JP2003080742A - Method and device for recording image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for recording an image wherein stable output density can be achieved irrespective of variation in a size of a diameter of a dot and in an arrival position of a dot and a high quality image can be formed irrespective of variation in a size of a diameter of a dot or in an arrival position of a dot without deteriorating the graininess or emphasizing the edge. SOLUTION: A diameter D of a dot recorded on a recording medium M is set to be in a range of 1.5A<=D<=A+150 [μm] with the proviso that A represents max(Pm, Ps), Pm represents a recording pitch in a main scanning direction and Ps represents a recording pitch in a sub-scanning direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for recording an image on a transmission image recording medium, and more specifically, while moving the recording medium in the sub-scanning direction, the recording medium is moved in the sub-scanning direction. A dot transmission image on the recording medium by ejecting ink droplets from the recording head while relatively moving the recording head in the main scanning direction intersecting with each other and adhering the ink droplets to the recording medium. The present invention relates to an image recording method and an image recording apparatus for forming an image.

[0002]

2. Description of the Related Art In recent years, in X-ray imaging, a CR imaging device (hereinafter
"CR": CR = Computed Radio
and X-ray flat panel detector (hereinafter “FPD”)
Say: Flat Panel Detector), etc.
An X-ray imaging apparatus that can take an X-ray image as an electric signal and hold it as digital image data has appeared. With the spread of so-called digital X-ray image capturing devices,
A digital X-ray image recording apparatus that records a medical image based on an electric signal acquired by a CR, FPD, or the like is also popular.

The most mainstream recording method at present is to replace the electric signal of the X-ray image obtained from the CR or FPD with the intensity of the laser beam and print it on a conventional silver halide film for development and then image processing. It is a silver salt laser writing method to be formed.

However, since a silver halide film is used as in the conventional method, there is a problem that it is complicated and costly. As a method that does not use a silver halide film, a thermal transfer method or a sublimation printer can be considered. However, in the case of thermal transfer, there is a problem that the ink of the recorded image is on the outermost surface of the film and the ink is easily transferred during handling. Further, in the case of a sublimation printer, a sufficient density is not obtained, and like thermal transfer, waste such as an ink ribbon is generated after image formation.

Recently, an ink jet type image recording apparatus has been widely used as a small and inexpensive printer capable of dramatically improving the resolution and image quality of a recorded image or the like. Therefore, it is an attempt to solve the above-mentioned inconvenience by using an inkjet recording apparatus for X-ray image formation, and it is possible to form an inexpensive and easy-to-see X-ray image by maximizing the strength of an inkjet printer. It is expected that it will be possible to provide a possible inkjet image forming method.

[0006]

For medical images mainly used for diagnosis, extremely high image quality is required not only in the ink jet system but also in all recording system image recording apparatuses.

The reason for this is that when a medical image is examined, it is always applied to a high-luminance Schaucasten and viewed as a transmission image, so that the visual density resolution is much higher than that of a reflection image.

[0008] In addition, as in the case of photographing with CR and FPD, 2
A three-dimensional X-ray photograph, a so-called X-ray simple photograph, is basically a monochrome image, but in the case of a monochrome image, the visual density resolution is high compared to other colors (for example, Y, M, C, etc.), Higher image quality is required for monochrome transmission images.

Here, it is examined whether or not an image quality level required for medical use can be achieved by an ink jet type recording apparatus with respect to three points of an index which is a criterion of image quality evaluation, gradation, sharpness and graininess. went.

[Gradation] In X-ray simple photography, the number of gradations required for diagnosis is 10 bits (= 1024 gradations), and the number of gradations that can be sufficiently diagnosed is 12 bits (= 4096 gradations). It is said that. In the case of expressing multiple gradations such as a medical image by the inkjet method, since the number of ink densities is limited, it is necessary to simulate the gradation expression of the recorded image. For example, there is a method in which one pixel of image data is composed of a plurality of matrices, for example, a 4 × 4 dither matrix, and 4 × 4 + 1 = 17 gradations are expressed by using a so-called dither method in each matrix unit.

Furthermore, the number of gradations that can be created increases innumerably when inks of the same color and a plurality of different densities, for example, four kinds of inks are used. However, in practice, it is general to select several to several tens of dither matrices out of all the dither matrices that can be created, and perform gradation expression by the error diffusion method using the several to several tens of dither matrices. Is.

References relating to the error diffusion method include, for example, "R.
FLOYD & L. STEINBERG, "AN ADA
PTIVE ALGORITHM FOR SPETI
ALGRAY SCALE ”, SID 75 DIJE
ST, pp 36-37 ". According to the gradation creating method that combines the dither method and the error diffusion method, 12-bit multi-gradation expression is possible, and if an appropriate dither matrix is selected and an appropriate error diffusion algorithm is used, smooth gradation can be obtained. It is possible to obtain tonality characteristics.

[Sharpness] Sharpness, that is, image contrast is important for medical images for the purpose of diagnosis. For example, with respect to the foot image, it is desired that the trabecular bone be clearly visible.

In the ink jet system, the recording unit is an ink dot, so that there is no other factor affecting the adjacent pixels than the spread of the ink dot diameter. Since the inkjet system is not affected by the optical blur in the silver salt laser writing system and the residual heat in the thermal transfer system, an image having a relatively high sharpness can be obtained.

[Granularity] Granularity, that is, smoothness without roughness is important for medical images for the purpose of diagnosis. For example, regarding the chest image, it is desired that the granularity is such that the shadow due to the lesion can be accurately recognized especially in the low density region.

In the ink jet system, since the recording unit is ink dots, the ink dots may not cover the entire image, resulting in gaps between the dots. As a result, the overall density may appear low or it may appear grainy, and the graininess is rather bad.

One means of improving the graininess is a method of ejecting ink droplets at an extremely high density. But,
When the dot diameter is small, it is necessary to eject a large number of ink droplets at substantially the same position in order to cover the entire image without any gap. Therefore, it is necessary to increase the ink absorption speed and the allowable ink absorption amount in the recording medium used for recording. Further, it is desirable that the maximum output density of the medical image used for diagnosis is 3.0 or more. Therefore, in order to achieve the maximum output density of 3.0 by inkjet, as a result, a considerable amount of ink droplets is required. You must use quantity.

As another means for improving the graininess, a method of increasing the dot diameter to eliminate the gap between dots can be considered. However, adjacent ink dots are connected,
So-called "beading" may occur and the graininess may worsen. Further, the easiness of occurrence of beading also changes depending on the external environment such as room temperature, so that a stable output density cannot always be obtained, and as a result, gradation may be impaired. Further, if the dot diameter is excessively increased, the recorded image may be blurred and the sharpness may be deteriorated.

Based on the above examination, when recording a transmission image, variations in the dot diameter and landing position of the ink have a great influence on the image when compared with the reflection image, and it is sufficient if the entire image is not covered with ink. It was found that a high image density could not be obtained.

The present invention has been made in view of the above problems, and an object thereof is to suppress image quality deterioration due to recording accuracy such as variation of ink dot diameter and landing position deviation, and to obtain a high quality print image. An object of the present invention is to provide an image recording method and apparatus which can be obtained.

[0021]

According to a first aspect of the invention for solving the above-mentioned problems, the recording medium is moved in the sub-scanning direction while recording in the main scanning direction intersecting the recording medium in the sub-scanning direction. In an image recording method for forming a transparent image by dots on the recording medium by ejecting ink droplets from the recording head while moving the head relatively and adhering the ink droplets to the recording medium,
In the image recording method, dots are formed on the recording medium so that the range of the dot diameter D recorded on the recording medium satisfies the following expression (1). 1.5 A ≦ D ≦ A + 150 [μm] (1) where A = max (Pm, Ps) Pm = recording pitch in the main scanning direction Ps = recording pitch in the sub-scanning direction The present invention is an image recording apparatus for recording an image on a recording medium on the basis of an image signal representing an image, which has a plurality of nozzles and a plurality of ejection drive elements for ejecting ink droplets from the plurality of nozzles. A recording head, a conveying means for conveying the recording medium in the sub-scanning direction, a driving means for driving the recording head in a main scanning direction intersecting the recording medium in the sub-scanning direction, and a surface of the recording medium. An image recording apparatus comprising: a control unit that controls the dot diameter so that the range of the dot diameter D formed by the ink droplets adhering satisfies the following expression (3). That. 1.5 A ≦ D ≦ A + 150 [μm] (3) where A = max (Pm, Ps) Pm = recording pitch in the main scanning direction Ps = recording pitch in the sub-scanning direction Dot diameter D range is 1.5A
By satisfying ≦ D ≦ A + 150 [μm], it is possible to obtain a high-quality printed image particularly in a transmission image without being affected by recording variation factors such as ink dot diameter and landing position deviation.

The image recording method according to claim 1, wherein dots are formed on the recording medium so that the range of the dot diameter D satisfies the following expression (2). Is. 2A ≦ D ≦ A + 75 [μm] (2) where A = max (Pm, Ps) Pm = recording pitch in the main scanning direction Ps = recording pitch in the sub-scanning direction 10. The image recording apparatus according to claim 9, wherein the control unit controls the dot diameter so that the dot diameter satisfies the following expression (4). 2A ≦ D ≦ A + 75 [μm] (4) where A = max (Pm, Ps) Pm = recording pitch in the main scanning direction Ps = recording pitch in the sub-scanning direction The range of the dot diameter D is 2A ≦ When D ≦ A + 75 [μm], it is possible to obtain a high-quality printed image, particularly in a transmission image, without being affected by recording variation factors such as ink dot diameter and landing position deviation. .

The invention according to claim 3 is the image recording method according to claim 1, wherein dots are formed on the recording medium so that the dot diameters are substantially the same size. In the invention according to claim 11, the control means is
11. The image recording apparatus according to claim 9, wherein the dot diameter is controlled so that the dot diameters are substantially the same size.

By forming dots on the recording medium so that the dot diameters are approximately the same size, the distribution of dot diameters becomes almost uniform throughout the image, and local variations in dot diameters are suppressed. Therefore, good image quality can be obtained.

According to a fourth aspect of the present invention, the dot diameter is set to n.
The number (n ≧ 1) of the sizes D1, D2, ..., Dn (D1 ≧
3. The image recording method according to claim 1 or 2, wherein dots are formed on the recording medium so that D2 ≧ ... ≧ Dn) and D1 satisfies the equation (1). Is.

According to a twelfth aspect of the present invention, the control means sets the dot diameter to n (n ≧ 1) sizes D1 and D.
10. The dot diameter is controlled so as to satisfy the equation (2), ..., Dn (D1 ≧ D2 ≧ ... ≧ Dn), and D1 is controlled so as to satisfy the equation (3).
Alternatively, the image recording apparatus according to item 10.

The dot diameter is n (n ≧ 1) size D
1, D2, ..., Dn (D1 ≧ D2 ≧ ... ≧ Dn), and dots are formed on the recording medium so that D1 satisfies the expressions (1) and (3). As a result, good image quality can be obtained even in an image recorded with only a Dmax dot diameter that is most likely to cause graininess in the image, and further, good image quality can be obtained using any combination of a plurality of dot diameters. it can.

The invention according to claim 5 is the image recording method according to claim 4, characterized in that the main scanning image sequence is completed by a plurality of times of main scanning. The invention according to claim 13 is the image recording apparatus according to claim 12, characterized in that the control means completes a main scanning image sequence by a plurality of main scans.

By completing the main scanning image sequence by a plurality of main scans, it is possible to reduce streak unevenness due to errors in the amount of recording medium conveyed in the sub-scanning direction, defective ink droplet ejection from nozzles, and the like.

According to a sixth aspect of the present invention, the dot diameter D1
Is Dave, the range of the writing pitch Pm ′ in the main scanning direction in one main scanning is Pm ′ ≧ 2D.
The image recording method according to claim 5, wherein dots are formed on the recording medium so as to satisfy ave.

According to a fourteenth aspect of the present invention, the control means sets the writing pitch Pm in the main scanning direction in one main scanning when the average value of the dot diameters D1 recorded on the recording medium is Dave. 14. The image recording apparatus according to claim 13, wherein the range is controlled so as to satisfy Pm '≧ 2Dave.

When the average value of the dot diameter D1 is Dave, dots are formed on the recording medium so that the range of the writing pitch Pm ′ in the main scanning direction in one main scanning satisfies Pm ′ ≧ 2Dave. By forming it, beading in the same scan (adjacent dots are connected) does not cause deterioration of graininess, edge enhancement, etc., and also with respect to variations in dot diameter and dot landing position. The image quality is good.

According to a seventh aspect of the present invention, the resolution is 360 dots / 25.4 mm (360 dpi, hereinafter dot / 2).
7. The image recording method according to claim 1, wherein the dots are formed so as to have a size of 5.4 mm or more).

According to a sixteenth aspect of the present invention, the control means controls the drive of the recording head so that the resolution becomes 360 dpi or more.
The image recording apparatus according to any one of 5 above.

By forming dots so that the resolution is 360 dpi or more, a high quality image can be obtained. The invention according to claim 8 has a resolution of 720 dpi.
7. The image recording method according to claim 1, wherein the dots are formed as described above.

The invention according to claim 17 is characterized in that the control means controls the drive of the recording head so that the resolution becomes 720 dpi or more.
The image recording apparatus according to any one of 5 above.

By forming dots so that the resolution is 720 dpi or higher, a high quality image can be obtained. A fifteenth aspect of the invention is the image recording apparatus according to any one of the ninth to fourteenth aspects, wherein the control means controls the amount of ink droplets ejected from the recording head.

By controlling the amount of ink droplets ejected from the recording head, the dot diameter can be easily controlled. Here, the terms used in the present invention will be explained. (1) Density "Density" represents the so-called optical density D, which is defined in JIS K
7653-1988 "Photograph-Density measurement-Third spectral condition"
Is the ISO visual density defined synonymously. For example, the optical density meter PDA-65 (manufactured by Konica Corporation) is provided with an amber filter to measure the diffused light density (hereinafter,
Simply referred to as "diffusion concentration"). The diffusion concentration Dt
Is defined as Dt = −log10T, and
T is a light attenuation factor (light transmittance in transmission density, light reflectance in reflection density). Since the present invention relates to a transmission image in particular, the density means the transmission diffusion density unless otherwise specified. The "image density" is an optical density of an image, and refers to the optical density of the entire image including the optical density of the recording material attached to the recording medium and the optical density of the recording medium. And (2) Transparent recording medium The "transparent recording medium" is a recording medium whose main purpose is to observe as a transparent image. (3) Transmitted image The "transmitted image" is an image observed with transmitted light as a main light source using a light box or the like. (4) Density gradation characteristics The "density gradation characteristics" means the signal value (horizontal axis) of an image signal and the density (vertical axis) of an image recorded on a recording medium based on the signal value. The image recording apparatus records an image on a recording medium based on this density gradation characteristic. (5) Recording pitch The "recording pitch" is the minimum recording size that can be controlled by the image recording apparatus. The recording pitch in the main scanning direction is the "main scanning recording pitch", and the recording pitch in the sub-scanning direction is the "sub-scanning direction". Scan recording pitch ". Specifically, using FIG. 8 as an example, the length of one side of the grid in the horizontal direction is the main scanning recording pitch, and the length of one side of the grid in the vertical direction is the sub-scanning recording pitch. The grid points in the figure are all pixel positions (target ink ejection positions) from which ink can be ejected. An arbitrary image can be recorded by arbitrarily selecting whether or not to eject the ink according to the image signal. (6) Writing pitch The "writing pitch" refers to the positional interval at which ink is ejected from the recording head within the same main scan. Specifically, taking FIG. 14B-2 as an example, the writing pitch is the distance between the centers of the two dots (circles). In an inkjet recording apparatus, the "writing pitch" is the interval at which ink is ejected from the recording head, and is therefore called "ejection pitch". (7) Resolution "Resolution" is an index representing the recording density in an image recording system including an image recording device, a recording medium, and a recording material, and is dpi (dot per inch: 1i).
nch = about 25.4 mm) is often used. Normally,
It is used to mean the smallest recording size (so-called recording pitch) that can be controlled by the image recording apparatus. For example, 300 dp
For i, the recording pitch is 25400 μm / 360 dpi =
This corresponds to about 70 μm. The “output image size” means an output size corresponding to one pixel in the image signal, and at least satisfies the relationship of (output pixel size) ≧ (recording pitch). "Resolution is 360 dpi or higher" means 3
It has a recording pitch smaller than the recording pitch corresponding to 60 dpi. That is, it corresponds to having a recording pitch of about 70 μm or less. (8) Main scanning image sequence “Main scanning image sequence” is an image sequence that is continuous in the main scanning direction. (9) "Completing an image""Completing an image" means a state in which an arbitrary ink ejection control is performed by a predetermined ink ejection control method and a printing operation is completed. (10) Dot Diameter The “dot diameter” refers to the diameter of a substantially circular dot of the recording material fixed on the recording medium. For example, dots in an inkjet image recording device are formed by ink.

[0039]

DETAILED DESCRIPTION OF THE INVENTION An image recording apparatus according to an embodiment of the present invention will be described with reference to the drawings. The image forming apparatus according to the present embodiment forms an image by ejecting ink particles based on an input image signal by a known method such as a piezo effect or a method utilizing expansion of bubbles due to heating. It is a device that outputs an image by an inkjet.

Hereinafter, the present invention is not limited to this embodiment. (Overall Configuration) First, the overall configuration of the image recording apparatus according to the present embodiment will be described with reference to FIG. The image recording apparatus of this embodiment is a medical inkjet recording apparatus.

The ink jet recording apparatus 40 performs pseudo halftone processing such as error diffusion and dithering on the input image signal, adheres the ink to the recording medium by an ink jet method based on the processed image signal, and forms an intermediate image. It is possible to form an image having a tone.

In this ink jet recording apparatus 40, the apparatus main body 41 is provided with the feeding trays 42 in, for example, two stages, and one of them, for example, the recording medium M set in the lower feeding tray 42 is fed. Send it into the device body 41,
The recording medium M on which the images G1 and G2 are formed is ejected by the ejection unit 43.
It is designed to be taken out.

Next, the electrical construction of the ink jet recording apparatus 40 of FIG. 2 will be described with reference to FIG. The recording medium M can be moved in the arrow A direction (sub-scanning direction) by the transport roller 12.

The recording head unit 101 is movable in a direction (arrow B direction: main scanning direction) substantially orthogonal to the moving direction of the recording medium M (sub scanning direction). The printhead unit 101 of the present embodiment is provided with a row of printheads 102 that eject yellow (Y), magenta (M), cyan (C), and black (K) inks. These heads may be integrated or may be separately provided individually.

An arbitrary color image can be recorded by combining inks having different color tones. Further, a monochrome image can be recorded by using color ink such as YMC. These recording heads may be integrated or may be separately provided separately.

Further, not only the combination of inks having different color tones such as YMCK but also the combination of inks of the same color having different densities may be used. "Similar color inks having different densities" are inks that use dyes or pigments of similar colors and have different dye (pigment) concentration ratios. For example, when recording four kinds of substantially uniform density images on a recording medium using only one ink of K1, K2, K3, and K4, which is an ink in which only the dye concentration ratio is changed using the same K dye, This is a case where the recorded images have different optical densities. By recording an image using inks of the same color but different densities, it is possible to form a monochromatic image of higher gradation.

Further, each recording head 102 is provided with a plurality of recording elements (nozzles) having an array pitch X in the sub-scanning direction. Image data input from the outside of the device (external photographing device, storage device) is subjected to pseudo halftone processing such as error diffusion and dither by the image processing unit 121, and the recording head 102 of the recording head unit 101 via the recording element driving unit 517. Sent to.

The control means 103 drives the recording head unit 101 in the main scanning direction via the recording head transport means 104 according to the head transport signal obtained by the image processing means 121, and via the transport roller drive means 122. The recording medium M is driven in the sub-scanning direction.

FIG. 4 is a block diagram of an example of the recording head of FIG. In the drawing, the nozzle 10 of each recording head 102
A piezo element 102a is provided in the vicinity of 2b, and expansion / contraction is caused by a voltage applied to the piezo element 102a, and ink droplets are ejected from the nozzle tip toward the recording medium M according to an image signal. Has become.

Further, the control means 103 drives the recording head 102 of the recording head unit 101 via the recording element driving means 517 in accordance with the image data obtained by the image processing means 121 to display an image on the recording medium M. Form.

The recording element driving means 517 will be described with reference to FIG. FIG. 3 shows the recording element driving means 517.
3 is a block diagram showing the internal configuration of FIG. The recording element driving unit 517 demodulates and amplifies the image data into an analog waveform, and a drive signal generation circuit 304 and a drive signal generation circuit 304.
Drive signal shaping circuit 30 for shaping the drive signal generated in
6 and.

Here, by making the drive signals supplied to the drive elements of the recording head 102 have the same waveform, the amount of ink droplets ejected from the tip of the nozzle can be kept constant and formed on the recording medium. It is possible to control the dot diameters to be approximately the same size. Knowing the extent of spread of the ejected ink droplets when they land on the recording medium is suitable for obtaining a desired dot diameter for various combinations of ink and recording medium. Ink ejection control can be performed.

Further, by controlling the drive signal intricately, the amount of ink droplets ejected from the nozzle tip is controlled in several stages, and dots of various sizes (so-called "multi-size dots") are formed on the recording medium. Can be formed.

As a method of forming multi-size dots without complicated control of the drive signal, a method of masking the common drive signal to generate a plurality of types of drive signals can also be used.

FIG. 5 is a block diagram showing the internal structure of the drive signal shaping circuit 306 for forming multi-size dots. The drive signal shaping circuit 306 includes a shift register 330.
, Data latch 332, and mask signal generation circuit 334.
A mask pattern register 336 and a mask circuit 33.
8 and. The shift register 330 converts the image data (serial print signal) PRT into parallel data of 2 bits × 4 channels. Here, "1 channel" means a signal for one nozzle. The print signal PRT for one pixel of one nozzle includes the upper bit DH and the lower bit D.
It consists of 2 bits of L. Mask signal generation circuit 3
34 denotes mask pattern data V0 to V3 given from the mask pattern register 336 and 2 of each channel.
1-bit mask signal MSK (i) (i) for each channel according to the bit print signal PRT (DH, DL)
= 1-4) is generated. The mask circuit 338 responds to the supplied mask signal MSK (i) by the common drive signal CO
It is an analog switch circuit for masking part or all of the signal waveform in one pixel section of MDRV. Here, “masking the common drive signal” means turning on / off the connection of the signal line of the common drive signal COMDRV in each piezo element.

FIG. 6 is a timing chart showing drive signal waveforms in the drive signal shaping circuit of FIG. Figure 6 (a)
As shown in, the common drive signal COMDRV is a signal in which the same pulse W1 is generated three times in one pixel section. As shown in FIGS. 6B, 6C, and 6D, when recording a small dot MS, only the first pulse is left and other pulses are masked to record a medium dot MM. In this case, the third pulse is masked while leaving the first and second pulses, and when recording the large dot ML, the common drive signal COMDRV is used as it is without masking. By performing such masking processing in accordance with the serial print signal PRT in each pixel, it is possible to selectively print any one of the three types of dots having different sizes at each pixel position.

Next, the recording medium M will be described with reference to FIG. 7, which is a structural diagram of the recording medium M. In the recording medium M, a receiving layer 41 that easily absorbs ink is formed on the surface 40a of a transparent support 40, and an image is recorded in the receiving layer 41. It is preferable to provide a back coat layer on the back surface 40b with functions such as curl prevention, adsorption to other recording media, and antistatic function because the recording medium can be easily handled. Furthermore, by providing a layer having an antireflection function on the front surface and / or the back surface, reflected light can be reduced,
This is preferable because it is easier to diagnose. Further, a receiving layer may be formed on the back surface and an image may be recorded on the back surface.

The transparent support 40 of this embodiment is
For example, those described in JP-A-10-76751 are preferably used. The preferred support is a polyester obtained from the polycondensation of diols and dicarboxylic acids. Preferred dicarboxylic acids include terephthalic acid, isophthalic acid,
Includes phthalic acid, naphthalenedicarboxylic acid, adipic acid and sebacic acid. Preferred diols include ethylene glycol, trimethylene glycol, tetramethylene glycol and cyclohexanedimethanol.
Specific polyesters suitable for use in this invention are polyethylene terephthalate, polyethylene-p-hydroxybenzoate, poly-1,4-cyclohexylene dimethylene terephthalate and polyethylene-2,6-naphthalene carboxylate. Polyethylene terephthalate is the most preferred polyester for the support because of its excellent water resistance, chemical stability and durability.

The support layer 41 is coated on the support to form the support layer 41 coated on the support 40.
Is a binder composed of a water-soluble polymer and a water-insoluble polymer. The amount of the water-soluble polymer and the water-insoluble polymer combined is at least 1
5% by weight and not more than 90% by weight; and an inorganic particulate material having a hydrodynamic diameter in water not greater than 0.3 μm, the inorganic particulate material being a water-soluble polymer, water. It represents an amount of at least 50% by weight and not more than 95% by weight of the total coating weight of the insoluble polymer and the inorganic particulate material.

The water-soluble polymer is preferably polyvinyl alcohol, polyacrylamide, methyl cellulose,
It contains at least one compound selected from the group consisting of polyvinylpyrrolidone and gelatin. The water-soluble polymer further preferably comprises a polymer of monomers selected from the group consisting of vinyl alcohol, acrylamide and vinylpyrrolidone.

The water-insoluble polymer is preferably acrylic,
It contains at least one polymerized monomer selected from olefins, vinyls, urethanes and amides. The water insoluble polymer most preferably comprises at least one compound selected from acrylics, urethanes, polyolefins and vinyl latices. The water-insoluble polymer can include polar functional groups. However, the degree is below a level sufficient to form a water-soluble polymer.

The total coating weight of inorganic particulate material, water soluble polymer and water insoluble polymer is preferably at least 0.
It is 1 g / m ² . At a total coating amount of 0.1 g / m ² or less, the adhesiveness between the phase change ink and the receiving layer decreases to a level that is practically inappropriate. Furthermore, the coating efficiency is 0.1 g /
When it is less than m ^2, it is lowered, which is not preferable in terms of manufacturing cost of the medium. The total coating amount of inorganic particulate material, water-soluble polymer and water-insoluble polymer is at least 0.3g
/ M ² is more preferable.

When the recording medium M is a transmissive recording medium, it can be diagnosed as a transmissive image, and it is easy to distinguish a subtle density change in the subject area. Further, the effect of increasing the density of the non-subject region in the present embodiment is more visually recognized in the transmissive image than in the reflective image, so that the present invention can be applied to a transparent recording medium. preferable.

It is preferable that the recording medium M is colored because light reflection due to external light such as illumination can be reduced and an easy-to-see image can be obtained. It is preferable that the coloring is substantially blue, because the blue is a recessed color and the eyes do not get tired, so that it is easy to make a psychological diagnosis. Furthermore, when the transmission density of the colored transmission recording medium M is 0.03 or more and 0.2 or less, reflection is reduced without impairing the transparency, and an image capable of more accurate diagnosis is obtained, which is preferable.

<Relationship Between Dot Diameter and Graininess> Next, the relationship between the dot diameter of the ink, the recording pitch, and the graininess will be described. Here, the dot diameter refers to a substantially circular diameter formed of a dye or a pigment when an ink droplet is attached to a recording medium and then absorbed in the recording medium to substantially fix the ink. Further, the recording pitch refers to a dot interval in which ink dots are arranged in the main scanning direction or the sub scanning direction after recording is completed, and the former is referred to as a main scanning recording pitch and the latter is referred to as a sub scanning recording pitch. Further, the dot diameter-recording pitch ratio η is defined as η = (dot diameter) / (recording pitch) as an index representing the relationship between the dot diameter and the recording pitch.

FIG. 8 is a schematic diagram showing ink dot overlap when ink drops of the same density are uniformly ejected on a square grid at equal intervals. Hereinafter, main scanning 1440 dpi × sub scanning 14
An example will be given in which an image is recorded by an inkjet image recording apparatus having a resolution of 40 dpi (corresponding to a lattice spacing of about 17.5 μm on each side).

FIG. 8A shows a schematic diagram of dot overlap when the dot diameter is equal to the lattice spacing (η = 1.0), that is, when the dot diameter is 17.5 μm. Since the dots do not overlap with each other and a non-printed portion is generated, density variation easily occurs due to the difference in measurement position. Further, even if the ink landing deviation is slight, the gap portion is enlarged and is easily detected, so that higher ink landing accuracy is required, which is not preferable.

In FIG. 8B, the dot diameter is 1.5 times the lattice spacing (η = 1.5), that is, the dot diameter is 26.3.
The schematic diagram of the dot overlap when it is μm is shown. η =
Compared with the case of 1.0, there are many overlapping parts of dot diameter,
Concentration variation is less likely to occur at the measurement position.

In FIG. 8C, the dot diameter is 3 of the lattice spacing.
Double (η = 3.0), that is, a schematic diagram of dot overlap when the dot diameter is 52.5 μm. Compared with the case of η = 1.5, the overlapping portion of the dot diameter is further increased, the ink dots overlap in a wide range, and the ink dots cover the entire surface of the recording medium to obtain an extremely good uniform density image. be able to. Further, by making the dot diameter sufficiently large with respect to the recording pitch, even if the ink landing position shift occurs due to factors such as nozzle bending of the recording head or ink adhesion on the nozzle surface, a gap due to the ink position shift is less likely to occur. Has the effect of

FIG. 9 is a diagram showing the results of actually visual-based evaluation of graininess by creating uniform density images with different main-scan recording pitches. The image recording conditions for creating a uniform density image are only that the main scanning recording pitch is changed,
The sub-scanning recording pitch (1440 dpi), the amount of ejected ink droplets (about 7 pl per droplet), the recording medium composition, and the ink composition were all the same. By changing the driving speed of the recording head to the main scanning, the main scanning recording pitch is set to 20 to
It was changed to various values of 100 μm. The evaluation criteria are
◯: good level, Δ: somewhat worrisome level, x: worrisome level, which is a three-level evaluation. As a result of the evaluation, it was confirmed that a threshold value of good granularity was between η of 1.30 and 1.63, and sufficient granularity was obtained for η higher than that.

<Relationship Between Dot Diameter and Gradation (Density Stability)> The relationship between the ink dot diameter, recording pitch, and gradation will be described. The evaluation items relating to gradation include smoothness of gradation characteristic curve, gradation reproducibility, etc. Especially, the latter gradation reproducibility and density stability of an image recording apparatus will be considered. The density stability refers to a property of whether or not a stable image density can be obtained against variations in dot diameter due to displacement of landing positions of ink droplets and the like.

FIG. 10 is a diagram showing the relationship between the dot diameter and the average density. Here, the average density means that a uniform density image is recorded on a recording medium using an image recording device, the density is measured at arbitrary 5 different points using a commercially available diffusion densitometer, and the measured density Refers to the average value.
For example, in this example, the concentration was measured using PDA-65 (manufactured by Konica Corporation).

The image recording conditions for forming the uniform density image are as follows: the sub-scanning recording pitch (1440 dp) except that the dot diameter-to-pitch ratio η and the ink dye density ratio are changed.
i), the amount of ejected ink droplets (about 7 pl per droplet), and the composition of the recording medium are set to the same conditions, and the ink physical properties such as viscosity and density are adjusted so that the dot diameter of the ink on the recording medium is approximately the same size. did. With respect to (1), the main scanning recording pitch was changed to various values of 20 to 100 μm by changing the driving speed of the recording head to the main scanning, and images were created with 7 different dot diameter-pitch ratios η. With regard to (1), a uniform density image was created by evenly adhering one kind of density ink to a recording medium having a density of 0.20. The ink used had a dye density ratio of 1: 4: 7. Corresponds to □, △ plots filled with ◆, black.
A total of 21 types of uniform density images were created by combining and, and the average density was measured.

Regarding the dot diameter of the ink, a transmission electron microscope HU-12 type (manufactured by Hitachi, Ltd.) was used, and the ink dot recorded by the image recording apparatus of this embodiment was magnified 100 times. I asked from the photograph.

The horizontal axis represents the dot-to-recording pitch ratio η (dot diameter / recording pitch), and the vertical axis represents the average density of the uniform density image. When η is less than 1.4, there is a non-printed portion, and the average density increases as the ink coverage increases.

When η is larger than 1.4, the density varies depending on the degree of overlap of ink dots, but when η exceeds 3.0, the average density is almost stable. In this range, even if the dot diameter varies, the average density hardly changes.

Although there are physical limits such as the amount of ink absorbed by the recording medium and the stability of ink ejection, when ink droplets of the same density are ejected uniformly, the recording pitch is reduced in order to reduce the non-printed portion. It is preferable to make the dot diameter as large as possible.

Further, if the dot diameter is increased, streak unevenness in the sub-scanning direction can be filled up, so that there is an effect of reducing banding. On the other hand, if the scanning speed of the recording head is slowed down, the recording pitch can be reduced, and as a result, η can be increased, but at the same time, the recording speed is reduced, which is not preferable. Therefore, it is preferable to set the amount of ink droplets ejected from the recording head per dot to be constant, and to control the dot diameter to an appropriate size depending on the physical properties of the ink and the recording medium. For example, the dot diameter can be controlled by changing the viscosity of the ink, the surface energy of the recording medium, and the absorption speed, but the physical properties that can control the dot diameter are not limited to this.

<Relationship Between Dot Diameter and Sharpness> The relationship between the dot diameter of the ink, the recording pitch, and the sharpness will be described. Here, the sharpness means a so-called density contrast characteristic of a so-called chart image in which line images having a specific width are periodically recorded using inks of different densities.

FIG. 11 shows a schematic diagram of a line image having a width of 8 dots per line. D is the dot diameter, and A is the recording pitch, and represents a line image when the dot diameter-recording pitch ratio η = D / A is changed.

Η = 2.0 in (a) and η = in (b).
In FIGS. 4.0 and (c), η = 6.0, indicating that dark ink is applied to the high density portion and thin ink is applied to the low density portion substantially uniformly. In a transmission image, the density increases in proportion to the amount of dye or pigment contained in the ink, so the high density part (dark ink part) erodes the low density part (light ink part) and the low density part collapses. Will happen.

At η = 2.0, the width (L) of the low-density portion is sufficient, but as η becomes larger, the width (L) becomes narrower (η = 4.0), and at η = 6.0, it is almost the same. The low density part is crushed and cannot be seen.

In an image having a high density contrast and a small blank area, particularly in a character image such as patient information and imaging conditions accompanying X-ray simple photographs and CT images, there is a low density portion where no ink is applied. Since it is eroded by the high-density ink, the white spots in the image may look very bad. The dark ink on one edge is (D
-A) / 2 is eroded, so 2 × (D-
The low density area is eroded by the dark ink for a length of A) / 2 = (D−A). The width is 1 in the actual character image.
If it is 50 μm or more, it is within the range in which it can be recognized as a character. Therefore, in order to leave the blank portion without being eroded by the dark ink, DA−150 [μm], that is, D <A + 150.
It must be [μm]. Further, in reality, if the whiteout portion is at least half or more of the original image, that is, if 50 μm does not exist, the characters are crushed and become difficult to read. Therefore, D−A <75 [μm], that is, D <A + 75 [μm
m] is preferable. For example, the recording density is 1440 dpi in the main scan × 1440 dpi in the sub-scan (lattice interval of about 1
(Corresponding to 7.5 μm), the number of pixels is 1024 × 1024
Consider the case where the image is recorded with a pixel size of 70 μm (developed in a 4 × 4 dither matrix). At this time,
One side is about 71.2 mm, which is close to the output size actually used for diagnosis in X-ray CT images and MRI images. The width of the line in the character portion is approximately 2 pixels (140 μm), which corresponds to 8 dots per line when converted to the number of dots. The area where the blank areas remain without being eroded by the dark ink is D <
(17.5 + 150) μm, that is, D <117.5 μ
must be m. Further, it is preferable that the range in which the characters are not crushed and difficult to read is D <(17.5 + 75) μm, that is, D <92.5 μm.

<Comprehensive evaluation of image quality> From the viewpoints of graininess, stability of average density and sharpness, the dot diameter D of the ink is 1.5 A ≦ D ≦ A + 100 with respect to the recording pitch A.
It is preferably [μm]. In the above relational expression, it is premised that A ≦ 150 μm is satisfied, and A>
The resolution of 150 μm is not preferable from the viewpoint of image quality.

Furthermore, in order to obtain an image with good character dropout and better density stability, 2A ≦ D ≦ A + 75
It is preferably [μm]. In the above relational expression, it is assumed that A ≦ 75 μm is satisfied, and A> 75
The resolution of μm is not preferable in terms of image quality.

However, since there are variations in the ejection of ink in practice, most fixed ink dot diameters should fall within the above range. In this embodiment, the resolution of the inkjet recording apparatus is limited to 1440 dpi, but at least 360 d
A resolution of pi or higher is sufficient, and a high resolution of 720 dpi or higher is preferable for recording a high quality medical image.

The main scanning direction Pm and the sub scanning direction Ps are not always required.
It is not necessary to match the resolutions of and, but the lower resolution of both, that is, the one with a larger recording pitch, A = max
The above relationship may be established with respect to (Pm, Ps).

<Relationship Between Dot Diameter and Ink Ejection Frequency> The range of the dot diameter suitable for obtaining a good image quality has been described above. An image recording method for realizing that range will be described.

In a normal image recording method, ink of approximately the same diameter is ejected at a constant ejection interval by using a single nozzle or a plurality of nozzles during one scanning, and one main scanning row is ejected by one scanning. A method of completing an image, that is, a main scanning image sequence is used. Here, the main scanning row refers to a row continuous in the main scanning direction, and the sub-scanning row described below refers to a row continuous in the sub-scanning direction. When the image recording method is used, beading may occur on the surface of the recording medium depending on the combination of physical properties such as the surface energy of the recording medium and the ink absorption speed. This is a phenomenon that can occur when the next ink is ejected while the ejected ink remains on the surface of the recording medium.

FIG. 12 shows a schematic diagram from ink impact to absorption. After the ink droplet has landed on the surface of the recording medium M, if there is not enough space between the ink droplet and the next landing (see FIG. 12A),
When the ink dots landed immediately before are connected on the surface of the recording medium M (see FIG. 12B) and the ink is absorbed by the recording medium M, density unevenness occurs (see FIG. 12C).

Further, when ink is continuously ejected within one scan, stable landing position accuracy can be maintained, but when ink is ejected intermittently, the landing position may deviate particularly at the time of ink ejection start. . The deviation of the landing position facilitates mixing of the ink droplets, which easily causes beading. As a result, the output density locally varies, and it may appear as a pseudo contour in some cases, which may impair the image quality. Particularly in the case of a medical image, a portion having a pseudo contour may be mistakenly recognized as a lesion, which is not preferable.

Therefore, a method of ejecting ink having substantially the same diameter at a constant ejection interval by using a single nozzle or a plurality of nozzles during one scan, and completing an image for one sub-scanning row by a plurality of scans, It is conceivable to overcome the above problems by using a so-called multiple scanning recording method.

For example, the pitch at which ink is ejected when completing an image of one sub-scan image row during one scan, that is, the ejection pitch (writing pitch) B is equal to the main-scan recording pitch A, and n (n is an arbitrary natural number). ) When completing an image of one sub-scanning image row during scanning, the ejection pitch B may be B = nA. However, A corresponds to the recording pitch in the main scanning direction described above, and n is referred to as the number of divided scans.

FIG. 13 is a schematic diagram showing the multiple scanning recording method. Only the recording head 102 that is driven in the main scanning direction to eject ink from the nozzles and the recording medium M that is conveyed in the sub scanning direction are shown.

For simplification, the case where there is only one recording head 102 having five nozzles will be taken as an example. The nozzle spacing corresponds to four times the recording pitch (= 4 A). FIG.
From the middle figure (a) to the figure (h), it is the figure which showed the process until the image is actually completed in time series, and the black circle (●) attached to the recording medium M is printed with the scanning of the recording head. The white circles (○) indicate the already printed areas.

Printing is performed only when the recording head 102 moves forward,
This is so-called unidirectional printing, in which the recording head 102 ejects ink droplets while scanning the forward path and conveys the recording medium by a predetermined amount while the recording head 102 scans the backward path.

Thereafter, the image is recorded by repeating this operation. For example, as shown in FIG. 13, the number of divided scans n
= 2, the conveyance amount of the recording medium is “2A → 3A → 2A → 3A →
...... ", the ink ejection position is recorded as" an odd row (of the sub-scanning row) → an even row → an odd row → an even row → ... "by repeating a cyclic operation, thereby freely recording an arbitrary two-dimensional image. can do.

Further, by increasing the number of nozzles or recording heads 102 and combining a plurality of inks having different color tones or inks of the same color but different densities, multi-tone or multi-tone images can be recorded as designed. It becomes possible to do.

The average value of the dot diameter D recorded on the recording medium is Dave, and the ejection pitch to dot diameter ratio ε is ε = (ejection pitch) / (average dot diameter) = (number of divided scans) · (recording pitch) / (Dot diameter) = nA / D is defined.

FIG. 14 shows the image state after recording due to the difference in recording method (when η = 2.0). In the figure (a-1), ink is ejected every other dot diameter (ε = 1.
0). A circled number means that an ink dot corresponding to the position of the number is ejected with ink at the number of scanning times of the recording head to record an image, and the image is completed by scanning eight times. An image of one sub-scanning row is completed by scanning twice.

As shown in FIGS. (A-2) and (a-3), when the ink dots are connected, they are attracted to each other to form one large dot, and a gap is locally generated on the recording medium. Since density unevenness appears, it may lead to deterioration of graininess.

The diagram (b-1) corresponds to the case where ink is ejected every two dot diameters (ε = 2.0). Since there is a sufficient interval between dots (see FIG. (B-2)), each ink droplet is absorbed as it is in the ink receiving layer of the recording medium, so that the output density as designed can be obtained, and it is even better. An image is obtained (see FIG. (B-3)).

Further, when the number of division operations is small, the ratio of using the same nozzle for one main scanning image row is high, and therefore, even if there is even one defective nozzle from which ink droplets cannot be ejected, there is a streak. The unevenness may be noticeable. From this point of view, it is preferable to increase the number of divided scans.

FIG. 15 is a diagram showing the results of subjective evaluation of streak unevenness. The result of subjectivity evaluation by visual observation is shown in which a density uniform image is created when the number of divided scans is changed from 1 to 6 while keeping η = 2.17 constant.
It was confirmed that a good image in which streak unevenness was not detected was obtained when ε ≧ 2.0.

When the ejection pitch is excessively increased relative to the dot diameter and the number of divided scans is increased to record an image, it is expected that the recording time will increase as the number of nozzles used increases. Since the optimum number of divided scans is determined in consideration of the conveyance accuracy of the recording medium, the ink landing position accuracy of the nozzles, and the recording time, for example, it is preferable to set an appropriate number of divided scans within the range of 2 ≦ ε ≦ 8. good.

In this embodiment, the medical image used for diagnosis has been described. However, the image may be a reference image or may be applied to a transmission image such as an OHP (overhead projector) sheet without being limited to medical images. May be.

In the above-mentioned embodiment, the color image is used for explanation, but a better result can be obtained for a monochrome image. Although the present embodiment is limited to the ink jet recording apparatus, it can be widely applied to a method of forming an image using innumerable dots such as a wire dot recording method. In particular, in the inkjet method, image quality deterioration is likely to occur due to microscopic changes such as ink bleeding and beading, so this embodiment is a particularly preferable embodiment.

The present invention is also applicable to a color image, a monochrome image, or a combination of inks of similar colors / non-similar colors. In color images,
It is possible to suppress changes in color tone due to beading of ink droplets, and not only stable gradation characteristics can be obtained in monochrome images, but gray is more visible to human eyes than contrast resolution. Therefore, the effect of the present invention is particularly observed. Furthermore, it is preferable to record an image using inks of the same color because a monochromatic image with a single gradation and stable output density can be obtained.

Further, as an apparatus (device) for inputting image data to the image recording apparatus of this embodiment, an X-ray imaging apparatus, an X-ray computed tomography apparatus (X-ray CT apparatus) or a magnetic resonance image forming apparatus is used. (MRI device), ultrasonic image shadow diagnostic device, electronic endoscope, fundus camera, etc.
It is not limited to these.

In order to realize the functions of the above-described embodiment, the image recording apparatus of this embodiment, an apparatus for inputting image data to the image recording apparatus of this embodiment, and further this embodiment. For each computer (CPU or MPU) of the system including the image recording device of the embodiment and the device for inputting image data to the image recording device of the embodiment,
It is within the scope of the present invention to supply a program code of software for realizing the above-described embodiment and operate it according to a program stored therein.

Further, the program code itself of the software realizes the function of the embodiment, and the program code itself and the means for supplying the program code to the computer are also within the scope of the present invention. .

As means for supplying the program code to the computer, there is a storage medium, and the storage medium is a flexible disk, hard disk, optical disk, magneto-optical disk, CD-ROM, magnetic tape, non-volatile memory card, There is a ROM etc.

Further, by executing the supplied program code by the computer, not only the functions described in the above embodiments are realized, but also the OS (operating system) in which the program code is operating in the computer. It is needless to say that the program code is also included in the embodiment of the present invention when the functions shown in the above embodiment are realized in cooperation with other application software or the like.

Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the function expansion board or function expansion unit is instructed based on the instruction of the program code. It goes without saying that the present invention also includes a case where the CPU or the like included in the above performs some or all of the actual processing and the functions of the above-described embodiments are realized by the processing.

In the present embodiment, the effect of gradation correction is remarkable in medical images, particularly in the case of monochrome multi-gradation medical images obtained by simple X-ray imaging, which require extremely high image quality. It is effective because it appears in.

Further, although the example of the present embodiment has been mainly described by using the medical image recording apparatus, the present invention is not limited to the use of the image recording apparatus, and widely uses a digital printer. It is applicable in the field. Further, the present invention can be applied not only to a monochrome image but also to a color image in which primary colors of YMCK or RGB are combined.

[0117]

As described above, the invention according to claim 1
According to the invention of claim 9, the range of the dot diameter D recorded on the recording medium is 1.5 A ≦ D ≦ A + 150 [μ
m], it is not affected by recording variation factors such as ink dot diameter and landing position deviation,
In particular, a high-quality print image can be obtained in a transmission image.

According to the invention of claim 2 and the invention of claim 10, the range of the dot diameter D is 2A ≦ D ≦ A +.
With a thickness of 75 [μm], it is possible to obtain a high-quality printed image, particularly in a transmission image, without being affected by recording variation factors such as ink dot diameter and landing position deviation.

According to the invention described in claim 3 and the invention described in claim 11, dots are formed on the recording medium so that the dot diameters are substantially the same size. The distribution is substantially uniform, and local variations in dot diameter can be suppressed, so that good image quality can be obtained.

According to the invention of claim 4 and the invention of claim 12, the dot diameter is n (n ≧ 1) in size D.
1, D2, ..., Dn (D1 ≧ D2 ≧ ... ≧ Dn), and dots are formed on the recording medium so that D1 satisfies the expressions (1) and (3). As a result, good image quality can be obtained even in an image recorded with only a Dmax dot diameter that is most likely to cause graininess in the image, and further, good image quality can be obtained using any combination of a plurality of dot diameters. it can.

According to the invention described in claim 5 and the invention described in claim 13, by completing the main scanning image sequence by a plurality of main scans, the error of the conveyance amount of the recording medium in the sub-scanning direction, the nozzle It is possible to reduce streak unevenness due to defective ejection of ink droplets.

According to the invention of claim 6 and the invention of claim 14, when the average value of the dot diameter D1 is Dave, the writing pitch Pm ′ in the main scanning direction in one main scanning is By forming dots on the recording medium so that the range satisfies Pm ′ ≧ 2Dave, beading (adjacent dots are connected) in the same scan does not cause deterioration of graininess and edge enhancement. Also, the image quality becomes good with respect to variations in dot diameter size and dot landing position.

According to the invention described in claim 7 and the invention described in claim 16, high-quality images can be obtained by forming dots so that the resolution is 360 dpi or more.

According to the invention described in claim 8 and the invention described in claim 17, high-quality images can be obtained by forming dots so that the resolution is 720 dpi or more.

According to the fifteenth aspect of the invention, the dot diameter can be easily controlled by controlling the amount of ink droplets ejected from the recording head.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an electrical configuration of an inkjet recording apparatus according to an embodiment.

FIG. 2 is a diagram illustrating the overall configuration of the inkjet recording apparatus according to the present embodiment.

FIG. 3 is a block diagram showing an internal configuration of a recording element driving unit of FIG.

FIG. 4 is a configuration diagram of the recording head of FIG.

FIG. 5 is a block diagram showing an internal configuration of a drive signal shaping circuit that forms multi-size dots.

6 is a timing chart showing drive signal waveforms in the drive signal shaping circuit of FIG.

7 is a configuration diagram of the recording medium of FIG.

FIG. 8 is a schematic diagram of ink dot overlap when ink droplets of the same density are uniformly laid on a square grid at regular intervals.

FIG. 9 is a diagram showing the results of actual visual evaluation of graininess by creating uniform density images with different main scanning recording pitches.

FIG. 10 is a diagram showing the relationship between dot diameter and density.

FIG. 11 is a schematic diagram of a line image having a width of 8 dots per line.

FIG. 12 is a schematic diagram from ink impact to absorption.

FIG. 13 is a schematic diagram of a multi-scan recording method.

FIG. 14 is a diagram illustrating an image state after recording due to a difference in recording method.

FIG. 15 is a diagram showing a result of subjective evaluation of streak unevenness.

[Explanation of symbols]

M recording medium 101 recording head unit 102 recording head 103 control means

Continued front page    (72) Inventor: Honda Honda             Konica Stock, 1 Sakura-cho, Hino City, Tokyo             In the company F-term (reference) 2C056 EA04 EA24 EC76 ED01 ED07                       EE14                 2C057 AF23 AF29 AF39 BA04 BA14                       CA01 CA05 CA07

Claims (19)

[Claims] 1. An ink droplet is ejected from the recording head while moving the recording medium in the sub-scanning direction while relatively moving the recording head in the main scanning direction intersecting the sub-scanning direction with respect to the recording medium. Then, in the image recording method of forming a transmission image by dots on the recording medium by depositing the ink droplets on the recording medium, the range of the dot diameter D recorded on the recording medium is expressed by the following formula ( An image recording method, characterized in that dots are formed on the recording medium so as to satisfy 1). 1.5 A ≦ D ≦ A + 150 [μm] (1) where A = max (Pm, Ps) Pm = recording pitch in main scanning direction Ps = recording pitch in sub-scanning direction 2. The range of the dot diameter D is expressed by the following equation (2).
The image recording method according to claim 1, wherein dots are formed on the recording medium so as to satisfy the above condition. 2A ≦ D ≦ A + 75 [μm] (2) where A = max (Pm, Ps) Pm = recording pitch in main scanning direction Ps = recording pitch in sub-scanning direction 3. The image recording method according to claim 1, wherein dots are formed on the recording medium such that the dot diameters are substantially the same size. 4. The dot diameter is formed so as to have n (n ≧ 1) sizes D1, D2, ..., Dn (D1 ≧ D2 ≧ ... ≧ Dn), and the above (1) is applied to D1. The image recording method according to claim 1, wherein dots are formed on the recording medium so as to satisfy the formula. 5. The image recording method according to claim 4, wherein the main scanning image sequence is completed by a plurality of main scannings. 6. When the average value of the dot diameter D1 is Dave, on the recording medium such that the range of the writing pitch Pm ′ in the main scanning direction in one main scanning satisfies Pm ′ ≧ 2Dave. The image recording method according to claim 5, wherein dots are formed. 7. The resolution is 360 dots / 25.4 mm.
(360 dpi, hereinafter, dot / 25.4 mm is dpi
7. The image recording method according to claim 1, wherein the dots are formed in the above manner. 8. The image recording method according to claim 1, wherein the dots are formed so that the resolution is 720 dpi or more. 9. An image recording apparatus for recording an image on a recording medium based on an image signal representing an image, comprising a plurality of nozzles and a plurality of ejection drive elements for ejecting ink droplets from the plurality of nozzles. A recording head having a recording medium, a conveyance unit that conveys the recording medium in a sub-scanning direction, a driving unit that drives the recording head in a main scanning direction that intersects the recording medium in the sub-scanning direction, An image recording device, comprising: a control unit that controls the dot diameter so that the range of the dot diameter D formed by the ink droplets adhering to the surface of the ink satisfies the following expression (3). apparatus. 1.5 A ≦ D ≦ A + 150 [μm] (3) where A = max (Pm, Ps) Pm = recording pitch in main scanning direction Ps = recording pitch in sub-scanning direction 10. The image recording apparatus according to claim 9, wherein the control unit controls the dot diameter so that the dot diameter satisfies the following expression (4). 2A ≦ D ≦ A + 75 [μm] (4) where A = max (Pm, Ps) Pm = recording pitch in main scanning direction Ps = recording pitch in sub-scanning direction 11. The image recording apparatus according to claim 9, wherein the control unit controls the dot diameter so that the dot diameters are substantially the same size. 12. The control means comprises n (n ≧ 1) sizes D1, D2, ...
, Dn (D1 ≧ D2 ≧ ... ≧ Dn), and the dot diameter is controlled so as to satisfy the formula (3) with respect to D1. Image recording device. 13. The image recording apparatus according to claim 12, wherein the control unit completes a main scanning image sequence by performing main scanning a plurality of times. 14. The average value of the dot diameters D1 recorded on the recording medium is Da.
14. The image recording apparatus according to claim 13, wherein when it is ve, control is performed so that the range of the writing pitch Pm ′ in the main scanning direction in one main scanning satisfies Pm ′ ≧ 2Dave. 15. The image recording apparatus according to claim 9, wherein the control unit controls the amount of ink droplets ejected from the recording head. 16. The image recording apparatus according to claim 9, wherein the control unit controls the driving of the recording head so that the resolution is 360 dpi or more. 17. The image recording apparatus according to claim 9, wherein the control unit controls the drive of the recording head so that the resolution is 720 dpi or more. 18. The recording head is a recording head capable of ejecting similar color inks having different densities, and the control means controls to eject the similar color inks onto the recording medium. Claims 9 to 1
7. The image recording device according to any one of 7. 19. The image recording apparatus according to claim 9, wherein a medical image is recorded on the recording medium based on an image signal representing the medical image.