Title: Inkjet recording medium
Abstract: There is described an inkjet recording medium that can display image suitable for observation without employing wet development processing. The recording medium is substantially transparent and includes a supporting base shaped in a sheet; and an ink-absorbing layer that is formed on at least one of both sides of the supporting base, and that absorbs ink particles so as to form the image. The diffuse transmission density of a first area, being a part of the recording medium on which no image is formed, is in a range of 0.45-0.15, and a Q-factor of the first area is in a range of 1.50-1.00; and the recording medium is so constituted that a Q-factor of a second area, being a part of the recording medium on which an image is formed so as to adjust a diffuse transmission density at 1.00, is in a range of 1.20-1.00.
Patent Number: 6,896,364 Issued on 05/24/2005 to Nakazawa, et al.
| Inventors:
|
Nakazawa; Masayuki (Hachioji, JP);
Yamano; Akira (Hino, JP)
|
| Assignee:
|
Konica Corporation (Tokyo, JP)
|
| Appl. No.:
|
623892 |
| Filed:
|
July 21, 2003 |
Foreign Application Priority Data
| Jul 26, 2002[JP] | 2002-218409 |
| Current U.S. Class: |
347/105; 347/101; 428/32.1 |
| Intern'l Class: |
B41J 002/01; B32B003/00 |
| Field of Search: |
347/105,101,106
428/321,195
524/306,308,315,317
|
References Cited [Referenced By]
U.S. Patent Documents
| 6391954 | May., 2002 | Azizi et al.
| |
| 6474807 | Nov., 2002 | Honda.
| |
| 6613419 | Sep., 2003 | Ohbayashi et al.
| |
| 2003/0175450 | Sep., 2003 | Obayashi et al.
| |
Primary Examiner: Shah; Manish
Attorney, Agent or Firm: Squire, Sanders & Dempsey
Claims
1. A recording medium, being substantially transparent, for recording an image
through image-forming processes employing an ink-jetting method, comprising:
a supporting base shaped in a sheet; and
an ink-absorbing layer that is formed on at least one of both sides of said supporting
base, and that absorbs ink particles so as to form said image;
wherein a diffuse transmission density of a first area, being a part of said
recording medium on which no image is formed, is in a range of 0.45-0.15, and a
Q-factor of said first area is in a range of 1.50-1.00; and
wherein said recording medium is so constituted that a Q-factor of a second area,
being a part of said recording medium on which an image is formed so as to adjust
a diffuse transmission density at 1.00, is in a range of 1.20-1.00.
2. The recording medium of claim 1,
wherein said supporting base is made of a resin material.
3. The recording medium of claim 1,
wherein said recording medium is so constituted that a Q-factor of a third area,
being a part of said recording medium on which an image is formed so as to adjust
a diffuse transmission density at a value smaller than 1.00 and greater than said
diffuse transmission density of said first area, is in a range of 1.50-1.00.
4. The recording medium of claim 1,
wherein said recording medium is so constituted that said Q-factor of said first
area is in a range of 1.30-1.00.
5. The recording medium of claim 4,
wherein said recording medium is so constituted that a Q-factor of a third area,
being a part of said recording medium on which an image is formed so as to adjust
a diffuse transmission density at a value smaller than 1.00 and greater than said
diffuse transmission density of said first area, is in a range of 1.30-1.00.
6. The recording medium of claim 1,
wherein a haze of said first area is in a range of 15%-5%.
7. The recording medium of claim 1,
wherein a psychological hue angle, denoted by hab and defined in the CIE•LAB
color system by an equation of
is in a range of 250°-230°, when light, emitted from a fluorescent
light-source, transmit through said first area, and
wherein a value of (a*
2+b*
2)
0.5 is in a range
of 22-15.
8. The recording medium of claim 1,
wherein said ink-absorbing layer is an air-gap type ink-absorbing layer, mainly
composed of a high-polymer binder, inorganic micro-particles and/or organic micro-particles.
9. The recording medium of claim 8,
wherein an average particle-diameter of said inorganic micro-particles and/or
said organic micro-particles before condensing them is equal to or smaller than
15 nm.
10. The recording medium of claim 1,
wherein a thickness of said ink-absorbing layer is in a range of 50 μm-20
μm.
11. The recording medium of claim 1,
wherein said ink-jetting method employs three kinds of black inks, densities
of which are different relative to each other, so as to record a medical image.
12. A method for recording a medical image onto a recording medium, being substantially
transparent, which comprises a supporting base shaped in a sheet and an ink-absorbing
layer, formed on at least one of both sides of said supporting base and absorbing
ink particles so as to form said medical image, said method comprising the step of:
forming said medical image onto said recording medium through image-forming processes
employing an ink-jetting method;
wherein a diffuse transmission density of a first area, being a part of said
recording medium on which no image is formed, is in a range of 0.45-0.15, and a
Q-factor of said first area is in a range of 1.50-1.00; and
wherein said recording medium is so constituted that a Q-factor of a second area,
being a part of said recording medium on which an image is formed so as to adjust
a diffuse transmission density at 1.00, is in a range of 1.20-1.00.
13. The method of claim 12,
wherein said ink-jetting method employs three kinds of black inks, densities
of which are different relative to each other, so as to record said medical image.
14. The method of claim 12,
wherein said supporting base is made of a resin material.
15. The method of claim 12,
wherein said recording medium is so constituted that a Q-factor of a third area,
being a part of said recording medium on which an image is formed so as to adjust
a diffuse transmission density at a value smaller than 1.00 and greater than said
diffuse transmission density of said first area, is in a range of 1.50-1.00.
16. The method of claim 12,
wherein said Q-factor of said first area is in a range of 1.30-1.00.
17. The method of claim 16,
wherein said recording medium is so constituted that a Q-factor of a third area,
being a part of said recording medium on which an image is formed so as to adjust
a diffuse transmission density at a value smaller than 1.00 and greater than said
diffuse transmission density of said first area, is in a range of 1.30-1.00.
18. The method of claim 12,
wherein a haze of said first area is in a range of 15%-5%.
19. The method of claim 12,
wherein a psychological hue angle, denoted by hab and defined in the CIE•LAB
color system by an equation of
is in a range of 250°-230°, when light, emitted from a fluorescent
light-source, transmit through said first area, and
wherein a value of (a*
2+b*
2)
0.5 is in a range
of 22-15.
20. The method of claim 12,
wherein a thickness of said ink-absorbing layer is in a range of 50 μm-20 μm.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a transparent ink-jet recording medium for recording
images by an inkjet system.
In the past, in order to record and diagnose a digital medical image, the image
used to be recorded on a wet silver-salt film by wet development processing. Because
the wet development requires tap water piping and others for processing, installation
of a processing place is limited. Besides, the processing itself is not friendly
to the environment because it discharges waste water.
Because of the above, so called dry silver-salt recording method has been
developed, where image information is recorded as a latent image by light such
as laser and then the image is developed by heating or the image information is
recorded by heat, using thermal head. Thus, a recording method or recording device
that does not require wet development processing is becoming popular.
However, although an image obtained by a recording method or recording device
that does not require wet development processing was good for medical diagnosis,
but does not always satisfy doctors' requirements in every respect. The inventor
of the present invention has examined possible reasons for dissatisfaction and
found several factors.
The first factor is that an image appears differently depending upon the light
diffusion condition of the light source used for observation.
Generally, when a medical image is recorded on a recording medium and
then diagnosed, using a light box (for example, film view) that is made of a fluorescent
light, serving as the light source, covered with a diffusion plate, the recording
medium is set on the diffusion plate of the light box and transmitted image is
observed. That is, an observer observes the image under diffused light. If the
condition of the light diffused by the light box is perfect diffused light, visual
transmission density corresponds to diffuse transmission density. However, because
the light diffused by the light box is not always ideal and perfect diffused light,
the transmission density to be sensed visually is consequently a value between
the diffuse transmission density and parallel transmission density. The condition
of the light diffused by each light box differs from one to another and the light
transmitted through each light box differs in the ratio of the diffused components
to transmitted components. Because of this, what value between the diffuse transmission
density and parallel transmission density is visually sensed as the image density
depends upon each light box and so the image cannot be displayed in stable image quality.
Besides, if the relationship between the diffuse transmission density and
parallel transmission density of a recorded image varies tremendously by image
density, the ratio of the diffused components to transmitted components in the
transmitted light to be observed on a light box becomes different by density. Because
of the above, even if the diffuse transmission density of a test image for density
gradation correction is measured and the density gradation characteristic is adjusted
according to the measurement result, images cannot always be seen as intended depending
upon the condition of the light diffused by the light box.
The second factor is that the recording medium fogs depending upon the light
diffusion of the medium, particularly that of the medium on which no image is recorded.
Because the non-image portion (portion on which no image is recorded) of
a recording medium used in the dry silver-salt recording method has higher degree
of light diffusion and accordingly looks very foggy, the low-density portion of
an image cannot be observed smoothly.
SUMMARY OF THE INVENTION
To overcome the abovementioned drawbacks in conventional recording mediums, it
is an object of the present invention to provide an inkjet recording medium that
can display image suitable for observation without employing wet development processing.
Accordingly, to overcome the cited shortcomings, the abovementioned
object of the present invention can be attained by recording mediums and medical
image recording methods described as follow.
(1) A recording medium, being substantially transparent, for recording an
image through image-forming processes employing an ink-jetting method, comprising:
a supporting base shaped in a sheet; and an ink-absorbing layer that is formed
on at least one of both sides of the supporting base, and that absorbs ink particles
so as to form the image; wherein a diffuse transmission density of a first area,
being a part of the recording medium on which no image is formed, is in a range
of 0.45-0.15, and a Q-factor of the first area is in a range of 1.50-1.00; and
wherein the recording medium is so constituted that a Q-factor of a second area,
being a part of the recording medium on which an image is formed so as to adjust
a diffuse transmission density at 1.00, is in a range of 1.20-1.00.
(2) The recording medium of item 1, wherein the supporting base is made
of a resin material.
(3) The recording medium of item 1, wherein the recording medium is so constituted
that a Q-factor of a third area, being a part of the recording medium on which
an image is formed so as to adjust a diffuse transmission density at a value smaller
than 1.00 and greater than the diffuse transmission density of the first area,
is in a range of 1.50-1.00.
(4) The recording medium of item 1, wherein the recording medium is so constituted
that the Q-factor of the first area is in a range of 1.30-1.00.
(5) The recording medium of item 4, wherein the recording medium is so constituted
that a Q-factor of a third area, being a part of the recording medium on which
an image is formed so as to adjust a diffuse transmission density at a value smaller
than 1.00 and greater than the diffuse transmission density of the first area,
is in a range of 1.30-1.00.
(6) The recording medium of item 1, wherein a haze of the first area is
in a range of 15%-5%.
(7) The recording medium of item 1, wherein a psychological hue angle, denoted
by hab and defined in the CIE•LAB color system by an equation of
is in a range of 250°-230°, when light, emitted from a fluorescent
light-source, transmit through the first area, and wherein a value of (a*2+b*2)0.5
is in a range of 22-15.
(8) The recording medium of item 1, wherein the ink-absorbing layer is an
air-gap type ink-absorbing layer, mainly composed of a high-polymer binder, inorganic
micro-particles and/or organic micro-particles.
(9) The recording medium of item 8, wherein an average particle-diameter
of the inorganic micro-particles and/or the organic micro-particles before condensing
them is equal to or smaller than 15 nm.
(10) The recording medium of item 1, wherein a thickness of the ink-absorbing
layer is in a range of 50 μm-20 μm.
(11) The recording medium of item 1, wherein the ink-jetting method employs
three kinds of black inks, densities of which are different relative to each other,
so as to record a medical image.
(12) A method for recording a medical image onto a recording medium, being
substantially transparent, which comprises a supporting base shaped in a sheet
and an ink-absorbing layer, formed on at least one of both sides of the supporting
base and absorbing ink particles so as to form the medical image, the method comprising
the step of: forming the medical image onto the recording medium through image-forming
processes employing an ink-jetting method; wherein a diffuse transmission density
of a first area, being a part of the recording medium on which no image is formed,
is in a range of 0.45-0.15, and a Q-factor of the first area is in a range of 1.50-1.00;
and wherein the recording medium is so constituted that a Q-factor of a second
area, being a part of the recording medium on which an image is formed so as to
adjust a diffuse transmission density at 1.00, is in a range of 1.20-1.00.
(13) The method of item 12, wherein the ink-jetting method employs three
kinds of black inks, densities of which are different relative to each other, so
as to record the medical image.
(14) The method of item 12, wherein the supporting base is made of a resin material.
(15) The method of item 12, wherein the recording medium is so constituted
that a Q-factor of a third area, being a part of the recording medium on which
an image is formed so as to adjust a diffuse transmission density at a value smaller
than 1.00 and greater than the diffuse transmission density of the first area,
is in a range of 1.50-1.00.
(16) The method of item 12, wherein the Q-factor of the first area is in
a range of 1.30-1.00.
(17) The method of item 16, wherein the recording medium is so constituted
that a Q-factor of a third area, being a part of the recording medium on which
an image is formed so as to adjust a diffuse transmission density at a value smaller
than 1.00 and greater than the diffuse transmission density of the first area,
is in a range of 1.30-1.00.
(18) The method of item 12, wherein a haze of the first area is in a range
of 15%-5%.
(19) The method of item 12, wherein a psychological hue angle, denoted by
hab and defined in the CIE•LAB color system by an equation of
is in a range of 250°-230°, when light, emitted from a fluorescent
light-source, transmit through the first area, and wherein a value of (a*2+b*2)0.5
is in a range of 22-15.
(20) The method of item 12, wherein a thickness of the ink-absorbing layer
is in a range of 50 μm-20 μm.
Further, to overcome the abovementioned problems, other image-recording
apparatus, embodied in the present invention, will be described as follow:
(21) A transparent ink-jet recording medium, for recording an image formed
by an ink-jetting method, characterized in that
the transparent ink-jet recording medium is provided with a sheet-type supporting
base made of a resin material, and an ink-absorbing layer that is formed on at
least one of both sides of the supporting base and that absorbs ink so as to form
the image, and
a diffuse transmission density of a non-image portion, on which no image is formed,
is in a range of 0.45-0.15, and a Q-factor of the non-image portion is in a range
of 1.50-1.00, and
a Q-factor of an image-formed portion, on which an image is so formed that the
diffuse transmission density is 1.00, is in a range of 1.20-1.00.
The inventor has noticed that, by utilizing the ink-jet system, images can be
generated and recorded on a recording medium without wet development processing.
Then, the inventor has run various trial-and-error experiments for eliminating
the problems that the displayed image becomes unstable because of the difference
in the diffusion condition of the light source for observation and that the recording
medium become foggy depending upon the degree of light diffusion so that the displayed
image can be observed smoothly. At last, it is found that yellowish fogging due
to light diffusion can be eliminated if the diffuse transmission density of the
non-image portion, on which no image is formed, is in a range from 0.15 to 0.45,
both inclusive, and, at the same time, the Q factor of the non-image portion is
in a range from 1.00 to 1.50, both inclusive. It is also found that, if the Q factor
of the medium, on which an image is so formed that the diffuse transmission density
is 1.00, is in a range from 1.00 to 1.20, the image can be displayed in a stable
density gradation irrespective of the diffusion condition of the light source for observation.
That is to say, according to the invention described in item 21, yellowish fogging
due to light diffusion can be eliminated and even a portion of the image that has
lower image density after being generated can be displayed in favorable tone, and
also the image can be displayed in a stable density gradation irrespective of the
diffusion condition of the light source for observation. As a result, images suitable
for observation can be displayed without wet development processing.
(22) The ink-jet recording medium, described in item 21, characterized in that
a Q factor of an image-formed portion, on which an image is formed so that the
diffuse transmission density falls within a range from the diffuse transmission
density of the non-image portion to 1.00, exclusive, is in a range from 1.00 to
1.50, both inclusive.
According to the invention described in item 22, because the Q factor of
the image portion, on which the image is formed so that the diffuse transmission
density falls within a range from the diffuse transmission density of the non-image
portion to 1.00, exclusive, is in a range from 1.00 to 1.50, both inclusive, images
more suitable for observation can be displayed.
(23) A transparent ink-jet recording medium, for recording an image formed
by an ink-jetting method, characterized in that
a diffuse transmission density of a non-image portion, on which no image is formed,
is in a range of 0.45-0.15, and a Q-factor of the non-image portion is in a range
of 1.30-1.00, and
a Q-factor of an image-formed portion, on which an image is so formed that the
diffuse transmission density is 1.00, is in a range of 1.20-1.00.
According to the invention described in item 23, because the upper limit
of the Q factor of the non-image portion is 1.30, inclusive, yellowish fogging
can be better eliminated than on an image with the upper limit of 1.50, inclusive.
(24) The ink-jet recording medium, described in item 23, characterized in that
a Q factor of an image-formed portion, on which image is formed so that the diffuse
transmission density falls within a range from the diffuse transmission density
of the non-image portion to 1.00, exclusive, is in a range from 1.00 to 1.30, both inclusive.
According to the invention described in item 24, because the Q factor of
the image-formed portion, on which image is formed so that the diffuse transmission
density falls within a range from the diffuse transmission density of the non-image
portion to 1.00, exclusive, is in a range from 1.00 to 1.30, both inclusive, images
more suitable for observation can be displayed.
(25) The ink-jet recording medium, described in anyone of items 21-24, characterized
in that
a haze of the non-image portion is in a range from 5% to 15%, both inclusive.
The inventor has found in the course of the above experiments that, if the haze
of the non-image portion is in a range from 5% to 15%, both inclusive, light shadow
in low-density portions on an image after being generated can be observed smoothly.
That is, according to the invention described in claim 5, light shadow
can be observed smoothly even in low-density portions and hence diagnostic capability improves.
(26) The ink-jet recording medium, described in anyone of items 21-25, characterized
in that
hab (a psychological hue angle: hab=tan
-1(b*/a*) defined in the CIE•LAB
color system) is in a range of 250°-230°, both inclusive, when light,
emitted from a fluorescent light-source, transmit through the non-image portion, and
a value of (a*
2+b*
2)
0.5 is in a range of 22-15,
both inclusive.
According to the invention described in item 26, because the hab is in
a range from 230 degrees to 250 degrees, both inclusive, and (a*
2+b*
2)
0.5
is in a range from 15 to 22, both inclusive, images can be displayed in color
tone that does not cause fatigue to eyes.
(27) The ink-jet recording medium, described in anyone of items 21-26, characterized
in that
the ink absorbing layer is of a void type mainly comprising inorganic and/or
organic particles and high-polymer binder.
According to the invention described in item 27, because the ink absorbing
layer is of a void type mainly comprising inorganic and/or organic particles and
high-polymer binder, deposited ink can be well absorbed.
(28) The ink-jet recording medium, described in item 27, characterized in that
the average particle size of the inorganic and/or organic particles before agglomeration
is 15 nm or less.
According to the invention described in item 28, if the average particle
size of the inorganic and/or organic particles before agglomeration is 15 nm or
less, the haze or Q factor can be reduced easily and so the image can be smoothly
generated so that the haze or Q factor falls within the above range.
(29) The ink-jet recording medium, described in anyone of items 21-28, characterized
in that
a thickness of the ink absorbing layer is more than 20 μm, inclusive, and
less than 50 μm, inclusive.
It is preferable that the thickness of the ink absorbing layer is more than 20
μm, inclusive, because the Q factor can be made to fall within the above
range in generating the image. Besides, it is also preferable that the thickness
of the ink absorbing layer is less than 50 μm, inclusive, because the ink
absorbing layer becomes hard to break.
That is to say, according to the invention described in item 29, because the
thickness of the ink absorbing layer is in a range from 20 to 50 μm, both
inclusive, breakage of the ink absorption head is prevented and the Q factor can
be made to easily fall within the above range in generating the image.
(30) The ink-jet recording medium, described in anyone of items 21-29, characterized
in that
the inkjet recording medium is used in an ink-jet recording method that records
medical images using three or more black inks with different density.
With the invention described in item 30, since the inkjet recording medium is
used in an inkjet recording method that records medical images using three or more
black inks with different density, fine images can be generated without exhibiting
granular touch.
(31) An ink-jet recording method, characterized in that
a medical image is formed onto the recording medium, described in anyone of items
21-29, by an ink-jetting method.
According to the invention described in item 31, the same effect as in
any one of the items 21 to 29 can be produced.
(32) The ink-jet recording method, described in item 31, characterized in that
the medical image is formed and recorded by employing three or more black inks
with different density.
With the invention described in item 32, the same effect as in item 30 can be produced.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the present invention will become apparent
upon reading the following detailed description and upon reference to the drawings
in which:
FIG. 1 shows a side cross-sectional view of the integrating sphere type light
transmission factor measuring device for measuring the total light transmission
factor and diffuse transmission factor of the recording medium according to an
embodiment of the invention;
FIG. 2 shows a side cross-sectional view of the integrating sphere installed
on the integrating sphere type light transmission factor measuring device shown
in FIG. 1;
FIG. 3 shows a diagram showing the a*-b* curve that represents the phase angle
of the recording medium according to an embodiment of the invention; and
FIG. 4 shows a block diagram showing the main components of the image recording
device that generates an image on the recording medium shown in FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Detailed description of the preferred embodiments of the present invention
is given hereunder, using figures. The invention is not limited to the concrete
constructions, operations and values described in each embodiment below.
On the transparent recording medium (inkjet recording medium) used in this embodiment,
a monochrome image is depicted with liquid ink jetted out by an inkjet system.
The recording medium is a sheet with an area of practically 15 by 10 cm or more,
four corners being cut round, and comprises a supporting base made of light transmission
resin of 75 to 250 μm thick and an ink absorbing layer, formed at least on
one side of the supporting base, for absorbing and recording an image. If the thickness
is less than 75 μm, the medium is hard to handle because the sheet sags down
and, on the contrary, if it is more than 250 μm, its fairly heavy weight
results in disadvantage in bringing a pile of the sheets.
In the meantime, it is possible to depict a color image on this recording medium
and the shape of the medium may not necessarily be as specified above but can be
varied accordingly so as to match with an image to be depicted or correspond to
an image recording device.
Besides, it is preferable to provide a marking (for example, notch) on the
recording medium so that the surface and rear of the sheet can easily be recognized.
With this marking, even when a lot of recording medium need to be handled in a
short time, the surface and rear of each sheet can be judged easily and the films
can be handled efficiently.
Materials applicable to transparent supporting base are polyester type
such as polyethylene-terephthalate (PET), cellulose ester type such as nitro cellulose
and cellulose acetate, and besides, polysulfone, polyimide, and polycarbonate.
The sheet recording medium shall preferably be colored blue.
The surface of the supporting base on which the ink absorbing layer is to be
provided has been subjected to a corona discharge treatment, flame treatment or
UV ray irradiation treatment so as to improve adhesion with the ink absorbing layer.
If the ink absorbing layer is to be provided only on one side of the supporting
base, gelatin or water-soluble resin is applied to the other side for preventing
the sheet from curling. Besides, it is also allowable to provide the other side
of the supporting base with an antistatic treatment, coloring, or mat treatment,
by which mat particles having average particle size of 5 to 100 μm are dispersed
on the surface for preventing adhesion with other recording medium, or add metallic
oxide particles such as titanium oxide particle and lead oxide particle.
The supporting base is preferably colored blue, and dye used for coloring is
preferably one with the absorption maximum of 570 to 700 μm. That is, one
with required absorption maximum can be selected, for example, out of anthraxquinone
type, azo type, azomethine type, indo-aniline type, oxonole type, triphenyl-methane
type, carbo-cyanine type, and styryl type dyes. Dye may be mixed directly so as
to be contained in the supporting base or solid hydrophobic dye may be dispersed
so as to be contained in the back layer, or hydrophobic dye may be dispersed into
liquid, using high-boiling-point solvent and/or low-boiling-point solvent, and
the liquid be used.
Concrete examples of dyes preferably applicable to this embodiment are shown
in No. 1 to No. 9 below, but not limited thereto.
##STR1##
##STR2##
The ink absorbing layer is a void type layer of three-dimensional mesh structure
having the percentage of voids of 40% to 90%, and mat particles having the average
particle size of 5 to 100 μm are dispersed on the surface to prevent adhesion
with other recording medium.
The void type ink absorbing layer is mainly made of inorganic particles (such
as silica particles) and/or organic particles and high-polymer binder (for example,
water-soluble resin) so that the film thickness is in a range from 20 to 50 μm,
both inclusive. It is acceptable to add, or apply to the surface, surface active
agent as antistatic agent.
The average primary particle size of inorganic particles and/or organic particles
(average size of each particle before agglomeration) is preferably less than 15
nm, inclusive, and further preferably less than 8 nm, inclusive, in this embodiment.
Average particle size can be measured in a general manner. In this embodiment,
photo is taken by a transmission type electronic microscope, the number of particles
(n) observed per unit visual field on the photo and their particle sizes (diameter
X
i) are measured, and then the average particle size is obtained using
the formula below. (In the formula, X
i represents the diameter of the
i-th particle).
##EQU1##
Besides, the mass ratio of the inorganic particle and/or organic particle
to the water-soluble resin is preferably within a range of 1.2:1 to 12.1:1.
The voids of the three-dimensional mesh structure in the ink absorbing layer
consist of multiple pores. The multiple cores preferably have an average diameter
of 4 to 40 nm and the pore capacity is 0.3 to 1.0 ml/g. The specific surface area
of the ink absorbing layer is preferably 50 to 500 m
2/g. Since the ink
absorbing layer is of a void type that can efficiently absorb inks deposited on
the recording medium.
It is preferable that silica particles are of silicic acid, having two to three
silarol groups per surface area 1 nm
2, and that the three-dimensional
mesh structure is made of chains that are formed by the coupling of secondary particles,
having a size of 10 to 100 nm, of the aggregated silica particles.
Incidentally, applicable particles include, for example, colloidal
silica, potassium silicate, zeolite, kaolinite, halloysite, muscovite, talc, calcium
carbonate, calcium sulfate, and aluminum oxide.
Water-soluble resin shall preferably be polyvinyl alcohol, but gelatin
or one disclosed in the Japanese Application Patent Laid-open Publication No. HEI
7-276789 (1995) is also applicable.
The recording medium of this embodiment is so constructed that the diffuse transmission
density of the non-image portion, on which no image is generated, is in a range
from 0.15 to 0.45, both inclusive, and, at the same time, the Q factor of the non-image
portion is in a range from 1.00 to 1.50, both inclusive or preferably in a range
from 1.00 to 1.30, both inclusive. At the same time, the recording medium is so
constructed that the Q factor of the medium, on which an image is so generated
that the diffuse transmission density is 1.00, is in a range from 1.00 to 1.20.
Besides, it is further preferable that the recording medium is so constructed
that the Q factor of the image portion, on which image is generated so that the
diffuse transmission density falls within a range from the diffuse transmission
density of the non-image portion to 1.00, exclusive, is in a range from 1.00 to
1.50, both inclusive, (or preferable to 1.30, inclusive).
To be concrete, in forming the recording medium, for example, coloring of the
supporting base and/or coloring and thickness of the ink absorbing layer is determined
so that the diffuse transmission density and Q factor fall within the above range.
Since the recording medium is so constructed that the diffuse transmission
density and Q factor fall within the above range as explained above, yellowish
fogging due to light diffusion can be eliminated and even a portion of the image
that has lower image density after being generated can be displayed in favorable
tone, and also the image can be displayed in a stable density gradation irrespective
of the diffusion condition of the light source for observation. As a result, images
suitable for observation can be displayed without wet development processing.
Besides, it is preferable to construct the recording medium so that the
haze of the non-image portion is in a range from 5% to 15%, both inclusive. With
this, light shadow can be observed smoothly even in low-density portions and hence
diagnostic capability improves.
The diffuse transmission density, Q factor and haze of the recording medium can
be adjusted not only by varying the coloring and thickness as above but also by
selecting different material for the ink absorbing layer. Besides, even if the
same material is used, the Q factor and haze can be varied through different forming
process of the ink absorbing layer. For example, defoaming in the preparation process
of the coating liquid of the ink absorbing layer is very important. That is, if
foams in the coating liquid are removed by sufficient vacuuming in the course of
dispersion or filtration after dispersion, the Q factor and haze can be adjusted
to a desirous level.
The diffuse transmission factor and Q factor of the recording medium is calculated
based on the total light transmission factor, diffuse transmission factor and parallel
light transmission factor obtained through a measuring method specified in JIS K7105-1981.
To measure the total light transmission factor, diffuse transmission factor and
parallel light transmission factor, JIS specifies two measuring methods: method
A and method B. Since the inkjet recording medium used in this embodiment is thinner
than {fraction (1/10)} the inside diameter of the opening of the integrating sphere
(to be explained later), the measuring method A is employed.
According to the measuring method A, the total light transmission factor
and diffuse transmission factor are measured by an integrating sphere type light
transmission factor measuring device shown in FIG.
1. The integrating sphere
type light transmission factor measuring device
200 is equipped with an
integrating sphere
201; the light from a light source
202 emitting
standard light A is directed through a lens
203 and a diaphragm
204
and then irradiated on a test specimen S; the light transmitted through the test
specimen S is collected onto a light receptor
205 by the integrating sphere;
and the light receptor
205 measures the light transmitted through the test
specimen S.
The integrating sphere
201 is of approximately spherical shape which is
empty, as shown in FIG. 2, and of which inside surface is made to reflect light.
The integrating sphere is equipped with a circular inlet opening
201a,
on which the test specimen S is mounted and from which the light transmitted through
the test specimen S enters, a circular outlet opening
201b opposed
to the inlet opening
201a, and a light receptor opening
201
on which the light receptor
205 is mounted. The sum (a+b+c) of area a of
the inlet opening
201a, area b of the outlet opening
201b
and area c of the light receptor opening
201c shall be less than
4%, inclusive, of the inside surface area of the sphere. Besides, the centerline
from the outlet opening
201b to the inlet opening
201a
is located on the identical great circle of the sphere and the angle between
the lines from the center of the inlet opening
201a to the diameter
of the outlet opening
201b is made within 8 degrees.
The integrating sphere
201 is also equipped with a standard white plate
206 that shuts down the outlet opening
201b and a detachable
light trap
207 that covers the outlet opening
201b and standard
white plate
206 from outside the integrating sphere
201.
The standard white plate
206 has a uniform high reflectance in entire
range of the wavelength of visual light and reflects the incoming light from the
inlet opening
201a into the inside of the integrating sphere
201.
Material having the high reflectance as above includes magnesium oxide, barium
sulfate and aluminum oxide. The inside of the integrating sphere
201 is
coated with the material having the same reflectance as the standard white plate
206.
A light flux L irradiating the test specimen S must be nearly parallel and no
beam
shall shift from the light axis by 3 degrees or more. The center of the light flux
L shall be aligned to the center of the outlet opening
201b. The
cross section of the light flux L at the outlet opening
201b shall
be circular and very clear. Given that the above is met, the angle between the
lines from the center of the inlet opening
201a to the diameter of
the light flux L shall be made smaller than the angle between the lines from the
center of the inlet opening
201a to the diameter of the outlet opening
201b by 1.3±0.1 degree.
When the test specimen S is not mounted on the inlet opening
201a
or the standard white plate
206 is made open, the light trap
207
absorbs all emitted light completely.
The total sensitivity of the light receptor
205 shall conform to the value
Y of the Luther condition (Y of the tristimulus values X, Y, Z) measured by a visual
degree filter under standard light C. If particularly specified, however, a receptor
that meets the value Y of the Luther condition measured under standard light A
may be used.
The test specimen S is a piece cut off from the recording medium in this embodiment
into a size suitable for measurement (for example, 50×50 mm, with thickness
unchanged from the original). The number of test specimens is preferably three.
How to measure by the integrating sphere type light transmission factor measuring
device
200 is explained hereunder. First, the operator shuts up the outlet
opening
201b with the standard white plate
206 and adjusts
the quantity of light from the light source
202 so that the light receptor
indicates 100 (T
1). Since T
1 is set to 100, the quantity
of the transmitted light (density) corresponds to the transmission factor.
Then, with the standard white plate
206 being shut, the operator mount
the test specimen S on the inlet opening
201a and measure the total
light transmission factor (T
2) of the test specimen S.
After the above, the operator opens the standard white plate
206, removes
the test specimen S and mounts the light trap
207, and then measures the
quantity of diffused light (T
3) by the device.
Finally, with the light trap
207 mounted, the operator mounts the
test specimen S and measures the quantity of diffused light (T
4) by
the device and test specimen S.
After each quantity of light (T
2 to T
4) is measured,
the total light transmission factor T
t (%), diffuse transmission factor
T
d (%) and parallel light transmission factor T
p (%) are
calculated using the quantities of light.
Formulas for calculating the total light transmission factor T
t
(%), diffuse transmission factor T
d (%) and parallel light transmission
factor T
p (%) are: T
t=T
2, T
d=(T
4-T
3)×(T
2/100),
T
p=T
t-T
d. Each total light transmission factor
T
t (%), diffuse transmission factor Td (%) and parallel light transmission
factor T
p (%) shall be calculated down to the first decimal place.
Then, the diffuse transmission density, Q factor and haze H are calculated
from the formulas: (D
d=-log(T
t/100), D
p=-log(T
p/100),
Q=D
p/D
d, H (%)=T
d/T
t×100.
For the recording medium, which are formed so that the diffuse transmission density,
Q factor and haze fall within the range shown above, it is preferable that, when
light from a F6 or F10 fluorescent light source specified by JIS is transmitted
through a fresh recording medium on which no image has been generated, the hab
(psychological hue angle defined by the CIELAB color specification: hab=tan
-1(b*/a*))
is in a range from 230 degrees to 250 degrees, both inclusive, (FIG. 3) and (a*
2+b*
2)
0.5
is in a range from 15 to 22, both inclusive. Because of the above, the background
(no-image portion) of the recording medium after generating an image stays in blue
and so dazzling due to the transmitted light is prevented and a generated image
suitable for observation can be displayed. In addition, the image can be displayed
in color tone that does not cause fatigue to eyes during observation.
Variables a* and b* described above are defined by the CIELAB color specification
recommended by the CIE (Committee of Internationale de l'Eclairage, or International
Commission of Illumination): a* is a scale of the red-blue contribution factor
and b* is a scale of the yellow-blue contribution factor. hab is the psychological
hue angle defined by a formula hab=tan
-1(b*/a*). Although values of
a*, b* and hab may vary depending upon the spectral property of the light source,
in this specification, unless otherwise specified, values of a*, b* and hab are
those in the visual field of 2 degrees under F6 fluorescent light source (ordinary
type white fluorescent light) or F10 fluorescent light source (three-wavelength-band
luminescent type fluorescent light). The spectrum property of each F6 fluorescent
light source and F10 fluorescent light source is specified in JIS Z 8719-1996 "Metamerism
index: Evaluation method of degree of metamerism for change in illuminant" and
the light source has the relative spectrum distribution shown in Table 1.
| TABLE 1 |
| |
| |
Relative |
|
Relative |
|
Relative |
| |
spectrum |
|
spectrum |
|
spectrum |
| Wavelength |
distribution |
Wavelength |
distribution |
Wavelength λ |
distribution |
| λ (nm) |
F6 |
F10 |
λ (nm) |
F6 |
F10 |
(nm) |
F6 |
F10 |
| |
| 380 |
1.05 |
1.11 |
515 |
6.30 |
1.88 |
650 |
4.16 |
3.19 |
| 385 |
1.31 |
0.80 |
520 |
6.60 |
1.59 |
655 |
3.55 |
2.77 |
| 390 |
1.63 |
0.62 |
525 |
7.12 |
1.47 |
660 |
3.02 |
2.29 |
| 395 |
1.90 |
0.57 |
530 |
7.94 |
1.80 |
665 |
2.57 |
2.00 |
| 400 |
3.11 |
1.48 |
535 |
9.07 |
5.71 |
670 |
2.20 |
1.52 |
| 405 |
14.80 |
12.16 |
540 |
10.49 |
40.98 |
675 |
1.87 |
1.35 |
| 410 |
3.43 |
2.12 |
545 |
25.22 |
73.69 |
680 |
1.60 |
1.47 |
| 415 |
3.30 |
2.70 |
550 |
17.46 |
33.61 |
685 |
1.37 |
1.79 |
| 420 |
3.68 |
3.74 |
555 |
15.63 |
8.24 |
690 |
1.29 |
1.74 |
| 425 |
4.07 |
5.14 |
560 |
17.22 |
3.38 |
695 |
1.05 |
1.02 |
| 430 |
4.45 |
6.75 |
565 |
18.53 |
2.47 |
700 |
0.91 |
1.14 |
| 435 |
32.61 |
34.39 |
570 |
19.43 |
2.14 |
705 |
0.81 |
3.32 |
| 440 |
10.74 |
14.86 |
575 |
21.97 |
4.86 |
710 |
0.71 |
4.49 |
| 445 |
5.48 |
10.40 |
580 |
23.01 |
11.45 |
715 |
0.61 |
2.05 |
| 450 |
5.78 |
10.76 |
585 |
19.41 |
14.79 |
720 |
0.54 |
0.49 |
| 455 |
6.03 |
10.67 |
590 |
18.56 |
12.16 |
725 |
0.48 |
0.24 |
| 460 |
6.25 |
10.11 |
595 |
17.42 |
8.97 |
730 |
0.44 |
0.21 |
| 465 |
6.41 |
9.27 |
600 |
16.09 |
6.52 |
735 |
0.43 |
0.21 |
| 470 |
6.52 |
8.29 |
605 |
14.64 |
8.31 |
740 |
0.40 |
0.24 |
| 475 |
6.58 |
7.29 |
610 |
13.15 |
44.12 |
745 |
0.37 |
0.24 |
| 480 |
6.59 |
7.91 |
615 |
11.68 |
34.55 |
750 |
0.38 |
0.21 |
| 485 |
6.56 |
16.64 |
620 |
10.25 |
12.09 |
755 |
0.35 |
0.17 |
| 490 |
5.56 |
16.73 |
625 |
8.95 |
12.15 |
760 |
0.39 |
0.21 |
| 495 |
6.42 |
10.44 |
630 |
7.74 |
10.52 |
765 |
0.41 |
0.22 |
| 500 |
6.28 |
5.94 |
635 |
6.69 |
4.43 |
770 |
0.33 |
0.17 |
| 505 |
6.20 |
3.34 |
640 |
5.71 |
1.95 |
775 |
0.26 |
0.12 |
| 510 |
6.19 |
2.35 |
645 |
4.87 |
2.19 |
780 |
0.21 |
0.09 |
| |
To measure the Q factor of the medium on which an image is so generated that
the
diffuse transmission density is 1.00, it is necessary to record an image so that
the diffuse transmission density is 1.00 throughout a certain area. The area can
be of any size so far as the integrating sphere type light transmission factor
measuring device shown in FIG. 1 can take measurement. Although a real image used
for observation may not always contain an area throughout which the diffuse transmission
density is 1.00, it is possible to record multiple test image signals having a
constant signal value and measure them for the above purpose. For example, given
that the recordable maximum density is D
max, recordable minimum density
is D
min, and n is an integer from 0 to 10, a test image is so generated
and recorded that the density of an image recorded in the n-th square of eleven
squares, each with a size of 50 mm by 50 mm, has a specific signal value corresponding
to D
min+0.1×n×(D
max-D
min), and the diffuse
transmission density of each square is measured. If a square with the diffuse transmission
density of 1.00 is found, measuring the Q factor of the square will do. If no square
exhibits the diffuse transmission density of 1.00 exactly, measure the Q factor
at a portion where the diffuse transmission density is measured higher but closest
to 1.00 and also lower but closest to 1.00, and then calculate the Q factor at
the diffuse transmission density of 1.00 by interpolation.
Next, an image recording device of the inkjet recording system that generates
an image on the inkjet recording medium of the present invention is described hereunder,
using FIG.
4.
The image recording device
100 of the present embodiment comprises an
image processing means
110 into which image signals are inputted from an
external medical photographic device or storage device and which executes necessary
image processing; recording head unit
120 which records images on a recording
medium
4 by ink emission; recording head scanning means
140 that
scans the recording head unit in the main scan direction; carriage roller
130
that carries the recording medium
4 in the sub scan direction; and control
means
101 that controls each portion of the device.
Besides, an image signal inputted into image-processing means
110
from an external device may be sent via a network of various types. The image signal
processed and obtained by the image processing means
110 is sent to the
image control means
101.
The recording head unit
120 is equipped with four recording heads
120a
to
120d in series for black ink K
1 to K
4 of different
density, respectively, and a recording head control signal is supplied from the
control means
101 to each of them. These recording heads
120a
to
120d may be integrated or installed separately. Generating
an image using four different types of ink as above enables to obtain higher quality
and better multi-gradation as an image used for medical diagnosis or reference.
To generate an image for medical use that is required to have multi-gradation,
it is preferable to use three to four kinds of ink of different density.
The ink emission mechanism of the ink-jet head may be an ink-jet type that utilizes
the piezo electric effect or utilizes a bubble forming force generated at the time
when the ink is heated momentarily. The number of nozzle holes suitable for an
ink-jet type for medical application is about 64 to 512. The traveling speed of
ink particles is preferably 2 to 20 m/s and the amount of ink particles per emitted
drop is preferable 1 to 50 pico litter.
Numeral
130 indicates a carriage roller that carries the recording
medium
4 in a direction indicated by arrow A, based on the recording medium
conveying signal.
Numeral
140 indicates a recording head carriage means that carries
the recording head unit
120 in a direction perpendicular to the carriage
direction of the recording medium
4 by means of carriage roller
130
so as to scan in the direction indicated by arrow B.
The recording head carriage means
140 moves the recording head unit
120
in the arrow B direction according to the head carriage signal. Each of the recording
heads
120a to
120d generates an image on the recording
medium
4 based on the recording head control signal. To the control means
101, an
