U.S. patent application number 13/114963 was filed with the patent office on 2011-09-15 for device having power generating black mask and method of fabricating the same.
This patent application is currently assigned to QUALCOMM MEMS Technologies. Invention is credited to Ion Bita, Chun-Ming Wang, Gang Xu.
Application Number | 20110222140 13/114963 |
Document ID | / |
Family ID | 40954865 |
Filed Date | 2011-09-15 |
United States Patent
Application |
20110222140 |
Kind Code |
A1 |
Bita; Ion ; et al. |
September 15, 2011 |
DEVICE HAVING POWER GENERATING BLACK MASK AND METHOD OF FABRICATING
THE SAME
Abstract
A power generating black mask comprising an anti-reflection
layer deposited over a substrate, a first electrode layer deposited
over the anti-reflection layer, a semi-conductor layer deposited
over the first electrode layer and a second electrode layer
deposited over the semi-conductor layer.
Inventors: |
Bita; Ion; (San Jose,
CA) ; Wang; Chun-Ming; (Fremont, CA) ; Xu;
Gang; (Cupertino, CA) |
Assignee: |
QUALCOMM MEMS Technologies
San Diego
CA
|
Family ID: |
40954865 |
Appl. No.: |
13/114963 |
Filed: |
May 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12371538 |
Feb 13, 2009 |
7969641 |
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13114963 |
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61028721 |
Feb 14, 2008 |
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Current U.S.
Class: |
359/290 |
Current CPC
Class: |
G02F 1/13324 20210101;
G02B 26/001 20130101; G02F 1/133512 20130101; Y02E 10/52
20130101 |
Class at
Publication: |
359/290 |
International
Class: |
G02B 26/00 20060101
G02B026/00 |
Claims
1. An electronic device comprising: a display area comprising a
plurality of optical display elements, and a photovoltaic black
mask deposited in the areas between the optical display elements of
the display area and positioned between a substrate and the optical
display elements, wherein the photovoltaic black mask comprises: at
least one layer being configured to absorb light, and at least one
layer being configured to generate power.
2. The electronic device of claim 1, wherein the photovoltaic black
mask comprises at least ten percent of the display area.
3. The electronic device of claim 1, wherein the photovoltaic black
mask comprises an anti-reflection layer deposited over a
substrate.
4. The electronic device of claim 3, wherein the anti-reflection
layer comprises at least one layer of material.
5. The electronic device of claim 3, wherein: the photovoltaic
black mask is patterned such that an opening is formed through a
second electrode layer and a semiconductor layer to a first
electrode layer, the first electrode layer being deposited over the
anti-reflection layer, the semiconductor layer being deposited over
the first electrode layer, and the second electrode layer being
deposited over the semiconductor layer, an insulator is positioned
over the second electrode layer and semiconductor layers, and the
insulator is patterned such that an opening is formed through the
insulator to the second first electrode layer.
6. The electronic device of claim 1, wherein the photovoltaic black
mask is patterned into discrete sections.
7. The electronic device of claim 6, wherein electrodes in the
sections are connected in series or in parallel.
8. The electronic device of claim 1, further comprising: a
processor that is configured to communicate with the plurality of
optical display elements, the processor being configured to process
image data; and a memory device that is configured to communicate
with the processor.
9. The electronic device of claim 8, further comprising: a driver
circuit configured to send at least one signal to the plurality of
optical display elements.
10. The electronic device of claim 9, further comprising: a
controller configured to send at least a portion of the image data
to the driver circuit.
11. The electronic device of claim 8, further comprising: an image
source module configured to send the image data to the
processor.
12. The electronic device of claim 11, wherein the image source
module includes at least one of a receiver, transceiver, and
transmitter.
13. The electronic device of claim 8, further comprising: an input
device configured to receive input data and to communicate the
input data to the processor.
14. An electronic device comprising: a display area comprising a
plurality of optical display elements; means for absorbing light;
and means for generating power; wherein the absorbing means and the
power generating means are deposited in the areas between the
optical display elements of the display area and positioned between
a substrate and the optical display elements.
15. The electronic device of claim 14, wherein the absorbing means
and the power generating means comprise at least ten percent of the
display area.
16. The electronic device of claim 14, further comprising an
anti-reflection layer deposited over a substrate.
17. The electronic device of claim 16, wherein the anti-reflection
layer comprises at least one layer of material.
18. The electronic device of claim 14, wherein the absorbing means
and the power generating means are patterned into discrete
sections.
19. The electronic device of claim 18, wherein electrodes in the
sections are connected in series or in parallel.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and is a continuation of
U.S. patent application Ser. No. 12/371,538, filed Feb. 13, 2009;
which application is hereby expressly incorporated by reference in
its entirety. U.S. patent application Ser. No. 12/371,538 claimed
the benefit of U.S. Provisional Patent Application No. 61/028,721,
titled "DEVICE HAVING POWER GENERATING BLACK MASK AND METHOD OF
FABRICATING THE SAME," filed Feb. 14, 2008, which is incorporated
by reference, in its entirety.
BACKGROUND
[0002] 1. Field of the Invention
[0003] The field of the invention relates to microelectromechanical
systems (MEMS).
[0004] 2. Description of the Related Technology
[0005] Microelectromechanical systems (MEMS) include micro
mechanical elements, actuators, and electronics. Micromechanical
elements may be created using deposition, etching, and/or other
micromachining processes that etch away parts of substrates and/or
deposited material layers or that add layers to form electrical and
electromechanical devices. One type of MEMS device is called an
interferometric modulator. As used herein, the term interferometric
modulator or interferometric light modulator refers to a device
that selectively absorbs and/or reflects light using the principles
of optical interference. In certain embodiments, an interferometric
modulator may comprise a pair of conductive plates, one or both of
which may be transparent and/or reflective in whole or part and
capable of relative motion upon application of an appropriate
electrical signal. In a particular embodiment, one plate may
comprise a stationary layer deposited on a substrate and the other
plate may comprise a metallic membrane separated from the
stationary layer by an air gap. As described herein in more detail,
the position of one plate in relation to another can change the
optical interference of light incident on the interferometric
modulator. Such devices have a wide range of applications, and it
would be beneficial in the art to utilize and/or modify the
characteristics of these types of devices so that their features
can be exploited in improving existing products and creating new
products that have not yet been developed.
SUMMARY
[0006] In one embodiment, an electronic device comprises a display
area comprising a plurality of optical display elements, and a
photovoltaic black mask deposited in the areas between the optical
display elements of the display area, wherein the photovoltaic
black mask comprises at least one layer being configured to absorb
light, and at least one layer being configured to generate
power.
[0007] In another embodiment, a method of making a photovoltaic
black mask comprises depositing an anti-reflection layer over a
substrate, depositing a first electrode over the anti-reflection
layer, depositing a semiconductor layer over the first electrode
layer, depositing a second electrode over the semiconductor layer,
and patterning a portion of the anti-reflection layer, the first
electrode layer, the semiconductor layer, and the second electrode
layer.
[0008] In another embodiment, an electronic device comprises a
display area comprising a plurality of optical display elements,
means for absorbing light, and means for generating power wherein
the absorbing means and the power generating means are deposited in
the areas between the optical display elements of the display
area.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is an isometric view depicting a portion of one
embodiment of an interferometric modulator display in which a
movable reflective layer of a first interferometric modulator is in
a relaxed position and a movable reflective layer of a second
interferometric modulator is in an actuated position.
[0010] FIG. 2 is a system block diagram illustrating one embodiment
of an electronic device incorporating a 3.times.3 interferometric
modulator display.
[0011] FIG. 3 is a diagram of movable minor position versus applied
voltage for one exemplary embodiment of an interferometric
modulator of FIG. 1.
[0012] FIG. 4 is an illustration of a set of row and column
voltages that may be used to drive an interferometric modulator
display.
[0013] FIG. 5A illustrates one exemplary frame of display data in
the 3.times.3 interferometric modulator display of FIG. 2.
[0014] FIG. 5B illustrates one exemplary timing diagram for row and
column signals that may be used to write the frame of FIG. 5A.
[0015] FIGS. 6A and 6B are system block diagrams illustrating an
embodiment of a visual display device comprising a plurality of
interferometric modulators.
[0016] FIG. 7A is a cross section of the device of FIG. 1.
[0017] FIG. 7B is a cross section of an alternative embodiment of
an interferometric modulator.
[0018] FIG. 7C is a cross section of another alternative embodiment
of an interferometric modulator.
[0019] FIG. 7D is a cross section of yet another alternative
embodiment of an interferometric modulator.
[0020] FIG. 7E is a cross section of an additional alternative
embodiment of an interferometric modulator.
[0021] FIG. 8A is a top view of a portion of an interferometric
modulator array illustrating non-active areas containing structures
included in a plurality of optical display elements.
[0022] FIG. 8B is a top elevational view of a portion of an
interferometric modulator array illustrating non-active areas
containing structures included in a plurality of optical display
elements.
[0023] FIG. 9 shows a cross-section through a MEMS device having a
mask or light-absorbing region in accordance with one
embodiment.
[0024] FIG. 10 illustrates a power generating black masking
according to an embodiment.
[0025] FIGS. 11A-11G illustrate a method of manufacture for a power
generating black mask according to an embodiment.
[0026] FIGS. 12A-12B illustrate a power generating black mask
according to another embodiment.
[0027] FIG. 13 illustrates a power generating black mask connected
in series according to another embodiment.
[0028] FIG. 14A is a graph illustrating the amount of light
reflected and absorbed by en embodiment of the power generating
black mask.
[0029] FIG. 14B is a table illustrating the materials and thickness
of the layers of an embodiment of the power generating black.
DETAILED DESCRIPTION
[0030] The following detailed description is directed to certain
specific embodiments. However, other embodiments may be used and
some elements can be embodied in a multitude of different ways. In
this description, reference is made to the drawings wherein like
parts are designated with like numerals throughout. As will be
apparent from the following description, the embodiments may be
implemented in any device that is configured to display an image,
whether in motion (e.g., video) or stationary (e.g., still image),
and whether textual or pictorial. More particularly, it is
contemplated that the embodiments may be implemented in or
associated with a variety of electronic devices such as, but not
limited to, mobile telephones, wireless devices, personal data
assistants (PDAs), hand-held or portable computers, GPS
receivers/navigators, cameras, MP3 players, camcorders, game
consoles, wrist watches, clocks, calculators, television monitors,
flat panel displays, computer monitors, auto displays (e.g.,
odometer display, etc.), cockpit controls and/or displays, display
of camera views (e.g., display of a rear view camera in a vehicle),
electronic photographs, electronic billboards or signs, projectors,
architectural structures, packaging, and aesthetic structures
(e.g., display of images on a piece of jewelry). MEMS devices of
similar structure to those described herein can also be used in
non-display applications such as in electronic switching
devices.
[0031] The desire for more power efficient mobile device displays
while maintaining the visual quality of previous displays is
facilitated by optical masks with power generating capabilities.
For these and other reasons, it is desirable to decrease the amount
of power used by the device or even generate enough power to charge
additional components, while minimizing the amount of additional
passive or non-active optical contents in a display. In one
embodiment, a multi-purpose optical component that acts as a power
generating optical mask, e.g., a "black mask," to absorb ambient or
stray light and to improve the optical response of a display device
by increasing the contrast ratio, and to also generate power for
the device using the black mask. A power generating black mask may
be used in visual displays and may generate power in order to
reduce the overall power consumption of the device. In addition, a
power generating black mask may generate enough power to charge a
component of the device. In some applications, the black mask can
reflect light of a predetermined wavelength to appear as a color
other than black. In one embodiment, a MEMS display device, for
example, an array of interferometric modulators, comprises a
dynamic optical component (e.g., a dynamic interferometric
modulator) and a static optical component (e.g., a static
interferometric modulator) laterally offset from the dynamic
optical component. The static optical component functions as the
"black mask" to absorb ambient or stray light in non-active areas
of a display to improve the optical response of the dynamic optical
component, and acts as a power generating component. For example,
non-active areas can include one or more areas of a MEMS display
device other than the area corresponding to a movable reflective
layer. A non-active area can also include an area of a display
device that is not used to display an image or data rendered on the
display device.
[0032] Although a MEMS device, which includes an interferometric
modulator, will be used to illustrate one embodiment, it is to be
understood that portions of the present disclosure may be applied
to other optical devices such as various imaging display and
optoelectronic devices in general, which have non-active areas
which are required to be light-absorbing, but which do not include
interferometric modulators (e.g., LCD, LED and plasma displays). As
will be apparent from the following description, portions of the
present disclosure may be implemented in any device that is
configured to display an image, whether in motion (e.g., video) or
stationary (e.g., still image), and whether textual or pictorial.
More particularly, the present disclosure may be applied to a
variety of electronic devices such as, but not limited to, mobile
telephones, wireless devices, personal data assistants (PDAs),
hand-held or portable computers, GPS receivers/navigators, cameras,
MP3 players, camcorders, game consoles, wrist watches, clocks,
calculators, television monitors, flat panel displays, computer
monitors, auto displays (e.g., odometer display, etc.), cockpit
controls and/or displays, display of camera views (e.g., display of
a rear view camera in a vehicle), electronic photographs,
electronic billboards or signs, projectors, architectural
structures, packaging, and aesthetic structures (e.g., display of
images on a piece of jewelry). MEMS devices of similar structure to
those described herein can also be used in non-display applications
such as in electronic switching devices. In addition, the present
disclosure is not in any way limited to use in visual display
devices.
[0033] One interferometric modulator display embodiment comprising
an interferometric MEMS display element is illustrated in FIG. 1.
In these devices, the pixels are in either a bright or dark state.
In the bright ("on" or "open") state, the display element reflects
a large portion of incident visible light to a user. When in the
dark ("off" or "closed") state, the display element reflects little
incident visible light to the user. Depending on the embodiment,
the light reflectance properties of the "on" and "off" states may
be reversed. MEMS pixels can be configured to reflect predominantly
at selected colors, allowing for a color display in addition to
black and white.
[0034] FIG. 1 is an isometric view depicting two adjacent pixels in
a series of pixels of a visual display, wherein each pixel
comprises a MEMS interferometric modulator. In some embodiments, an
interferometric modulator display comprises a row/column array of
these interferometric modulators. Each interferometric modulator
includes a pair of reflective layers positioned at a variable and
controllable distance from each other to form a resonant optical
gap with at least one variable dimension. In one embodiment, one of
the reflective layers may be moved between two positions. In the
first position, referred to herein as the relaxed position, the
movable reflective layer is positioned at a relatively large
distance from a fixed partially reflective layer. In the second
position, referred to herein as the actuated position, the movable
reflective layer is positioned more closely adjacent to the
partially reflective layer. Incident light that reflects from the
two layers interferes constructively or destructively depending on
the position of the movable reflective layer, producing either an
overall reflective or non-reflective state for each pixel.
[0035] The depicted portion of the pixel array in FIG. 1 includes
two adjacent interferometric modulators 12a and 12b. In the
interferometric modulator 12a on the left, a movable reflective
layer 14a is illustrated in a relaxed position at a predetermined
distance from an optical stack 16a, which includes a partially
reflective layer. In the interferometric modulator 12b on the
right, the movable reflective layer 14b is illustrated in an
actuated position adjacent to the optical stack 16b.
[0036] The optical stacks 16a and 16b (collectively referred to as
optical stack 16), as referenced herein, typically comprise several
fused layers, which can include an electrode layer, such as indium
tin oxide (ITO), a partially reflective layer, such as chromium,
and a transparent dielectric. The optical stack 16 is thus
electrically conductive, partially transparent, and partially
reflective, and may be fabricated, for example, by depositing one
or more of the above layers onto a transparent substrate 20. The
partially reflective layer can be formed from a variety of
materials that are partially reflective such as various metals,
semiconductors, and dielectrics. The partially reflective layer can
be formed of one or more layers of materials, and each of the
layers can be formed of a single material or a combination of
materials.
[0037] In some embodiments, the layers of the optical stack 16 are
patterned into parallel strips, and may form row electrodes in a
display device as described further below. The movable reflective
layers 14a, 14b may be formed as a series of parallel strips of a
deposited metal layer or layers (orthogonal to the row electrodes
of 16a, 16b) deposited on top of posts 18 and an intervening
sacrificial material deposited between the posts 18. When the
sacrificial material is etched away, the movable reflective layers
14a, 14b are separated from the optical stacks 16a, 16b by a
defined gap 19. A highly conductive and reflective material such as
aluminum may be used for the reflective layers 14, and these strips
may form column electrodes in a display device.
[0038] With no applied voltage, the gap 19 remains between the
movable reflective layer 14a and optical stack 16a, with the
movable reflective layer 14a in a mechanically relaxed state, as
illustrated by the pixel 12a in FIG. 1. However, when a potential
difference is applied to a selected row and column, the capacitor
formed at the intersection of the row and column electrodes at the
corresponding pixel becomes charged, and electrostatic forces pull
the electrodes together. If the voltage is high enough, the movable
reflective layer 14 is deformed and is forced against the optical
stack 16. A dielectric layer (not illustrated in this Figure)
within the optical stack 16 may prevent shorting and control the
separation distance between layers 14 and 16, as illustrated by
pixel 12b on the right in FIG. 1. The behavior is the same
regardless of the polarity of the applied potential difference. In
this way, row/column actuation that can control the reflective vs.
non-reflective pixel states is analogous in many ways to that used
in conventional LCD and other display technologies.
[0039] FIGS. 2 through 5B illustrate one exemplary process and
system for using an array of interferometric modulators in a
display application.
[0040] FIG. 2 is a system block diagram illustrating one embodiment
of an electronic device that may incorporate aspects of the
invention. In the exemplary embodiment, the electronic device
includes a processor 21 which may be any general purpose single- or
multi-chip microprocessor such as an ARM, Pentium.RTM., Pentium
II.RTM., Pentium III.RTM., Pentium IV.RTM., Pentium.RTM. Pro, an
8051, a MIPS.RTM., a Power PC.RTM., an ALPHA.RTM., or any special
purpose microprocessor such as a digital signal processor,
microcontroller, or a programmable gate array. As is conventional
in the art, the processor 21 may be configured to execute one or
more software modules. In addition to executing an operating
system, the processor may be configured to execute one or more
software applications, including a web browser, a telephone
application, an email program, or any other software
application.
[0041] In one embodiment, the processor 21 is also configured to
communicate with an array driver 22. In one embodiment, the array
driver 22 includes a row driver circuit 24 and a column driver
circuit 26 that provide signals to a display array or panel 30. The
cross section of the array illustrated in FIG. 1 is shown by the
lines 1-1 in FIG. 2. For MEMS interferometric modulators, the
row/column actuation protocol may take advantage of a hysteresis
property of these devices illustrated in FIG. 3. It may require,
for example, a 10 volt potential difference to cause a movable
layer to deform from the relaxed state to the actuated state.
However, when the voltage is reduced from that value, the movable
layer maintains its state as the voltage drops back below 10 volts.
In the exemplary embodiment of FIG. 3, the movable layer does not
relax completely until the voltage drops below 2 volts. Thus, there
exists a window of applied voltage, about 3 to 7 V in the example
illustrated in FIG. 3, within which the device is stable in either
the relaxed or actuated state. This is referred to herein as the
"hysteresis window" or "stability window." For a display array
having the hysteresis characteristics of FIG. 3, the row/column
actuation protocol can be designed such that during row strobing,
pixels in the strobed row that are to be actuated are exposed to a
voltage difference of about 10 volts, and pixels that are to be
relaxed are exposed to a voltage difference of close to zero volts.
After the strobe, the pixels are exposed to a steady state voltage
difference of about 5 volts such that they remain in whatever state
the row strobe put them in. After being written, each pixel sees a
potential difference within the "stability window" of 3-7 volts in
this example. This feature makes the pixel design illustrated in
FIG. 1 stable under the same applied voltage conditions in either
an actuated or relaxed pre-existing state. Since each pixel of the
interferometric modulator, whether in the actuated or relaxed
state, is essentially a capacitor formed by the fixed and moving
reflective layers, this stable state can be held at a voltage
within the hysteresis window with almost no power dissipation.
Essentially no current flows into the pixel if the applied
potential is fixed.
[0042] In typical applications, a display frame may be created by
asserting the set of column electrodes in accordance with the
desired set of actuated pixels in the first row. A row pulse is
then applied to the row 1 electrode, actuating the pixels
corresponding to the asserted column lines. The asserted set of
column electrodes is then changed to correspond to the desired set
of actuated pixels in the second row. A pulse is then applied to
the row 2 electrode, actuating the appropriate pixels in row 2 in
accordance with the asserted column electrodes. The row 1 pixels
are unaffected by the row 2 pulse, and remain in the state they
were set to during the row 1 pulse. This may be repeated for the
entire series of rows in a sequential fashion to produce the frame.
Generally, the frames are refreshed and/or updated with new display
data by continually repeating this process at some desired number
of frames per second. A wide variety of protocols for driving row
and column electrodes of pixel arrays to produce display frames are
also well known and may be used in conjunction with the present
invention.
[0043] FIGS. 4, 5A, and 5B illustrate one possible actuation
protocol for creating a display frame on the 3.times.3 array of
FIG. 2. FIG. 4 illustrates a possible set of column and row voltage
levels that may be used for pixels exhibiting the hysteresis curves
of FIG. 3. In the FIG. 4 embodiment, actuating a pixel involves
setting the appropriate column to -V.sub.bias, and the appropriate
row to +.DELTA.V, which may correspond to -5 volts and +5 volts,
respectively. Relaxing the pixel is accomplished by setting the
appropriate column to +V.sub.bias, and the appropriate row to the
same +.DELTA.V, producing a zero volt potential difference across
the pixel. In those rows where the row voltage is held at zero
volts, the pixels are stable in whatever state they were originally
in, regardless of whether the column is at +V.sub.bias, or
-V.sub.bias. As is also illustrated in FIG. 4, it will be
appreciated that voltages of opposite polarity than those described
above can be used, e.g., actuating a pixel can involve setting the
appropriate column to +V.sub.bias, and the appropriate row to
-.DELTA.V. In this embodiment, releasing the pixel is accomplished
by setting the appropriate column to -V.sub.bias, and the
appropriate row to the same -.DELTA.V, producing a zero volt
potential difference across the pixel.
[0044] FIG. 5B is a timing diagram showing a series of row and
column signals applied to the 3.times.3 array of FIG. 2 which will
result in the display arrangement illustrated in FIG. 5A, where
actuated pixels are non-reflective. Prior to writing the frame
illustrated in FIG. 5A, the pixels can be in any state, and in this
example, all the rows are at 0 volts, and all the columns are at +5
volts. With these applied voltages, all pixels are stable in their
existing actuated or relaxed states.
[0045] In the FIG. 5A frame, pixels (1,1), (1,2), (2,2), (3,2) and
(3,3) are actuated. To accomplish this, during a "line time" for
row 1, columns 1 and 2 are set to -5 volts, and column 3 is set to
+5 volts. This does not change the state of any pixels, because all
the pixels remain in the 3-7 volt stability window. Row 1 is then
strobed with a pulse that goes from 0, up to 5 volts, and back to
zero. This actuates the (1,1) and (1,2) pixels and relaxes the
(1,3) pixel. No other pixels in the array are affected. To set row
2 as desired, column 2 is set to -5 volts, and columns 1 and 3 are
set to +5 volts. The same strobe applied to row 2 will then actuate
pixel (2,2) and relax pixels (2,1) and (2,3). Again, no other
pixels of the array are affected. Row 3 is similarly set by setting
columns 2 and 3 to -5 volts, and column 1 to +5 volts. The row 3
strobe sets the row 3 pixels as shown in FIG. 5A. After writing the
frame, the row potentials are zero, and the column potentials can
remain at either +5 or -5 volts, and the display is then stable in
the arrangement of FIG. 5A. It will be appreciated that the same
procedure can be employed for arrays of dozens or hundreds of rows
and columns. It will also be appreciated that the timing, sequence,
and levels of voltages used to perform row and column actuation can
be varied widely within the general principles outlined above, and
the above example is exemplary only, and any actuation voltage
method can be used with the systems and methods described
herein.
[0046] FIGS. 6A and 6B are system block diagrams illustrating an
embodiment of a display device 40. The display device 40 can be,
for example, a cellular or mobile telephone. However, the same
components of display device 40 or slight variations thereof are
also illustrative of various types of display devices such as
televisions and portable media players.
[0047] The display device 40 includes a housing 41, a display 30,
an antenna 43, a speaker 45, an input device 48, and a microphone
46. The housing 41 is generally formed from any of a variety of
manufacturing processes as are well known to those of skill in the
art, including injection molding and vacuum forming. In addition,
the housing 41 may be made from any of a variety of materials,
including, but not limited to, plastic, metal, glass, rubber, and
ceramic, or a combination thereof. In one embodiment, the housing
41 includes removable portions (not shown) that may be interchanged
with other removable portions of different color, or containing
different logos, pictures, or symbols.
[0048] The display 30 of exemplary display device 40 may be any of
a variety of displays, including a bi-stable display, as described
herein. In other embodiments, the display 30 includes a flat-panel
display, such as plasma, EL, OLED, STN LCD, or TFT LCD as described
above, or a non-flat-panel display, such as a CRT or other tube
device, as is well known to those of skill in the art. However, for
purposes of describing the present embodiment, the display 30
includes an interferometric modulator display, as described
herein.
[0049] The components of one embodiment of exemplary display device
40 are schematically illustrated in FIG. 6B. The illustrated
exemplary display device 40 includes a housing 41 and can include
additional components at least partially enclosed therein. For
example, in one embodiment, the exemplary display device 40
includes a network interface 27 that includes an antenna 43, which
is coupled to a transceiver 47. The transceiver 47 is connected to
a processor 21, which is connected to conditioning hardware 52. The
conditioning hardware 52 may be configured to condition a signal
(e.g., filter a signal). The conditioning hardware 52 is connected
to a speaker 45 and a microphone 46. The processor 21 is also
connected to an input device 48 and a driver controller 29. The
driver controller 29 is coupled to a frame buffer 28 and to an
array driver 22, which in turn is coupled to a display array 30. A
power supply 50 provides power to all components as required by the
particular exemplary display device 40 design.
[0050] The network interface 27 includes the antenna 43 and the
transceiver 47 so that the exemplary display device 40 can
communicate with one or more devices over a network.
[0051] In one embodiment, the network interface 27 may also have
some processing capabilities to relieve requirements of the
processor 21. The antenna 43 is any antenna known to those of skill
in the art for transmitting and receiving signals. In one
embodiment, the antenna transmits and receives RF signals according
to the IEEE 802.11 standard, including IEEE 802.11(a), (b), or (g).
In another embodiment, the antenna transmits and receives RF
signals according to the BLUETOOTH standard. In the case of a
cellular telephone, the antenna is designed to receive CDMA, GSM,
AMPS, or other known signals that are used to communicate within a
wireless cell phone network. The transceiver 47 pre-processes the
signals received from the antenna 43 so that they may be received
by and further manipulated by the processor 21. The transceiver 47
also processes signals received from the processor 21 so that they
may be transmitted from the exemplary display device 40 via the
antenna 43.
[0052] In an alternative embodiment, the transceiver 47 can be
replaced by a receiver. In yet another alternative embodiment,
network interface 27 can be replaced by an image source, which can
store or generate image data to be sent to the processor 21. For
example, the image source can be a digital video disc (DVD) or a
hard-disc drive that contains image data, or a software module that
generates image data.
[0053] Processor 21 generally controls the overall operation of the
exemplary display device 40. The processor 21 receives data, such
as compressed image data from the network interface 27 or an image
source, and processes the data into raw image data or into a format
that is readily processed into raw image data. The processor 21
then sends the processed data to the driver controller 29 or to
frame buffer 28 for storage. Raw data typically refers to the
information that identifies the image characteristics at each
location within an image. For example, such image characteristics
can include color, saturation, and gray-scale level.
[0054] In one embodiment, the processor 21 includes a
microcontroller, CPU, or logic unit to control operation of the
exemplary display device 40. Conditioning hardware 52 generally
includes amplifiers and filters for transmitting signals to the
speaker 45, and for receiving signals from the microphone 46.
Conditioning hardware 52 may be discrete components within the
exemplary display device 40, or may be incorporated within the
processor 21 or other components.
[0055] The driver controller 29 takes the raw image data generated
by the processor 21 either directly from the processor 21 or from
the frame buffer 28 and reformats the raw image data appropriately
for high speed transmission to the array driver 22. Specifically,
the driver controller 29 reformats the raw image data into a data
flow having a raster-like format, such that it has a time order
suitable for scanning across the display array 30. Then the driver
controller 29 sends the formatted information to the array driver
22. Although a driver controller 29, such as a LCD controller, is
often associated with the system processor 21 as a stand-alone
Integrated Circuit (IC), such controllers may be implemented in
many ways. They may be embedded in the processor 21 as hardware,
embedded in the processor 21 as software, or fully integrated in
hardware with the array driver 22.
[0056] Typically, the array driver 22 receives the formatted
information from the driver controller 29 and reformats the video
data into a parallel set of waveforms that are applied many times
per second to the hundreds and sometimes thousands of leads coming
from the display's x-y matrix of pixels.
[0057] In one embodiment, the driver controller 29, array driver
22, and display array 30 are appropriate for any of the types of
displays described herein. For example, in one embodiment, driver
controller 29 is a conventional display controller or a bi-stable
display controller (e.g., an interferometric modulator controller).
In another embodiment, array driver 22 is a conventional driver or
a bi-stable display driver (e.g., an interferometric modulator
display). In one embodiment, a driver controller 29 is integrated
with the array driver 22. Such an embodiment is common in highly
integrated systems such as cellular phones, watches, and other
small area displays. In yet another embodiment, display array 30 is
a typical display array or a bi-stable display array (e.g., a
display including an array of interferometric modulators).
[0058] The input device 48 allows a user to control the operation
of the exemplary display device 40. In one embodiment, input device
48 includes a keypad, such as a QWERTY keyboard or a telephone
keypad, a button, a switch, a touch-sensitive screen, or a
pressure- or heat-sensitive membrane. In one embodiment, the
microphone 46 is an input device for the exemplary display device
40. When the microphone 46 is used to input data to the device,
voice commands may be provided by a user for controlling operations
of the exemplary display device 40.
[0059] Power supply 50 can include a variety of energy storage
devices as are well known in the art. For example, in one
embodiment, power supply 50 is a rechargeable battery, such as a
nickel-cadmium battery or a lithium ion battery. In another
embodiment, power supply 50 is a renewable energy source, a
capacitor, or a solar cell including a plastic solar cell, and
solar-cell paint. In another embodiment, power supply 50 is
configured to receive power from a wall outlet.
[0060] In some embodiments, control programmability resides, as
described above, in a driver controller which can be located in
several places in the electronic display system. In some
embodiments, control programmability resides in the array driver
22. Those of skill in the art will recognize that the
above-described optimizations may be implemented in any number of
hardware and/or software components and in various
configurations.
[0061] The details of the structure of interferometric modulators
that operate in accordance with the principles set forth above may
vary widely. For example, FIGS. 7A-7E illustrate five different
embodiments of the movable reflective layer 14 and its supporting
structures. FIG. 7A is a cross section of the embodiment of FIG. 1,
where a strip of metal material 14 is deposited on orthogonally
extending supports 18. In FIG. 7B, the moveable reflective layer 14
is attached to supports at the corners only, on tethers 32. In FIG.
7C, the moveable reflective layer 14 is suspended from a deformable
layer 34, which may comprise a flexible metal. The deformable layer
34 connects, directly or indirectly, to the substrate 20 around the
perimeter of the deformable layer 34. These connections are herein
referred to as support posts. The embodiment illustrated in FIG. 7D
has support post plugs 42 upon which the deformable layer 34 rests.
The movable reflective layer 14 remains suspended over the gap, as
in FIGS. 7A-7C, but the deformable layer 34 does not form the
support posts by filling holes between the deformable layer 34 and
the optical stack 16. Rather, the support posts are formed of a
planarization material, which is used to form support post plugs
42. The embodiment illustrated in FIG. 7E is based on the
embodiment shown in FIG. 7D, but may also be adapted to work with
any of the embodiments illustrated in FIGS. 7A-7C, as well as
additional embodiments not shown. In the embodiment shown in FIG.
7E, an extra layer of metal or other conductive material has been
used to form a bus structure 44. This allows signal routing along
the back of the interferometric modulators, eliminating a number of
electrodes that may otherwise have had to be formed on the
substrate 20.
[0062] In embodiments such as those shown in FIG. 7, the
interferometric modulators function as direct-view devices, in
which images are viewed from the front side of the transparent
substrate 20, the side opposite to that upon which the modulator is
arranged. In these embodiments, the reflective layer 14 optically
shields the portions of the interferometric modulator on the side
of the reflective layer opposite the substrate 20, including the
deformable layer 34. This allows the shielded areas to be
configured and operated upon without negatively affecting the image
quality. Such shielding allows the bus structure 44 in FIG. 7E,
which provides the ability to separate the optical properties of
the modulator from the electromechanical properties of the
modulator, such as addressing and the movements that result from
that addressing. This separable modulator architecture allows the
structural design and materials used for the electromechanical
aspects and the optical aspects of the modulator to be selected and
to function independently of each other. Moreover, the embodiments
shown in FIGS. 7C-7E have additional benefits deriving from the
decoupling of the optical properties of the reflective layer 14
from its mechanical properties, which are carried out by the
deformable layer 34. This allows the structural design and
materials used for the reflective layer 14 to be optimized with
respect to the optical properties, and the structural design and
materials used for the deformable layer 34 to be optimized with
respect to desired mechanical properties.
[0063] FIGS. 8A and 8B illustrate an example of a portion of a
display with display elements that can incorporate a black mask.
FIGS. 8A and 8B illustrate an exemplary portion of a display that
includes an array of interferometric modulators. A black mask can
be used in the array shown in FIGS. 8A and 8B, and in any type of
display where it is useful to mask off certain areas of the display
from ambient light. FIG. 8A shows a plurality of pixels 12 of the
array. FIG. 8B shows an example of supports 18 located on the
plurality of pixels of the array of interferometric modulators that
can be masked to improve the optical response of the display, from
the "back" side of the substrate opposite the viewed "front" side
of the display. To improve an optical response (e.g., contrast) of
the display, it can be desirable to minimize light reflected from
certain areas of the array. Any area of an interferometric
modulator that increases the reflectance of the display in the dark
state can be masked off (e.g., by disposing a mask between the
structure and light entering the interferometric modulator) using a
black mask in order to increase the contrast ratio. Some of the
areas that can be masked to advantageously affect the display
include, but are not limited to, row cuts between interferometric
modulators 72 (FIG. 8A), the supports 18, bending areas of the
movable minor layers connecting to and/or around the supports 18
that are visible from the viewed side of the display, and areas
between movable minor layers of adjacent interferometric modulators
76 (FIG. 8A). The mask can be disposed in such areas so that it is
spaced apart from the movable minor of the interferometric
modulators, e.g., so that ambient light can propagate to and
reflect from the movable mirror, but the areas other than the
movable minor are masked, thus inhibiting ambient light from
reflecting from any other structures in the masked areas. These
areas that are masked can be referred to as "non-active areas"
because they are static or not intended to provide light
modulation, e.g., the areas do not include the movable mirror. In
some embodiments, the mask can be disposed so that light entering
the interferometric modulator falls onto either the masked area or
the movable mirror. In other embodiments, at least a portion of the
non-active areas are masked.
[0064] FIG. 9 shows a cross-sectional view of a simplified
representation of two elements of a multiple element display 100,
according to one embodiment. The display comprises two optical
components (other optical components not shown for clarity) which
are, in this embodiment, interferometric modulators 104. As
described above, interferometric modulator devices 104 comprise an
arrangement of reflective and/or transmissive films that produce a
desired optical response when the movable active area is driven
towards a substrate 202 in a direction indicated by arrows 106. In
FIG. 9, reference numerals 108 indicate non-active areas of the
interferometric modulators 104. Typically, it is desirable that the
non-active areas 108 be light-absorbing or to function as a black
mask so that when a viewer looks at the display 100 from a
direction indicated by the viewing arrow 110, the optical response
produced by the interferometric modulator devices 104 is not
degraded by the reflection of ambient light from the non-active
areas 108. In other embodiments, it can be desirable to mask the
non-active areas 108 with a colored mask (for example, green, red,
blue, yellow, etc.) other than black.
[0065] A mask for a non-active area 108 may be fabricated from
materials selected to have an optical response which absorbs or
attenuates light. The materials used to fabricate the mask may be
electrically conductive. According to embodiments herein, a mask
for each non-active area 108 can be fabricated as a stack of thin
films. For example, in one embodiment, the stack of thin films may
comprise a reflector layer positioned over an absorber layer which
is positioned over a non-light absorbing dielectric layer. In other
embodiments, the non-active areas 108 may comprise a single layer
of organic or inorganic materials which attenuates or absorbs
light, and a layer of a conductive material such as chrome or
aluminum.
[0066] FIG. 10 illustrates a power generating black mask 1024
according to an embodiment. The power generating black mask 1024
comprises a substrate 1004, an anti-reflection layer 1008
positioned over the substrate 1004, a first electrode layer 1012
positioned over the anti-reflection layer 1008, a semi-conductor
layer 1016 is positioned over the first electrode layer 1012, and a
second electrode layer 1020 is positioned over the semi-conductor
layer 1016. Black masks improve the visual quality of display
devices. This improvement is provided by a variety of features of
the black mask. For example, black masks minimize the amount of
additional passive or non-active optical contents in a display. In
addition, black masks absorb ambient or stray light and improve the
optical response of a display device by increasing the contrast
ratio. A power generating black mask according to an embodiment
provides all of the benefits listed above and provides additional
benefits. The power generating component of the black mask may
allow the device to use less power. In addition, the power
generating component of the black mask may be used to generate
power to charge at least one component in the device. For example,
the power generating black mask may generate enough power to charge
a battery used by the device. Or, the power generating black mask
may provide power to other components in the device.
[0067] FIGS. 11A-11G illustrate a method of manufacturing a power
generating black mask 1128 according to an embodiment. In this
embodiment, the power generating black mask 1128 is manufactured
for use in a display device. In FIG. 11A, the method starts with a
substrate 1104. The substrate 1104 may comprise glass or any other
material suitable for use as a substrate. In FIG. 11B, an
anti-reflection layer 1108 is positioned over the substrate 1104.
The anti-reflection layer 1108 reduces the amount of incoming light
that is reflected back out of the device by optically matching the
substrate 1104 and subsequent layer 1112. The anti-reflection layer
1108 may comprise multiple layers with alternating high and low
refractive indices. Additionally, the anti-reflection layer may
comprise SiO2, SiNx, MgF2, ITO, Al2O3, Yi2O3, ZnO or any other
material suitable for use as an anti-reflection layer. In FIG. 11C,
a first electrode layer 1112 is positioned over the anti-reflection
layer 1108. The first electrode layer 1112 may comprise ITO, or
other substantially transparent materials suitable for use as an
electrode. In FIG. 11D, a semi-conductor layer stack 1116 is
positioned over the first electrode layer 1112. The semi-conductor
layer stack 1116 may comprise p-n or p-i-n junction set of layers
corresponding to typical Si, CdTe or any other semiconductor
material set suitable for a photovoltaic cell. In FIG. 11E, the
second electrode layer 1120 is positioned over the semi-conductor
layer 1116. The second electrode layer 1120 may comprise ITO, Al,
or any other material suitable for use as an electrode. The second
electrode layer 1120 may be transparent or reflective. The power
generating black mask 1128 comprises the anti-reflection layer
1108, the first electrode layer 1112, the semi-conductor layer 1116
and the second electrode layer 1120. In FIG. 11F, the power
generating black mask 1128 is patterned. In this embodiment, the
power generating black mask 1128 is patterned to allow pixel
elements of the visual display to be positioned over the gaps in
the power generating black mask 1128. A planarization layer 1124
may be deposited over the patterned power generating black mask
1128, as shown in FIG. 11G. The planarization layer 1124 allows the
patterned power generating black mask 1128 to be used as an
engineered substrate 1132 in other manufacturing processes.
Manufacturing processes may build structures on top of the
engineered substrate 1132 as if they were directly building onto a
plain substrate such as glass, plastic, etc. For example, visual
displays comprising IMOD's may be built on top of the surface of
the engineered substrate 1132.
[0068] FIG. 12A shows a power generating black mask according to
another embodiment. In this embodiment, the method of manufacture
is similar to FIGS. 11A-11E. An insulator layer 1224 is deposited
over the power generating black mask 1228. The insulator 1224 is
then patterned such that an opening is formed to the second
electrode layer 1220. This exposes the second electrode layer 1220
and allows other structures to connect to the second electrode
layer 1220.
[0069] FIG. 12B shows a power generating black mask according to
yet another embodiment. In this embodiment, the method of
manufacture is similar to FIGS. 11A-11E. The power generating black
mask 1228 is patterned such that an opening is formed to the first
electrode layer 1212. An insulator layer 1224 is deposited over the
opening formed to the first electrode layer. The insulator layer
1224 is then patterned such that an opening is formed to the first
electrode layer 1212. This exposes the first electrode layer 1212
and allows other structures to connect to the first electrode layer
1212.
[0070] FIG. 13 illustrates a power generating black mask according
to another embodiment. This embodiment uses the embodiments
described in FIGS. 12A-12B. The power generating black mask 1300 is
shown from a top view. The power generating black mask 1300 is
patterned to correspond to pixel elements which are located around
openings 1320 and is divided into discrete sections 1304, 1308,
1312, and 1316. The sections 1304, 1308, 1312, and 1316 may be
configured to expose the first electrode layer 1212 as illustrated
in FIG. 12B or may be configured to expose the second electrode
layer 1220 as illustrated in FIG. 12A. Or the sections 1304, 1308,
1312, and 1316 may be configured such that a portion of the section
exposes the first electrode layer and a portion of the section 1312
exposes the second electrode layer. This allows the sections to be
connected in series or in parallel. In FIG. 13, the sections 1312
are connected in series by pairs of columns. Section 1316 is
connected to section 1312 in series and section 1308 and section
1304 are connected in series. The specification in no way limits
the configurations of the connections or the configurations of the
exposed electrode layers. The sections of the power generating
black mask 1304, 1308, 1312, and 1316 may be connected in series,
in parallel or a combination of both. The sections of the power
generating black mask may expose the first electrode layer 1212,
the second electrode layer 1330 or a combination of both. The
configuration of the sections and the electrode layers may be
specific to the device that uses the power generating black mask
1300. For example, a device requiring a higher voltage may connect
the sections 1304, 1308, 1312, and 1316 in series and connect the
electrode layers as shown in FIG. 13.
[0071] The following is a conservative estimate for the amount of
power generated by a power generating black mask according to an
embodiment. The power generating black mask comprises approximately
10% of the display area of a 1.8 inch diagonal IMOD display. The
width of the display is 0.035 meters and the height of the display
is 0.040 meters resulting in a display area of 0.0014 meters
squared. The black mask covers approximately 10% of the display
area, which is 0.00014 meters squared. The electrical efficiency of
the power generating black mask is 10%. The amount of incoming
sunlight is 1000 W/m.sup.2 and for a conservative estimate, only
50% of the incoming sunlight is assumed to be reaching the power
generating black mask. The 1000 W/m.sup.2 is the amount of sunlight
received under optimal conditions. Optimal conditions may include
receiving sunlight during noon-time, in an area closer to the
equator and in an area without clouds or fogs. With the conditions
given in the following example, the estimated amount of power
generated by a 1.8 inch diagonal display is 7 milliwatts or 0.007
watts. This is calculated as 500 W/m.sup.2 multiplied by the black
mask area which is 0.00014 m.sup.2 which is then multiplied by the
10% electrical efficiency of the power generating black mask. Black
masks may cover approximately 10%-30% of the display area. The
power generating black mask may have electrical efficiencies in the
range of 5%-20%. The amount of incoming light that reaches the
power generating black mask may depend on the time of the day, the
weather (i.e. clouds or fog), geographic location and a variety of
other conditions that may affect the amount of sunlight that may
reach the device. The following example merely illustrates a
conservative estimate of the amount of power generated by a power
generating black mask and in no way limits the amount of power that
may be generated by a power generating black mask. The amount of
power generated may be different for different embodiments.
[0072] FIG. 14A is a graph illustrating the amount of light
reflected and absorbed by a power generating black mask. The x-axis
of the graph represents the different wavelengths of incoming
light. The y-axis represents a percentage. The y-axis is on a scale
of 1, meaning that at 0.10, the percentage is 10%. As is show in
the graph, the power generating black mask generally reflects small
amounts of incoming light and absorbs the majority of incoming
light. For example, at a 550 nm wavelength of light, approximately
0.5% of the incoming light is reflected and 99.5% percent of the
incoming light is absorbed.
[0073] FIG. 14B is a table that illustrates the thickness and the
materials used in the electrode and semiconductor layers of a power
generating black mask according to an embodiment. The first
electrode layer is transparent and comprises ITO and is
approximately 72 nm thick. The semiconductor layer comprises a-Si
and is approximately 15 nm thick. The second electrode layer is
reflective and comprises Cr and is approximately 100 nm thick. The
power generating black mask illustrated in this embodiment reflects
approximately 0.5% of incoming light.
[0074] The embodiments described above provide the functionality of
a black mask while providing additional benefits. A power
generating black mask according to an embodiment allows devices
which use a black mask to be more power efficient while reflecting
less then one percent of incoming light. The power generating black
mask may be used to reduce the amount of power used by the device
using the power generating black mask. In addition, the power
generating black mask may be used to generate power to run or
charge at least one component of a device using the power
generating black mask. In another embodiment, the power generating
black mask may be patterned to provide openings to either the first
or the second electrode layer or both. In another embodiment, the
power generating black mask make be divided into discrete sections
and the sections may be connected in series or in parallel or in
both. While various embodiments described herein pertain to MEMS or
visual displays, it will be understood that the disclosure is not
limited to use in such devices. Any device that uses a black mask
may use embodiments of the invention.
[0075] It will be understood that numerous and various
modifications can be made from those previously described
embodiments and that the forms of the invention described herein
are illustrative only and are not intended to limit the scope of
the invention. The detailed description of certain embodiments
presents various descriptions of specific embodiments of the
invention. However, the invention can be embodied in a multitude of
different ways as defined and covered by the claims.
[0076] The terminology used in the description presented herein is
not intended to be interpreted in any limited or restrictive
manner, simply because it is being utilized in conjunction with a
detailed description of certain specific embodiments of the
invention. Furthermore, embodiments of the invention may include
several novel features, no single one of which is solely
responsible for its desirable attributes or which is essential to
practicing the inventions herein described.
* * * * *