U.S. patent application number 10/099639 was filed with the patent office on 2002-07-11 for low power high resolution electrochemical display.
Invention is credited to Kikinis, Dan.
Application Number | 20020089487 10/099639 |
Document ID | / |
Family ID | 24909896 |
Filed Date | 2002-07-11 |
United States Patent
Application |
20020089487 |
Kind Code |
A1 |
Kikinis, Dan |
July 11, 2002 |
Low power high resolution electrochemical display
Abstract
A flat-panel display comprises a gelatinous material between two
panels having a matrix of pixel electrodes formed between the
panels. Suspended ionic particles in the gelatinous material, of a
color contrasting to the color of the gelatinous material, are
translated in the gelatinous material by activating individual ones
of the electrodes, and collecting near the electrodes against one
of the panels, form pixels of the color of the particles against a
background of the color of the gelatinous material. In preferred
embodiments data receiving and control circuitry are provided with
the flat panel display for activating electrodes in patterns
according to received data, the patterns forming images on a
screen. Flat panel displays thus formed require power only when an
image on the screen is changed. No power is required to maintain an
image once formed. Such a display is especially suitable for
forming pages of text for various purposes.
Inventors: |
Kikinis, Dan; (San Jose,
CA) |
Correspondence
Address: |
CENTRAL COAST PATENT AGENCY
PO BOX 187
AROMAS
CA
95004
US
|
Family ID: |
24909896 |
Appl. No.: |
10/099639 |
Filed: |
March 15, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10099639 |
Mar 15, 2002 |
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08724304 |
Sep 19, 1996 |
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6369792 |
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Current U.S.
Class: |
345/107 |
Current CPC
Class: |
G02F 1/167 20130101 |
Class at
Publication: |
345/107 |
International
Class: |
G09G 003/34 |
Claims
What is claimed is:
1. A display panel comprising: a first panel; a second panel spaced
apart from the first panel, providing a volume therebetween; an
open-celled, opaque gelatinous material having a first color in the
volume between the panels; multiple ionic particles having a second
color suspended in the gelatinous material; and a matrix of
electrodes implemented over a surface of at least one of the
panels; wherein activating individual ones of the electrodes in the
matrix of electrodes causes groups of the multiple ionic particles
to translate through the gelatinous material and collect against
the first panel, forming a pattern of pixels of the second color
against a background of the first color.
2. The display panel of claim 1 wherein the first color is white
and the second color is black.
3. The display of claim 1 wherein the matrix of electrodes
comprises individual electrodes spaced in a Cartesian array on one
of the two panels and a common electrode surface implemented on the
other of the two panels.
4. The display of claim 3 wherein the individual electrodes are
formed in a polysilicon layer deposited on the one of the two
panels, and wherein circuitry for controlling activation of the
electrodes is also formed on the one of the two panels.
5. The display of claim 1 wherein individual electrodes are formed
by a first set of substantially parallel lines of transparent,
electrically conductive material formed on one of the two panels,
and a second set of substantially parallel lines of electrically
conductive material at right angles to the first set of
substantially parallel lines of transparent, electrically
conductive material, the second set of lines formed on the other of
the two panels, individual electrodes being formed at the
intersections of individual lines on one panel with individual
lines on the other panel.
6. The display panel of claim 1 further comprising a data port and
control circuitry connected to the data port, the control circuitry
adapted for addressing and activating individual electrodes
according to a data stream received at the data port.
7. A method for forming an image on a display panel comprising
steps of: (a) forming a matrix of pixel electrodes between two
parallel, spaced apart panels; (b) filling volume between the
panels with an open-celled, gelatinous material having a first
color; (c) suspending ionic particles having a second color in the
gelatinous material; and (d) activating individual ones of the
pixel electrodes causing multiples of the ionic particles to
translate through the gelatinous material and to form near the
activated electrodes, forming thereby an image
8. The method of claim 7 wherein the first color is white and the
second color is white.
9. The method of claim 7 wherein the matrix of pixel electrodes
comprises individual electrodes spaced in a Cartesian array on one
of the two panels and a common electrode surface implemented on the
other of the two panels.
10. The method of claim 9 wherein the individual electrodes are
formed in a polysilicon layer deposited on the one of the two
panels, and wherein circuitry for controlling activation of the
electrodes is also formed on the one of the two panels.
11. The method of claim 9 wherein individual electrodes are formed
by a first set of substantially parallel lines of transparent,
electrically conductive material formed on one of the two panels,
and a second set of substantially parallel lines of electrically
conductive material at right angles to the first set of
substantially parallel lines of transparent, electrically
conductive material, the second set of lines formed on the other of
the two panels, individual electrodes being formed at the
intersections of individual lines on one panel with individual
lines on the other panel.
12. The method of claim 7 further comprising steps for forming a
data port and control circuitry connected to the data port, the
control circuitry adapted for addressing and activating individual
electrodes according to a data stream received at the data port.
Description
FIELD OF THE INVENTION
[0001] The present invention is in the area of display technology,
and pertains in particular to an electrophoretic display with high
resolution and low power consumption using electrically-induced
motion of charged display markers in a gelatinous base material to
present a display.
BACKGROUND OF THE INVENTION
[0002] The advent of portable personal computers, such as notebook
and laptop computers, required, because of the form factors
required, flat panel displays, and several sorts of flat-panel
displays have been developed and marketed. Perhaps the two most
successful types of such displays are liquid-crystal displays and
plasma displays.
[0003] Flat-panel displays have been optimized for displaying color
and motion, and for operation at low power levels, which is
desirable for computers like laptops and notebooks that are, at
least part of the time, operated from batteries. In this
optimization light weight and resolution have been sacrificed. Flat
panel displays optimized in this way typically have resolution of
from 50-100 dots per inch (DPI) in each direction. In the case of
color displays, because three color dots are needed for each pixel,
resolution is even poorer.
[0004] There are technologies available which allow resolution as
high as 2000 DPI, but the size of such displays is typically
limited to fractions of an inch in each direction. Two important
reasons for the resolution limits of flat panel displays are power
consumption and refresh rate. Given a certain technology,
active-matrix LCD for example, power consumption is a function of
resolution because each pixel element consumes power. Given a
specific screen size, doubling resolution (DPI) quadruples the
number of pixels, and therefore quadruples power consumption. Also,
increasing the number of pixels increases the amount of data needed
to keep the overall display updated.
[0005] As an example, a computer display considered to be high
resolution might have 1024.times.768 pixels, each in 3 colors, each
addressed by eight bits, and refreshed approximately 70 times per
second (70 Hz refresh rate). Such a system requires 165 Mbytes of
data per second.
[0006] Consider now a small document with printed characters, like
a newspaper, with a resolution of about 300 DPI. An 8 inch by 11
inch printed area of such a document represents a resolution of
2400.times.3300 pixels (monochrome). Data rates in this situation
are in excess of 550 Mbytes per second. Also, using any of the
popular conventional technologies, such a display would be quite
heavy and would consume considerable power.
[0007] What is needed is a new display technology, allowing
ultra-light (by today's standards), and ultra high-resolution
displays, requiring a very low refresh rate and very low power
consumption. It is to these ends that the present invention,
described in detail below, is directed.
SUMMARY OF THE INVENTION
[0008] In a preferred embodiment of the present invention a display
panel is provided comprising a first panel; a second panel spaced
apart from the first panel, providing a volume therebetween; an
open-celled, opaque gelatinous material having a first color in the
volume between the panels; multiple ionic particles having a second
color suspended in the gelatinous material; and a matrix of
electrodes implemented between the two panels or on one of the two
panels. Activating individual ones of the electrodes in the matrix
causes groups of the multiple ionic particles to translate through
the gelatinous material and collect against the first panel,
forming a pattern of pixels of the second color against a
background of the first color.
[0009] In some embodiments the first color is white and the second
color is black. In others other colors may be used, with the
preference that the colors be easily distinguishable from each
other.
[0010] The matrix of electrodes in some embodiments comprises
individual electrodes spaced in a Cartesian array on one of the two
panels and a common electrode surface implemented on the other of
the two panels. In these embodiments individual electrodes are
formed in or on a polysilicon layer deposited on the one of the two
panels, and circuitry for controlling activation of the electrodes
is also formed on the one of the two panels. In other embodiments
individual electrodes are formed by a first set of substantially
parallel lines of transparent, electrically conductive material
formed on one of the two panels, and a second set of substantially
parallel lines of electrically conductive material at right angles
to the first set of substantially parallel lines of transparent,
electrically conductive material, the second set of lines separated
from the first by means of a semiconducting material. By exceeding
the breakdown voltage between those lines, the immediate
surroundings become conductive, and individual electrodes are
formed at the intersections of individual lines on one panel These
areas again act in attracting or repelling suspended ionic
particles, resulting in formation of a visible pattern.
[0011] In preferred embodiments the display panel comprises a data
port and control circuitry connected to the data port, the control
circuitry adapted for addressing and activating individual
electrodes according to a data stream received at the data port.
Methods are provided for forming such displays.
[0012] A very big advantage for displays according to embodiments
of the present invention is that these displays require power only
when altering the displayed image. While a display is maintained,
no power is required; that is, the image need not be refreshed.
Displays according to embodiments of the present invention are thus
especially suited for displaying pages of text, as the mean time
between updates for such display can be expected to be relatively
long. Another big advantage, which accrues because of the
low-voltage, low-power aspects of the unique technology used for
embodiments of this invention, is that resolution may be
substantially increased without increasing power requirements. High
resolution is also possible because the structure of devices
according to embodiments of the present invention lends itself to
small geometry, hence high resolution.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is an isometric view of a display panel according to
the present invention.
[0014] FIG. 2A is a cross-section view of a portion of the display
of FIG. 1 taken along section line 2A-2A of FIG. 1, and shows a
blank display condition
[0015] FIG. 2B is the cross-section of FIG. 2A showing an active
display condition.
[0016] FIG. 3 is a cross-section of a panel in an alternative
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] In the present invention, as described more fully below, a
gelatinous (gel) material is used in combination with charged
visual marker particles suspended in the gel material. The gel
material is provided between plates wherein one of the plates has a
matrix of addressable electrodes and the other may be electrically
biased relative to any of the electrodes. In a preferred embodiment
the gel is provided in a light color, such as white, and the
suspended particles are provided in a dark color, such as black, to
provide contrast with the gel.
[0018] The charged marker particles suspended in the gel are
capable of translating through the gel under the influence of an
electrical field, but tend to remain in the last position acquired
when the electrical field is removed The gel material for such a
display has preferably a long lifetime, is insensitive to
electrolysis, and has good optical attributes as well as being
opaque as opposed to translucent or transparent. Several gel
materials are available having such attributes if properly
prepared, such a polyacrylamide gels as used in electrophoresis
apparatus. In this case the prepared gel is colored by addition of
a coloring agent to be white or another light color. Many benign
agents for this purpose are well-known in the arts of paints and
pigments and the like. A number of alternatives exist as well for
the marker particles suspended in the gel material. One such is the
type of material used as toner for laser printers.
[0019] FIG. 1 is an isometric view of a display 11 according to an
embodiment of the present invention, having a border area 13 and a
display screen 15. This particular display is shown with a data
input 17 for providing data to display 11 to drive the previously
mentioned matrix of electrodes for providing images on display
screen 15, but data may be provided in other ways as well, such as
by a docking bay with a PC card. The display in many embodiments of
the present invention is particularly suited to use for displaying
text, and as such is suited as well for system implementation for
electronic books and the like.
[0020] Displays such as that shown may be implemented in a wide
variety of ways. Two such displays, for example, may be attached
side by side with a hinge apparatus, so the sides may close against
each other like a book. An electronic book may be loaded to such a
display combination, and controls (noy shown in FIG. 1) may be
provided for functions like turning pages, changing fonts, zooming,
and the like.
[0021] The matrix of electrodes, while not shown specifically in
FIG. 1, may be implemented in more than one way as known in the
art, such as by electrodes fashioned in a transparent polysilicon
layer by techniques of semiconductor circuit manufacture, in a
similar manner that such electrodes are fashioned for active matrix
liquid-crystal (LCD) displays. Alternatively columns of
transparent, conductive material, such as titanium nitride, may be
formed on one surface and rows of conductive material may be
fashioned on an opposite surface (opposite sides of the gel
material) such that activating a single row and a single column
places a voltage across the gel at a point (one pixel in the
display). This is a well-known method used for electroluminescent
displays.
[0022] FIG. 3 is a cross-section of a portion of one plate of a
display according to an alternative embodiment of the present
invention wherein a matrix of electrodes is formed by yet another
method. In the embodiment of FIG. 3 a glass panel 302 has multiple
vertical electrode lines formed thereon, side-by-side and parallel
(preferably). Only one such electrode line is seen in FIG. 3
because of the section nature of the figure. A layer of
semiconductor material 304 is formed over the vertical electrode
lines, and a set of multiple electrode lines 301 are formed in on
the semiconductor material, also side-by-side and parallel, and at
substantially right angles to the multiple vertical electrode lines
303.
[0023] In this electrode scheme, just as in the crossed line
embodiment described above, activating any one line in one set with
a line in the other creates and electrical field between the lines
just at the point that they cross and come in nearest proximity.
Since the lines are both in semiconductor material, the electric
field at this point bleeds through to the inside surface of the
structure (opposite the glass plate) and creates are small charged
area on the surface, as illustrated by area 305. In this manner
particles embedded in a gel material adjacent to the structure can
be attracted to or repelled by pixel areas on the structure.
[0024] Regardless of the method for activation, typically in
flat-panel displays electronic circuitry for decoding data sent to
the display via a data link (17) is contained in the borders (15)
of the display panel. This is true as well in preferred embodiments
of the present invention.
[0025] While FIG. 1 is a preferred form for a display according to
the present invention, such displays may take many other external
forms, such as physically attached to a body of a portable
computer, as is well-known in laptop and notebook computers, or as
stand-alone panels to hang on a vertical or semi-vertical surface.
It will be apparent to those with skill in the art that there are
many alternatives for the physical external form of displays
according to embodiments of the present invention, all while
staying well within the spirit and scope of the invention.
[0026] FIG. 2A is a cross-section of display panel 11 of FIG. 1
taken along section line 2A-2A of FIG. 1, showing the display panel
of FIG. 1 in a blanked condition. FIG. 2B is the same section
showing the display panel in an active display state. A front glass
100 requires no filters, with the exception of an optional
anti-glare filter on the viewing side (not shown in FIG. 2A or 2B).
A polysilicon layer 101 in this embodiment comprises driver
circuits (not specifically shown) and has a matrix of electrodes
such as electrodes 120-128 embedded therein. These electrodes
because of the section nature of FIG. 2A and FIG. 2B show a line of
nine electrodes of all the pixel electrodes in the display, which
number in the tens of thousands. It is understood that there are
also electrodes in lines at right angles to those shown, forming an
orthogonal matrix of electrodes. The resolution in the direction
not shown may the same as that shown or different.
[0027] The process to manufacture such polysilicon structures is
about the same as used in active-matrix LCD displays, except there
is no requirement for a storage capacitor, since after writing the
voltage can be removed, as will be further described below.
[0028] A back wall 104 of the display is coated with a conductive
material that need not be transparent, which coating serves as a
common electrode 103 for all the matrix of front electrodes. There
are many useful materials for back electrode 103, including a
number of metals which may be applied in several different ways to
form the electrode surface.
[0029] Front glass 100 with polysilicon layer and circuitry 101 is
spaced apart from back wall 104 with electrode coating 103 by gap
102. The space between the front and back structures is filled with
gel 106. Marker particles 105 are suspended relatively
homogeneously in the gel material before the gel is applied.
[0030] The width of gap 102 is preferably quite small, such as
several microns (shown much exaggerated in the figures), such that
the display viewed from the front appears white and solid. In this
embodiment particles 105 are preferably black, and exhibit a
strong, negative ionic behavior. By applying a positive pulse to
back electrode 103 particles 105 are moved through the gel toward
the back wall and away from the front wall, becoming sufficiently
immersed in the gel to be invisible from the viewing side of the
display. This is the condition essentially s shown in FIG. 2A,
although it is not really necessary that the particles be all
against the back wall as shown, but only sufficiently immersed in
the gel that they are not visible from the front.
[0031] By now selectively applying a positive voltage to some
electrodes, patterns can be written to the panel, and become
visible, as the marker particles travel through the gel to those
electrodes that are positive (121, 124 and 127 in FIG. 2B) The
particles emerge from the gel against the transparent electrodes
forming a black pixel at each activated electrode. Electrodes for
pixels not intended to be black are held negative to avoid an
accidental display in those areas. Clusters of charged particles
131-133 are shown formed just below the positive electrodes, and
form now visible black clusters. Some particles in this process of
activating the display can also get stranded, such as particles
134, remaining visually buried, since still immersed in the
gel.
[0032] Very important to the present invention, voltage applied to
selected electrodes to form an image can now be removed, and the
image formed remains visible. As the invention thus implemented in
the embodiment described above provides a monochrome black and
white display, and because there are time constraints on moving the
charged particles in the gel, the display I this embodiment is
particularly suited to text display in pages. For this particular
purpose a very short delay in writing a new page is relatively
innocuous to a user, and the display draws power only when a new
page is written.
[0033] To start a new page, a reset cycle is required, pulling all
the particles to the back, and then new writing can begin. Writing
can of course be done in subsequent phases, creating an illusion of
some motion.
[0034] Such a display has important use for such as electronic
books and teaching aids, and in many other ways as will be clear to
those with skill in the art, and it is clear that many of the
elements can be replaced or made in a different way, without
departing from the spirit and scope of the invention. For example,
the charge of the particles can be changed, which would require a
reversal of all the voltages described. Also, the gel could be
replaced with a sponge or a paper, containing a liquid allowing
electrophoresis. The active matrix could be replaced with a cross
matrix with a layer providing a tunneling effect, where the
breakdown would result in charge applied to the surface, which
could slowly trickle it away. While the charge is there, it would
attract those particles as well as resulting in a display. There
are similarly many other alternatives to the descriptions above.
well within the spirit and scope of the invention.
* * * * *