A correction step of correcting image data based on each temperature characteristic and an image forming step of forming an image based on the image data corrected in the correction step are provided.

According to another aspect of the present invention, there is provided a recording head having a plurality of image recording elements arranged therein, an image forming mode for forming an image using all the image recording elements of the recording head, and the recording head. An image forming method having an image forming mode of a partial image recording element for forming an image using a part of the image recording element of the A correction step of correcting the image data based on the temperature characteristics of the element, and an image forming step of forming an image using the partial image recording element of the recording head based on the image data corrected in the correction step. Equipped with.

[0009]

In the above structure, the correcting means corrects the image data based on the difference in the print density characteristics of the plurality of image recording elements arranged in the recording head and the temperature characteristics of the plurality of image recording elements. The image forming means forms an image based on the image data corrected by the correcting means.

According to another aspect of the invention, the correcting means corrects the image data based on the temperature characteristics of all the image recording elements of the recording head and the temperature characteristics of the partial image recording elements of the recording head, and the image forming means. However, an image is formed using the partial image recording element of the recording head based on the image data corrected by the correction unit.

Another aspect of the present invention is an image forming method including a recording head in which a plurality of image recording elements are arranged, the difference in print density characteristics of the plurality of image recording elements and the plurality of image recording elements. Image data is corrected based on each temperature characteristic, and an image is formed based on the corrected image data.

According to another aspect of the invention, there is provided a recording head having a plurality of image recording elements arranged therein, and an image forming mode for forming an image using all the image recording elements of the recording head, and the recording head. An image forming method having an image forming mode of a partial image recording element for forming an image using a part of the image recording element, wherein the temperature characteristics of all the image recording elements of the recording head and the partial image recording of the recording head are performed. Image data is corrected based on the temperature characteristics of the element, and an image is formed using the partial image recording element of the recording head based on the corrected image data.

[0013]

EXAMPLES Examples according to the present invention for solving the above problems will be described below. As the overall configuration of the embodiment, the first embodiment will describe a method of correcting a print density and an apparatus therefor when an image is formed by using all nozzles of an inkjet multi-head, and the second to fifth embodiments
A method for correcting the print density and an apparatus for correcting the print density when the mode for forming an image using all the nozzles of the inkjet multi-head and the mode for forming the image using only one nozzle of the inkjet multi-head are provided at the same time will be described. In Examples 6 to 8, a mode of forming an image by using all nozzles of the inkjet multi-head, a mode of forming an image by using only one nozzle of the inkjet multi-head, and further of the inkjet multi-head A printing density correction method and apparatus for simultaneously providing a mode for forming an image using only the central nozzle will be described. (Embodiment 1) In Embodiment 1, a method of correcting a print density when an image is formed by using all nozzles of an inkjet multi-head and an apparatus therefor will be described in detail below.

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

To achieve the above object, the image forming apparatus of this embodiment includes a multi-head (10a, 10b, 10c) in which a plurality of image recording elements are arranged in a predetermined direction. This multi-head causes variations in image density during image formation mainly due to the following two factors, and deteriorates image quality.

One of the factors will be described below.

The nozzles of a multi-head (hereinafter also referred to as a recording head) generally have different printing characteristics mainly due to manufacturing variations. An example of this is shown in FIG.
The image density characteristic when the input signal level to each nozzle is made uniform is shown. Here, the horizontal axis represents the nozzle number and the vertical axis represents the corresponding image density. It can be seen that there is density unevenness corresponding to each nozzle.

Another factor will be described below.

Since the temperature distribution is non-uniform depending on the location of the nozzles, the printing characteristics are also non-uniform.

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

The horizontal axis of the curve 5001 represents the nozzle number, and the vertical axis represents the image recording density. FIG.
5000, the head temperature T2 at both ends of the recording head is equal to the head temperature T in the central region of the recording head.
It becomes lower than 1 (T1> T2) As a result,
There is a problem that the amount of ink droplets ejected from the recording nozzles on both ends of the multi-nozzle recording head is reduced, the recording dot diameter is reduced, and the recording density is reduced on both ends of the multi-nozzle recording head. Occur.

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

As described above, the image density varies 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 the test pattern formed by the image recording element (nozzle) of the multi-head. Then, from the read value, the density unevenness calculating unit (the CPU 100 executes the density unevenness calculating 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 amount of density unevenness, the first density unevenness correction units (34a, 34b, 34c, 34d, 37a, 37).
b, 37c, 37d) corrects the image data consisting of the input brightness data or density data. The corrected image data is processed by the gradation correction unit (39a, 39b, 39c,
39d) gradation correction, and then binarization processing (40a,
40b, 40c, 40d) and then printing with the multi-head (10a, 10b, 10c, 10d).

By the processing based on the above configuration, it is possible to form a high-quality image with little variation.

The first embodiment of the present invention will be described below in more detail and specifically with reference to the drawings.

FIG. 1 is a schematic diagram for explaining the whole of the image forming apparatus of this embodiment.
A color image scanner unit (hereinafter abbreviated as “reader unit”) 1 that outputs digital color image data, and a recording paper 4 that outputs the digital color image data output from the reader unit 1.
The image forming apparatus of the present embodiment is constituted by the printer unit 2 for recording on.

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

The main image processing unit 106 uses masking,
Image processing such as black extraction, binarization and γ correction is performed. A synchronous memory 110 is connected to the printer control CPU 102 and the main image processing unit 106. This synchronous memory 1
Reference numeral 10 is for absorbing the time variation of the input operation and for correcting the delay due to the mechanical arrangement of the recording heads described above. Then, 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 by controlling the.

The printer control CPU 102 is connected to a printer unit drive system 114 which controls the input drive of the printer unit.

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

Further, the input system image processing unit 116 is provided with a CC
The D sensor 3 is connected, and the input system image processing unit 1
Reference numeral 16 is connected to the main image processing unit 106.

FIG. 2 is a schematic diagram for explaining the printer unit 2 of the image forming apparatus of this embodiment, which is roughly classified 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 necessary amount to the head 10, and has an ink tank 14 and an ink pump 13. The ink supply section 14 and the head 10 are connected by an ink supply tube 12, and normally, the ink is ejected from the head by a capillary action and is automatically supplied to the head 10. Further, at the time of 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 respectively mounted on a head carriage 11 and an ink carriage (not shown), and a belt 16 provided between pulleys 17a and 17b is connected to a shaft 18 of a motor 19 to 19
Along the guide rails 15a, 15b according to the rotation of
It is configured to reciprocate in the direction of arrow S.

The head recovery section 20 maintains the head 1 at the home position HP in order to maintain the stability of the head.
It is provided so as to face 0, and specifically, the following operation is performed. During operation, the head 10 is moved forward in the direction of arrow f to cap the head 10 at the home position to prevent evaporation of ink from inside the head nozzle (capping operation), or bubbles or dust in the nozzle before image recording is started. In order to discharge the ink, it is necessary to press the ink flow path in the head with an ink pump to forcibly discharge the ink from the nozzle (pressure recovery operation). Performs functions such as collecting.

FIG. 3 is a perspective view showing a schematic structure of the ink jet recording head 10. This head undergoes a semiconductor manufacturing process such as etching, vapor deposition, sputtering, etc., and electrothermal conversion formed on the substrate 21. It is composed of a body 22, an electrode 23, a nozzle wall 24, and a top plate 25.

The recording ink is stored in the ink tank 14 (see FIG.
(See (1)) to the common liquid chamber 26 of the recording head 10 through the ink supply tube 12. Reference numeral 27 is a supply pipe connector.

The ink supplied to the common liquid chamber 26 is supplied to the inside of the nozzle 28 due to the capillary phenomenon, and is stably held by forming a meniscus on the ejection port surface at the tip of the nozzle.

When the electrothermal converter 22 is energized, the ink on the surface of the electrothermal converter is heated and a bubbling phenomenon occurs, and the energy of the bubbling causes the ejection port surface 29.
Ink droplets are ejected from.

With the configuration as described above, the nozzle density is 1
128 nozzles with a high-density nozzle arrangement of 6 nozzles / mm
It is possible to manufacture a multi-nozzle inkjet recording head having nozzles or 256 nozzles.

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

Image signals 36a, 36b, 36c, 36d
Is an unevenness correction table 37a, 37b, 37c, 3 controlled by the unevenness correction signals 35a, 35b, 35c, 35d.
It is converted by 7d so as to correct the unevenness of the heads 10a, 10b, 10c and 10d. The unevenness correction table is
As shown in FIG. 12, there are 61 correction (γ) straight lines having different slopes of 0.01 from Y = 0.70x to Y = 1.30x, and the unevenness correction signals 35a, 35b, 35c, 3 are provided.
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 when a nozzle having a small dot system is selected, a correction straight line having a large inclination is selected to correct the image signal.

The unevenness correction RAM stores a selection signal of a correction straight line necessary for correcting the unevenness of each head. That is, the unevenness correction signals having 61 kinds of values of 0 to 60 are stored for 256 nozzles, and the unevenness correction signals 35a, 35b, 35c, 3 and 3 are synchronized with the input image signal.
Output 5d. The signals 38a, 38b, 38 in which the unevenness is corrected by the γ straight line selected by the unevenness correction signal
c and 38d are tone correction tables 39a, 39b and 39.
c, 39d, where the gradation characteristics of each head are corrected and output.

The signal is then converted into binary circuits 40a, 40a.
b, 40c, 40d are binarized, and the head 10a,
A color image is formed by driving 10b, 10c, and 10d.

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

First, by a control signal (not shown), the unevenness correction tables 37a, 37b, 37c, 37d are all set to a straight line having an inclination of 1.0, and the unevenness correction is not performed at all. Subsequently, the unevenness correction pattern is output from a signal source (not shown) to the unevenness correction table, and the heads 10a, 10b,
By 10c and 10d, this is recorded (printed out) on a sheet or the like. The unevenness correction pattern may be a uniform pattern having an arbitrary printing duty, but a duty of about 30 to 75% is suitable. Here, a uniform halftone of 50% duty is recorded in each color of cyan, magenta, yellow, and yellow.

The output pattern is read by the reading unit 30, and the read signals 31a, 31b, 3 of the three colors at that time are read.
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. Further, the number of pixels of CCD is at least larger than 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 uneven distribution of the cyan head, the green signal shows the uneven distribution of the magenta head, the blue signal shows the uneven distribution data of the yellow head, and the red signal, the green signal, and the blue signal. The distribution of the black head is obtained from the signal obtained by processing the signal. Here, for simplification, a case will be described in which the unevenness distribution of the cyan head is obtained, the first correction data calculation unit creates the first density unevenness correction data, and the unevenness correction is performed.

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

On the other hand, Cn = -log Rn / R0 Here, R0 is a constant such that Rn ≧ R0. Then, the cyan density signal Cn is converted to obtain the density unevenness distribution.

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 corresponding to (ΔC) n is expressed as ΔSn = Kx ΔCn, where K is a coefficient. Ask in.

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

In this way, a different γ straight line for each nozzle is selected according to 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, it is possible to form a high-quality image with little variation.

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

The machine may automatically read the printed sample.

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

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

In FIG. 14, 2000 indicates all nozzles (256
Among them, the temperature characteristics are shown when half of the nozzles (nozzle numbers 1-128) are used. The horizontal axis shows each nozzle number, and the vertical axis shows the corresponding image density. 2001 is
The image density characteristics when printing with half the nozzles (nozzle numbers 1-128) are shown. As is clear from the curve shape of 2001, the nozzle temperature T2 at both ends of half the nozzles (nozzle numbers 1-128) becomes lower than the nozzle temperature T1 in the central region (T1> T2). However, the amount of ink droplets ejected from the recording nozzles on both ends decreases, the recording dot diameter decreases, and the recording density decreases on both ends.

On the other hand, 2000 (see FIG. 14) shows an image density characteristic when an image is formed in the reduction recording mode by using the image forming apparatus of the first embodiment. As can be seen from the 2000 curve shape, half the nozzles (nozzle numbers 1-12
8) The nozzle temperature T2 at the right end becomes lower than the nozzle temperature T1 in the central region (T1> T2), and as a result, the amount of ink droplets ejected from the recording nozzles at both ends decreases. As a result, the recording dot diameter becomes smaller, and the recording density lowers at the right end. On the other hand, half the nozzles (nozzle numbers 1-12)
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 of nozzles N is corrected by the above-described method, the recording paper 4 is formed with the total nozzle width L of the multi-nozzle recording head. Recording width pitch L on top
In the case of recording with, the image signal having a uniform density can be recorded over the front surface of the recorded image by correcting the image signal with the density unevenness correction data.
As shown in FIG.
With 0, when recording is performed with the recording width pitch L / 2 for each nozzle number N / 2, the recording head temperature in the nozzle region M at the center of the recording head 10 decreases, and the recording density is reduced. As a result, low density unevenness of a width of 2M is generated in the recorded image for each pitch L, and the quality of the recorded image is significantly deteriorated.

For example, as shown in FIG. 6, among the recording heads of 256 nozzles, nozzle No. 1 to nozzle No. 1 (l
(= 128), when the recording operation is performed with the recording nozzle width corresponding to 128 nozzles, which is the first half, the second correction data calculating unit prevents a decrease in recording density due to a decrease in the head temperature in the central area of the recording head. Therefore, 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 n nozzles (nozzle No. in this embodiment) at the end portion of the central area of the print head corresponding to the density lowering nozzle area M where the print density of the print head is decreased. The image data corresponding to 124 to 128 (a total of 5 nozzles) is corrected.

FIG. 16 is a view showing the arrangement of the image forming apparatus according to the second embodiment. Referring to this figure, the difference from the configuration of the first embodiment (see FIG. 4) is mainly in the multiplier (6
0a, 60b, 60c, 60d), the second unevenness correction table 1000, and the recording element (nozzle) number control unit 41 are further added. Since the configurations of the other blocks are basically the same, description of those operations will be omitted.

Second unevenness correction table 1000 (FIG. 4)
5 stores the corresponding value of the nozzle number to the correction coefficient F shown in FIG. 5, and when the nozzle number used for printing is designated by the CPU 100, the second unevenness correction table 10
00, the corresponding correction coefficient F value is output. Although the outputs include Fa, Fb, Fc, and Fd, the same correction coefficient F value is output in this embodiment.

Fa, Fb, Fc, and Fd are input to the multiplier 60a, multiplier 60b, and multiplier 60c, respectively. And the multiplier 6
0a, multiplier 60b, multiplier 60c,
Each of the multipliers 60d also has an unevenness correction RA.
M34a, unevenness correction RAM34b, unevenness correction RAM34
c, each unevenness correction signal from the unevenness correction RAM 34d is multiplied. That is, the unevenness correction RAMs 34a, 34b, 34 tuned for correction in the all-nozzle recording mode
The uneven correction signals from c and 34d are corrected in the reduction recording mode by the correction coefficient F value from the second uneven correction table, and the resulting signals are the uneven correction tables 37a, 37b, and 37c. , 37d. Unevenness correction tables 37a, 37b, 37c, 37d
The subsequent processing is the same as in the first embodiment.

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

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

The CPU 100 inputs 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 the correction coefficient 1.0 is given,
The second unevenness correction table 1000 outputs the correction coefficient 1.0 to the multipliers 60a, 60b, 60c and 60d. That is, it is equivalent to not correcting. Also,
In 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. And outputs the correction coefficient to the multipliers 60a, 60b, 60c, 60d.

With the above configuration, a high quality image can be formed by using either the all nozzles recording mode or the reduction recording mode.

As described above, the first density unevenness correction data, that is, the correction data for the all-nozzle print mode is set for the area of the number of nozzles n corresponding to the nozzle area M (FIG. 14) where the print density is reduced. To 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 recording mode is superimposed, and the decrease in the recording density due to the temperature decrease in the central area of the recording head is offset to correct the uneven density. it can.

In this embodiment, of the 256 nozzles,
Although the correction method using the first half 128 pieces is shown, this is the same method when the latter half 128 pieces are used, that is, the second unevenness correction table corresponds to the latter half 128 temperature characteristics. Needless to say, this can be realized by storing the input / output relationship.

The second unevenness correction table stores the stepwise input / output relationship of the nozzle number-image data correction coefficient F shown in FIG. 5, but is specified by this stepwise input / output relationship. It is needless to say that the relationship is not limited to the above, but may be an input / output relationship that compensates the 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 print nozzles is changed, the input / output relationship of the second unevenness correction table can be rewritten so that the print density unevenness due to the state of the temperature gradient distribution of the print head does not occur. , You can easily record high quality images. (Third Embodiment) In the first embodiment, the stepwise input / output relationship of the nozzle number-image data correction coefficient F shown in FIG. Then, the nozzle number-correction coefficient F shown in FIG.
A method of performing density unevenness correction using the input / output relationship of is shown.

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 of the second embodiment. Here, the horizontal axis represents the nozzle number of each recording head, and the vertical axis represents 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 n nozzles (nozzles in the present embodiment are provided at the end portions of the central area of the print head corresponding to the density lowering nozzle area M where the print density of the print head is decreased.
The image data corresponding to No. 124 to 128 (total of 5 nozzles) is corrected. Second unevenness correction table 100
0 (FIG. 16) 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 is performed. From the table 1000, the corresponding correction coefficient F value is output.

For example, among the recording heads having 256 recording nozzles with a recording width L, nozzle No. 1 to nozzle No. 1
When performing recording with a recording width L / 2 using recording nozzles of 128 nozzles, which is a half of (1 = 128), when the density unevenness correction for each recording nozzle is performed, a second density unevenness correction coefficient F is set as The density unevenness correction amount for each recording nozzle has a gradient corresponding to the head temperature gradient.

That is, as indicated by reference numeral 2001 in FIG. 14, the temperature distribution of the print head is in a temperature gradient state in which the temperature drop due to heat dissipation increases toward the end side of the print nozzle that performs the print operation. The correction amount of the density unevenness data for each recording nozzle is corrected according to the size of the temperature gradient of each recording nozzle, and the correction amount of the second density unevenness data for the recording nozzle having a large temperature drop is large and By setting the second density unevenness data correction amount for the recording nozzle, which has a small decrease, to be small,
The density unevenness can be corrected more uniformly.

In the first embodiment, the correction having the stepwise input / output relationship was performed, but when the image density gradient on the end side shown in 2001 of FIG. 14 is seen, the correction having the gradient shown in FIG. 7 was performed. The correction accuracy can be improved more. (Embodiment 4) In Embodiments 1 and 2, the temperature characteristics of each multi-nozzle recording head were treated as static, but in reality, due to changes in the surrounding environment and heat generation of the image forming apparatus itself, etc. Since the temperature fluctuates with respect to time, in the fourth embodiment, this temperature fluctuation is also introduced as one parameter for correction, and even when the temperature of the print head changes for each print head. Provide a correction method capable of forming a higher quality image.

This image forming apparatus is provided with the all-nozzle recording mode and the reduced recording mode at the same time as in the second to third embodiments.

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 represents the nozzle number of each recording head, and the vertical axis represents 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 n nozzles (main nozzles) at the end of the central area of the print head corresponding to the density lowering nozzle area M in which the print density of the print head is decreased. In the examples, nozzle Nos. 124-1
The image data output by 28 nozzles (5 nozzles in total) is corrected.

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

It should be noted that this temperature is determined by the temperature sensors 80a, 80b, 8 attached to the respective color output heads, that is, the recording heads 10a, 10b, 10c, 10d.
The temperature value is transferred to the CPU 100 by being sensed by 0c and 80d. Based on the temperature value, the CPU 100 quantizes the temperature T1, T2, T3, T4, T5 shown in FIG. Transfer to 1000.

The generated correction coefficient F value (Fa, Fb, F
Subsequent processing regarding (c, Fd) is the same as that of the third embodiment, and thus the description thereof is omitted.

As described above, in the fourth embodiment, the recording head temperature detecting sensor for detecting the temperature value of each recording head is provided on each recording head 10, and the second unevenness correction table is used to detect the temperature. The size of the density unevenness correction coefficient F (T) is switched according to the size of the print head temperature detected by each print head temperature sensor.

That is, the temperature value of each recording head differs depending on the history of recording operation by each recording head, the installation / operating condition of the image forming apparatus, or the installation environment condition. Therefore, the recording operation is performed. Since the degree of temperature decrease and the temperature gradient state on the end side of the recording nozzles differ depending on the temperature state of each recording head, in the present embodiment, each recording is performed using the second unevenness correction table. The density unevenness correction coefficient F (T) is made different depending on the size of the temperature of the print head detected by the head temperature sensor, and the print nozzles at the end side when the print head temperature is high (T5). Second density unevenness data correction coefficient F for
By increasing (T5) and decreasing the second density unevenness data correction coefficient F (T1) for the recording nozzle on the end side when the recording head temperature is low (T1, T1 <T5). Even when the temperature of the print head changes with respect to each print head, it is possible to realize more accurate density unevenness correction. [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 for performing density unevenness correction will be described using the nozzle number-correction coefficient F input / output relationship shown in FIG.

Generally, the nozzle number shown in FIG.
The input / output relationship of the correction coefficient F corresponds more closely 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 correction. That is, it means that the number of nozzles to be corrected increases as the temperature rises.

This relationship is reflected in the nozzle number-correction coefficient F input / output relationship shown in FIG. If the image data is corrected by using the input / output relationship of the nozzle number-correction coefficient F, higher quality image formation can be performed.

The configuration of the image forming apparatus of this embodiment is the same as that 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 print head temperature sensor for detecting the temperature value of the print head is provided on each print head 10, and the print head temperature sensor detects the temperature value by using the second unevenness correction table. The number of recording nozzles for which density unevenness correction is performed and the density unevenness correction coefficient F (T) corresponding to each recording nozzle are increased or decreased depending on the size of each print head temperature.

That is, the temperature value of each recording head varies depending on the history of recording operation by each recording head, the installation / operation conditions of the image forming apparatus, or the installation environment conditions, and therefore the recording operation is performed. Since the degree of temperature drop distribution and the temperature gradient state on the end side of the recording nozzles differ depending on the temperature state of each recording head, in the present embodiment, the second unevenness correction table is used. , The number n of recording nozzles for which density unevenness correction is performed and the density unevenness correction coefficient F corresponding to each recording nozzle according to the magnitude of the temperature value of the print head detected by each print head temperature sensor.
By changing the size of (T), as shown in FIG. 9B, the number of recording nozzles for performing density unevenness correction with respect to the recording nozzles on the end side when the recording head temperature is high (T5). (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 recording nozzles is also increased. On the contrary, when the temperature of the recording head is low (T1, T
For the recording nozzles on the end side of 1 <T5), the number of recording nozzles n for density unevenness correction is set to be smaller than that when the recording head temperature is high (nozzle Nos. 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 that when the print head temperature is high, in accordance with the temperature distribution / gradient of the print head. Correct density unevenness with high accuracy. (Embodiment 6) In Embodiments 2 to 5, the image forming apparatus capable of forming an image of good quality is described by using either the all-nozzle recording mode or the reduction recording mode. Was used for the correction method of image data in the case of forming an image using a plurality of nozzles on either end of the nozzle array.

The sixth embodiment further describes an image forming apparatus having a method of correcting image data when an image is formed by using a plurality of nozzles in the center of the nozzle arrangement as the usage of the nozzles in the reduced recording mode. Explained.

The configuration of the image forming apparatus of the sixth embodiment is almost the same as that of FIG. 16, except that the input / output characteristic data stored in the second unevenness correction table is different, and the recording element ( In addition to designation of all-nozzle recording mode and reduction recording mode, the nozzle number control unit 41 further designates which part of the head is used when the reduction recording mode is designated, that is, whether the left nozzle or the right nozzle is used. The difference is that the nozzle designation for the central nozzle is also performed. Also, the CPU 10
0 is from the recording element (nozzle) number control unit 41,
It is also different in that these nozzle designations are further input and the nozzle designations are also performed in the second unevenness correction table 1000.

Hereinafter, these different points will be described.

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

FIG. 18 shows temperature characteristics when the central nozzle (nozzle number 65 to 192) is used among all the nozzles (256 nozzles). The horizontal axis shows each nozzle number, and the vertical axis shows the corresponding image density. Reference numeral 9000 indicates an image density characteristic when printing is performed by the nozzles (nozzle numbers 1 to 128) in the central portion without correction in this embodiment. As is clear from the curve shape of 9001, the nozzle temperature T2 at both ends of half the nozzles (nozzle numbers 1-128) becomes lower than the nozzle temperature T1 in the central region (T1> T2). However, the amount of ink droplets ejected from the recording nozzles on both ends decreases, the recording dot diameter decreases, and the recording density decreases on 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 represents the nozzle number of each recording head, and the vertical axis represents 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, nozzle No. 187 to nozzle No. 192 where the recording density of the recording head begins to decrease,
The image data corresponding to No. 70 to No. 65 is corrected. The second unevenness correction table 1000 (see FIG.
6) stores the corresponding values of the nozzle number and the correction coefficient F shown in FIG. 19, and the CPU 100 specifies the central 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 recording heads having the recording width L and all the recording nozzles of 256 nozzles, the nozzle No. 65 to the nozzle No.
By the recording nozzle of 128 nozzles of half to 192,
In the case of performing recording with the recording width L / 2, when performing density unevenness correction for each recording nozzle, a second density unevenness correction coefficient F is set as a density unevenness correction amount for each recording nozzle and a gradient corresponding to the head temperature gradient. To have.

That is, as indicated by reference numeral 9001 in FIG. 18, the temperature distribution of the print head is in a temperature gradient state in which the temperature drop due to heat dissipation increases toward the end side of the print nozzle for performing the printing operation. The correction amount of the density unevenness data for each recording nozzle is corrected according to the size of the temperature gradient of each recording nozzle, and the correction amount of the second density unevenness data for the recording nozzle having a large temperature drop is large and By setting the second density unevenness data correction amount for the recording nozzle, which has a small decrease, to be small,
The density unevenness can be corrected more uniformly. (Embodiment 7) In Embodiment 6, the temperature characteristics of each multi-nozzle recording head are treated as static, but in reality, due to changes in the surrounding environment, heat generation of the image forming apparatus itself, etc. Since the temperature fluctuates, in the seventh embodiment, this temperature fluctuation is also introduced as one parameter for correction, and a higher quality image can be formed when the image is formed using the central nozzle in the reduced recording mode. Provide a correction method.

The configuration of the image forming apparatus according to the seventh embodiment is almost the same as that of FIG. 17, except that the input / output characteristic data stored in the second unevenness correction table is different from that of the recording element ( In addition to designation of all-nozzle recording mode and reduction recording mode, the nozzle number control unit 41 further designates which part of the head is used when the reduction recording mode is designated, that is, whether the left nozzle or the right nozzle is used. The difference is that the nozzle designation for the central nozzle is also performed. Also, the CPU 10
0 is from the recording element (nozzle) number control unit 41,
It is also different in that these nozzle designations are further input and the nozzle designations are also performed in the second unevenness correction table 1000.

Hereinafter, these different points will be mainly described.

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 of the seventh embodiment. Here, the horizontal axis represents the nozzle number of each recording head, and the vertical axis represents the correction coefficient F of the image data corresponding to the nozzle number corresponding to each temperature of each recording head.

On the basis of the input / output characteristics at each temperature shown in FIG. 20, the image data output from the nozzles at both ends where the recording density of the recording head decreases is corrected.

The input / output characteristic data at each temperature shown in FIG. 20, that is, the corresponding value of the nozzle number to the correction coefficient F shown in FIG. 20, is the second unevenness correction table 1000 for each temperature.
In FIG. 17, the CPU 100 stores the nozzle numbers used for printing (via the nozzle number designation line of 70) and the temperature values of each head (10a, 10b, 10c) (temperature designation of 71). When (through a line) is specified, the corresponding correction coefficient F value is output from the second unevenness correction table 1000.

It should be noted that this temperature is the temperature sensor attached to each color output head, that is, each of the recording heads 10a, 10b, 10c, and 10d, 80a, 80b, 8
The temperature value is transferred to the CPU 100 by being sensed by 0c and 80d. Based on the temperature value, the CPU 100 quantizes the temperature T1, T2, T3, T4, T5 shown in FIG. Transfer to 1000.

The generated correction coefficient F value (Fa, Fb, F
Subsequent processing regarding (c, Fd) is the same as that of the third embodiment, and thus the description thereof is omitted.

As described above, in the fourth embodiment, the print head temperature detection sensor for detecting the temperature value of each print head is provided on each print head 10, and the second unevenness correction table is used to detect the temperature. The size of the density unevenness correction coefficient F (T) is switched according to the size of the print head temperature detected by each print head temperature sensor.

That is, the temperature value of each recording head differs depending on the history of recording operation by each recording head, the installation / operating conditions of the image forming apparatus, or the installation environment conditions, and therefore the recording operation is performed. Since the degree of temperature decrease and the temperature gradient state on the end side of the recording nozzles differ depending on the temperature state of each recording head, in the present embodiment, each recording is performed using the second unevenness correction table. The density unevenness correction coefficient F (T) is made different depending on the size of the temperature of the print head detected by the head temperature sensor, and the print nozzles at the end side when the print head temperature is high (T5). Second density unevenness data correction coefficient F for
By increasing (T5) and decreasing the second density unevenness data correction coefficient F (T1) for the recording nozzle on the end side when the recording head temperature is low (T1, T1 <T5). Therefore, it becomes possible to realize the density unevenness correction with higher accuracy. (Embodiment 8) In Embodiment 7, in order to realize the correction when the central nozzle is used in the reduced recording mode, FIG.
Although the input / output relationship between the nozzle number and the image data correction coefficient F shown in FIG. 21 is stored, the eighth embodiment shows a method for performing density unevenness correction using the input / output relationship between the nozzle number and the correction coefficient F shown in FIG. .

Generally, the input / output relationship of nozzle number-correction coefficient F shown in FIG. 21 corresponds more closely to the actual temperature characteristics of each head, and the range of nozzles to be corrected differs depending on the difference in each temperature. As can be seen from FIG. 21,
As the temperature rises, the number of nozzles to be corrected increases. If the image data is corrected by using the input / output relationship of the nozzle number-correction coefficient F, higher quality image formation can be performed.

The structure of the image forming apparatus of this embodiment is the same as the structure described in the seventh embodiment, and is different in the second embodiment.
The difference is that the input / output-related data stored in the nonuniformity correction table is different.

In the eighth embodiment, a print head temperature sensor for detecting the temperature value of each print head is provided on each print head 10, and the print head temperature sensor detects the temperature value using the second unevenness correction table. The number of recording nozzles for which density unevenness correction is performed and the density unevenness correction coefficient F (T) corresponding to each recording nozzle are set to be large or small depending on the size of the print head temperature.

That is, the temperature value of each recording head differs depending on the history state of the recording operation by each recording head, the installation / operating condition of the image forming apparatus, or the installation environment condition, and therefore the recording operation is performed. Since the degree of temperature drop distribution and the temperature gradient state on the end side of the recording nozzles differ depending on the temperature state of each recording head, in the present embodiment, the second unevenness correction table is used. , The number n of recording nozzles for which density unevenness correction is performed and the density unevenness correction coefficient F corresponding to each recording nozzle according to the magnitude of the temperature value of the print head detected by each print head temperature sensor.
By making the size of (T) different, as shown in FIG. 21, the number of recording nozzles for density unevenness correction is increased with respect to the recording nozzles on the end side when the recording head temperature is high (T5) ( In this embodiment, nozzle Nos. 122 to 128),
As shown in FIG. 9A, the density unevenness correction coefficient F (T) corresponding to each of these recording nozzles is also increased. On the contrary, when the print head temperature is low (T1, T1 <T
For the recording nozzles on the end side of 5), the number of recording nozzles n for performing density unevenness correction is set to be smaller than that when the printhead temperature is high, and the density unevenness correction coefficient F (T ) Also corrects the density unevenness with higher accuracy in accordance with the temperature distribution / gradient of the print head so that the print head temperature becomes smaller than that when the print head temperature is high. INDUSTRIAL APPLICABILITY The present invention exerts excellent effects particularly in a recording apparatus having an inkjet recording head that performs recording by forming flying droplets by utilizing thermal energy among inkjet recording systems.

Regarding its typical structure and principle, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal transducer arranged corresponding to the sheet or liquid path in which is stored, which corresponds to the recorded information and gives a rapid temperature rise exceeding nucleate boiling. Since the electrothermal converter is caused to generate heat energy to cause film boiling on the heat-acting surface of the recording head, as a result, bubbles in the liquid (ink) corresponding to the drive signal in a one-to-one relationship can be formed. It is valid. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal in a pulse shape, because bubbles can be grown and contracted immediately and appropriately, and thus a liquid (ink) with excellent responsiveness can be achieved.

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, excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, A configuration using US Pat. No. 4,558,333 or US Pat. No. 4,459,600, which discloses a configuration in which the heat-acting surface is arranged in a bending region, may be used.

In addition, JP-A-59-123670, which discloses a structure in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and a pressure wave of thermal energy is absorbed. It is also possible to adopt a configuration based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a configuration in which the opening corresponds to the ejection portion.

Further, as a full line type recording head having a length corresponding to the width of the maximum recording medium which can be recorded by the recording apparatus, the length can be increased by combining a plurality of recording heads as disclosed in the above-mentioned specification. Either of the structure satisfying the requirement or the structure as one recording head integrally formed may be used.

In addition, by being mounted on the apparatus main body, it can be electrically connected to the apparatus main body and can be supplied with ink from the apparatus main body by a replaceable chip type recording head or the recording head itself. Alternatively, a cartridge type recording head provided with an ink tank may be used.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. . Specific examples thereof include capping means, cleaning means, pressurizing or suctioning means for the recording head, preheating means using an electrothermal converter or another heating element or a combination thereof, and recording. It is also effective to perform a stable recording by performing a preliminary discharge mode in which another discharge is performed.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrally formed or a plurality of combinations may be used. Alternatively, the device may be provided with at least one of full-color mixed colors.

In the embodiments of the present invention described above, the ink is described as a liquid, but it is an ink that solidifies at room temperature or lower and that softens at room temperature, or is a liquid, or the above-mentioned. In the inkjet method, it is common to control the temperature of the ink itself within a range of 30 ° C to 70 ° C to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. It is sufficient that the ink is liquid.

In addition, the temperature rise due to the thermal energy is positively prevented by using it as the energy for the state change of the ink from the solid state to the liquid state, or the ink is solidified in the standing state for the purpose of preventing the evaporation of the ink. In some cases, such as ink that is liquefied by applying heat energy according to a recording signal and ejected as a liquid ink, or one that has already started to solidify when it reaches a recording medium. The use of an ink having a property of being liquefied only by heat energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or JP-A-60-71260, a mode in which the porous sheet is opposed to the electrothermal converter in the state of being held as a liquid or solid in the recess or through hole of the porous sheet. 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.

Further, as a form of the recording apparatus according to the present invention, the recording apparatus according to the present invention is integrally or separately provided as an image output terminal of information processing equipment such as a word processor or a computer as described above, and is combined with a reader or the like. It may be in the form of a copying machine or a facsimile machine having a transmission / reception function. The present invention may be applied to a system including a plurality of devices or an apparatus including a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

As described above, according to this embodiment,
Even if the distribution of the number of recording nozzles that perform the recording operation changes depending on the recording operation mode, it is possible to print a high-quality image with no uneven recording density.

[0128]

As described above, according to the present invention, it is possible to form a stable and high quality image by correcting the variation in the print density due to the image recording element including the multi-head.

[0129]

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining the entire image forming apparatus of this embodiment.

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

FIG. 3 is a schematic view of an inkjet recording head.

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

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

FIG. 6 is an explanatory diagram of a recording method by 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 differences in nozzle characteristics of the 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 showing the states of the print head temperature and the print image density during the print operation state according to the first embodiment.

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

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

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

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

FIG. 18 is a diagram showing the states of print head temperature and print image density during print operation states in Examples 6, 7 and 8.

FIG. 19 is a diagram illustrating a density unevenness correction method according to the 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]

 1 Reader Unit 2 Printer Unit 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 Shaft 19 Motor 20 Recovery Unit 21 Board 22 Electrothermal Converter 23 Electrode 24 Nozzle Wall 25 Top plate 26 Common liquid chamber 27 Connector 28 Nozzle 29 Discharge port 30 Reader 31 Read signal 32 RAM 33 Mura correction data 34 Mura correction RAM 35 Mura correction signal 36 Image signal 37 Mura correction table 38 Mura corrected image signal 39 Gradation correction Table 40 Binarization circuit 41 Recording element number control means 42 Recording element number 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

Claims (40)

[Claims] 1. An image forming apparatus comprising a recording head in which a plurality of image recording elements are arranged, the image forming apparatus being based on a difference in print density characteristics of the plurality of image recording elements and respective temperature characteristics of the plurality of image recording elements. And an image forming unit that forms an image based on the image data corrected by the correcting unit. 2. The temperature characteristic is a temperature characteristic in which the temperature of the image recording elements near both ends of the arrangement of the plurality of image recording elements is lower than the temperature near the center, and the image recording elements near the both ends. The image density formed by the image forming unit is lower than the image density formed by the image forming unit by using the image recording element near the center. The image forming apparatus described. 3. The correcting means corrects the density of image data to be image-formed by using image recording elements near both ends of the arrangement of the plurality of image recording elements. The image forming apparatus according to item 1. 4. The image forming apparatus according to claim 1, wherein the image data is brightness data or density data. 5. The image forming apparatus according to claim 1, wherein the image data is color data. 6. An all-image-recording-element image forming mode in which a recording head having a plurality of image recording elements arranged therein is used to form an image using all the image-recording elements of the recording head, and an image recording element of the recording head. An image forming apparatus having a partial image recording element image forming mode in which an image is partially formed, wherein temperature characteristics of all image recording elements of the recording head and temperature characteristics of partial image recording elements of the recording head On the basis of,
Correction means for correcting the image data, and based on the image data corrected by the correction means,
An image forming apparatus comprising: an image forming unit that forms an image using the partial image recording element of the recording head. 7. The partial image recording element of the recording head comprises:
7. The image forming apparatus according to claim 6, wherein the image forming element is the left end side or the right end side of all the image recording elements arranged in the recording head. 8. The partial image recording element of the recording head comprises:
The image forming apparatus according to claim 6, wherein the image recording element is a central portion of all the image recording elements arranged in the recording head. 9. The temperature characteristic of the partial image recording element of the recording head is a temperature characteristic in which the temperature of the image recording elements near both ends of the arrangement of the partial image recording elements is lower than the temperature near the center. The image density formed by the image forming unit by using the image recording elements near both ends is lower than the image density formed by the image forming unit by using the image recording elements near the center. The image forming apparatus according to claim 7, which is characterized in that. 10. The temperature characteristic of the partial image recording element of the recording head is a temperature characteristic in which the temperature of the image recording elements near both ends of the arrangement of the partial image recording elements is lower than the temperature near the center, The image density formed by the image forming unit by using the image recording elements near both ends is lower than the image density formed by the image forming unit by using the image recording elements near the center. The image forming apparatus according to claim 8, which is characterized in that. 11. The correcting means corrects so as to increase the density of image data to be image-formed by using the image recording elements near both ends of the arrangement of the partial image recording elements of the recording head. Item 9. The image forming apparatus according to Item 9. 12. The correcting means corrects so as to increase the density of image data to be image-formed by using image recording elements near both ends of the arrangement of the partial image recording elements of the recording head. Item 9. The image forming apparatus according to Item 9. 13. The correction means determines the temperature characteristics of all image recording elements of the recording head, the temperature characteristics of partial image recording elements of the recording head, and the difference in print density characteristics of all image recording elements. The image forming apparatus according to claim 6, wherein the image data is corrected based on the image data. 14. An image reading unit that reads an image formed by the image forming unit, wherein the correction unit prints the plurality of image recording elements based on the image data obtained by the image reading unit. Difference in density characteristics, detecting each temperature characteristic of the plurality of image recording elements, based on the difference in print density characteristics of the detected plurality of image recording elements and each temperature characteristic of the plurality of image recording elements, The image forming apparatus according to claim 1, wherein the image data is corrected. 15. An image reading unit for reading an image formed by the image forming unit, wherein the correction unit is based on the image data obtained by the image reading unit, and all image recording elements of the recording head. The temperature characteristics of the partial image recording elements of the recording head and the temperature characteristics of all the image recording elements of the recording head and the temperature characteristics of the partial image recording elements of the recording head, The image forming apparatus according to claim 6, wherein data is corrected. 16. The image forming apparatus according to claim 6, wherein the image data is brightness data or density data. 17. The image forming apparatus according to claim 6, wherein the image data is color data. 18. The image forming apparatus according to claim 1, wherein the recording head is an inkjet recording head that ejects ink to perform recording. 19. The recording head is a recording head that ejects ink by using thermal energy, and is an inkjet recording head that includes a thermal energy converter for generating thermal energy applied to the ink. The image forming apparatus according to claim 1 or claim 6. 20. The correction means uses first correction data based on temperature characteristics of all image recording elements of the recording head and second correction data based on temperature characteristics of partial image recording elements of the recording head. The image forming apparatus according to claim 6, wherein the image data is corrected based on the image data. 21. An image forming method comprising a recording head in which a plurality of image recording elements are arranged, the method being based on a difference in print density characteristics of the plurality of image recording elements and respective temperature characteristics of the plurality of image recording elements. And an image forming step of forming an image based on the image data corrected in the correcting step. 22. The temperature characteristic is a temperature characteristic in which the temperature of the image recording elements near both ends of the arrangement of the plurality of image recording elements is lower than the temperature near the center, and the image recording elements near the both ends. 22. The image density formed by the image forming step is lower than the image density formed by the image forming step using the image recording element near the center.
The image forming method described in 1 .. 23. The correction step is performed so as to increase the density of image data to be image-formed by using image recording elements near both ends of the array of the plurality of image recording elements. The image forming method described in 1 .. 24. The image forming method according to claim 21, wherein the image data is luminance data or density data. 25. The image forming method according to claim 21, wherein the image data is color data. 26. An all-image-recording-element image forming mode in which a recording head having a plurality of image recording elements arranged therein is used to form an image using all the image-recording elements of the recording head, and an image recording element of the recording head An image forming method comprising a partial image recording element image forming mode in which an image is formed by using a part thereof, wherein the temperature characteristics of all the image recording elements of the recording head and the temperature characteristics of the partial image recording element of the recording head are On the basis of,
A correction step of correcting image data, and based on the image data corrected in the correction step,
An image forming step of forming an image using the partial image recording element of the recording head. 27. The partial image recording element of the recording head is an image recording element on a left end side or a right end side of all image recording elements arranged in the recording head. Image forming method. 28. The image forming apparatus according to claim 26, wherein the partial image recording element of the recording head is an image recording element in a central portion of all the image recording elements arranged in the recording head. Method. 29. The temperature characteristic of the partial image recording element of the recording head is a temperature characteristic in which the temperature of the image recording elements near both ends of the arrangement of the partial image recording elements is lower than the temperature near the center. The image density formed by the image forming step using the image recording elements near both ends is lower than the image density formed by the image forming step using the image recording elements near the center. 27. The method according to claim 27, wherein
The image forming method described in 1 .. 30. The temperature characteristic of the partial image recording element of the recording head is a temperature characteristic in which the temperature of the image recording elements near both ends of the arrangement of the partial image recording elements is lower than the temperature near the center, The image density formed by the image forming step using the image recording elements near both ends is lower than the image density formed by the image forming step using the image recording elements near the center. 29. The method according to claim 28.
The image forming method described in 1 .. 31. The correction step is performed so as to increase the density of image data to be image-formed by using image recording elements near both ends of the arrangement of the partial image recording elements of the recording head. Item 29. The image forming method according to Item 29. 32. The correction step is performed so as to increase the density of image data to be image-formed by using image recording elements near both ends of the arrangement of the partial image recording elements of the recording head. Item 29. The image forming method according to Item 29. 33. In the correction step, the temperature characteristics of all image recording elements of the recording head, the temperature characteristics of partial image recording elements of the recording head, and the difference in print density characteristics of all image recording elements are further included. The image forming method according to claim 26, wherein the image data is corrected based on the image data. 34. An image reading step of reading an image formed by the image forming step is further provided, and the correction step is a printing of the plurality of image recording elements based on the image data obtained by the image reading step. Difference in density characteristics, detecting each temperature characteristic of the plurality of image recording elements, based on the difference in print density characteristics of the detected plurality of image recording elements and each temperature characteristic of the plurality of image recording elements, The image forming method according to claim 21, wherein the image data is corrected. 35. An image reading step of reading an image formed by the image forming step is further provided, and the correcting step is based on the image data obtained by the image reading step, and all image recording elements of the recording head. The temperature characteristics of the partial image recording elements of the recording head and the temperature characteristics of all the image recording elements of the recording head and the temperature characteristics of the partial image recording elements of the recording head, 27. The image forming method according to claim 26, wherein data is corrected. 36. The image forming method according to claim 26, wherein the image data is luminance data or density data. 37. The image forming method according to claim 26, wherein the image data is color data. 38. The image forming method according to claim 1, wherein the recording head is an ink jet recording head that performs recording by ejecting ink. 39. The recording head is a recording head which ejects ink by utilizing thermal energy, and is an inkjet recording head which is provided with a thermal energy converter for generating thermal energy applied to the ink. 27. The image forming method according to claim 1 or claim 26. 40. The correction step includes first correction data based on temperature characteristics of all image recording elements of the recording head and second correction data based on temperature characteristics of partial image recording elements of the recording head. 27. The image forming method according to claim 26, wherein the image data is corrected based on the image data.