Title: Image display medium and image recording apparatus
Abstract: The invention provides an image display medium comprising: a first transparent substrate disposed on an observation side; a second substrate disposed on a further side from the observation side than the first substrate; and a display layer formed between the first substrate and the second substrate and containing a plurality of developer particles; the first substrate including a color filter having at least one group of a plurality of light-transmitting filter films of different colors. The invention also provides an image recording apparatus including a recording head for recording an image on the medium and a positioning device for positioning the filter films of the color filter and the recording head. The invention further provides an image recording method comprising the steps of positioning the filter films of the medium and the recording head, and recording an image by the recording head on the medium having the filter films positioned.
Patent Number: 6,922,204 Issued on 07/26/2005 to Kanazawa, et al.
| Inventors:
|
Kanazawa; Masaharu (Suita, JP);
Yogome; Keyaki (Kyoto, JP);
Ikegawa; Akihito (Sakai, JP)
|
| Assignee:
|
Minolta Co., Ltd. (Osaka, JP)
|
| Appl. No.:
|
406593 |
| Filed:
|
April 4, 2003 |
Foreign Application Priority Data
| Apr 05, 2002[JP] | 2002-104216 |
| Current U.S. Class: |
347/112; 347/153; 345/84; 345/107; 359/296 |
| Intern'l Class: |
B41J 002/41; G11B 003/00; G09C 003/34 |
| Field of Search: |
347/112,153
345/84,107
359/296
|
References Cited [Referenced By]
U.S. Patent Documents
| 5708453 | Jan., 1998 | Tsuchida et al.
| |
| 5892558 | Apr., 1999 | Ge et al.
| |
| 5920299 | Jul., 1999 | Ohshima et al.
| |
| 5982346 | Nov., 1999 | Sheridon et al.
| |
| 6184856 | Feb., 2001 | Gordon, II et al.
| |
| 6271823 | Aug., 2001 | Gordon et al.
| |
| 6323989 | Nov., 2001 | Jacobson et al.
| |
| 6333754 | Dec., 2001 | Oba et al.
| |
| 6407763 | Jun., 2002 | Yamaguchi et al.
| |
| 6411316 | Jun., 2002 | Shigehiro et al.
| |
| 2002/0009655 | Jan., 2002 | Miyamoto et al.
| |
| 2004/0051934 | Mar., 2004 | Machida et al.
| |
| Foreign Patent Documents |
| 10-232630 | Sep., 1998 | JP.
| |
Primary Examiner: Hirshfeld; Andrew H.
Assistant Examiner: Hinze; Leo T.
Attorney, Agent or Firm: McDermott Will & Emery LLP
Claims
1. An image display medium comprising:
a first transparent substrate disposed on an observation side;
a second substrate disposed on a further side from the observation side than
the first substrate;
a display layer formed between the first substrate and the second substrate and
including a plurality of developer particles;
a plurality of partition walls arranged between the first substrate and the second
substrate to partition the display layer into a plurality of sections; and
a color filter, comprising at least one group of a plurality of light-transmitting
filter films having different colors, positioned at the first substrate; wherein
the distance between neighboring partition walls is greater than the width of
any of the filter films, and at least two kinds of filters films are positioned
between the neighboring partition walls.
2. An image display medium according to claim 1, wherein a the width of the a
partition wall is smaller than the width of any of the filter films of the color filter.
3. An image display medium according to claim 2, wherein the filter films are
arranged at a pitch independent of arrangement of the partition wall.
4. An image display medium according to claim 1, wherein the developer particles
include those having a high light reflectance.
5. An image display medium according to claim 1, wherein the developer particles
include light-interrupting particles.
6. An image display medium according to claim 1, wherein the first substrate
serves also as the color filter.
7. An image display medium according to claim 1, wherein the developer particles
are dry developer particles and wherein the display layer allows the dry particles
to move in a space between the substrates for image display.
8. An image display medium according to claim I, wherein the display layer has
a liquid between the substrates, and allows the developer particles to move in
the liquid for image display.
9. An image display medium according to claim 1, wherein a positioning portion
is provided in a specified positional relation with the filter films.
10. An image display medium according to claim 9, wherein the positioning portion
comprises at least one concavity or convexity provided on the surface of the first
substrate or the second substrate.
11. An image display medium according to claim 9, wherein the positioning portion
comprises a float electrode provided on the surface of the first substrate or the
second substrate.
12. An image display medium according to claim 1, wherein the display layer contains
a darkly colored opaque liquid and brightly colored opaque particles between the substrates.
13. An image display medium comprising:
a first transparent substrate disposed on an observation side;
a second transparent substrate disposed on a further side from the observation
side than the first substrate;
a display layer formed between the first substrate and the second substrate and
including a plurality of opaque developer particles;
a transparent partition wall provided between the first substrate and the second
substrate for partitioning the display layer into a plurality of sections; and
a color filter, comprising at least one group of a plurality of light-transmitting
filter films having different colors, positioned at the first substrate;
wherein none of the filter films of the color filter overlaps the partition wall.
14. An image display medium comprising:
a first transparent substrate disposed on an observation side;
a second substrate disposed on a further side from the observation side than
the first substrate;
a display layer formed between the first substrate and the second substrate and
including a dry developer which contains at least two kinds of dry developer particles
having different chargeable polarities and different optical reflection densities;
a partition wall provided between the first substrate and the second substrate
for partitioning the display layer into a plurality of sections; and
a color filter, comprising at least one group of a plurality of light-transmitting
filter films having different colors, positioned at the first substrate;
wherein the width of the partition wall is smaller than the width of any of the
filter films, and wherein the filter films are arranged at a pitch independent
of arrangement of the partition wall.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is based on Japanese patent application No. 2002-104216 filed
in Japan on Apr. 5, 2002, the entire content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image display medium which is allowed to
perform image display by a display layer including developer particles. The invention
also concerns with an image recording apparatus for recording an image on an image
display medium (especially an image display medium capable of performing color
image display).
2. Description of Related Art
In recent years, rewritable image display mediums called electronic paper or
digital
paper have been proposed as the image display medium (image recording medium) to
be used in place of paper sheet for image recording and display of recorded image.
Various types of image display mediums have been proposed as such mediums.
Such image display mediums generally have a display layer which is capable of changing
one or more optical characteristics such as light reflectance, light transmittance,
color, optical reflection density and the like.
Image recording (image formation) is executed on the mediums to display an
image by changing the optical characteristic(s) in a region corresponding to each
pixel in the display layer according to an image information (image data) of the pixel.
Typical examples of the mediums having such a display layer are twist ball
type, electrophoresis type and dry developer-including type. The display layer
in the medium of twist ball type, electrophoresis type or dry developer-including
type includes a plurality of particles (i.e., developer particles) for use in image display.
In the mediums having a display layer containing a plurality of such developer
particles, a partition wall for partitioning the display layer into sections may
be provided, e.g., to suppress the bias of developer particles in a direction in
parallel with the display layer. The partition wall is generally provided between
a pair of substrates having the display layer therebetween.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an image display medium which
has a display layer containing a plurality of developer particles, the medium being
capable of performing color display.
Another object of the present invention is to provide an image display medium
wherein a display layer containing a plurality of developer particles is held between
a pair of substrates and wherein a partition wall is formed for partitioning the
display layer into sections, the medium being capable of color display and capable
of inhibiting the partition wall from obstructing the view of displayed color image.
A further object of the present invention is to provide an image recording apparatus
and an image recording method, the apparatus and the method being capable of recording
an image on an image display medium capable of color display without displacement
of position and capable of color display in a desired color condition on the medium.
The invention provides the following image display medium, image recording apparatus
and image recording method.
(1) Image Display Medium
An image display medium comprising:
a first transparent substrate disposed on an observation side;
a second substrate disposed on a further side from the observation side than
the
first substrate; and
a display layer formed between the first substrate and the second substrate and
containing a plurality of developer particles;
wherein the first substrate has a color filter comprising at least one group
of a plurality of light-transmitting filter films having different colors.
(2) Image Recording Apparatus
An image recording apparatus for recording an image on a image display medium
including a display layer capable of changing an optical characteristic of the
medium, and a color filter superimposed on the display layer and having at least
one group of a plurality of light-transmitting filter films having different colors,
the apparatus comprising:
an image recording head for recording an image on the medium; and
a positioning device for positioning the filter films of the color filter and
the
recording head.
(3) Image Recording Method
An image recording method of recording an image on an image display medium including
a display layer capable of changing an optical characteristic of the medium, and
a color filter superimposed on the display layer and having at least one group
of a plurality of light-transmitting filter films having different colors, the
method comprising the steps of:
positioning the filter films of the image display medium and an image
recording head for recording an image by changing the optical characteristic of
the display layer; and
recording an image by the recording head on the medium having the filter
films positioned.
The foregoing and other objects, features, aspects and advantages of the present
invention will become more apparent from the following detailed description and
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic plan view showing an example of the developer-including
type image display medium.
FIG. 2 is a schematic sectional view showing the image display medium of FIG. 1.
FIG. 3 is a view showing an image being recorded by applying an electric field
to the display layer of the image display medium of FIG. 1.
FIG. 4 is a diagram showing pixels and sub-pixels in executing image recording
on the image display medium of FIG. 1.
FIG. 5 is a schematic sectional view showing another example of the developer-including
type image display medium.
FIG. 6 is a schematic sectional view showing a further example of the developer-including
type image display medium.
FIG. 7(A) to FIG. 7(C) are schematic sectional views showing other
examples of the developer particles.
FIG. 8 is a schematic sectional view showing a still further example of the
developer-including type image display medium.
FIG. 9(A) and FIG. 9(B) are schematic sectional views showing
additional examples of the developer-including type image display medium.
FIG. 10 is a schematic sectional view showing an example of the electrophoresis
type image display medium.
FIG. 11 is a perspective view schematically showing the structure of an example
of the image recording apparatus.
FIG. 12 is a plan view schematically showing the structure of the image recording
apparatus of FIG. 11.
FIG. 13 is a sectional view schematically showing the structure of the image
recording apparatus shown in FIG. 11 and FIG. 12.
FIG. 14 is a schematic plan view showing another example of the image recording apparatus.
FIG. 15 is a schematic plan view showing a further example of the image recording apparatus.
FIG. 16 is a schematic sectional view showing a still further example of the
image recording apparatus.
FIG. 17(A) and FIG. 17(B) are schematic sectional views showing
other example of the image recording apparatus.
FIG. 18 is a schematic perspective view showing other examples of the image
display medium and the image recording apparatus.
FIG. 19 is a schematic sectional view showing the image display medium and the
image recording apparatus shown in FIG. 18.
FIG. 20 is a schematic sectional view showing other examples of the image display
medium and the image recording apparatus.
FIG. 21 is a schematic sectional view showing a further example of the image
recording apparatus.
FIG. 22 is a schematic perspective view showing other examples of the image
display medium and the image recording apparatus.
FIG. 23 is a schematic sectional view showing the image display medium and the
image recording apparatus shown in FIG. 22.
FIG. 24(A) and FIG. 24(B) are schematic sectional views showing
other example of the image recording apparatus.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Image Display Medium
The first to fifth type image display mediums described below as preferred embodiments
of the invention basically have:
a first transparent substrate disposed on an observation side;
a second substrate disposed on a further side from the observation side than
the
first substrate; and
a display layer formed between the first substrate and the second substrate and
containing a plurality of developer particles;
wherein the first substrate has a color filter including at least one array
of light-transmitting filter films having different colors.
The above-mentioned medium can be used both for light-reflecting type display
and for light-transmitting type display.
The displayed image on the medium is observed from the side of the first substrate.
That is, the first substrate is one arranged on the observation side (substrate
arranged closer to an observer who observes the displayed image).
The second substrate is one arranged on the other side than the observation side
(substrate on a further side from the observer who observes the displayed image
than the first substrate).
In the following description, the side closer to the observation side (front
side)
may be referred to "front side" whereas the side further from the observation side
may be referred to "underside".
The first substrate disposed on the observation side (front side) is transparent
and has a light-transmitting property. The first substrate is typically colorless
and transparent. In providing reflecting-type display, the second substrate may
be opaque or transparent. In providing light-transmitting type display, the second
substrate may be transparent (typically colorless and transparent).
The first substrate and/or the second substrate is, for example, made of a resin
(e.g., resin film) or glass. If the resin substrate is used as the first and second
substrates, the substrate is more likely to suppress the breakage than the glass
substrate, and a more lightweight and/or thinner substrate could be produced. The
resin film used as the first and second substrates may be flexible.
The display layer is formed between the first and second substrates. At least
in a region wherein the display layer is formed between the first and second substrates,
the first and second substrates are arranged with a specified gap therebetween.
The first and second substrates may be closed by heat and pressure in the periphery
of a region in which the display layer is formed.
The display layer is formed for producing image display and contains a plurality
of particles (developer particles) useful for image display. The display layer
may include only one kind of developer particles or two or more kinds of developer
particles different in optical characteristics and in electrical characteristics.
Examples of the Display Layer are Given Later.
The color filter is arranged on the first substrate on the observation side.
The color filter includes at least one group of a plurality of light-transmitting
filter films different in color from each other.
More specifically, the color filter includes at least a first light-transmitting
filter film of a first color (first transparent film in a first color), and a second
light-transmitting filter film of a second color different from the first color
(second transparent film in a second color).
The color filter may further include a third filter film, i.e., a light-transmitting
filter film of a third color, namely a color which is different from any of the
first and second colors, or may additionally include a fourth, fifth and more light-transmitting
filter films different in color. Typically these filter films may be periodically
arranged in a specified array pattern.
Typically an RGB color filter to be used as the color filter comprises
at least three filter films of three colors, namely a light-transmitting red (R)
filter film, a light-transmitting green (G) filter film and a light-transmitting
blue (B) filter film.
These red, green and blue filter films are typically periodically arranged
in a specified array pattern. For example, red, green and blue filter films may
be arranged in a stripe array, a mosaic array or a delta array.
Light rays are transmitted through a color filter and filtered by the color
filter and can be colored in the color of the filter film through which light rays
have been transmitted. Thereby color display can be achieved.
The display layer to be used may be, for example, one to be used in a conventional
twist ball type medium. The display layer formed in the twist ball type medium
typically includes a plurality of developer particles having two surface regions
(called first surface region and second surface region) which are different from
each other in color and in electrical characteristics.
The first surface region and second surface region may have, for example, a white
color and a black color, respectively. The first surface region and second surface
region are different from each other, e.g., in zeta potential, charged polarity
and like electrical characteristics.
Typically these developer particles are dispersed within a transparent
support laid between two substrates. The developer particles are all held by the
support in a state as surrounded with a liquid (e.g., a dielectric liquid) and
therefore are rotatable with respect to the support.
When an electric field is applied to such a display layer, the first surface
region or second surface region of the developer particles can be turned toward
the first substrate on the observation side according to the orientation of the
electric field.
On application of an electric field, the developer particles are rotated due
to
a difference in electrical characteristics between the first surface region and
second surface region so that the first surface region or second surface region
can be turned toward the first substrate. The twist ball type display layer is
proper to achieve light-reflecting type display.
The display layer may be one to be used for conventional electrophoresis type
mediums (mediums wherein image recording is executed utilizing an electrophoretic
phenomenon). The display layer of electrophoresis type medium typically includes
a plurality of developer particles having an electrophoretic capability (electrophoretic mobility)
These developer particles are dispersed in a dispersion medium arranged between
the substrates. Useful dispersion mediums are, for example, liquids. The dispersion
mediums may be those which maintain a solid state at room temperature but become
melted when heated. The dispersion medium having developer particles dispersed
therein may be enclosed in transparent microcapsules.
The display layer may be formed by interposing a plurality of such microcapsules
between the substrates. The developer particles and the dispersion medium to be
used are those differing from each other in optical characteristics.
When an electric field is applied to the display layer, the developer particles
are electrophoretically moved in the dispersion medium and can be moved toward
the side of the first or second substrate according to the orientation of the electric field.
Image recording can be executed due to a difference in optical characteristics
between the developer particles and the dispersion medium. For example, light-reflecting
type display can be achieved by use of opaque black developer particles and opaque
white dispersion medium.
In this case, black display is achieved in a region wherein black developer particles
have gathered on the side of the first substrate. In a region wherein black developer
particles have gathered on the side of the second substrate (namely a white dispersion
medium chiefly exists on the side of the first substrate), display is achieved
in the color(s) of the filter film(s) in the color filter superimposed in the region.
The display layer may be one which is used in a dry developer-including type
medium. The display layer for use in the dry developer-including type medium typically
includes two kinds of developer particles, i.e., first and second developer particles,
which are different from each other in optical characteristics and electrical characteristics.
The dry developer containing the first and second developer particles may contain
one or more kinds of other developer particles. The dry developer is accommodated
in a sealed space (closed space) formed between the substrates.
The first and second developer particles constituting the dry developer are different
from each other in optical characteristics such as optical reflection density,
color, light reflectance, light transmittance and the like. The first and second
developer particles differ from each other also in charged polarities and like
electrical characteristics. The first and second developer particles typically
may be those having a frictionally electrifying capability (frictional chargeability).
The first and/or second developer particles may be magnetic.
When an electric field is applied to the display layer, the first or second
developer particles can be moved toward the side of the first substrate according
to the orientation of the electric field. Image display can be achieved due to
a difference in optical characteristics between the first and second developer particles.
For example, light-reflecting type display can be achieved by use of opaque black
developer particles and opaque white developer particles as the first and second
developer particles, respectively. In this case, black display is produced in a
region wherein the first black developer particles have gathered on the side of
the first substrate. In a region wherein second white developer particles have
gathered on the side of the first substrate, display is achieved in the color(s)
of the filter film(s) in the color filter superimposed in the region.
At least one partition wall for partitioning the display layer into a plurality
of sections may be provided between the first and second substrates in the medium.
The spacing between the first and second substrates can be kept constant by the
partition wall formed therebetween.
When the electrophoresis type display layer is used, the partition wall can
suppress the bias of the developer particles having an electrophoretic capability
in a direction in parallel with the substrate surface. Likewise, when the dry developer-including
type display layer is used, the partition wall can suppress the bias of the dry
developer in a direction in parallel with the substrate surface. Optionally the
partition wall may be formed integrally with the first or second substrate.
At least one electrode may be formed on the first and/or second substrate in
the
medium for application of an electric field to the display layer. The electrode
may be provided when required. The electrode formed on the first substrate on the
observation side may be transparent (typically colorless and transparent). The
electrode formed on the second substrate may be transparent (typically colorless
and transparent) in producing light-transmitting display and may be transparent
or opaque in producing light-reflecting type display.
Next, the following description is given as to the features of first to fifth
type image display mediums.
The first type image display medium comprises:
a first transparent substrate disposed on an observation side,
a second substrate disposed on a further side from the observation side than
the
first substrate,
a display layer formed between the first substrate and the second substrate and
including a plurality of developer particles,
a partition wall formed between the first substrate and the second substrate
for
partitioning the display layer into a plurality of sections, and
a color filter formed on the first substrate and comprising at least one group
of a plurality of light-transmitting filter films having different colors,
wherein width of the partition wall is smaller than width of any filter film
of the color filter.
In the first type medium, the width of the partition wall is smaller than the
width of any filter film of the color filter so that the partition wall existing
in a display region is unnoticeable. Thus, the displayed image can be better observed.
Useful color filters include, for example, the above-mentioned RGB color filter
(a color filter comprising a light-transmitting red filter film, a light-transmitting
green filter film and a light-transmitting blue filter film). In this case, the
width of the partition wall is narrower than typically the width of any of red,
green and blue filter films.
The first type medium can be applied to any of twist ball type, electrophoresis
type and developer-including type. Further the first type medium can be used in
achieving any of the light-reflecting type and light-transmitting type display.
The second type image display medium comprises:
a first transparent substrate disposed on an observation side,
a second substrate disposed on a further side from the observation side than
the
first substrate,
a display layer formed between the first substrate and the second substrate and
including a plurality of developer particles,
a partition wall formed between the first substrate and the second substrate
for
partitioning the display layer into a plurality of sections, and
a color filter formed on the first substrate and comprising at least one group
of a plurality of light-transmitting filter films having different colors,
wherein none of filter films of the color filter overlap the partition wall.
In the second type medium, none of filter films of the color filter overlap the
partition wall so that the partition wall can be made unnoticeable in the displayed
image. Thus, the displayed image can be better observed.
Useful color filters include, for example, the above-mentioned RGB color filter
(a color filter comprising a light-transmitting red filter film, a light-transmitting
green filter film and a light-transmitting blue filter film).
In this case, the red, green and blue filter films are formed in a manner not
to overlap the partition wall. For example, the red, green and blue filter films
corresponding to the same pixel may be arranged in a position adjacent to the partition
wall. The red, green and blue filter films may be arranged in a stripe pattern
and the partition wall may be set in a stripe pattern between the substrates so
that the red, green and blue filter films corresponding to the same pixel may be
disposed in the neighboring interval of the partition wall.
The second type medium can be applied to any of twist ball type, electrophoresis
type and developer-including type. Further the second type medium can be used in
achieving any display of the light-reflecting type and light-transmitting type.
The third type image display medium comprises:
a first transparent substrate disposed on an observation side,
a second substrate disposed on a further side from the observation side than
the
first substrate,
a display layer formed between the first substrate and the second substrate and
including a plurality of developer particles, and
a color filter formed on the first substrate and comprising at least one group
of a plurality of light-transmitting filter films having different colors,
wherein the first substrate itself is a color filter.
In the third type medium, the first substrate on the observation side is a color
filter by itself so that the structure of the medium can be simplified.
The third type medium can be applied to any of twist ball type, electrophoresis
type and developer-including type. Further the third type medium can be used in
producing any of the light-reflecting type and light-transmitting type display.
The fourth type image display medium comprises:
a first transparent substrate disposed on an observation side,
a second substrate disposed on a further side from the observation side than
the
first substrate,
a display layer formed between the first substrate and the second substrate and
including a plurality of developer particles, and
a color filter formed on the first substrate and comprising at least one group
of a plurality of light-transmitting filter films having different colors,
wherein the display layer contains developer particles having a high light reflectance.
The fourth type medium is suitable to achieve the light-reflecting type display.
In the fourth type medium, the display layer contains developer particles having
a high light reflectance so that brighter display can be performed in a region
wherein light is reflected by the developer particles having a high light reflectance.
When the color filter is set in the medium, display is provided especially on
a light-reflecting type medium by light passing through the color filter twice
so that the displayed image is likely to become dark, but bright display can be
achieved by use of developer particles having higher light reflectance.
The fourth type medium can be applied to any of twist ball type, electrophoresis
type and developer-including type.
The developer particles having a high light reflectance may include a deposited
metal layer for increasing the light reflectance of the developer particles. The
deposited metal layer may be formed of, e.g., aluminum (Al), platinum (Pt), nickel
(Ni) or the like.
The deposited metal layer can be formed, for example, by vapor deposition of
metal(s) such as Al, Pt, Ni or the like over the surface of base material particle
made of, e.g., a resin. Another transparent layer may be formed on the deposited
metal layer. For example, the deposited metal layer may be coated with a transparent
resin to impart a frictional chargeability to the developer particles.
The developer particles having a high light reflectance may contain a nacreous
pigment for increasing the light reflectance of the developer particles. For example,
particles formed of a binder resin having the nacreous pigment dispersed therein
may be used as the developer particles. Optionally base particles formed of a resin
may be coated with a resin having a nacreous pigment dispersed therein to provide
developer particles.
In the developer particles containing a nacreous pigment, the uppermost surface
of the particles may be coated with a transparent resin.
The fifth type image display medium comprises:
a first transparent substrate disposed on an observation side,
a second transparent substrate disposed on a further side from the observation
side than the first substrate,
a display layer formed between the first substrate and the second substrate and
including a plurality of developer particles, and
a color filter formed on the first substrate and comprising at least one group
of a plurality of light-transmitting filter films having different colors,
wherein the display layer contains light-tight (light-interrupting or light-absorbing)
developer particles, and light rays transmitting from the second substrate side
to the first substrate side in the display layer are selectively intercepted according
to the position of light-tight developer particles in the display layer to provide
light-transmitting-type display.
The fifth type medium is allowed to achieve light-transmitting type display.
The fifth type medium can be applied to electrophoresis type and developer-including
type mediums.
In the fifth type medium, both of first and second substrates are transparent.
The display layer of the medium contains light-tight developer particles. The light
rays transmitting from the second substrate side to the first substrate side in
the display layer are selectively intercepted according to the position of light-tight
developer particles in the display layer to achieve light-transmitting type display.
For example, when an electrophoresis type display layer is used, the display
layer may contain, for example, a plurality of light-tight developer particles
(e.g., opaque and black developer particles) and a transparent (typically colorless
and transparent) dispersion medium.
In this case, an electric field oriented according to the image information of
the pixels may be applied to a region corresponding to each pixel of the display
layer, and light-tight developer particles are gathered on the side of first or
second substrate, whereby light-transmitting type display can be achieved as follows.
In a region wherein the light-tight developer particles have gathered on the
side
of first substrate on the observation side, light incident on the display layer
from the side of second substrate is intercepted by the light-tight developer particles
and can not pass from the side of first substrate toward the observer. Consequently
the color (e.g., black) of light-tight developer particles is displayed in this region.
On the other hand, in a region wherein the light-tight developer particles have
gathered on the side of second substrate, namely in a region wherein mainly a transparent
dispersion medium exists on the side of first substrate of the display layer, light
incident on the display layer from the side of second substrate is emitted from
the side of first substrate and is transmitted through the color filter formed
on the first substrate toward the observer.
Therefore the color(s) of filter film(s) of the color filter through which
the light is allowed to pass is displayed in this region, whereby light-transmitting
type color display can be performed.
When a dry developer-including type display layer is used, the display layer
(dry developer in the display layer) is allowed to include, e.g., light-tight (light-interrupting
or light-absorbing) developer particles (e.g., opaque and black developer particles)
and transparent (typically colorless and transparent) developer particles.
An electric field oriented according to the image information of the pixels is
applied to a region corresponding to each pixel in the display layer, and one group
of light-tight developer particles and light-transmitting developer particles is
gathered on the side of first substrate while the other is gathered on the side
of second substrate, whereby light-transmitting type display can be performed as follows.
In a region wherein the light-tight developer particles have gathered on the
side
of first substrate on the observation side, light incident on the display layer
from the side of second substrate is intercepted by the light-tight developer particles
and can not be emitted from the side of first substrate of the display layer toward
the observer. Consequently the color (e.g., black) of light-tight developer particles
is displayed in this region.
On the other hand, in a region wherein the light-tight developer particles have
gathered on the side of second substrate, namely in a region wherein the light-transmitting
developer particles exist on the side of first substrate of the display layer,
light incident on the display layer from the side of second substrate is transmitted
through the light-transmitting developer particles and is emitted through the color
filter formed on the first substrate toward the observer.
Therefore the color(s) of filter film(s) of the color filter through which
the light is allowed to pass is displayed in this region, whereby light-transmitting
type color display can be achieved.
In the fifth type medium, a partition wall may be laid between the first substrate
and the second substrate for partitioning the display layer into a plurality of
sections. The partition wall is preferably transparent (typically colorless and transparent).
More specifically, preferably a transparent partition wall may be arranged between
the substrates such that the partition wall is disposed in a display region. If
no partition wall is set in the fifth type medium, the following trouble would
occur: e.g., when the light-tight developing particles are gathered on the side
of second substrate in the entire display region or a wide region to provide white
display by the RGB color filter, it would become difficult to pass light into the
display layer from the side of second substrate, and substantially no light is
emitted from the side of first substrate of the display layer, making it difficult
to achieve white display.
When a transparent partition wall is laid, light can be passed into the display
layer via the transparent partition wall and white display can be achieved over
the entire display region or a wide display region.
A light-reflecting layer may be formed on a surface of the partition wall opposed
to the first substrate. With this structure, light incident on the inside of the
display layer from the bottom of the transparent partition wall opposed to the
second substrate is not emitted from the top of the partition wall opposed to the
first substrate so that image display can be achieved with a higher contrast.
The light reflected by the light-reflecting layer of the partition wall is partly
emitted from a region wherein light can be emitted from the side of first substrate
of the display layer, so that brighter display can be achieved. The light-reflecting
layer may be a white layer, e.g., formed of a white coating composition.
When such light-reflecting layer is formed on the front surface of the partition
wall, a black light-absorbing layer may be provided on the side of first substrate
further from the light-reflecting layer on the front surface of the partition wall
opposed to the first substrate.
In this way, the quantity of light reflected by the front surface of partition
wall can be reduced, and display with a higher contrast can be achieved. The black
light-absorbing layer may be formed, for example, on the light-reflecting layer
of the partition wall. The black light-absorbing layer may be formed on a region
corresponding to the partition wall in the color filter.
The above-described characteristic structures of first type to fifth type image
display mediums may be provided in combination unless they bring about a disadvantage.
Image Recording Apparatus
(Image Forming Apparatus)
The description of three, i.e., first to third type image recording apparatuses
(image forming apparatuses) for recording an image on the image recording medium
are given below as preferred embodiments of the invention.
Any type of the image recording apparatus can be used to record an image on the
above mentioned first to fifth type image display mediums.
Any type of the image recording apparatus is provided to record an image on an
image display medium having a display layer capable of changing the optical characteristic(s)
and a color filter comprising at least one group of a plurality of light-transmitting
color filter films of different colors and superimposed on the display layer.
The display layer is capable of changing the optical characteristic(s) such as
light reflectance, light transmittance and the like. The display layer may be one
including the above-mentioned developer particles (e.g., twist ball type, electrophoretic
type or developer-including type display layer). The display layer may be optionally
one which does not include the developer particles such as a liquid crystal layer.
The color filter is superimposed on the display layer. The color filter may be
directly superimposed on the display layer, or may be indirectly superimposed on
the display layer via other members (such as substrates for holding the display
layer therebetween). The color filter may be, for example, the above-mentioned
RGB color filter.
Any type of the image recording apparatus is basically provided with a positioning
device for positioning the image recording apparatus and the filter films of the
color filter in the medium. The positioning device can suppress the displacement
of position between them, can realize precise color reproduction and allows the
medium to accomplish good color display.
Described below are the features of each type of image recording apparatus.
The first type image recording apparatus is provided to record an image on an
image display medium including a display layer capable of changing an optical characteristic
of the medium, and a color filter superimposed on the display layer and having
at least one group of a plurality of light-transmitting filter films having different colors.
The first type image recording apparatus comprises an image recording head capable
of changing the optical characteristic of the display layer, wherein image recording
is executed on the medium while moving the recording head relatively to the medium,
and wherein when the image recording is executed on the medium while moving the
recording head relatively to the medium, the image recording position can be determined
by detecting at least one of the positions of the filter films of the color filter
on the medium.
In the first type image recording apparatus, image recording is executed using
the recording head capable of changing the optical characteristic of the display
layer (the recording head for changing the optical characteristic of the display layer).
The recording head may be of the type capable of executing image recording for
one sub-pixel at one time or may be of the type capable of executing image recording
for a plurality of sub-pixels at one time.
The recording head may be, for example, of the type capable of executing image
recording for all sub-pixels on one line at one time or may be of the type capable
of executing image recording for one or more sub-pixels on each of plural lines
at one time.
Image recording is executed while moving the recording head relatively to the
medium. Image recording is achieved while scanning an image recording region (image
display region) of the medium with the recording head by moving the recording head
relatively to the medium.
That is to say, the image recording may be executed with the medium disposed
at a specified position while moving the recording head, or the image recording
may be executed with the recording head disposed at a specified position while
moving the medium.
The image recording may be executed while moving both the medium and the recording
head. The more the number of sub-pixels capable of performing image recording by
the recording head at one time is, the shorter the time required for recording
the entire image is.
The sub-pixel is a pixel element for constituting a single pixel. The single
pixel is composed of a plurality of sub-pixels. The sub-pixels constituting the
single pixel is disposed in a region wherein the sub-pixels are superimposed on
filter films of different colors in the color filter, respectively.
When, for example, the above-mentioned RGB color filter is used as the color
filter, typically a single pixel is composed of a sub-pixel superimposed on a red
filter film, a sub-pixel superimposed on a green filter film and a sub-pixel superimposed
on a blue filter film. A single filter film may be formed either to provide a single
sub-pixel or to provide a plurality of sub-pixels.
In executing image recording on an image display medium having a color filter,
the recorded image (displayed image) would be likely to be different in color,
color tone or like color conditions from desired ones, if image recording is not
achieved at a proper position, or if image recording is not achieved according
to image information of each sub-pixel (e.g., if an electric field to be oriented
according to the image information of the sub-pixel is not applied to a region
of the display layer corresponding to each sub-pixel), in other words, if image
recording is carried out according to the image information of a sub-pixel different
from the intended sub-pixel due to displacement of image recording position.
When image recording is performed on the first type image recording apparatus
while moving the recording head relatively to the medium as described above, an
image recording site is positioned by detecting the filter films of the color filter
on the medium (i.e., by detecting the positional relation between the recording
head and the filter films of the color filter).
Further, the positions of the sub-pixels superimposed on the filter films
are detected by detecting the positions of filter films of the color filter in
the medium. Thereby image recording can be achieved at a proper position by the
recording head. Therefore, the first type image recording apparatus can form a
color image in the intended color condition.
The position of each of the filter films of the color filter may be directly
detected or may be indirectly detected by detecting the position of a medium component
disposed in a specified positional relation with the filter films to detect the
positions of the filter films based on the position of the medium component. More
specifically, the detection of the filter films may be carried out, for example,
as follows.
For example, the positions of the filter films may be directly detected using
a photosensor (e.g., color photosensor) confronting the color filter and held in
a specified positional relation with the recording head. That is to say, when image
recording is executed on the medium while moving the recording head relatively
to the medium, the positions of filter films of the color filter may be (directly)
detected by the photosensor.
The photosensor may be mounted, e.g., on the recording head. In this case, the
position of at least one of filter films in the color filter may be detected by
the photosensor in executing image recording.
Of course, the positions of all filter films may be detected or the positions
of not all but plural filter films (e.g., filter films of specified colors) may
be detected.
For example, when a specified positional relation with each other exists between
two filter films, the position of one filter film can be indirectly detected by
detecting the position of the other filter film. Consequently the positions of
all filter films can be detected by detecting at least one of filter films in the
color filter with the photosensor.
When the medium has a transparent partition wall for partitioning the display
layer into sections (e.g., when the medium has first and second transparent substrates
holding the display layer therebetween and a partition wall laid therebetween for
partitioning the display layer into sections) and when the filter films of the
color filter are disposed in a specified positional relation with the transparent
partition wall, the positions of filter films of the color filter may be indirectly
detected as follows. Namely the detection is carried out in a manner as described
below using a light-receiving element opposed to one surface of the medium and
an light-emitting element opposed to the other surface thereof, these elements
being held in a specified positional relation with the recording head.
When image recording is carried out on the medium while moving the recording
head relatively to the medium, light rays emitted from the light-emitting element
and passing through the transparent partition wall laid for partitioning the display
layer are detected by the light-receiving element to detect the position of the
transparent partition wall.
At least one of the positions of the filter films of the color filter held in
a specified positional relation with the transparent partition wall is detected
based on the position of transparent partition wall. The light-receiving element
held in a specified positional relation with the recording head may be mounted,
e.g., on the recording head.
The light-emitting element may be disposed in a specified positional relation
with the recording head or may not. When the medium has a plurality of partition
walls arranged at a specified pitch in a relatively moving direction, the position
of at least one partition wall may be detected in executing image recording.
The second type image recording apparatus is also provided to record an image
on an image display medium including a display layer capable of changing an optical
characteristic of the medium, and a color filter superimposed on the display layer
and having at least one group of a plurality of light-transmitting filter films
having different colors.
The second type image recording apparatus comprises a positioning device for
mechanically positioning the image recording apparatus and filter films of the
color filter in the medium, wherein image recording is executed on the medium.
The second type image recording apparatus is provided with the positioning device
for mechanically positioning the medium and the apparatus so that the filter films
of the color filter can be set with respect to the apparatus without displacement
of position. Thereby the second type image recording apparatus can suppress the
displacement of position in executing image recording.
For example, when a first engagement portion such as a convex portion or concave
portion is formed in the medium and the filter films of color filter are disposed
in a specified positional relation with the first engagement portion, a positioning
operation may be carried out, for example, to position the image recording apparatus
and the filter films of the color filter as follows.
That is, a second engagement portion which can be engaged with the first engagement
portion provided in the medium is formed in the image recording apparatus and the
first engagement portion of the medium is engaged with the second engagement portion
of the apparatus, whereby a positioning operation is performed to position the
filter films of the color filter held in the specified positional relation with
the first engagement portion.
The second engagement portion of the apparatus may be in a shape corresponding
to the first engagement portion of the medium. When the first engagement portion
takes, for example, a concave form (or convex form), the second engagement portion
takes a convex form (or concave form) which can be engaged with the concave portion
(convex portion) of the medium.
Stated more specifically, the second type image recording apparatus is, for
example, as described below in (a) and (b).
(a) For example, the image recording apparatus is provided with a pixel electrode
substrate superimposed on one surface of the image display medium and having a
plurality of sub-pixel electrodes corresponding to the sub-pixels. The pixel electrode
substrate has the second engagement portion in a specified positional relation
with the sub-pixel electrodes, the second engagement portion being engageable with
the first engagement portion formed in the medium.
By engagement of the first engagement portion of the medium with the second engagement
portion of the pixel electrode substrate, a positioning operation can be carried
out to position the sub-pixel electrodes (in a specified positional relation with
the second engagement portion) of the pixel electrode substrate and to position
the filter films of the color filter held in a specified positional relation with
the first engagement portion.
(b) As described above, the image recording apparatus is allowed to execute image
recording on the medium while moving the recording head capable of changing the
optical characteristic of the display layer in the medium (the recording head for
changing the optical characteristic of the display layer in the medium) relatively
to the medium.
In this case, the recording head has, for example, a convex portion (second engagement
portion) which can be engaged in a linear groove (first engagement portion) formed
in the medium, whereby a positioning operation can be done to position the filter
films of the color filter held in a specified positional relation with the groove
and to position the recording head by engagement of the convex portion of the recording
head in the groove of the medium.
The recording head may be moved relatively to the medium while guiding the convex
portion of the recording head in the groove of the medium. The recording head may
have a plurality of convex portions engageable in a plurality of grooves (e.g.,
two grooves extending in parallel with each other) formed in the medium.
Optionally the recording head may have a linear groove (second engagement
portion) which can be engaged with a convex portion (first engagement portion)
formed on the medium.
A positioning operation can be done to position the filter films of the color
filter
held in a specified positional relation with the convex portion of the medium and
to position the recording head by engagement of the convex portion of the medium
in the groove of the recording head. The recording head may be moved relatively
to the medium while guiding the convex portion of the medium in the groove of the
recording head.
The recording head may have a plurality of linear grooves formed in parallel
with each other which are engageable with a plurality of (e.g., two) convex portions
formed in the medium.
The third type image recording apparatus is also one for recording an image on
an image display medium including a display layer capable of changing an optical
characteristic of the medium, and a color filter superimposed on the display layer
and having at least one group of a plurality of light-transmitting filter films
having different colors.
The third type image recording apparatus comprises a positioning device for electrically
positioning the apparatus and the filter films of the color filter, wherein image
recording is executed on the above-mentioned medium.
In the third type image recording apparatus, the apparatus and the filter films
of the color filter can be positioned by the positioning device, whereby an image
can be recorded on the medium without displac
