JP2001260328A - Apparatus and method for ink jet type recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute gradation printing without a separate image processing means. SOLUTION: After controlling the height of a printing stage 30 whereon a printing object 60 is set, printing is executed by jetting ink onto the printing object 60 from an ink jet head 11 in a carriage 10. When a head-object distance L being a distance between the ink jet head 11 and the printing object 60 is enlarged, the position of arrival of the ink at the printing object 60 is shifted and a gradation effect can be obtained. An image of a desired gradation degree can be printed by adjusting the head-object distance L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink-jet recording apparatus and an ink-jet recording method for performing printing on a printing object by ejecting ink from an ink-jet head.

[0002]

2. Description of the Related Art Conventionally, there has been known an ink jet recording apparatus which records an image by ejecting ink from an ink jet head toward a printing object.

[0003] The point of achieving high image quality is how to accurately land (reach) an ink dot at a target position. However, in an ink jet recording apparatus, the distance between an ink jet head and a print target is limited. The farther away you are, the more likely you are to be affected by disturbances, etc.
This causes the image quality to deteriorate. Therefore, in order to realize high image quality in the conventional ink jet recording apparatus, the distance between the ink jet head and the print target is kept as small as possible and is constant (usually about 0.5 mm).

[0004]

Incidentally, in some cases, it may be desirable to perform a blurring process to perform printing with a different impression from the original image. In such a case, the above-described ink jet recording apparatus cannot perform the blurring processing, and usually performs image processing on the image data using a personal computer or the like and prints the obtained image data. Obtains such a blurred image. For this reason, an image processing means such as a personal computer provided with image processing software such as retouch software capable of performing a blurring process has been separately required.

The present invention is intended to overcome the above-mentioned problems in the prior art, and it is a first object of the present invention to provide an ink jet recording apparatus and an ink jet recording method which can perform blur printing without an image processing means. The purpose of. It is a second object of the present invention to provide an ink jet recording apparatus and an ink jet recording method capable of obtaining a blurring effect that cannot be achieved by image processing.

[0006]

According to one aspect of the present invention, there is provided an ink jet recording apparatus for performing printing on a printing object by ejecting ink from an ink jet head. There is provided a distance changing means for changing a distance between the head objects, which is a distance from the printing object.

According to a second aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the distance changing means changes a supporting height of the printing object.

According to a third aspect of the present invention, in the ink jet recording apparatus according to the first aspect, the distance changing means changes a supporting height of the ink jet head.

According to a fourth aspect of the present invention, there is provided the ink jet type recording apparatus according to any one of the first to third aspects, wherein the designation signal for the degree of blur can be received, and the designated designation is received. And control means for controlling the distance changing means so as to change the head-to-head distance according to the degree of blur in a signal.

According to a fifth aspect of the present invention, in the ink jet recording apparatus according to the fourth aspect, the designation signal designates a different degree of blur for each part of the printing object. The control means controls the distance changing means so as to change the head-to-head object distance for each of the portions in accordance with the degree of blur specified by the specifying signal.

According to a sixth aspect of the present invention, there is provided the ink jet recording apparatus according to the fourth or fifth aspect,
Further, the apparatus further comprises related information storage means for storing related information for obtaining the head-to-head distance from the degree of blur, wherein the control means refers to the related information and corresponds to the degree of blur specified by the designation signal. And a distance control means for controlling the distance changing means so that the actual distance between the head objects becomes the optimum distance.

According to a seventh aspect of the present invention, in the ink jet recording apparatus according to the sixth aspect, the related information is a first correspondence indicating a correspondence relationship between the degree of blur and a spatial frequency modulation transfer function. Information and second correspondence information indicating the correspondence between the head-subject distance and the spatial frequency modulation transfer function.

According to an eighth aspect of the present invention, there is provided the ink jet recording apparatus according to any one of the first to seventh aspects, wherein the distance changing means increases the distance between the head targets from the ink jet head. The distance at which the flying speed of the ink reaches the terminal speed or a distance longer than the distance can be set.

Further, according to a ninth aspect of the present invention, there is provided a distance changing step of changing a distance between a head and an object, which is a distance between the ink jet head and the object to be printed, and printing on the object by ejecting ink from the ink jet head. And a printing step to be performed.

[0015]

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

<1. First Embodiment >><< 1-1. Apparatus Configuration >> FIGS. 1 and 2 show an ink jet recording apparatus 1A according to a first embodiment of the present invention.
It is the schematic which looked at from the front and side. FIG. 3 is a diagram showing a personal computer 100 in addition to the blocks of the drive control system of the ink jet recording apparatus 1A. Hereinafter, a mechanical configuration and a drive control configuration of the ink jet recording apparatus 1A will be described with reference to FIGS.

A carriage 10 having an ink jet head 11 is driven by a carriage drive motor 12 via a belt (not shown), and repeats a reciprocating movement in a main scanning direction along a guide pipe 20. The height of the printing stage 30 that horizontally supports the printing object 60 can be adjusted by a jack 40 as a height adjusting mechanism driven by a jack driving motor 41.

A base 70 to which the jack 40 is fixed.
Slides on the linear guide 50 and is driven by the sub-scanning drive motor 51. The base 70 is fed by a predetermined distance such as one ink dot in the sub-scanning direction each time one main scan is completed.

As shown in FIG. 3, the ink jet type recording apparatus 1A has a CPU 81 internally provided with a flash ROM.
A control unit 80, which is a microcomputer to which the RAM 82 and the RAM 83 are connected, is provided. A personal computer 100 having input means such as a keyboard and a mouse is connected to the ink jet recording apparatus 1A via an I / F 85. Image data and image data from the personal computer 100 are transmitted to the CPU 81 of the control unit 80. A designation signal for designating a degree of blur (described later) corresponding to the degree of blur in the present invention can be input.

Then, the CPU 81 controls the flash ROM 8
2 to read and execute the control program, the carriage drive motor 12, the jack drive motor 4
1 and the sub-scanning drive motor 51 to control the position of the carriage 10 with respect to the printing target 60, and to control the ink-jet head 11 based on the image data temporarily stored in the RAM 83 to print ink on the printing target 60. The printing is performed by ejecting the ink to 60.

<< 1-2. Processing Outline >> Next, an outline of processing for changing the degree of blur (or sharpness) of a print image will be described. In this embodiment, the degree of blur of a print image is adjusted by adjusting the distance L (hereinafter, referred to as “head-object distance”) between the inkjet head 11 and the print target 60.

FIG. 4 is a diagram showing the relationship between the ejection direction of the ink 200 and the displacement amount of the landing position. First, the relationship between the head object distance L and the degree of blur will be considered with reference to FIG. Injection direction of ink 200 (inkjet head 1
(The direction of the perpendicular 101 from 1 to the print target 60) and the landing position, which is the arrival position at the surface of the print target 60, are d, the distance between the head targets is L, and the landing position from the tip of the inkjet head 11 to the landing position. When the angle of deviation from the direction of ink ejection in the direction

[0023]

(Equation 1)

## EQU1 ## Here, as the landing position deviation amount d increases, the sharpness deteriorates, and the blurring effect increases. Here, since the deviation angle θ is considered to have a statistical distribution without depending on the head-subject distance L, if the standard deviation is σθ, from the equation (1),

[0025]

(Equation 2)

Is obtained. From the equation (2), it can be seen that the standard deviation σ _d of the landing position deviation amount d which is an index of the blurring effect is proportional to the head object distance L. Landing position deviation amount d
FIG. 5 is a graph showing the relationship between the distance L and the distance L between head targets.
This is reflected in that.

If σθ can be measured, it is possible to predict the degree of blurring from the equation (2), but it is very difficult to actually measure σθ.

Therefore, in this embodiment, a reference test chart image is printed by changing the distance L between head objects stepwise in various steps, and the degree of blur is measured in advance and stored in the flash ROM 82. The distance L between head targets is set according to the degree of blur desired by the user.

FIG. 6 is a diagram showing an image printed with the distance L between head objects being a normal state (a state in which blur printing is not performed). FIG. FIG.

In FIG. 6, the distance L between head objects is 0.5 mm.
In FIG. 7, the distance L between head targets is set to 10 mm. As is clear from a comparison between FIG. 6 and FIG. 7, it can be seen that as the distance L between the head objects increases, the sharpness deteriorates and the effect of blurring becomes effective.

In this embodiment, by increasing the distance L between head objects by a predetermined value or more, the degree of blur is increased, and a printed image that looks like a scene can be obtained. Specifically, the inkjet head 1
Such an effect is obtained by increasing the distance L between head targets so that the flying speed of the ink dots ejected from No. 1 reaches the terminal speed.

Hereinafter, a method of obtaining the terminal speed distance, which is the distance L between head targets, at which the flying speed of the ink dots ejected from the ink jet head 11 reaches the terminal speed will be described.

FIG. 8 is a diagram showing an image printed with the distance L between head targets being normal, and FIG. 9 is a diagram showing the image printed when the flying speed of the ink dots ejected from the ink jet head 11 reaches the terminal speed. It is a figure which shows the image.
As is apparent from a comparison between FIG. 8 and FIG. 9, FIG. 9 has an effect of blurring to the extent that the prototype of FIG. This is because, when the flying speed of the ink dot reaches the terminal speed, the initial ejection speed of the ink dot is affected by the influence of the surrounding disturbance (for example, generation of an air current by scanning of the carriage 10), so that the initial ejection speed is increased. This is because the ratio of the velocity component in the direction perpendicular to the direction becomes relatively large, and the landing position of the ink on the printing target 60 largely deviates from the normal position.

FIG. 10 is a diagram showing the mechanical relationship of the particulate ink 200 ejected downward from the ink jet head 11. Hereinafter, a method of obtaining the terminal speed distance will be described with reference to FIG. In addition,
In FIG. 10, the downward direction is the positive direction of the y-axis.
When the rate of 00 ejection direction (y-direction) and V _y, the force acting on the ink 200 is air resistance kV _y and gravity mg. At this time, the equation of motion of the ink 200 in the y-axis direction is

[0035]

(Equation 3)

However,

[0037]

(Equation 4)

[0038]

(Equation 5)

Is as follows. As shown in equation (4), a Stokes resistance law is assumed here. A is the radius of the ink 200, η is the viscosity of air, m is the mass of the ink 200, and ρ _i is the ink density. From equation (3)

[0040]

(Equation 6)

[0041]

(Equation 7)

[0042]

(Equation 8)

Is as follows. Where α = k / m = 9η / 2ρ _i
is a ^2, V _y0 is the first speed when the ink 200 is ejected.

When the limit of the time t → ∞ is obtained from the formulas (7) and (8), V _y = g / α, and the falling speed is kept constant. In practice, k is an appropriate constant larger than “1”, and the time until V _y = k · g / α is reached is the terminal time.
The flying distance at that time is set as the terminal speed distance, and the distance L between head targets may be set to be equal to or more than that value.

FIG. 11 is a graph showing the relationship between the flying speed of the ink jet head 11 and the flying distance. Here, the ink ejection speed V _y0 = 9 m / s, 36
A = 2.1 × 10 ⁻⁶ (m) at 0 dpi, (ink diameter φ = 42 μm), a = 1.05 at 720 dpi
× 10 ⁻⁶ (m) (ink diameter φ = 21 μm), η = 1
8.2 × 10 ⁻⁶ (Pa · s) (25 ° C., 1 atm), ρ
_i = 1 × 10 ³ (kg / m ³ ), and t = 0.0 to
It is plotted up to 0.1 s. At 360 dpi, the terminal speed almost reaches at y = 50 mm (terminal speed distance),
Continued to drop at a constant speed at V _y = 52.8 mm / s, and
At 0 dpi, the terminal speed almost reaches at y = 12.5 mm (terminal speed distance), and continues to fall at a constant speed at V _y = 13.2 mm / s.

The case where the ink 200 is ejected downward has been described above. However, when the ink 200 is ejected in the horizontal direction, the gravitational term disappears and the terminal speed becomes "0", which makes the ink 200 more susceptible to disturbance. .

As described above, if the ink ejection speed V _y0 , the ink diameter φ, and the ink density ρ _i are measured in advance, the ink 2
The terminal speed distance at which 00 reaches the terminal speed can be obtained, and by setting the distance L between head targets to such a distance, an image like a scene as shown in FIG. 9 can be printed.

<< 1-3. Specific processing >> Hereinafter, specific processing in this embodiment will be described. In this embodiment, an MTF database is created in advance before actually performing blur printing. Here, MTF (m
The odulation transfer function, that is, the spatial frequency modulation transfer function, is a spatial frequency characteristic obtained as a transfer characteristic of the modulation degree of the sine wave distribution, and in this embodiment, is an index related to the sharpness of printing. In particular,
As will be described later, the ratio is given by the ratio between the input modulation and the output modulation for each spatial frequency of the image. The MTF database is a numerical table showing the correspondence between the distance L between head targets and the MTF value at each spatial frequency.

FIG. 12 is a flowchart showing the processing procedure of the MTF database creation processing. Hereinafter, the MTF database creation processing will be described with reference to FIG.

Firstly, between the head object distance L is set to the minimum distance L _min of the normal state (printing is not performed blur) (FIG. 12: step S100), to print a predetermined test chart image (FIG. 12 : Step S102). 13 and 14 show examples of test chart images. FIG. 13 shows an example of a test chart image for a monochrome image, and FIG. 14 shows an example of a test chart image for a color image.
In FIG. 14, the colors of each pattern are actually B (blue), G (green), R (red), Y (yellow), M (magenta), C (cyan), and K (black). I have. As shown in FIGS. 13 and 14, the test chart includes partial images having various spatial frequencies.

Next, the MTF is measured for the print image of the obtained test chart (FIG. 12: step S1).
04).

FIG. 15 is a diagram showing a group of graphs related to MTF, where (a) shows the input modulation for each frequency, (b) shows the output modulation for each frequency,
(C) shows a graph of modulation transmission with respect to the spatial frequency. Here, the input modulation m _i, when the offset value of the input in the test chart image in the group b, or the amplitude a, m _i = a / b
And the output modulation m
_“o ” means that when the offset value in the printed test chart image is b ′ and the amplitude is a ′, _mi = a ′ /
This is a value represented by b '.

At this time, the MTF is given by the ratio between the two modulations. That is, the MTF value defined by representing the M = m _o / m _i at M.

[0054] As shown in FIG. 15, MTF is an input modulation m _i, and a modulation m _o of the output was measured, determined by calculating the ratio thereof among the spatial frequency. CA in FIG. 15, CB and CC are show different spatial frequency domain, respectively, the input modulation m _i are the same. On the other hand, the output modulation m _o is to reflect the spatial frequency characteristic of the reproduction system (output unit of the ink jet recording apparatus), indicating each different value for each spatial frequency. Assuming that the γ characteristic of the reproduction system is linear, the ratio between the two for each spatial frequency represents the distribution of the MTF value of the system (inkjet recording apparatus 1A).

The input image used for measuring the MTF is basically a sine wave pattern. However, since it is difficult to actually create a sine wave pattern, the re-development of the knife edge image is differentiated to obtain an LSF (Line spread function). )
A square wave MTF is obtained by using a method in which the reflectance is obtained by Fourier transform or a pattern in which the reflectance changes in a square wave as used in the resolution measurement shown in the test charts of FIGS. Generally, a method of performing Coltman correction as a correction using a square wave is generally used. In this embodiment, the latter method is used.

When calculating the MTF, for the input modulation and the output modulation, the base density of the recording material (paper) and the maximum density indicated by the solid portion are set in a predetermined range (from "0" to "0" in FIG. 15). 255 "gradation).

Next, the obtained distribution of MTF values (hereinafter referred to as “MTF characteristics”) is stored in the flash ROM 82 as a database (FIG. 12: step S10).
6).

Then, the distance L between the head objects is increased by a predetermined distance increment ΔL (FIG. 12: step S108).
It is determined whether or not the distance L between head targets is greater than the maximum distance _{Lmax. If the} distance is not large, the process returns to step S102; Thus, step S
Repeat steps 102～S110, if the head object distance L is greater than the maximum set value L _max the measurement is completed (FIG. 12: step S110). here,
The maximum distance _Lmax is a value equal to or greater than the above-mentioned terminal speed distance. That is, the distance L between head targets is variously changed from a normal state to a distance equal to or longer than the terminal speed distance, and the MTF value is obtained to be a numerical table. This numerical table is MTF
It is a database.

FIG. 16 is a schematic diagram showing a change in MTF characteristics due to a difference in head object distance L. As shown in the drawing, the MTF value decreases over the entire spatial frequency as the head-to-target distance L increases, and the correlation between the input and output decreases as the head-target distance L increases.
This means that the effect of blurring is high for printed matter.

The MTF database has been created as described above. Further, in this ink jet recording apparatus 1A,
An MTF pattern indicating the correspondence between the degree of blur and the distribution of MTF values at each spatial frequency is also obtained in advance for each degree of blur and stored in the flash ROM 82. A method of obtaining an MTF pattern group, which is a set of MTF patterns for each degree of blur, is as follows. First, printing is performed by changing the MTF for a plurality of images having different dominant spatial frequencies, and an evaluation value of the degree of blur of the obtained image is determined. Then, for various evaluation values of the degree of blur, M
The distribution of the TF value is obtained and converted into a numerical table to form an MTF pattern group.

FIG. 17 is a schematic diagram showing the relationship between MTF characteristics and MTF patterns. In FIG. 17, the MTF characteristic is indicated by a broken line, and the MTF pattern is indicated by a solid line. In this case, the degree of blur is represented by a five-level evaluation from "1" to "5", and the larger the number, the greater the degree of blur. As shown in FIG. 17, a different MTF pattern is created for each blur level. FIG. 17 means that a print image with a blur level of “1” cannot be generated due to the performance of the ink jet recording apparatus.

As described above, in this embodiment,
At least the head-to-head distance L at the maximum degree of blur
Creates an MTF pattern corresponding to the terminal speed distance. In the example of FIG. 17, the degree of blurring “3” to “5” corresponds to the terminal speed distance (L = 10 mm).

Note that the same MTF pattern group is stored in the flash ROM 82 even in different ink jet recording apparatuses 1A.

Next, the blur printing process will be described. FIG. 18 is a flowchart showing the processing procedure for blur printing.

First, the user selects and sets a desired degree of blur (FIG. 18: step S112). Then, the MTF pattern corresponding to the degree of blur is automatically selected by the CPU 81 (FIG. 18: step S114). FIG.
As described with reference to FIG. 7, the flash ROM 82 stores the MTF patterns corresponding to the respective blur levels, and the MTF pattern of the designated blur level is selected from the stored MTF patterns.

The setting of the degree of blur by the user is performed by the personal computer 100. At that time, it is also possible to set a different degree of blur for each partial region in the image. For example, in the case of print image data such as a portrait photograph, if the face is to be sharp and the background is to be blurred, the image area of the face portion is selected by a predetermined method (for example, the outline of the area to be selected with the mouse is set to each polygon. Select by a method such as enclosing while clicking at the vertex position), and set a small degree of blur for the face area and a large degree of blur for the background area.

[0067] CPU81 selects the head object distance L having a matching or closest MTF characteristics MTF pattern corresponding to a desired blurring degree in dominant spatial frequency domain of the print image data as the optimum distance L _d (Fig. 18:
Step S116). Note that the MT adjacent to the MTF characteristic
When there are two F patterns, the MTF characteristic closer to the MTF pattern is adopted. Here, the MTF pattern and M
As a method of evaluating the distance from the TF characteristic, the square of the difference between the MTF characteristic at each spatial frequency and the MTF value between the MTF pattern adjacent thereto is integrated over the entire dominant spatial frequency of the print image, It is determined that the smaller the value is, the closer it is.

For example, in FIG. 17, when the dominant spatial frequency range is 6 to 8 (mm ^-1 ) and the degree of blur is "3", the MTF pattern having the degree of blur of "3" and the distance between the head object Region A between the MTF characteristic of L = 5 mm and the MTF characteristic of head object distance L = 10 mm
About 1 and A2, by integrating the square of the difference between the MTF value of the MTF characteristics and the MTF pattern, and so on adopting the value is smaller head target distance L = 10 mm as the optimum distance L _d. Since the dominant spatial frequency range differs for each image, the CPU 81 performs Fourier transform on the image data and obtains a frequency region having an intensity equal to or higher than a predetermined intensity threshold in the print image.

However, as a method of evaluating the distance between the MTF pattern and the MTF characteristic, the MTF pattern and the MTF
Other known methods may be used, such as taking an average value in the spatial frequency range where the difference between the MTF value and the TF characteristic is dominant.

[0070] Also, since the MTF pattern so that at least the maximum terminal velocity distances to blurring degree corresponding as described above is created, if it is set at least the maximum blurring degree optimum distance L _d is terminated Speed distance.

When a partially different degree of blur is set as described above, the head object distance L
And temporarily store them in the RAM 83.

Finally, the distance between the head objects is actually adjusted (changed) and printing is performed (FIG. 18: step S11).
8).

FIG. 19 is a flowchart showing the procedure of the distance adjustment and printing processing when the degree of blurring of the entire image is constant.

[0074] When the overall blurring degree is constant, first, adjusting the distance L between the head target optimum distance L _d (step S
120). Specifically, the control unit 80 drives the jack 40 to adjust the height of the printing stage 30.

Next, printing is performed for all pixels (step S121). As a result, printing is performed with a desired degree of blur.

When partially different degrees of blur are set as described above, printing is performed while adjusting the optimum distance for each area. FIG. 20 is a flowchart showing the procedure of the distance setting and print processing when the degree of blur in the image differs for each area. Hereinafter, specific processing will be described with reference to FIG.

First, the first pixel is set as a target pixel (step S122).

Next, to obtain the optimum distance L _d of the region including the target pixel (step S124). The optimum distance L _d is obtained by reading the temporarily stored value to RAM83 in step S116 of FIG. 18.

Next, to adjust the optimum distance L _d of the region including the target pixel the distance L between the head object (step S1
26). Here, the control unit 80 drives the jack 40 to adjust the height of the printing stage 30. If the previous pixel and the target pixel are included in the same region, the head target distance L is not changed.

Next, printing of the target pixel is performed (step S128).

Next, it is determined whether or not printing has been completed for all pixels (step S130). If printing has not been completed, the next pixel is set as a target pixel (step S132), and the process returns to step S124. The processing from S124 to S132 is repeated until the processing is completed for all the pixels. If the processing has been completed for all the pixels, the distance setting and the printing processing are completed. As described above, it is possible to obtain print images having different degrees of blur for each area.

As described above, according to the first embodiment, since the distance L between head targets is changed, the landing position of the ink dot becomes unstable. Printing is possible.

Further, since the distance L between head objects is changed according to the designated degree of blur, the degree of blur can be adjusted according to the designation.

Further, since the distance L between head objects can be changed in accordance with designation of a different degree of blur for each part in the image, a blurred image having a different degree of blur for each part can be obtained.

An MTF pattern group and an MTF pattern as related information for obtaining a head-to-subject distance from the degree of blur are described below.
With reference to the database, a print result close to a desired degree of blur is obtained because the distance between head objects corresponding to the specified degree of blur is determined as an optimum distance, and the actual distance between head objects is changed to be the optimum distance. Can be obtained.

An MTF pattern group as first correspondence information indicating the correspondence between the degree of blur and the spatial frequency modulation transfer function, and the second correspondence indicating the correspondence between the head object distance and the spatial frequency modulation transfer function. to determine the optimum distance L _d with MTF database as information, by using a common MTF pattern group throughout the different ink jet recording apparatus, obtains the optimal distance corresponding to the blurring degree is specified in a device independent In practice, the distance between head targets can be set to the optimum distance.

Since the distance L between head targets can be set to a distance at which the flying speed of the ink ejected from the ink jet head 11 reaches the terminal speed or more than the distance, the ink reaching the terminal speed is affected by disturbance. Therefore, the degree of blurring of the print becomes very large, so that it is possible to obtain a printed image that is completely different in impression from the original image.

It should be noted that the blurring effect can be obtained even if printing is performed by an ordinary ink jet printer after performing the blurring process by image processing. However, in the printing of a normal inkjet printer, printing is performed in a regular pattern peculiar to gradation reproduction such as an error diffusion method. In contrast, in the present embodiment, there is no rule pattern, and the ink arrival position is random. For this reason, an image having a considerably different impression is formed as compared with a case where printing is performed by a normal inkjet printer.

<2. 2. Second Preferred Embodiment FIGS. 21 and 22 are schematic views of an ink jet recording apparatus 1B according to a second preferred embodiment of the present invention as viewed from the front and side. FIG. 23 is a block diagram of a drive control system of the ink jet recording apparatus 1B. Hereinafter, the mechanical configuration and drive control configuration of the ink jet recording apparatus 1B are shown in FIG.
This will be described with reference to FIGS.

In the ink jet recording apparatus 1A according to the first embodiment shown in FIGS. 1 and 2, the print stage 30 supporting the print object 60 is driven up and down to adjust the distance L between head objects. However, in the ink jet recording apparatus 1B according to the second embodiment, the carriage 10 having the ink jet head 11 can be moved up and down so as to be able to approach and separate from the slide base 90. Specifically, a ball screw (not shown) is provided in the slide base 90, and a vertical shaft 91 attached to the ball screw is connected to the slide base 9.
0 It protrudes downward from the lower end so as to be vertically movable. An elevating drive motor 92 for rotating a ball screw is provided in the slide base 90, and the carriage 10 attached to the lower end of the vertical shaft 91 can be driven up and down by the drive. This allows the CPU 81 of the control unit 80 to adjust the head target distance L by controlling the elevation drive motor 92.

The slide base 90 is driven by a main scanning drive motor 93 via a belt (not shown), and repeats a reciprocating movement along the guide 21 in the main scanning direction. The printing stage 30 supporting the printing object 60 is
Is slidable on the linear guide 50 in the sub-scanning direction by the sub-scanning drive motor 51 as in the first embodiment.

The other configuration and print processing are the same as in the first embodiment.

With the above configuration, the same effects as in the first embodiment can be obtained in the second embodiment.

<3. Modifications> In the above embodiments, examples of the ink jet recording apparatus and the ink jet recording method have been described, but the present invention is not limited to these.

For example, in the first embodiment, the height of the print stage 30 is increased by driving the jack 40, and in the second embodiment, the height of the carriage 10 is adjusted by driving the lifting drive motor 92. Are automatically adjusted. However, the height of the print stage 30 and the carriage 10 can be directly adjusted manually, or the jack 40 can be adjusted.
The driving of the height adjustment mechanism such as may be performed manually.

Further, in the above embodiment, MTF is introduced as a quantity for describing the degree of blur, but the relationship between the subjective evaluation value of the degree of blur and the distance L between the head objects is directly obtained without measuring the MTF, and this is calculated. It may be used as a table. Also in this case, the distance L between head objects is variously changed for a plurality of test charts having different dominant spatial frequencies, and the subjective value of the degree of blur is measured. Thus, the optimum distance can be easily obtained without using the MTF. However, since the subjective value in this case is specific to the ink jet recording apparatus to be evaluated, it cannot be used in a different ink jet recording apparatus.

In the above embodiment, the maximum distance L _max
Is calculated on the basis of the ink ejection speed V _y0 , the ink drop diameter φ, and the ink density ρ _i , but if these numerical values are unknown, the process proceeds to step S 11 in FIG.
The maximum distance _{Lmax of} 0 may be set to be sufficiently large, and may be experimentally obtained.

Further, in the above embodiment, the MTF pattern group and the MTF database are stored in the flash ROM 82 in the control unit 80. However, the MTF pattern group and the MTF database are stored in a storage means such as a hard disk in the personal computer 100, and are stored. If necessary, the ink jet recording apparatuses 1A and 1B may read and use them.

[0099]

As described above, according to the first to ninth aspects of the present invention, the printing of ink dots is performed in order to change the head-to-head distance which is the distance between the ink-jet head and the printing target. Since the arrival position in the object becomes unstable, blur printing can be performed without an additional image processing unit. Further, a tasteful image that cannot be obtained by image processing can be obtained.

According to the fourth aspect of the present invention, since the distance between head objects is changed in accordance with the designated degree of blur, the degree of blur can be adjusted in accordance with the designation.

According to the fifth aspect of the present invention, since the distance between head objects is changed for each part according to the designated degree of blur, it is possible to obtain a blurred image having a different degree of blur for each part.

According to the present invention, the distance between head objects corresponding to the designated degree of blur is determined as the optimum distance by referring to the related information for obtaining the distance between head objects from the degree of blur. In this case, the actual distance between the head targets is set to the optimum distance, so that a print result close to a desired degree of blur can be obtained.

According to the seventh aspect of the present invention, the related information is the first correspondence information indicating the correspondence between the degree of blur and the spatial frequency modulation transfer function, and the head inter-object distance and the spatial frequency modulation transfer function. Since the second correspondence information indicating the correspondence relationship is included, the first related information is used in common even in different ink jet recording apparatuses, so that the optimum distance corresponding to the designated degree of blur is obtained independently of the apparatus. ,
Actually, the distance between the head objects can be set to the optimum distance.

According to the present invention, the distance between the head objects can be set to a distance at which the flying speed of the ink ejected from the ink jet head reaches the terminal speed or a distance equal to or longer than the terminal speed. The reached ink is susceptible to disturbance, and the degree of blurring of the printing becomes very large, so that it is possible to obtain a printed image that is completely different in impression from the original image.

[Brief description of the drawings]

FIG. 1 is a schematic view of an ink jet recording apparatus according to a first embodiment of the present invention, as viewed from the front.

FIG. 2 is a schematic view of the inkjet recording apparatus according to the first embodiment of the present invention as viewed from a side.

FIG. 3 is a block diagram of a drive control system of the ink jet recording apparatus.

FIG. 4 is a diagram illustrating a relationship between an ink ejection direction and a landing position deviation amount.

FIG. 5 is a graph showing a relationship between a landing position deviation amount and a distance between head targets.

FIG. 6 is a diagram showing an image printed with the head target distance set to a normal state.

FIG. 7 is a diagram illustrating an image printed with a head-subject distance increased.

FIG. 8 is a diagram showing an image printed with the head target distance set to a normal state.

FIG. 9 is a diagram showing an image printed in a state where the flying speed of the ink dots has reached the terminal speed.

FIG. 10 is a diagram illustrating a mechanical relationship of ink ejected from an inkjet head.

FIG. 11 is a diagram showing a graph in which the relationship between the flying speed and the flying distance of the inkjet head is plotted.

FIG. 12 is a flowchart illustrating a processing procedure for setting a distance between head targets.

FIG. 13 is a diagram illustrating an example of a test chart for a monochrome image.

FIG. 14 is a diagram illustrating an example of a test chart for a color image.

FIG. 15 is a graph related to MTF.

FIG. 16 is a schematic diagram illustrating a change in MTF characteristics due to a difference in head object distance.

FIG. 17 is a flowchart illustrating a processing procedure of blur printing.

FIG. 18 is a schematic diagram showing the relationship between MTF characteristics and MTF patterns.

FIG. 19 is a flowchart illustrating a processing procedure of distance setting and print processing when the degree of blur of the entire image is constant.

FIG. 20 is a flowchart illustrating a procedure of distance setting and printing processing when the degree of blur in an image is different for each region.

FIG. 21 is a schematic view of an ink jet recording apparatus according to a second embodiment of the present invention as viewed from the front.

FIG. 22 is a schematic view of an ink jet recording apparatus according to a second embodiment of the present invention as viewed from a side.

FIG. 23 is a block diagram of a drive control system of the ink jet recording apparatus.

[Explanation of symbols]

1A, 1B Ink jet recording apparatus 11 Ink jet head 40 Jack 41 Jack drive motor (Distance changing means together with 40) 60 Printed object 81 CPU (Control means, Optimal distance determination means, Distance control means) 82 Flash ROM (Measurement result storage means) ) 91 distance change means with a vertical axis 92 lifting drive motor (91) 200 ink L head object distance L _d optimal distance

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hideaki Nakanishi 2-3-1, Azuchicho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. (reference) 2C056 EC08 EC13 EC33 HA12

Claims (9)

[Claims] 1. An ink jet recording apparatus for performing printing on a print target by ejecting ink from an ink jet head, wherein a distance that changes a head target distance that is a distance between the ink jet head and the print target. An ink jet recording apparatus comprising a changing unit. 2. The ink jet recording apparatus according to claim 1, wherein the distance changing means changes a supporting height of the printing target. 3. An ink jet recording apparatus according to claim 1, wherein said distance changing means changes a supporting height of said ink jet head. 4. The ink jet recording apparatus according to claim 1, further comprising: a receiving unit for receiving a designation signal for a degree of blurring, and according to the degree of blurring in the received designation signal. Control means for controlling the distance changing means so as to change the distance between the head targets. 5. The ink jet recording apparatus according to claim 4, wherein the designation signal designates a different degree of blur for each part of the print target, and wherein the control means includes a command for the designation signal. And controlling the distance changing means so as to change the head-to-head distance for each of the portions in accordance with the degree of blur specified by (1). 6. The ink jet recording apparatus according to claim 4, further comprising: related information storage means for storing related information for obtaining the head-to-head distance from the degree of blur. Control means, with reference to the related information, an optimum distance determining means for obtaining a head inter-object distance corresponding to the degree of blur specified by the specifying signal as an optimum distance; and And a distance control means for controlling the distance change means. 7. The ink jet recording apparatus according to claim 6, wherein the related information is first correspondence information indicating a correspondence relationship between the degree of blur and a spatial frequency modulation transfer function, and the distance between the head targets. An ink jet recording apparatus comprising second correspondence information indicating a correspondence between the transfer function and the spatial frequency modulation transfer function. 8. The ink jet recording apparatus according to claim 1, wherein the distance changing unit determines that the flying speed of the ink ejected from the inkjet head is equal to the distance between the head targets. An ink jet recording apparatus characterized in that the distance can be equal to or longer than the terminal speed. 9. A distance changing step of changing a head-to-head distance, which is a distance between the inkjet head and the printing target, and a printing step of performing printing on the printing target by skipping ink from the inkjet head. An ink jet recording method characterized by the above-mentioned.