U.S. patent application number 13/929729 was filed with the patent office on 2013-10-31 for electronic display comprising an adjustable color filter.
The applicant listed for this patent is Creator Technology B. V.. Invention is credited to Hjalmar Edzer Ayco HUITEMA, Petrus Johannes Gerardus van LIESHOUT.
Application Number | 20130286466 13/929729 |
Document ID | / |
Family ID | 44511441 |
Filed Date | 2013-10-31 |
United States Patent
Application |
20130286466 |
Kind Code |
A1 |
LIESHOUT; Petrus Johannes Gerardus
van ; et al. |
October 31, 2013 |
ELECTRONIC DISPLAY COMPRISING AN ADJUSTABLE COLOR FILTER
Abstract
A color display and an electronic apparatus including the color
display are described herein. The color display includes a first
substrate having an illuminating area, a color filter unit, a
plurality of power sources and a colored fluid. The color filter
unit has a first and second electrode on the illuminating area,
wherein the first electrode includes a plurality of patterned
electrodes. Each of the patterned electrodes of the first electrode
is connected to one of the power sources, whereby different
voltages are applied on the patterned electrodes. The colored fluid
disposed between the first and second electrodes and partially
covering the surface of the illuminating area, wherein a covered
area of the illuminating area by the colored fluid is controlled by
the voltage applied on the first and second electrodes
Inventors: |
LIESHOUT; Petrus Johannes Gerardus
van; (Beek en Donk, NL) ; HUITEMA; Hjalmar Edzer
Ayco; (Veldhoven, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Creator Technology B. V. |
Breda |
|
NL |
|
|
Family ID: |
44511441 |
Appl. No.: |
13/929729 |
Filed: |
June 27, 2013 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12855426 |
Aug 12, 2010 |
|
|
|
13929729 |
|
|
|
|
Current U.S.
Class: |
359/296 |
Current CPC
Class: |
G02F 1/133514 20130101;
G02B 5/201 20130101; G02F 1/167 20130101 |
Class at
Publication: |
359/296 |
International
Class: |
G02F 1/167 20060101
G02F001/167 |
Claims
1. A display, comprising: a first substrate having an illuminating
area; a color filter unit having a first and second electrode on
the illuminating area, wherein the first electrode comprises a
plurality of patterned electrodes; a plurality of power sources,
wherein each of the patterned electrodes of the first electrode is
connected to one of the power sources, whereby different voltages
are applied on the patterned electrodes; and a colored fluid
disposed between the first and second electrodes and partially
covering the surface of the illuminating area, wherein a covered
area of the illuminating area by the colored fluid is controlled by
the voltage applied on the first and second electrodes.
2. The display as claimed in claim 1, further comprising a black
matrix disposed on the first substrate.
3. The display as claimed in claim 2, wherein the black matrix
partially covers the illuminating area which is covered by the
colored fluid.
4. The display as claimed in claim 1, further comprising a control
unit disposed between the first and second electrodes for
controlling at least a level of the colored fluid.
5. The display as claimed in claim 1, further comprising a third
electrode, wherein the second electrode is disposed between the
first and third electrodes.
6. The display as claimed in claim 1, wherein the colored fluid is
oil or is oil-based.
7. The display as claimed in claim 1, further comprising a power
supply electrically connected with the second electrode for
supplying control voltage to the second electrode.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of U.S. patent application
Ser. No. 12/855,426 filed Aug. 12, 2010, the disclosure of which is
hereby incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to an electronic color display
comprising a color filter. The invention further relates to an
electronic device comprising an electronic color display provided
with a color filter.
[0004] 2. Description of the Related Art
[0005] An embodiment of an electronic display provided with a color
filter is known from WO2007/063440. The known electronic display
comprises a display effect layer, which may be arranged to reflect
or to emit light with a broad spectrum (white light) over which a
color filter layer is superposed. The color filter layer is
arranged to change the white light into colored light by
intercepting specific wavelengths. The display effect layer and the
color filter layer need to be properly aligned, for example to
prevent parallax or aperture problems.
BRIEF SUMMARY OF THE INVENTION
[0006] In some instances, a compromise between brightness and color
saturation has to be made in color displays. Display effects such
as reflective electrophoretic or reflective/transmissive LCD enable
good black and white brightness. Color is usually implemented by
combining these black and white displays with an array of color
filters. In order to produce saturated colors, the color filters
need a substantially high absorption for wavelengths of a different
color. This may decrease the brightness of white by 50-70% compared
to the original black/white pixel brightness.
[0007] Handheld, display-based devices, such as e-readers, mobile
phones, PDA's, or the like are used for a great variety of
applications. For reading, usually a black and white display is
preferable, while for picture or graphics viewing, a full-color
display may be needed. In addition, the display has to have
sufficient brightness and/or contrast for a variety of ambient
lighting conditions, for example for an indoor and outdoor use.
[0008] It is an object of at least one invention contemplated
herein to provide a color display enabling substantially optimized
brightness and/or contrast for a variety of ambient lighting
conditions and/or use modes.
[0009] To this end the electronic color display according to one
contemplated invention comprises a color filter arranged with a
plurality of color filter elements, said color filter being
overlaid on an illuminating area of the display, said illuminating
area being arranged to emit, transmit or reflect light in a range
of wavelengths, wherein respective transmission of the color filter
elements is adjustable.
[0010] The technical measure of one contemplated invention is based
on the insight that by allowing a purposeful adjustment of the
transmission of a color filter element either transmission of part
of the said range of wavelengths, or transmission of substantially
the full said range of wavelengths may easily be enabled in a
reproducible way.
[0011] The technical measure of one contemplated invention is based
on a further insight that by providing the filter elements of the
color filter with adjustable transmission, preferably with
adjustable transmission and saturation, the electronic display
properties, like brightness and/or contrast and/or saturation do
not have to be optimized for a given application, but, instead,
these display properties may be tuned on demand based upon a
currently used application or ambient conditions.
[0012] In accordance with one contemplated invention respective
transmissions of the color filter elements are modified for a
selected wavelength or wavelengths. Such modification or adjustment
may be carried out pursuant to an envisaged utilization mode of the
device, or pursuant to ambient parameters, like ambient lighting
conditions.
[0013] In particular, the illumination unit may be arranged to
produce white or black pixels. The illumination unit may relate to
a reflective active-matrix display, although this embodiment is not
limiting. The filter elements of the color filter may
advantageously be arranged to enable high or maximum transmission
to wavelengths corresponding to a substantially white spectrum. In
this way displaying of a black/white picture is enabled. It will be
appreciated that grey shades are seen as intermediate levels
between black and white. Alternatively, when the pixels of the
color filter are adjusted to enable high or maximum transmission
only for part of the visible-light spectrum, for example, for red,
blue or green color, a colored displaying mode is enabled. As a
result, a versatile color display is provided, which has optimum
brightness or, optionally optimum brightness and contrast, in
particular for black and white displaying. Furthermore, it is noted
that the lowest reflectance in black can be obtained by displaying
black using the illumination unit and switching the pixels of the
color filter to pass only part of the visible-light spectrum,
thereby roughly reducing the overall black reflectance by a factor
of three. However, for this black level to be used in conjunction
with other shades of grey or colors, the color filter pixels need
to be individually addressable.
[0014] In an embodiment of the color display according to one
contemplated invention the color filter comprises an array of
switchable elements, the switching state of these elements
determining the part of the visible-light spectrum that is
transmitted by the switchable elements.
[0015] It is found to be particularly preferable to provide the
color filter with filter elements operating using the
electrowetting principle, because in this way a substantially
instantaneous and independent adjustment of the filter elements is
possible. Implementation of red, blue or green filter elements may
be provided by using respectively colored liquids arranged within
such filter elements. The principle of electrowetting is known in
the art. An example of an apparatus arranged with actuatable fluid
is known from US 2007/0243110.
[0016] It will be appreciated that although in the US 2007/0243110
reference is made to a macroscopic device, manufacturing of a
filter array comprising substantially microscopic filter elements
operating using the electrowetting principle lies within ordinary
skill of the artisan. However, it will be appreciated that for
enabling operating of the adjustable filter elements filled with
the actuatable fluid, each cell comprising the actuatable fluid
should have electrodes fed by a power supply. The power supply,
electrically connected to a common unpatterned electrode, may be
controllable by a suitable processor for setting a desired voltage
across the cell for altering spatial filling of the cell by the
actuatable fluid. More details on this embodiment will be presented
with reference to FIG. 3a.
[0017] In a further embodiment of the color display according to
one contemplated invention the illuminating area is arranged with
black and white pixels, the filter elements of the color filter
dimensionally correspond to and are aligned with said black and
white pixels.
[0018] It is found to be advantageous that the elements of the
color filter correspond to the pixels of the illumination area. In
this way a one-to-one translation of envisaged display mode
requirements to suitable filter characteristics can be made.
[0019] In a particular embodiment color display brightness and/or
resolution of the color display are adjustable.
[0020] It is found that the respective resolutions of the display
and the controllable color filter comprising color filter elements
do not have to be the same. For example, should the resolution of
the display be 2 times higher in x- and y-directions than the
resolution of the color filter, in the color mode, such difference
in resolution may be used to generate extra colors and/or adjust
brightness. Should the resolution of the color filter be higher
than the resolution of the display, this difference may be used to
optimize use of the white channel in color mode.
[0021] In a still further embodiment of the color display according
to one contemplated invention the color filter comprises a first
display portion and at least a second display portion, the filter
elements of the first display portion and the at least second
display portion being controlled independently from each other.
[0022] It is found to be advantageous instead of having one area to
provide a suitable plurality of such areas. This may result in
enabling different settings with respect to color saturation and
brightness for different areas of the color filter. Such
functionality may be advantageous, for example, when different
viewing areas of the display have different purposes. Such
embodiment may be enabled by replacing the unpatterned common
electrode in the switchable filter element stack by two or more
patterned electrodes. In this case a provision of a suitable
plurality of independent power sources may be required. This
embodiment is discussed in further details with reference to FIG.
3c.
[0023] In a still further embodiment of the color display according
to one contemplated invention a substrate has a display counter
electrode for controlling the illumination area and a color filter
electrode for controlling the color filter, the display counter
electrode and the color filter electrode being joined. This feature
has an advantage that by choosing a suitable material for a
substrate layer normally separating the display counter electrode
and a color filter electrode, said electrodes may be joined. As a
result the overall brightness of the illumination unit may
increase. This feature will be further discussed with reference to
FIG. 1.
[0024] In a still further embodiment of the color display according
to one contemplated invention the illumination area comprises an
array of transmissive elements.
[0025] It is found to be advantageous to combine the color filter
with an illumination unit having a transmissive display effect. In
this case the color filter may be combined either with a backlight,
or with reflective pixel pads. For such arrangements, it is
possible to position the color filter in front of the illumination
unit, or between the illumination unit and backlight or reflection
layer.
[0026] One contemplated invention further relates to an electronic
portable device comprising an electronic color display as is
described with reference to the foregoing. The electronic portable
device relates, by way of example, to a mobile phone, an e-reader,
an organizer, a palm-top or the like. Advantageously, the color
display may be settable in a first mode and in a second mode,
wherein said transmission for the selected wavelength and for said
wavelength range may be adjustable based on the first mode and the
second mode. Preferably, the first mode corresponds to a reading
mode and the second mode corresponds to a picture viewing mode. In
an exemplary case, said first mode is arranged for enabling
monochromic displaying, said second mode is arranged for enabling
polychromic displaying.
[0027] For example, for e-reading, the color display may be set
into a high-resolution, high-brightness monochrome mode. For
picture viewing, the display can be put in color mode. In the color
mode, color saturation may be increased while somewhat decreasing
brightness. Mode selection of the display may be carried out by a
single power source to which the display is connected. It will be
appreciated that the illumination unit may comprise electrophoretic
material and may be driven in accordance with conventional driving
used for actuating an electrophoretic display.
[0028] These and other aspects of the invention will be discussed
in further detail with reference to drawings, wherein like
reference signs represent like elements. It will be appreciated
that the drawings are provided for illustrative purposes only and
may not be used for limiting the scope of the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The appended claims set forth the features of the present
invention with particularity. The invention, together with its
objects and advantages, may be best understood from the following
detailed description taken in conjunction with the accompanying
drawings of which:
[0030] FIG. 1 presents schematic cross-sectional views of an
embodiment of a color display provided with an adjustable color
filter according to the invention;
[0031] FIG. 2 is an illustrative depiction of an embodiment of an
electronic device incorporating a color display according to the
invention;
[0032] FIG. 3a presents a schematic view of an embodiment of a
color display according to the invention provided with a single
power source for switching the filter elements;
[0033] FIG. 3b schematically depicts a top view of the electrodes 1
a and 2b (of FIG. 3a) required for implementing such operation of
the device; and
[0034] FIG. 3c schematically depicts an embodiment of a color
display according to the invention provided with a plurality of
power sources adapted for switching filter elements in different
areas of the display separately.
DETAILED DESCRIPTION OF THE INVENTION
[0035] The following description is of the best-contemplated mode
of carrying out the invention. This description is made for the
purpose of illustrating the general principles of the invention and
should not be taken in a limiting sense. The scope of the invention
is best determined by reference to the appended claims.
[0036] FIG. 1 presents a schematic view of an embodiment of a color
display provided with an adjustable color filter according to an
embodiment of the invention. The color display 15 according to the
embodiment comprises an illumination unit 14 implemented as a
display feature comprising a lower substrate 3 provided with a
suitable pixel pad 4 arranged to control suitable electrophoretic
capsules 5. The electrophoretic capsules 5 comprise, for example,
charged white particles 5a and black particles 5b dispersed in a
clear fluid (or white particles dispersed in for example black or
colored fluid, not shown) and may be arranged to operate in a
reflective way. In order to actuate the electrophoretic capsules
the illumination unit 14 comprises a display counter electrode 2a
arranged on a further substrate 2, wherein a suitable actuation
voltage may be applied between electrodes 4 and 2a. In accordance
with the illustrative embodiment the illuminating unit 14 is
overlaid with a color filter arranged with a plurality of color
filter elements 16a, 16b, 16c, wherein respective transmissions of
the color filter elements 16a, 16b, 16c are adjustable to allow
either transmission for a selected wavelength emanating from
elements 7b, 8b, 9b in said range of wavelengths, or transmission
for a number of or all the wavelengths from said range of
wavelengths.
[0037] In the illustrative embodiment of the color display 15, the
color filter comprises an array of filter elements 16a, 16b, 16c
comprising respective fluids 7b, 8b, 9b, wherein said fluids are
actuated using electrowetting principle using among others suitable
control means 7a, 8a, 9a arranged for implementing the
electrowetting principle. Preferably, the color filter 16 is
arranged with basic red-green-blue filters, which may be
implemented by providing suitably colored oil 7b, 8b, 9b in a
suitable coupling medium 17, for example water, which may at least
partially fill respective color filter elements 16a, 16b, 16c. In
order to actuate the color oils, the color filter comprises a
filter counter electrode 1a arranged to apply a suitable actuating
voltage on a wall of the filter element corresponding to the filter
elements 16a, 16b, 16c. The filter counter electrode 1a is
preferably positioned on a still further substrate 1. Finally, the
color display 15 may comprise a black matrix 6 arranged either on
top of the substrate 1 as shown in FIG. 1 or on the bottom side of
the substrate 1 (not shown). An embodiment of an actuation mode of
the color filter will be discussed with reference to views 10a, 10b
and 10c.
[0038] In view 10a an actuation mode is shown wherein the color
filter elements are set for allowing high or maximum transmission
to a wide range of light wavelengths emanating from the
illumination unit 14. By way of example, substantially whole white
light spectrum is transmitted. For this purpose a first actuating
voltage is applied to the respective walls of the color filter
elements 16a, 16b, 16c so that the colored oil is substantially
limited to an area below the black matrix 6. The actuation voltage
may be applied between the electrodes 2b and 1a. It will be
appreciated that the colored oil 7b, 8b, 9b may be fed to the
respective pixels from corresponding reservoirs. It is possible
that, alternatively, the filter elements 16a, 16b, 16c are actuated
in such way that the respective colored oils are transported away
from the filter elements 16a, 16b, 16c towards the reservoir.
[0039] A corresponding image resulting from such actuation mode may
be represented by a series of black and white pixels 11a, 11b, 11c.
It can also represent grey tones. This image may have high
resolution, high brightness and is substantially monochrome, which
may correspond to a reading mode of the color display 15.
[0040] In view 10b a further mode is given, wherein the filter
elements 16a, 16b, 16c are actuated in such way that the respective
color oils 7b, 8b, 9b partially cover respective area of the color
filter elements. A corresponding image is represented by a series
of polychrome pixels 12a, 12b, 12c which may have a normal
resolution, medium brightness and medium color saturation. The
color of the pixels 12a, 12b, 12c correspond to the color of the
respective liquids, for example oils 7b, 8b, 9b. Those skilled in
the art would readily appreciate, in view of the disclosure
pateherein, which class of liquids is suitable for
electrowetting.
[0041] In view 10c a still further mode is given, wherein the
filter elements 16a, 16b, 16c are actuated in such way that
respective area of the color filter elements are fully filled with
the respective color oils. The resulting image is represented by a
sequence of pixels 13a, 13b, 13c which may have normal resolution,
low brightness and high color saturation.
[0042] It will be appreciated that instead of providing
non-patterned electrodes 2b and 1a, either one of the electrodes
may be patterned resulting in different portions of the color
filter having different settings, for example with respect to color
saturation and brightness. In this way, however, each filter
portion must have its own power source. This further embodiment is
discussed in further detail with reference to FIG. 3c.
[0043] In addition or alternatively, the substrate 2 may be
arranged for joining electrodes 2a and 2b. Omission of one
electrode layer may result in an increase of an overall
brightness.
[0044] It will be appreciated that the color display 15, instead of
using display effect based on electrowetting effect, other display
effects may be used, like for example a display effect based on
Ch-LC (Cholesteric Liquid Crystal), GH-LC (Guest-Host Liquid
Crystal), based on PDLC (Polymer Dispersed Liquid Crystal) or based
on MEMS (Micro Electro-Mechanical Systems).
[0045] FIG. 2 presents an embodiment of an electronic device
according to an illustrative example of the invention. The
electronic device 20 comprises a housing 22 and a retractable,
notably wrappable display 25, preferably arranged on a rigid cover
22a. The display 25 is provided with the adjustable color filter as
is described with reference to the foregoing. The display 25 may be
arranged in accordance with the embodiment described with reference
to FIG. 1. Alternatively, the display 25 may be arranged with other
suitable means to enable due adjustment of the filter elements
transmission for one or more wavelengths. The rigid cover 22a may
be arranged to be wound together with the display 25 around the
housing 22 to a position 21a. The rigid cover 22a may comprise an
edge member 23 provided with rigid areas 23a and flexible areas
24a, 24b cooperating with hinges 26a, 26b of the cover 22a. When
the display 25 is being retracted to the position wound about the
housing 22, the surface of the display 25 may abut the housing 22.
Preferably, the housing 22 or display 25 comprise means (not shown)
for enabling selection of the mode for controlling transmission
settings of the individual color filter elements for providing
optimum viewing mode with regard to at least brightness and
resolution. Selection of the viewing mode can be on the initiative
of the user or it can be coupled to metadata of the image to be
displayed. Alternatively, if no metadata is available, the
properties of the image to be displayed can be determined by image
analysis or be controlled by the application (computer program
executing on the device 20) that is used to render the image. It
will be appreciated that instead of a wrappable display the
electronic apparatus may comprise a rollable display, so that the
flexible display 25 is arranged to be rolled over a suitable roller
upon storage, preferably inside a portion of a housing, or a rigid
display, arranged on the outside of a device housing.
[0046] FIG. 3a schematically presents an embodiment of a color
display according to an embodiment of the invention provided with a
single power source for switching the filter elements.
[0047] The color display 15, according to an aspect of the
illustrative embodiment of the invention, is arranged for enabling
a unified response from all filter elements 16a, 16b, 16c, as the
respective actuatable fluids 7b, 8b and 9b are controlled by a
common power supply 30 via the respective control means 7a, 8a and
9a. When a trigger voltage is provided across a cell corresponding
to liquids, using electrodes 1a and 2b, respective spatial
distribution of the actuatable fluids across the filter elements
16a, 16b, 16c may be changed, see views 10a, 10b and 10c presented
in FIG. 1.
[0048] It will be appreciated that other items depicted in FIG. 3a
may be substantially the same as items discussed with reference to
FIG. 1. Accordingly, respective electrophoretic capsules 5 may
comprise charged white particles 5a and black particles 5b
dispersed in a clear fluid (or white particles dispersed in for
example black or colored fluid, not shown) and may be arranged to
operate in a reflective way. In order to actuate the
electrophoretic capsules the illumination unit 14 comprises a
display counter electrode 2a arranged on a further substrate 2,
wherein a suitable actuation voltage may be applied between
electrodes 4 and 2a. In accordance with the invention the
illuminating unit 14 is overlaid with a color filter arranged with
a plurality of color filter elements 16a, 16b, 16c, wherein
respective transmissions of the color filter elements 16a, 16b, 16c
are adjustable to allow either transmission for a selected
wavelength emanating from elements 7b, 8b, 9b in said range of
wavelengths, or transmission for a number of, or all, the
wavelengths from said range of wavelengths. FIG. 3b schematically
presents a top view of the electrodes 1a and 2b required for
implementing such operation of the device.
[0049] FIG. 3c presents in a schematic way an embodiment of a color
display according to the invention provided with a plurality of
power sources adapted for switching filter elements in different
areas of the display separately. In this embodiment instead of
having one electrode area as shown in FIG. 3b a plurality of
electrode areas is patterned, 101a, 101a', 101a'', 101a''''. The
bottom electrode 2b may be left common for all filter elements 16a,
16b, 16c.
[0050] In order to implement regional switching, each patterned
electrode 101a, 101a', 101a'', 101a''' is connected to a dedicated
power source 30a, 30b, 30c, 30d. each of such power sources is
arranged to apply a control voltage between an unpatterned bottom
electrode 2b and a respective patterned sub-electrode 101a, 101a',
101a'', 101a'''. Such functionality is advantageous as it supports
area-related switching of the display, allowing for presenting
information on specifically designated display areas. For example,
one area may be designated for control menu's, while another area
may be designated for reading, e-mailing and so on.
[0051] Such sub-areas may even enable definition of different
settings with respect to color saturation and brightness for
different areas of the color filter. Such functionality may be
advantageous, for example, when different viewing areas of the
display have different purposes.
[0052] It will be appreciated that although specific embodiments of
the color display and the electronic apparatus according to the
invention are discussed separately for clarity purposes,
interchangeability of compatible features discussed with reference
to isolated figures is envisaged.
[0053] It will further be appreciated that in the present
application the following terms shall have the following
meaning:
[0054] "illuminating area" relates to a reflective, emissive and/or
transmissive area of a display;
[0055] "brightness" relates to luminance in an emissive or backlit
transmissive display; and reflectance in a reflective display;
[0056] "selected wavelength" relates to a part of the visible-light
spectrum; can be associated with a certain color;
[0057] "filter element" relates to an element that passes selected
wavelengths and suppresses other wavelengths.
[0058] While specific embodiments have been described above, it
will be appreciated that the invention may be practiced otherwise
than as described. The descriptions above are intended to be
illustrative, not limiting. Thus, it will be apparent to one
skilled in the art that modifications may be made to the invention
as described in the foregoing without departing from the scope of
the claims set out below.
* * * * *