U.S. patent application number 14/673475 was filed with the patent office on 2015-07-23 for optical touch device with pixilated light-turning features.
The applicant listed for this patent is QUALCOMM MEMS Technologies, Inc.. Invention is credited to David William Burns, Russell Wayne Gruhlke, Lai Wang, Ye Yin.
Application Number | 20150205443 14/673475 |
Document ID | / |
Family ID | 47992105 |
Filed Date | 2015-07-23 |
United States Patent
Application |
20150205443 |
Kind Code |
A1 |
Gruhlke; Russell Wayne ; et
al. |
July 23, 2015 |
OPTICAL TOUCH DEVICE WITH PIXILATED LIGHT-TURNING FEATURES
Abstract
This disclosure provides systems, methods and apparatus for a
touch screens configured to determine a position of a touch event
by selectively redirecting light to correlated locations on a light
sensor. In one aspect, the touch screen apparatus can include a
light guide forming a touch interface, a light source for injecting
light into the light guide, a light sensor for detecting the
injected light, and a pixilated light-turning layer. The pixilated
light-turning layer can include a plurality of light-turning
features forming pixels. The pixels can receive incident light
corresponding to the emitted light scattered by an object
contacting the light guide. The pixels can redirect the incident
scattered light towards the light sensor such that light
selectively propagates to one or more correlated light receiving
locations. A processor can map the light receiving location to an
area contacted by the object, thereby determining a position of a
touch event.
Inventors: |
Gruhlke; Russell Wayne;
(Milpitas, CA) ; Yin; Ye; (Santa Clara, CA)
; Wang; Lai; (Milpitas, CA) ; Burns; David
William; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM MEMS Technologies, Inc. |
San Diego |
CA |
US |
|
|
Family ID: |
47992105 |
Appl. No.: |
14/673475 |
Filed: |
March 30, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13307353 |
Nov 30, 2011 |
9019240 |
|
|
14673475 |
|
|
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|
61541014 |
Sep 29, 2011 |
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Current U.S.
Class: |
345/175 |
Current CPC
Class: |
G06F 3/0428 20130101;
G02B 26/08 20130101; G02B 26/001 20130101; G02B 6/0053 20130101;
G02B 6/0011 20130101; G06F 3/0421 20130101; G02F 1/13338
20130101 |
International
Class: |
G06F 3/042 20060101
G06F003/042; G02B 26/08 20060101 G02B026/08; G02B 26/00 20060101
G02B026/00 |
Claims
1. (canceled)
2. A touch screen apparatus comprising: a light source including a
plurality of light emitters each configured to emit collimated
light; a light guide having: a major surface defining a touch input
surface of the touch screen apparatus; and a light input surface
configured to receive light emitted by the plurality of light
emitters; a light sensor having a plurality of light receiving
locations; and a pixilated light-turning layer including a
plurality of light-turning features forming pixels, each of the
pixels configured to selectively redirect light emitted from the
light source and scattered by an object above the touch input
surface, wherein the scattered light is redirected to one or more
correlated light receiving locations of the light sensor.
3. The apparatus of claim 2, wherein the apparatus further
comprises a processor configured to determine a coordinate
corresponding to one axis of the major surface based on which light
emitter of the plurality of light emitters emitted the collimated
light into the light guide that was scattered by the object.
4. The apparatus of claim 2, wherein the apparatus further
comprises a processor configured to correlate a light receiving
location receiving scattered light with a discrete area of the
major surface.
5. The apparatus of claim 4, wherein each discrete area on the
major surface overlies one or more of the pixels, and wherein each
of the one or more of the pixels is configured to redirect
scattered light to a matching one of the one or more correlated
light receiving locations.
6. The apparatus of claim 2, wherein the plurality of light
emitters are each configured to sequentially emit collimated light
into the first edge of the light guide.
7. The apparatus of claim 6, further comprising a processor
configured to determine positions of the major surface
simultaneously contacted by two different objects based at least
partly on particular light receiving locations receiving scattered
light associated with the two different objects and times at which
the scattered light associated with the two different objects
strike the particular light receiving locations.
8. The apparatus of claim 2, further comprising a processor
configured to determine positions of the major surface
simultaneously contacted by two different objects based at least
partly on particular light receiving locations receiving scattered
light associated with the two different objects and wavelengths of
the scattered light associated with the two different objects
strike the particular light receiving locations.
9. The apparatus of claim 2, wherein the light sensor is disposed
on a second edge of the light guide, and wherein the second edge is
disposed on an axis transverse to the first edge.
10. The apparatus of claim 9, further comprising: a second
plurality of light emitters configured to emit collimated light
into a third edge of the light guide; and a second light sensor
disposed on a fourth edge of the light guide, wherein the fourth
edge is disposed on an axis crossing the third edge.
11. The apparatus of claim 2, wherein the light turning features
are diffractive light turning features.
12. The apparatus of claim 2, wherein the pixilated light-turning
layer is a holographic layer, and wherein the light-turning
features form holographic pixels.
13. The apparatus of claim 2, wherein the light source is
configured to emit infrared light.
14. The apparatus of claim 2, wherein the light sensor is formed by
an array of discrete light sensing devices.
15. A touch screen apparatus comprising: a light guide having a
major surface for receiving a touch input; means for injecting
collimated light into the light guide; a light sensor having a
light receiving surface, the light receiving surface having a
plurality of light receiving locations; and means for redirecting
light injected into the light guide and scattered by an object
contacting the major surface such that each of the plurality of
light receiving locations selectively receives the scattered light
substantially only from an area of the major surface correlated
with the each of the plurality of light receiving locations.
16. The apparatus of claim 15, wherein the light-turning means
includes a plurality of light-turning features forming pixels, each
pixel configured to selectively redirect light to a correlated
light receiving location.
17. The apparatus of claim 15, wherein the light-turning means is a
holographic layer.
18. The apparatus of claim 15, further comprising a processor
configured to determine a coordinate corresponding to one axis of
the major surface based at least partly on a time at which the
light sensor receives the scattered light at a particular light
receiving location of the plurality of light receiving
locations.
19. The apparatus of claim 15, further comprising a processor
configured to determine positions of the major surface
simultaneously contacted by two different objects.
20. A method of detecting at least one touch event on a touch
screen, the method comprising: receiving light directed from a
pixilated light-turning layer at a light sensor location on a light
sensor, the pixilated light-turning layer including pixels
configured to redirect at least a portion of incident light
scattered by an object above a light guide to the light sensor
location; mapping the light sensor location receiving the incident
light with a location of the object, wherein the mapping includes
determining which light source of a plurality of light sources
emitted light into the light guide that was scattered by the
object, and wherein the light sensor location is correlated with at
least one pixel of the pixilated light-turning layer; and
determining a position of a touch event based at least partly on
the mapping.
21. The method of claim 20, wherein the pixilated light-turning
layer is a holographic layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/307,353 filed on Nov. 30, 2011, titled
"OPTICAL TOUCH DEVICE WITH PIXILATED LIGHT-TURNING FEATURES," and
this application claims the benefit under 35 U.S.C. .sctn.119(e) of
U.S. Provisional Patent Application No. 61/541,014 filed on Sep.
29, 2011, titled "OPTICAL TOUCH DEVICE WITH PIXILATED LIGHT-TURNING
FEATURES," the entire disclosures of these priority applications
are hereby incorporated by reference herein in their
entireties.
TECHNICAL FIELD
[0002] This disclosure relates to user interface devices, and more
particularly, to touch screen apparatus.
DESCRIPTION OF THE RELATED TECHNOLOGY
[0003] Electromechanical systems include devices having electrical
and mechanical elements, actuators, transducers, sensors, optical
components (e.g., mirrors) and electronics. Electromechanical
systems can be manufactured at a variety of scales including, but
not limited to, microscales and nanoscales. For example,
microelectromechanical systems (MEMS) devices can include
structures having sizes ranging from about a micron to hundreds of
microns or more. Nanoelectromechanical systems (NEMS) devices can
include structures having sizes smaller than a micron including,
for example, sizes smaller than several hundred nanometers.
Electromechanical elements may be created using deposition,
etching, lithography, 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.
[0004] One type of electromechanical systems device is called an
interferometric modulator (IMOD). 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 some implementations, an
interferometric modulator may include a pair of conductive plates,
one or both of which may be transparent and/or reflective, wholly
or in part, and capable of relative motion upon application of an
appropriate electrical signal. In an implementation, one plate may
include a stationary layer deposited on a substrate and the other
plate may include a reflective membrane separated from the
stationary layer by an air gap. The position of one plate in
relation to another can change the optical interference of light
incident on the interferometric modulator. Interferometric
modulator devices have a wide range of applications, and are
anticipated to be used in improving existing products and creating
new products, especially those with display capabilities.
[0005] Many display systems include user interfaces having an input
component. The input component can include a screen with a contact
sensing mechanism configured to facilitate determination of a
location where contact with the screen is made. This contact with
the screen can be made by objects such as a fingertip, pen, or a
stylus. To meet market demands and design criteria for devices with
contact sensing, new input components are continually being
developed.
SUMMARY
[0006] The systems, methods and devices of the disclosure each have
several innovative aspects, no single one of which is solely
responsible for the desirable attributes disclosed herein.
[0007] One innovative aspect of the subject matter described in
this disclosure can be implemented in a touch screen apparatus that
includes a light guide, a light source, a light sensor, and a
pixilated light-turning layer. The light guide has a major surface
defining a touch input surface of the touch screen apparatus. The
light source is configured to inject light into the light guide.
The light sensor has a plurality of light receiving locations. The
pixilated light-turning layer includes a plurality of light-turning
features forming pixels. Each of the pixels is configured to
selectively redirect scattered light from the light source to one
or more correlated light receiving locations of the light sensor.
The scattered light can correspond to light emitted by the light
source that is scattered by an object upon the object contacting
the major surface.
[0008] The apparatus can also include a processor configured to
correlate a light receiving location receiving scattered light with
a discrete area of the major surface contacted by the object. In
some implementations, each discrete area on the major surface can
directly overlie one or more of the pixels and each of the one or
more of the pixels can be configured to redirect scattered light to
a matching one of the one or more correlated light receiving
locations. In some implementations, the plurality of light
receiving locations can have a one-to-one correlation with the
pixels. In some implementations, the pixilated light-turning layer
can be a holographic layer, in which the light-turning features
form holographic pixels.
[0009] The light guide can be disposed above the pixilated
light-turning layer and the apparatus can include a second light
guide below the pixilated light-turning layer that is configured to
propagate light from the pixilated light-turning layer towards the
light receiving locations of the light sensor. In some of these
implementations, the apparatus can also include an optical
decoupling layer between the light guide and the pixilated
light-turning layer.
[0010] The light source can include a first plurality of light
emitters configured to sequentially emit collimated light into a
first edge of the light guide, in which the light sensor is
disposed on a second edge of the light guide that is disposed on an
axis transverse to the first edge. In some of these
implementations, the apparatus can also include a second plurality
of light emitters configured to emit light into a third edge of the
light guide and another light sensor disposed on a fourth edge of
the light guide that is disposed on an axis crossing the third
edge.
[0011] Another innovative aspect of the subject matter described in
this disclosure can be implemented in an apparatus that includes a
light guide having a major surface for receiving a touch input, a
light source for injecting light into the light guide, a light
sensor, and a light turning means. The light sensor has a light
receiving surface having a plurality of light receiving locations.
The light-turning means redirects light injected into the light
guide and scattered by an object contacting the major surface such
that each of the plurality of light receiving locations selectively
receives the scattered light substantially only from an area of the
major surface correlated with the each of the plurality of light
receiving locations.
[0012] The light-turning means can include a plurality of
light-turning features forming pixels. Each of these pixels can be
configured to selectively redirect light to a correlated light
receiving location. In some implementations, the light-turning
features can be diffractive light-turning features. The
light-turning means can be a holographic layer.
[0013] The apparatus can also include a processor configured to
correlate a location of light striking the light receiving surface
with the area of the major surface contacted by the object.
[0014] The light source can include a plurality of light emitters
configured to sequentially emit collimated light into the light
guide. The sensor can be configured to detect light from the
plurality of light emitters. In some implementations, the apparatus
can include a processor configured to determine a coordinate
corresponding to one axis of the major surface based on which light
source of the plurality of light emitters injected the light into
the light guide.
[0015] The light guide can be disposed above the light-turning
means and the apparatus can also include another light guide below
the light-turning means and the light guide. The other light guide
can be configured to propagate light from the pixilated
light-turning layer towards the light sensor. In some of these
implementations, the apparatus can include an optical decoupling
layer between the light guide and the light-turning means.
[0016] Another innovative aspect of the subject matter described in
this disclosure can be implemented in a method of detecting at
least one touch event on a touch screen. The method includes
receiving light directed from a pixilated light-turning layer at a
light sensor location on a light sensor, the pixilated
light-turning layer including pixels configured to redirect at
least a portion of incident light scattered by an object above a
light guide to the light sensor location. The method also includes
mapping the light sensor location receiving the incident light with
a location of the object. The light sensor location is correlated
with at least one single pixel of the pixilated light-turning
layer. In addition, the method includes determining a position of a
touch event based on the mapping.
[0017] The locations on a light receiving surface of the light
sensor can have a one-to-one correspondence with a correlated
pixel, or a plurality of closely localized pixels, of the pixilated
light-turning layer. Alternatively or additionally, the pixilated
light-turning layer can be a holographic layer.
[0018] The method can also include causing a plurality of light
sources to sequentially emit collimated light into the light guide,
in which mapping the light sensor location includes determining
which light source of the plurality of light sources emitted light
scattered by the object.
[0019] The received light can be directed from the pixilated
light-turning layer to the light sensor location via another light
guide spaced apart from the light guide.
[0020] The method can also include receiving light directed from
the pixilated light-turning layer at a second light sensor
location; mapping the second light sensor location with a location
of a second object above the light guide, in which the second light
sensor location is correlated with a pixel of the pixilated
light-turning layer that is not correlated with the first light
sensor location; and determining a position of another touch event
based on mapping the second light sensor location with the location
of the second object, in which the touch event and the other touch
event are simultaneous.
[0021] Details of one or more implementations of the subject matter
described in this specification are set forth in the accompanying
drawings and the description below. Other features, aspects, and
advantages will become apparent from the description, the drawings,
and the claims. Note that the relative dimensions of the following
figures may not be drawn to scale.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 shows an example of an isometric view depicting two
adjacent pixels in a series of pixels of an interferometric
modulator (IMOD) display device.
[0023] FIG. 2 shows an example of a system block diagram
illustrating an electronic device incorporating a 3.times.3
interferometric modulator display.
[0024] FIG. 3 shows an example of a diagram illustrating movable
reflective layer position versus applied voltage for the
interferometric modulator of FIG. 1.
[0025] FIG. 4 shows an example of a table illustrating various
states of an interferometric modulator when various common and
segment voltages are applied.
[0026] FIG. 5A shows an example of a diagram illustrating a frame
of display data in the 3.times.3 interferometric modulator display
of FIG. 2.
[0027] FIG. 5B shows an example of a timing diagram for common and
segment signals that may be used to write the frame of display data
illustrated in FIG. 5A.
[0028] FIG. 6A shows an example of a partial cross-section of the
interferometric modulator display of FIG. 1.
[0029] FIGS. 6B-6E show examples of cross-sections of varying
implementations of interferometric modulators.
[0030] FIG. 7 shows an example of a flow diagram illustrating a
manufacturing process for an interferometric modulator.
[0031] FIGS. 8A-8E show examples of cross-sectional schematic
illustrations of various stages in a method of making an
interferometric modulator.
[0032] FIGS. 9A and 9B show examples of perspective views of a
touch screen apparatus with a pixilated light-turning layer.
[0033] FIGS. 10A and 10B show examples of plan and side views of an
implementation of a touch screen apparatus configured to detect the
presence and location of a contacting object.
[0034] FIGS. 10C and 10D show examples of selected light rays
scattered by an object contacting the touch screen of FIGS. 10A and
10B and redirected by a pixilated light-turning layer to a light
sensor.
[0035] FIGS. 11A and 11B show examples of plan and side views of
another implementation of a touch screen apparatus configured to
detect the presence and location of a contacting object.
[0036] FIGS. 11C and 11D show examples of selected light rays
scattered by an object contacting the touch screen of FIGS. 11A and
11B and redirected by a pixilated light-turning layer to a light
sensor.
[0037] FIG. 12A shows an example of a plan view of another
implementation of a touch screen apparatus configured to detect the
presence and location of a contacting obj ect.
[0038] FIG. 12B shows examples of selected light rays scattered by
an object contacting the touch screen of FIG. 12A and redirected by
a pixel of a pixilated light-turning layer to a light sensor.
[0039] FIG. 12C shows examples of selected light rays scattered by
two objects simultaneously contacting the touch screen of FIG. 12A
and redirected by a pixel of a pixilated light-turning layer to a
light sensor.
[0040] FIG. 12D shows an example of a plan view of another
implementation of a touch screen apparatus configured to detect the
presence and location of a contacting obj ect.
[0041] FIG. 13 shows an example of light-turning pixels correlated
with locations on a light sensor.
[0042] FIG. 14 shows an example of a flow diagram illustrating a
process for determining a position of a touch event according to
some implementations.
[0043] FIGS. 15A and 15B show examples of system block diagrams
illustrating a display device that includes a plurality of
interferometric modulators.
[0044] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0045] The following detailed description is directed to certain
implementations for the purposes of describing the innovative
aspects. However, the teachings herein can be applied in a
multitude of different ways. The described implementations 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, graphical or pictorial. More particularly, it
is contemplated that the implementations may be implemented in or
associated with a variety of electronic devices such as, but not
limited to, mobile telephones, multimedia Internet enabled cellular
telephones, mobile television receivers, wireless devices,
smartphones, Bluetooth.RTM. devices, personal data assistants
(PDAs), wireless electronic mail receivers, hand-held or portable
computers, netbooks, notebooks, smartbooks, tablets, printers,
copiers, scanners, facsimile devices, GPS receivers/navigators,
cameras, MP3 players, camcorders, game consoles, wrist watches,
clocks, calculators, television monitors, flat panel displays,
electronic reading devices (e.g., e-readers), computer monitors,
auto displays (e.g., odometer display, etc.), cockpit controls
and/or displays, camera view displays (e.g., display of a rear view
camera in a vehicle), electronic photographs, electronic billboards
or signs, projectors, architectural structures, microwaves,
refrigerators, stereo systems, cassette recorders or players, DVD
players, CD players, VCRs, radios, portable memory chips, washers,
dryers, washer/dryers, parking meters, packaging (e.g., MEMS and
non-MEMS), aesthetic structures (e.g., display of images on a piece
of jewelry) and a variety of electromechanical systems devices. The
teachings herein also can be used in non-display applications such
as, but not limited to, electronic switching devices, radio
frequency filters, sensors, accelerometers, gyroscopes,
motion-sensing devices, magnetometers, inertial components for
consumer electronics, parts of consumer electronics products,
varactors, liquid crystal devices, electrophoretic devices, drive
schemes, manufacturing processes, and electronic test equipment.
Thus, the teachings are not intended to be limited to the
implementations depicted solely in the Figures, but instead have
wide applicability as will be readily apparent to a person having
ordinary skill in the art.
[0046] In some implementations, an optical touch screen apparatus
is configured to determine the position of a touch event by
selectively redirecting scattered light from a touch event to
correlated locations on a light sensor. The light is scattered by
an object causing the touch event. The touch screen apparatus can
include a light guide having a major surface that forms the touch
interface of the touch screen apparatus, a light source for
injecting light into the light guide, a light sensor for detecting
scattered injected light, and a pixilated light-turning layer for
redirecting light to the light sensor. The pixilated light-turning
layer includes light-turning features that form pixels. The
light-turning layer can be a holographic layer in some
implementations, and can be disposed facing the major surface, for
example, directly under the light guide. A display can be provided
under the light-turning layer. Each pixel of the light-turning
layer can be configured to only redirect light to one or more
particular, predefined "correlated" locations on the light
receiving surface of the light sensor, without directing light to
other locations.
[0047] In operation, according to some implementations, the light
source can inject light into the light guide. When an object, such
as a finger, touches a major surface of the light guide, light from
the light source propagating through the light guide can be
scattered. The light-turning layer is disposed directly under the
object and receives the scattered light. Some of the scattered
light can be directed to a correlated location on the light sensor
by a pixel of the light-turning layer. The position of the touch
event can be determined by a processor based on the particular
sensor location receiving light redirected by the pixel. Because
the locations of the pixels over the surface of the touch interface
are fixed and known, and, in some implementations, using the
assumption that the pixels predominantly redirect light that has
been scattered downward, the location of the touch event is
understood to be directly above the pixel receiving the scattered
light, and the location of a touch event can be determined by
determining which part of light receiving surface of the light
sensor has received light. Thus, the receipt of light at a given
location on the light sensor indicates that an object has contacted
a particular area of the touch screen.
[0048] Particular implementations of the subject matter described
in this disclosure can be implemented to realize one or more of the
following potential advantages. Touch events can be accurately
detected based on optical principles with a touch screen having a
pixilated light-turning layer, such as a pixilated holographic
layer. For example, in some implementations, the pixilated
light-turning layer can reduce or prevent image degradation that
can result from conventional touch screens that utilize electrodes.
Because the touch screen can be disposed over a display, between a
viewer and the display, the electrodes can cause optical artifacts.
Obviating the electrodes may prevent these artifacts. In addition,
the optical touch screen can be simpler to manufacture than
electrode-based touch screens, since intricate electrode patterns
do not need to be formed. In addition, the light guide for the
touch screen may be integrated with a front light for the display
in some implementations, thereby reducing the number of parts for
the display system, which can have advantages for reducing
manufacturing and parts costs, and also for reducing the thickness
the display device.
[0049] An example of a suitable MEMS device, to which the described
implementations may apply, is a reflective display device.
Reflective display devices can incorporate interferometric
modulators (IMODs) to selectively absorb and/or reflect light
incident thereon using principles of optical interference. IMODs
can include an absorber, a reflector that is movable with respect
to the absorber, and an optical resonant cavity defined between the
absorber and the reflector. The reflector can be moved to two or
more different positions, which can change the size of the optical
resonant cavity and thereby affect the reflectance of the
interferometric modulator. The reflectance spectrums of IMODs can
create fairly broad spectral bands which can be shifted across the
visible wavelengths to generate different colors. The position of
the spectral band can be adjusted by changing the thickness of the
optical resonant cavity, i.e., by changing the position of the
reflector.
[0050] FIG. 1 shows an example of an isometric view depicting two
adjacent pixels in a series of pixels of an interferometric
modulator (IMOD) display device. The IMOD display device includes
one or more interferometric MEMS display elements. In these
devices, the pixels of the MEMS display elements can be in either a
bright or dark state. In the bright ("relaxed," "open" or "on")
state, the display element reflects a large portion of incident
visible light, e.g., to a user. Conversely, in the dark
("actuated," "closed" or "off") state, the display element reflects
little incident visible light. In some implementations, the light
reflectance properties of the on and off states may be reversed.
MEMS pixels can be configured to reflect predominantly at
particular wavelengths allowing for a color display in addition to
black and white.
[0051] The IMOD display device can include a row/column array of
IMODs. Each IMOD can include a pair of reflective layers, i.e., a
movable reflective layer and a fixed partially reflective layer,
positioned at a variable and controllable distance from each other
to form an air gap (also referred to as an optical gap or cavity).
The movable reflective layer may be moved between at least two
positions. In a first position, i.e., a relaxed position, the
movable reflective layer can be positioned at a relatively large
distance from the fixed partially reflective layer. In a second
position, i.e., an actuated position, the movable reflective layer
can be positioned more closely to the partially reflective layer.
Incident light that reflects from the two layers can interfere
constructively or destructively depending on the position of the
movable reflective layer, producing either an overall reflective or
non-reflective state for each pixel. In some implementations, the
IMOD may be in a reflective state when unactuated, reflecting light
within the visible spectrum, and may be in a dark state when
actuated, reflecting light outside of the visible range (e.g.,
infrared light). In some other implementations, however, an IMOD
may be in a dark state when unactuated, and in a reflective state
when actuated. In some implementations, the introduction of an
applied voltage can drive the pixels to change states. In some
other implementations, an applied charge can drive the pixels to
change states.
[0052] The depicted portion of the pixel array in FIG. 1 includes
two adjacent interferometric modulators 12. In the IMOD 12 on the
left (as illustrated), a movable reflective layer 14 is illustrated
in a relaxed position at a predetermined distance from an optical
stack 16, which includes a partially reflective layer. The voltage
V.sub.0 applied across the IMOD 12 on the left is insufficient to
cause actuation of the movable reflective layer 14. In the IMOD 12
on the right, the movable reflective layer 14 is illustrated in an
actuated position near or adjacent the optical stack 16. The
voltage V.sub.bias applied across the IMOD 12 on the right is
sufficient to maintain the movable reflective layer 14 in the
actuated position.
[0053] In FIG. 1, the reflective properties of pixels 12 are
generally illustrated with arrows indicating light 13 incident upon
the pixels 12, and light 15 reflecting from the pixel 12 on the
left. Although not illustrated in detail, it will be understood by
a person having ordinary skill in the art that most of the light 13
incident upon the pixels 12 will be transmitted through the
transparent substrate 20, toward the optical stack 16. A portion of
the light incident upon the optical stack 16 will be transmitted
through the partially reflective layer of the optical stack 16, and
a portion will be reflected back through the transparent substrate
20. The portion of light 13 that is transmitted through the optical
stack 16 will be reflected at the movable reflective layer 14, back
toward (and through) the transparent substrate 20. Interference
(constructive or destructive) between the light reflected from the
partially reflective layer of the optical stack 16 and the light
reflected from the movable reflective layer 14 will determine the
wavelength(s) of light 15 reflected from the pixel 12.
[0054] The optical stack 16 can include a single layer or several
layers. The layer(s) can include one or more of an electrode layer,
a partially reflective and partially transmissive layer and a
transparent dielectric layer. In some implementations, the optical
stack 16 is 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 electrode layer can be formed from a variety of
materials, such as various metals, for example indium tin oxide
(ITO). The partially reflective layer can be formed from a variety
of materials that are partially reflective, such as various metals,
e.g., chromium (Cr), 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. In some implementations, the optical
stack 16 can include a single semi-transparent thickness of metal
or semiconductor which serves as both an optical absorber and
conductor, while different, more conductive layers or portions
(e.g., of the optical stack 16 or of other structures of the IMOD)
can serve to bus signals between IMOD pixels. The optical stack 16
also can include one or more insulating or dielectric layers
covering one or more conductive layers or a conductive/absorptive
layer.
[0055] In some implementations, the layer(s) of the optical stack
16 can be patterned into parallel strips, and may form row
electrodes in a display device as described further below. As will
be understood by one having skill in the art, the term "patterned"
is used herein to refer to masking as well as etching processes. In
some implementations, a highly conductive and reflective material,
such as aluminum (Al), may be used for the movable reflective layer
14, and these strips may form column electrodes in a display
device. The movable reflective layer 14 may be formed as a series
of parallel strips of a deposited metal layer or layers (orthogonal
to the row electrodes of the optical stack 16) to form columns
deposited on top of posts 18 and an intervening sacrificial
material deposited between the posts 18. When the sacrificial
material is etched away, a defined gap 19, or optical cavity, can
be formed between the movable reflective layer 14 and the optical
stack 16. In some implementations, the spacing between posts 18 may
be on the order of 1-1000 um, while the gap 19 may be on the order
of <10,000 Angstroms (.ANG.).
[0056] In some implementations, each pixel of the IMOD, whether in
the actuated or relaxed state, is essentially a capacitor formed by
the fixed and moving reflective layers. When no voltage is applied,
the movable reflective layer 14 remains in a mechanically relaxed
state, as illustrated by the pixel 12 on the left in FIG. 1, with
the gap 19 between the movable reflective layer 14 and optical
stack 16. However, when a potential difference, e.g., voltage, is
applied to at least one of 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 applied voltage exceeds a
threshold, the movable reflective layer 14 can deform and move near
or against the optical stack 16. A dielectric layer (not shown)
within the optical stack 16 may prevent shorting and control the
separation distance between the layers 14 and 16, as illustrated by
the actuated pixel 12 on the right in FIG. 1. The behavior is the
same regardless of the polarity of the applied potential
difference. Though a series of pixels in an array may be referred
to in some instances as "rows" or "columns," a person having
ordinary skill in the art will readily understand that referring to
one direction as a "row" and another as a "column" is arbitrary.
Restated, in some orientations, the rows can be considered columns,
and the columns considered to be rows. Furthermore, the display
elements may be evenly arranged in orthogonal rows and columns (an
"array"), or arranged in non-linear configurations, for example,
having certain positional offsets with respect to one another (a
"mosaic"). The terms "array" and "mosaic" may refer to either
configuration. Thus, although the display is referred to as
including an "array" or "mosaic," the elements themselves need not
be arranged orthogonally to one another, or disposed in an even
distribution, in any instance, but may include arrangements having
asymmetric shapes and unevenly distributed elements.
[0057] FIG. 2 shows an example of a system block diagram
illustrating an electronic device incorporating a 3.times.3
interferometric modulator display. The electronic device includes a
processor 21 that may be configured to execute one or more software
modules. In addition to executing an operating system, the
processor 21 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.
[0058] The processor 21 can be configured to communicate with an
array driver 22. The array driver 22 can include a row driver
circuit 24 and a column driver circuit 26 that provide signals to,
e.g., a display array or panel 30. The cross section of the IMOD
display device illustrated in FIG. 1 is shown by the lines 1-1 in
FIG. 2. Although FIG. 2 illustrates a 3.times.3 array of IMODs for
the sake of clarity, the display array 30 may contain a very large
number of IMODs, and may have a different number of IMODs in rows
than in columns, and vice versa.
[0059] FIG. 3 shows an example of a diagram illustrating movable
reflective layer position versus applied voltage for the
interferometric modulator of FIG. 1. For MEMS interferometric
modulators, the row/column (i.e., common/segment) write procedure
may take advantage of a hysteresis property of these devices as
illustrated in FIG. 3. An interferometric modulator may require,
for example, about a 10-volt potential difference to cause the
movable reflective layer, or mirror, to change from the relaxed
state to the actuated state. When the voltage is reduced from that
value, the movable reflective layer maintains its state as the
voltage drops back below, e.g., 10-volts, however, the movable
reflective layer does not relax completely until the voltage drops
below 2-volts. Thus, a range of voltage, approximately 3 to
7-volts, as shown in FIG. 3, exists where there is a window of
applied voltage 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 30
having the hysteresis characteristics of FIG. 3, the row/column
write procedure can be designed to address one or more rows at a
time, such that during the addressing of a given row, pixels in the
addressed 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 near zero volts. After
addressing, the pixels are exposed to a steady state or bias
voltage difference of approximately 5-volts such that they remain
in the previous strobing state. In this example, after being
addressed, each pixel sees a potential difference within the
"stability window" of about 3-7-volts. This hysteresis property
feature enables the pixel design, e.g., illustrated in FIG. 1, to
remain stable in either an actuated or relaxed pre-existing state
under the same applied voltage conditions. Since each IMOD pixel,
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 steady voltage within the hysteresis
window without substantially consuming or losing power. Moreover,
essentially little or no current flows into the IMOD pixel if the
applied voltage potential remains substantially fixed.
[0060] In some implementations, a frame of an image may be created
by applying data signals in the form of "segment" voltages along
the set of column electrodes, in accordance with the desired change
(if any) to the state of the pixels in a given row. Each row of the
array can be addressed in turn, such that the frame is written one
row at a time. To write the desired data to the pixels in a first
row, segment voltages corresponding to the desired state of the
pixels in the first row can be applied on the column electrodes,
and a first row pulse in the form of a specific "common" voltage or
signal can be applied to the first row electrode. The set of
segment voltages can then be changed to correspond to the desired
change (if any) to the state of the pixels in the second row, and a
second common voltage can be applied to the second row electrode.
In some implementations, the pixels in the first row are unaffected
by the change in the segment voltages applied along the column
electrodes, and remain in the state they were set to during the
first common voltage row pulse. This process may be repeated for
the entire series of rows, or alternatively, columns, in a
sequential fashion to produce the image frame. The frames can be
refreshed and/or updated with new image data by continually
repeating this process at some desired number of frames per
second.
[0061] The combination of segment and common signals applied across
each pixel (that is, the potential difference across each pixel)
determines the resulting state of each pixel. FIG. 4 shows an
example of a table illustrating various states of an
interferometric modulator when various common and segment voltages
are applied. As will be readily understood by one having ordinary
skill in the art, the "segment" voltages can be applied to either
the column electrodes or the row electrodes, and the "common"
voltages can be applied to the other of the column electrodes or
the row electrodes.
[0062] As illustrated in FIG. 4 (as well as in the timing diagram
shown in FIG. 5B), when a release voltage VC.sub.REL is applied
along a common line, all interferometric modulator elements along
the common line will be placed in a relaxed state, alternatively
referred to as a released or unactuated state, regardless of the
voltage applied along the segment lines, i.e., high segment voltage
VS.sub.H and low segment voltage VS.sub.L. In particular, when the
release voltage VC.sub.REL is applied along a common line, the
potential voltage across the modulator (alternatively referred to
as a pixel voltage) is within the relaxation window (see FIG. 3,
also referred to as a release window) both when the high segment
voltage VS.sub.H and the low segment voltage VS.sub.L are applied
along the corresponding segment line for that pixel.
[0063] When a hold voltage is applied on a common line, such as a
high hold voltage VC.sub.HOLD.sub.--.sub.H or a low hold voltage
V.sub.HOLD.sub.--.sub.L, the state of the interferometric modulator
will remain constant. For example, a relaxed IMOD will remain in a
relaxed position, and an actuated IMOD will remain in an actuated
position. The hold voltages can be selected such that the pixel
voltage will remain within a stability window both when the high
segment voltage VS.sub.H and the low segment voltage VS.sub.L are
applied along the corresponding segment line. Thus, the segment
voltage swing, i.e., the difference between the high VS.sub.H and
low segment voltage VS.sub.L, is less than the width of either the
positive or the negative stability window.
[0064] When an addressing, or actuation, voltage is applied on a
common line, such as a high addressing voltage
VC.sub.ADD.sub.--.sub.H or a low addressing voltage
VC.sub.ADD.sub.--.sub.L, data can be selectively written to the
modulators along that line by application of segment voltages along
the respective segment lines. The segment voltages may be selected
such that actuation is dependent upon the segment voltage applied.
When an addressing voltage is applied along a common line,
application of one segment voltage will result in a pixel voltage
within a stability window, causing the pixel to remain unactuated.
In contrast, application of the other segment voltage will result
in a pixel voltage beyond the stability window, resulting in
actuation of the pixel. The particular segment voltage which causes
actuation can vary depending upon which addressing voltage is used.
In some implementations, when the high addressing voltage
VC.sub.ADD.sub.--.sub.H is applied along the common line,
application of the high segment voltage VS.sub.H can cause a
modulator to remain in its current position, while application of
the low segment voltage VS.sub.L can cause actuation of the
modulator. As a corollary, the effect of the segment voltages can
be the opposite when a low addressing voltage
VC.sub.ADD.sub.--.sub.L is applied, with high segment voltage
VS.sub.H causing actuation of the modulator, and low segment
voltage VS.sub.L having no effect (i.e., remaining stable) on the
state of the modulator.
[0065] In some implementations, hold voltages, address voltages,
and segment voltages may be used which always produce the same
polarity potential difference across the modulators. In some other
implementations, signals can be used which alternate the polarity
of the potential difference of the modulators. Alternation of the
polarity across the modulators (that is, alternation of the
polarity of write procedures) may reduce or inhibit charge
accumulation which could occur after repeated write operations of a
single polarity.
[0066] FIG. 5A shows an example of a diagram illustrating a frame
of display data in the 3.times.3 interferometric modulator display
of FIG. 2. FIG. 5B shows an example of a timing diagram for common
and segment signals that may be used to write the frame of display
data illustrated in FIG. 5A. The signals can be applied to the,
e.g., 3.times.3 array of FIG. 2, which will ultimately result in
the line time 60e display arrangement illustrated in FIG. 5A. The
actuated modulators in FIG. 5A are in a dark-state, i.e., where a
substantial portion of the reflected light is outside of the
visible spectrum so as to result in a dark appearance to, e.g., a
viewer. Prior to writing the frame illustrated in FIG. 5A, the
pixels can be in any state, but the write procedure illustrated in
the timing diagram of FIG. 5B presumes that each modulator has been
released and resides in an unactuated state before the first line
time 60a.
[0067] During the first line time 60a: a release voltage 70 is
applied on common line 1; the voltage applied on common line 2
begins at a high hold voltage 72 and moves to a release voltage 70;
and a low hold voltage 76 is applied along common line 3. Thus, the
modulators (common 1, segment 1), (1,2) and (1,3) along common line
1 remain in a relaxed, or unactuated, state for the duration of the
first line time 60a, the modulators (2,1), (2,2) and (2,3) along
common line 2 will move to a relaxed state, and the modulators
(3,1), (3,2) and (3,3) along common line 3 will remain in their
previous state. With reference to FIG. 4, the segment voltages
applied along segment lines 1, 2 and 3 will have no effect on the
state of the interferometric modulators, as none of common lines 1,
2 or 3 are being exposed to voltage levels causing actuation during
line time 60a (i.e., VC.sub.REL--relax and
VC.sub.HOLD.sub.--.sub.L--stable).
[0068] During the second line time 60b, the voltage on common line
1 moves to a high hold voltage 72, and all modulators along common
line 1 remain in a relaxed state regardless of the segment voltage
applied because no addressing, or actuation, voltage was applied on
the common line 1. The modulators along common line 2 remain in a
relaxed state due to the application of the release voltage 70, and
the modulators (3,1), (3,2) and (3,3) along common line 3 will
relax when the voltage along common line 3 moves to a release
voltage 70.
[0069] During the third line time 60c, common line 1 is addressed
by applying a high address voltage 74 on common line 1. Because a
low segment voltage 64 is applied along segment lines 1 and 2
during the application of this address voltage, the pixel voltage
across modulators (1,1) and (1,2) is greater than the high end of
the positive stability window (i.e., the voltage differential
exceeded a predefined threshold) of the modulators, and the
modulators (1,1) and (1,2) are actuated. Conversely, because a high
segment voltage 62 is applied along segment line 3, the pixel
voltage across modulator (1,3) is less than that of modulators
(1,1) and (1,2), and remains within the positive stability window
of the modulator; modulator (1,3) thus remains relaxed. Also during
line time 60c, the voltage along common line 2 decreases to a low
hold voltage 76, and the voltage along common line 3 remains at a
release voltage 70, leaving the modulators along common lines 2 and
3 in a relaxed position.
[0070] During the fourth line time 60d, the voltage on common line
1 returns to a high hold voltage 72, leaving the modulators along
common line 1 in their respective addressed states. The voltage on
common line 2 is decreased to a low address voltage 78. Because a
high segment voltage 62 is applied along segment line 2, the pixel
voltage across modulator (2,2) is below the lower end of the
negative stability window of the modulator, causing the modulator
(2,2) to actuate. Conversely, because a low segment voltage 64 is
applied along segment lines 1 and 3, the modulators (2,1) and (2,3)
remain in a relaxed position. The voltage on common line 3
increases to a high hold voltage 72, leaving the modulators along
common line 3 in a relaxed state.
[0071] Finally, during the fifth line time 60e, the voltage on
common line 1 remains at high hold voltage 72, and the voltage on
common line 2 remains at a low hold voltage 76, leaving the
modulators along common lines 1 and 2 in their respective addressed
states. The voltage on common line 3 increases to a high address
voltage 74 to address the modulators along common line 3. As a low
segment voltage 64 is applied on segment lines 2 and 3, the
modulators (3,2) and (3,3) actuate, while the high segment voltage
62 applied along segment line 1 causes modulator (3,1) to remain in
a relaxed position. Thus, at the end of the fifth line time 60e,
the 3.times.3 pixel array is in the state shown in FIG. 5A, and
will remain in that state as long as the hold voltages are applied
along the common lines, regardless of variations in the segment
voltage which may occur when modulators along other common lines
(not shown) are being addressed.
[0072] In the timing diagram of FIG. 5B, a given write procedure
(i.e., line times 60a-60e) can include the use of either high hold
and address voltages, or low hold and address voltages. Once the
write procedure has been completed for a given common line (and the
common voltage is set to the hold voltage having the same polarity
as the actuation voltage), the pixel voltage remains within a given
stability window, and does not pass through the relaxation window
until a release voltage is applied on that common line.
Furthermore, as each modulator is released as part of the write
procedure prior to addressing the modulator, the actuation time of
a modulator, rather than the release time, may determine the
necessary line time. Specifically, in implementations in which the
release time of a modulator is greater than the actuation time, the
release voltage may be applied for longer than a single line time,
as depicted in FIG. 5B. In some other implementations, voltages
applied along common lines or segment lines may vary to account for
variations in the actuation and release voltages of different
modulators, such as modulators of different colors.
[0073] The details of the structure of interferometric modulators
that operate in accordance with the principles set forth above may
vary widely. For example, FIGS. 6A-6E show examples of
cross-sections of varying implementations of interferometric
modulators, including the movable reflective layer 14 and its
supporting structures. FIG. 6A shows an example of a partial
cross-section of the interferometric modulator display of FIG. 1,
where a strip of metal material, i.e., the movable reflective layer
14 is deposited on supports 18 extending orthogonally from the
substrate 20. In FIG. 6B, the movable reflective layer 14 of each
IMOD is generally square or rectangular in shape and attached to
supports at or near the corners, on tethers 32. In FIG. 6C, the
movable reflective layer 14 is generally square or rectangular in
shape and suspended from a deformable layer 34, which may include a
flexible metal. The deformable layer 34 can connect, directly or
indirectly, to the substrate 20 around the perimeter of the movable
reflective layer 14. These connections are herein referred to as
support posts. The implementation shown in FIG. 6C has additional
benefits deriving from the decoupling of the optical functions of
the movable reflective layer 14 from its mechanical functions,
which are carried out by the deformable layer 34. This decoupling
allows the structural design and materials used for the reflective
layer 14 and those used for the deformable layer 34 to be optimized
independently of one another.
[0074] FIG. 6D shows another example of an IMOD, where the movable
reflective layer 14 includes a reflective sub-layer 14a. The
movable reflective layer 14 rests on a support structure, such as
support posts 18. The support posts 18 provide separation of the
movable reflective layer 14 from the lower stationary electrode
(i.e., part of the optical stack 16 in the illustrated IMOD) so
that a gap 19 is formed between the movable reflective layer 14 and
the optical stack 16, for example when the movable reflective layer
14 is in a relaxed position. The movable reflective layer 14 also
can include a conductive layer 14c, which may be configured to
serve as an electrode, and a support layer 14b. In this example,
the conductive layer 14c is disposed on one side of the support
layer 14b, distal from the substrate 20, and the reflective
sub-layer 14a is disposed on the other side of the support layer
14b, proximal to the substrate 20. In some implementations, the
reflective sub-layer 14a can be conductive and can be disposed
between the support layer 14b and the optical stack 16. The support
layer 14b can include one or more layers of a dielectric material,
for example, silicon oxynitride (SiON) or silicon dioxide
(SiO.sub.2). In some implementations, the support layer 14b can be
a stack of layers, such as, for example, a SiO.sub.2/SiON/SiO.sub.2
tri-layer stack. Either or both of the reflective sub-layer 14a and
the conductive layer 14c can include, e.g., an aluminum (Al) alloy
with about 0.5% copper (Cu), or another reflective metallic
material. Employing conductive layers 14a, 14c above and below the
dielectric support layer 14b can balance stresses and provide
enhanced conduction. In some implementations, the reflective
sub-layer 14a and the conductive layer 14c can be formed of
different materials for a variety of design purposes, such as
achieving specific stress profiles within the movable reflective
layer 14.
[0075] As illustrated in FIG. 6D, some implementations also can
include a black mask structure 23. The black mask structure 23 can
be formed in optically inactive regions (e.g., between pixels or
under posts 18) to absorb ambient or stray light. The black mask
structure 23 also can improve the optical properties of a display
device by inhibiting light from being reflected from or transmitted
through inactive portions of the display, thereby increasing the
contrast ratio. Additionally, the black mask structure 23 can be
conductive and be configured to function as an electrical bussing
layer. In some implementations, the row electrodes can be connected
to the black mask structure 23 to reduce the resistance of the
connected row electrode. The black mask structure 23 can be formed
using a variety of methods, including deposition and patterning
techniques. The black mask structure 23 can include one or more
layers. For example, in some implementations, the black mask
structure 23 includes a molybdenum-chromium (MoCr) layer that
serves as an optical absorber, a layer, and an aluminum alloy that
serves as a reflector and a bussing layer, with a thickness in the
range of about 3-80 .ANG., 500-1000 .ANG., and 500-6000 .ANG.,
respectively. The one or more layers can be patterned using a
variety of techniques, including photolithography and dry etching,
including, for example, carbon tetrafluoride (CF.sub.4) and/or
oxygen (O.sub.2) for the MoCr and SiO.sub.2 layers and chlorine
(Cl.sub.2) and/or boron trichloride (BCl.sub.3) for the aluminum
alloy layer. In some implementations, the black mask 23 can be an
etalon or interferometric stack structure. In such interferometric
stack black mask structures 23, the conductive absorbers can be
used to transmit or bus signals between lower, stationary
electrodes in the optical stack 16 of each row or column. In some
implementations, a spacer layer 35 can serve to generally
electrically isolate the absorber layer 16a from the conductive
layers in the black mask 23.
[0076] FIG. 6E shows another example of an IMOD, where the movable
reflective layer 14 is self supporting. In contrast with FIG. 6D,
the implementation of FIG. 6E does not include support posts 18.
Instead, the movable reflective layer 14 contacts the underlying
optical stack 16 at multiple locations, and the curvature of the
movable reflective layer 14 provides sufficient support that the
movable reflective layer 14 returns to the unactuated position of
FIG. 6E when the voltage across the interferometric modulator is
insufficient to cause actuation. The optical stack 16, which may
contain a plurality of several different layers, is shown here for
clarity including an optical absorber 16a, and a dielectric 16b. In
some implementations, the optical absorber 16a may serve both as a
fixed electrode and as a partially reflective layer.
[0077] In implementations such as those shown in FIGS. 6A-6E, the
IMODs function as direct-view devices, in which images are viewed
from the front side of the transparent substrate 20, i.e., the side
opposite to that upon which the modulator is arranged. In these
implementations, the back portions of the device (that is, any
portion of the display device behind the movable reflective layer
14, including, for example, the deformable layer 34 illustrated in
FIG. 6C) can be configured and operated upon without impacting or
negatively affecting the image quality of the display device,
because the reflective layer 14 optically shields those portions of
the device. For example, in some implementations a bus structure
(not illustrated) can be included behind the movable reflective
layer 14 which provides the ability to separate the optical
properties of the modulator from the electromechanical properties
of the modulator, such as voltage addressing and the movements that
result from such addressing. Additionally, the implementations of
FIGS. 6A-6E can simplify processing, such as, e.g., patterning.
[0078] FIG. 7 shows an example of a flow diagram illustrating a
manufacturing process 80 for an interferometric modulator, and
FIGS. 8A-8E show examples of cross-sectional schematic
illustrations of corresponding stages of such a manufacturing
process 80. In some implementations, the manufacturing process 80
can be implemented to manufacture, e.g., interferometric modulators
of the general type illustrated in FIGS. 1 and 6, in addition to
other blocks not shown in FIG. 7. With reference to FIGS. 1, 6 and
7, the process 80 begins at block 82 with the formation of the
optical stack 16 over the substrate 20. FIG. 8A illustrates such an
optical stack 16 formed over the substrate 20. The substrate 20 may
be a transparent substrate such as glass or plastic, it may be
flexible or relatively stiff and unbending, and may have been
subjected to prior preparation processes, e.g., cleaning, to
facilitate efficient formation of the optical stack 16. As
discussed above, the optical stack 16 can be electrically
conductive, partially transparent and partially reflective and may
be fabricated, for example, by depositing one or more layers having
the desired properties onto the transparent substrate 20. In FIG.
8A, the optical stack 16 includes a multilayer structure having
sub-layers 16a and 16b, although more or fewer sub-layers may be
included in some other implementations. In some implementations,
one of the sub-layers 16a, 16b can be configured with both
optically absorptive and conductive properties, such as the
combined conductor/absorber sub-layer 16a. Additionally, one or
more of the sub-layers 16a, 16b can be patterned into parallel
strips, and may form row electrodes in a display device. Such
patterning can be performed by a masking and etching process or
another suitable process known in the art. In some implementations,
one of the sub-layers 16a, 16b can be an insulating or dielectric
layer, such as sub-layer 16b that is deposited over one or more
metal layers (e.g., one or more reflective and/or conductive
layers). In addition, the optical stack 16 can be patterned into
individual and parallel strips that form the rows of the
display.
[0079] The process 80 continues at block 84 with the formation of a
sacrificial layer 25 over the optical stack 16. The sacrificial
layer 25 is later removed (e.g., at block 90) to form the cavity 19
and thus the sacrificial layer 25 is not shown in the resulting
interferometric modulators 12 illustrated in FIG. 1. FIG. 8B
illustrates a partially fabricated device including a sacrificial
layer 25 formed over the optical stack 16. The formation of the
sacrificial layer 25 over the optical stack 16 may include
deposition of a xenon difluoride (XeF.sub.2)-etchable material such
as molybdenum (Mo) or amorphous silicon (a-Si), in a thickness
selected to provide, after subsequent removal, a gap or cavity 19
(see also FIGS. 1 and 8E) having a desired design size. Deposition
of the sacrificial material may be carried out using deposition
techniques such as physical vapor deposition (PVD, e.g.,
sputtering), plasma-enhanced chemical vapor deposition (PECVD),
thermal chemical vapor deposition (thermal CVD), or
spin-coating.
[0080] The process 80 continues at block 86 with the formation of a
support structure e.g., a post 18 as illustrated in FIGS. 1, 6 and
8C. The formation of the post 18 may include patterning the
sacrificial layer 25 to form a support structure aperture, then
depositing a material (e.g., a polymer or an inorganic material,
e.g., silicon oxide) into the aperture to form the post 18, using a
deposition method such as PVD, PECVD, thermal CVD, or spin-coating.
In some implementations, the support structure aperture formed in
the sacrificial layer can extend through both the sacrificial layer
25 and the optical stack 16 to the underlying substrate 20, so that
the lower end of the post 18 contacts the substrate 20 as
illustrated in FIG. 6A. Alternatively, as depicted in FIG. 8C, the
aperture formed in the sacrificial layer 25 can extend through the
sacrificial layer 25, but not through the optical stack 16. For
example, FIG. 8E illustrates the lower ends of the support posts 18
in contact with an upper surface of the optical stack 16. The post
18, or other support structures, may be formed by depositing a
layer of support structure material over the sacrificial layer 25
and patterning portions of the support structure material located
away from apertures in the sacrificial layer 25. The support
structures may be located within the apertures, as illustrated in
FIG. 8C, but also can, at least partially, extend over a portion of
the sacrificial layer 25. As noted above, the patterning of the
sacrificial layer 25 and/or the support posts 18 can be performed
by a patterning and etching process, but also may be performed by
alternative etching methods.
[0081] The process 80 continues at block 88 with the formation of a
movable reflective layer or membrane such as the movable reflective
layer 14 illustrated in FIGS. 1, 6 and 8D. The movable reflective
layer 14 may be formed by employing one or more deposition steps,
e.g., reflective layer (e.g., aluminum, aluminum alloy) deposition,
along with one or more patterning, masking, and/or etching steps.
The movable reflective layer 14 can be electrically conductive, and
referred to as an electrically conductive layer. In some
implementations, the movable reflective layer 14 may include a
plurality of sub-layers 14a, 14b, 14c as shown in FIG. 8D. In some
implementations, one or more of the sub-layers, such as sub-layers
14a, 14c, may include highly reflective sub-layers selected for
their optical properties, and another sub-layer 14b may include a
mechanical sub-layer selected for its mechanical properties. Since
the sacrificial layer 25 is still present in the partially
fabricated interferometric modulator formed at block 88, the
movable reflective layer 14 is typically not movable at this stage.
A partially fabricated IMOD that contains a sacrificial layer 25
may also be referred to herein as an "unreleased" IMOD. As
described above in connection with FIG. 1, the movable reflective
layer 14 can be patterned into individual and parallel strips that
form the columns of the display.
[0082] The process 80 continues at block 90 with the formation of a
cavity, e.g., cavity 19 as illustrated in FIGS. 1, 6 and 8E. The
cavity 19 may be formed by exposing the sacrificial material 25
(deposited at block 84) to an etchant. For example, an etchable
sacrificial material such as Mo or amorphous Si may be removed by
dry chemical etching, e.g., by exposing the sacrificial layer 25 to
a gaseous or vaporous etchant, such as vapors derived from solid
XeF.sub.2 for a period of time that is effective to remove the
desired amount of material, typically selectively removed relative
to the structures surrounding the cavity 19. Other etching methods,
e.g. wet etching and/or plasma etching, also may be used. Since the
sacrificial layer 25 is removed during block 90, the movable
reflective layer 14 is typically movable after this stage. After
removal of the sacrificial material 25, the resulting fully or
partially fabricated IMOD may be referred to herein as a "released"
IMOD.
[0083] Electronic devices, such as displays including
interferometric modulators, can include touch screens to accept
user inputs. In some implementations, the touch screen apparatus
can be optically-based and detect light to determine the location
of an object, for example, a user's finger, in contact with a touch
input surface of the touch screen. Scattered light from the
contacting object can be detected by a light sensor to determine
the occurrence and location of a touch event. A light-turning layer
may be used to direct the scattered light from the contacting
object to the light sensor.
[0084] FIGS. 9A and 9B show examples of perspective views of a
touch screen apparatus 900 with a pixilated light-turning layer,
according to some implementations. The touch screen apparatus 900
can include a light guide 910, a light sensor 920, a light source
940, and a pixilated light-turning layer 912. In the implementation
shown in FIG. 9B, the touch screen apparatus 900 can also include a
display 930.
[0085] With reference to FIG. 9A, the light guide 910 can include a
front major surface 911, which can function as a touch input
surface for receiving contact with an object such as a user's
finger. A back major surface 915 is opposite the front surface 911.
At a corner of the light guide 910, a light input surface 916a may
be provided for receiving light emitted by the light source 940. In
some implementations, the light guide 910 can include two or more
light input surfaces. The light guide 910 can also include a
light-output surface 913 for providing light to the light sensor
920. While the light input and light output surfaces 918 and 913
are illustrated at edges of the light guide 910, in various
implementations, it is possible for the light input and output
surfaces to be disposed as portions of one or more of the front
surface 911 or the back surface 915, or on one or more of the edges
of the light guide disposed about the front 911 and back 915
surfaces (for example, edges 915, 916, 917, or 918). In some
implementations, as illustrated, to reduce background noise, the
light source 940 and light sensor 920 are not directly facing one
another.
[0086] The light sensor 920 can be disposed along the light-output
surface 913 of the light guide 910. In some implementations, the
light sensor 920 may be a single light sensing device (for example,
an image sensor such as a CMOS or CCD sensor) having a light
receiving surface with an array of discrete light receiving
locations. In some other implementations, the light sensor 920 can
include a plurality of light sensing devices that are arrayed
together.
[0087] In some implementations, the light sensor 920 may be capable
of sensing light, including light at wavelengths outside of the
visible spectrum, and the light source 940 can be configured to
emit light of at least of those wavelengths. Suitable wavelengths
include, without limitation, UV and infrared, as well as light of
wavelengths within the visible range. As discussed herein, the
light guide 910 may be provided with light-turning features forming
pixels P that redirect incident light towards the light sensor 920.
In some implementations where it is desirable to reduce
interactions with visible light, such as where the touch screen
apparatus 900 includes a display 930 (FIG. 9B), the light source
940 and light sensor 920 may be configured to emit and detect light
at wavelengths outside the visible spectrum. This can reduce the
impact of those pixels P on visible light (from a display) passing
through the light guide 910 (to a viewer).
[0088] The light source 940 can include any element suitable to
inject light into the light guide 910 at a suitable wavelength. The
light source 940 may be a light emitting device such as, but not
limited to, one or more light emitting diodes (LED), one or more
incandescent bulbs, a light bar, one or more lasers, or any other
form of light emitter. In some implementations, the light source
940 in one of a spaced-apart array of light emitters.
[0089] With continued reference to FIG. 9A, the pixilated
light-turning layer 912 can include light-turning features formed
onto and/or facing one of the major surfaces of the light guide
910, for example the back surface 915 of the light guide 910. The
light-turning features are grouped into pixels P. Each pixel P is a
region of the light turning layer 912 formed by one or more light
turning features, each of which are configured to repeatably direct
light to the same location, or the same set of locations, i.sub.1
to i.sub.n on the light sensor 920. This location or set of
locations i.sub.1 to i.sub.n may be referred to as the pixel P's
correlated location on the light sensor 920. Different pixels may
each have different groups of light turning features that direct
light to different correlated locations on the light sensor 920. In
some implementations, there can be a one-to-one correspondence
between pixels of the pixilated light-turning layer 912 and
locations on the light receiving surface of the light sensor 920.
In some implementations, the light-turning pixel P can occupy a
rectangular area that may form a part of a grid of light-turning
pixels. For instance, each pixel in the grid may be rectangular
and/or square. In some implementations, each pixel can have
dimensions of about 5 .mu.m to about 5 mm by about 5 .mu.m to about
5 mm. In some of these implementations, each pixel can have
dimensions of about 50 .mu.m to about 1 mm by about 50 .mu.m to
about 1 mm. As one example, each pixel can have dimensions of about
1 mm by about 1 mm. In other implementations, the pixels may have
other shapes, such as circular, triangular, hexagonal, the like, or
any combination thereof, as desired, depending upon the application
or the manufacturing process. Pixels of the pixilated light-turning
layer 912 may have different shapes and/or sizes from one another
in some implementations.
[0090] The pixels P of the pixilated light-turning layer 912 may
include holograms, diffraction gratings, microstructures,
light-turning facets, or other optical features capable of acting
upon light incident on the light-turning features within a range of
incident angles and causing the incident light to be selectively
redirected only toward a particular location or set of locations on
the light sensor 920, without directing light to other locations on
the light sensor 920. In some implementations, the light turning
layer 912 is a holographic film and each light-turning pixel P may
be a holographic pixel formed of holographic light turning
features. The holographic light turning features may be part of a
surface or volume hologram and the holographic pixels may be formed
in or on a holographic film disposed on the back surface 915 of the
light guide 910. In some implementations, the holographic film may
be laminated onto the light guide 910. In some other
implementations, the pixilated light-turning layer 912 may be
integral to the light guide 910 and may be the portion of the light
guide 910 in which pixels P are formed.
[0091] To reduce background noise and improve the precision of
touch event detection, each light-turning pixel P may be configured
to redirect only particular types of incident light. For example,
with continued reference to FIG. 9A, each light-turning pixel P may
only redirect light rays r incident upon that pixel within an
acceptance cone S2 centered about a normal to the top surface 911.
The larger the acceptance cone S2, the more scattered light with
different polar and azimuth angles of incidence can be redirected
by the pixel P to its correlated location on the sensor 920. The
acceptance cone S2 can be selected such that light scattered by an
object in contact with the front surface 911 of the light guide 910
is accepted and light emitted by the light source 940 propagating
through the light guide 910 that is not scattered by an object in
contact with the front surface 911 of the light guide 910 is not
accepted. In some implementations, the acceptance cone S2 for the
light-turning pixel P include a range of angles of incident light,
relative to a normal to the front surface 911, of less than about
.+-.45.degree., less than about .+-.35.degree., less than about
.+-.25.degree., less than about .+-.15.degree., less than about
.+-.10.degree., or less than about .+-.5.degree.. In some
implementations, the acceptance cones S2 for each light-turning
pixel P can each be approximately the same size. In some other
implementations, pixels of the pixilated light-turning layer can
have acceptance cones S2 of different sizes.
[0092] In addition to having limited acceptance cones S2, in some
implementations, as discussed herein, each light-turning pixel P
may only redirect light rays r within a particular range of
wavelengths. The light-turning pixel P can be configured to
redirect only particular wavelengths of light within a range that
corresponds to light emitted by the light source 940. In some
implementations, the light redirected by light-turning pixel P may
include wavelengths outside of the visible spectrum, such as UV or
infrared light.
[0093] Some implementations of the touch screen apparatus 900 may
include one or more processors (such as processor 21 of FIGS. 2 and
15B) in communication with the light sensor 920 and/or light source
940, and configured to map data corresponding to locations on the
sensor 920 receiving light with a particular pixel and/or a
particular position on the front surface 911. The one or more
processors can be configured with specific executable instructions
to determine the position where an object contacts the front
surface 911. Given a known mapping of light-turning pixels P to
locations on the light sensor 920 receiving light, the one or more
processors may be configured to determine a position of a touch
event.
[0094] Referring now to FIG. 9B, some implementations of the touch
screen apparatus 900 may include a display 930 underlying the light
guide 910. In some implementations, the display 930 is a reflective
display. For example, the display 930 may be an interferometric
modulator reflective display that includes display elements such as
the interferometric modulators 12 (FIG. 1), arranged in an array 30
(FIG. 2). In some implementations with a reflective display
underlying the light guide 910, the light guide 910 may form part
of a front light for illuminating the reflective display 930. In
such implementations, the light guide 910 may include light turning
features that eject light out of the light guide 910, towards the
display 930 to illuminate that display. The light to be ejected may
be injected into the light guide 910 by light source 940. For
example, the light source 940 may emit a broad range of wavelengths
of light, including light within the visible spectrum for use in
illuminating the display 930 and light outside the visible spectrum
for use with the touch screen functionality discussed herein. In
other implementations, the touch screen apparatus 900 may further
include a separate light source (not shown) for use as a front
light.
[0095] As discussed herein, the touch screen apparatus 900 may be
implemented in various configurations with various arrangements of
light sources and light sensors. Some of these configurations are
discussed below with reference to FIGS. 10A-13. While not shown for
ease of discussion and illustration, display 930 (FIG. 9B) may be
provided underlying each of the touch screen structures illustrated
in these figures.
[0096] FIGS. 10A and 10B show examples of plan and side views of an
implementation of a touch screen apparatus 1000 configured to
detect the presence and location of a contacting object. The touch
screen apparatus 1000 can include the light source 940, the light
guide 910, the pixilated light-turning layer 912, and light
absorbing structures 1010a and 1010b. For illustrative purposes,
pixels of the light-turning layer 912 are illustrated in the plan
view shown in FIG. 10A. As illustrated, two light sensors 920a and
920b are provided, each corresponding to the light sensor 920 of
FIGS. 9A and 9B. Two light sensors 920a and 920b are positioned
along different edges of the light guide 910. Directly across the
light guide 910 from the light sensors 920a and 920b are the light
absorbing structures 1010a and 1010b. The light absorbing
structures 1010a and 1010b can be any structure suitable for
absorbing light rays 942 from the light source 940 and/or
preventing light rays 942 from being directed back into the light
guide 910. Alternatively or additionally, the light absorbing
structures 1010a and 1010b can be any structures suitable for
absorbing ambient light injected into the light guide 910.
[0097] With continued reference to FIGS. 10A and 10B, the light
source 940 can be disposed relative to the light guide 910 so as to
inject light rays 942 into the light guide 910. Light rays 942 from
the light source 940 are injected into the light guide 910 such
that a portion of the light propagates in a direction across at
least a portion of the light guide 120 at a low-graze angle
relative to the major surfaces of the light guide 910 such that the
light is reflected within the light guide 910 by total internal
reflection ("TIR"). In this way, light rays 942 emitted from the
light source 940 can propagate though the light guide 910. The
light source 940 can be configured such that the light rays 942 in
the light guide 910 are provided to substantially all of the front
surface 911 of the light guide 910. In the example implementation
illustrated in FIGS. 10A-D, the light source 940 can be positioned
at a corner of the light guide 910. Such a placement of the light
source 940 can evenly distribute light rays 942 though the light
guide 910 and/or reduce flooding a particular area of the light
guide 910 with light. In some other implementations, one or more
light sources 940 can be interspersed between portions of the light
sensor 920, on the same edge of the light guide 910 as the light
sensor 920.
[0098] In some implementations, as discussed herein, the light
source 940 can be configured so that the light rays 942 are
sufficiently distinguishable from ambient and/or background light.
For example, an infrared light emitting diode (LED) can be utilized
to distinguish the light rays 942 and the redirected light from
ambient visible light. In certain implementations, the light source
940 can be pulsed in a known manner to distinguish the light rays
942 from the background where infrared light is also present.
[0099] FIGS. 10C and 10D show examples of selected light rays
scattered by an object 140 contacting the touch screen of FIGS. 10A
and 10B and redirected by a pixilated light-turning layer to a
light sensor. The object 140 can be, for example, a finger, a pen,
a stylus, or the like. In some implementations, the light rays are
scattered, in which light rays propagating through the light guide
910 are prevented from totally internally reflecting at the point
of contact of the object 140 with the light guide 910. The light
can strike the object 140 and be scattered or diffusely reflected
by the object down to the light-turning layer 912. For example, as
shown in FIGS. 10C and 10D, the object 140 can scatter one of the
light rays 942 down to the pixilated light-turning layer 912, where
it strikes pixel P, which redirects that light to that pixel P's
correlated location on the sensor 920a or 920b. As illustrated, the
correlated location is location i.sub.x on the sensor 920b.
[0100] Upon receiving the light input, the light sensor 920 can
generate a signal indicative of light from the light source 940
scattered by the object 140 striking a particular light-receiving
location of the light sensor 920. From the generated signal, a
location of the touch event (i.e., the object 140 touching the
front surface of the light guide 910) can be derived based on which
pixel of the pixilated light-turning layer 912 corresponds to the
sensor location receiving the scattered light. A processor (for
example, the processor 21 of FIG. 2 and/or FIG. 15B) can be
configured to determine a location of a touch event based on the
signal indicative of the touch event generated by the light sensor
920. For instance, the processor can map a first position of light
striking the light sensor 920 with a second position of the pixel P
of the pixilated light-turning layer 912 directing the scattered
light to the light sensor 920. This can indicate the position of
the object 140 scattering light to the underlying pixel P.
[0101] Although the object 140 is shown above one pixel P for
illustrative purposes, the object 140 can come into contact with
the major surface of the light guide 910 over only a portion of one
pixel or over two or more pixels. The touch screen apparatus
described herein can determine a touch event based on signals
generated in response to light striking more than one sensor
location that correspond to more than one pixel of the pixilated
light-turning layer 912. From these signals, a position of a touch
event can be determined. For instance, a center position of the
touch event can be derived from such signals indicating the receipt
of scattered light by multiple pixels of the light-turning layer
912.
[0102] With reference now to FIGS. 11A and 11B, examples of plan
and side views of another implementation of a touch screen
apparatus 1100 configured to detect the presence and location of a
contacting object is shown. The touch screen apparatus 1100 can be
substantially the same as the touch screen apparatus 1000, except
the touch screen apparatus 1100 can additionally include an optical
decoupling layer 1110 and a second light guide 1120. The optical
decoupling layer 1110 is between the light guide 910 and the second
light guide 1120.
[0103] The optical decoupling layer 1110 is configured to optically
decouple the second light guide 1120 from the overlying light guide
910. The pixilated light-turning layer 912 can be disposed between
the optical decoupling layer 1110 and the light guide 1120. The
optical decoupling layer 1110 can be formed of an optically
transmissive material having a low refractive index relative to the
refractive index of material of the light guide 910 and configured
to promote TIR off the surface of the light guide 910 to which the
optical decoupling layer 1110 is attached. For example, the
refractive index of the material of the optical decoupling layer
1110 can be at least about 0.1 lower than the refractive index of
material of the light guide 910. According to some implementations,
the optical decoupling layer 1110 can be air or a solid state
material.
[0104] FIGS. 11C and 11D show examples of selected light rays
scattered by the object 140 contacting the touch screen of FIGS.
11A and 11B and redirected by the pixilated light-turning layer 912
to the light sensor 920. Light rays 942 can propagate within the
light guide 910 until being scattered by the object 140 touching
the front surface 911 of the light guide 910. The optical
decoupling layer 1110 prevents light incident at grazing angles
from passing through it, but at least some of the scattered light
from the object 140 is normal to a directly underlying portion of
the optical decoupling layer 1110 and passes through that layer
1110. The light passing through the optical decoupling layer 1110
can strike a pixel P of the pixilated light-turning layer 912. The
pixel P then redirects the light to its correlated location i.sub.x
on the light sensor 920. The pixilated light-turning layer 912 is
transmissive and light propagates, as shown by the dashed arrow
944, through the second light guide 1120 disposed below the
pixilated light-turning layer 912 to reach the light sensor
920.
[0105] With continued reference to FIGS. 11A-11D, adding a second
light guide 1120 below the pixilated light-turning layer 912 can,
among other things, reduce noise detected by the light sensor 920
in some implementations. For example, light from the one or more
light sources 940 can be kept propagating in the light guide 910
until it is scattered into the second light guide 1120. Because
there may be less light propagating through the second light guide
1120, less noise may be detected by the light sensor 920. For
example, light may not be present in the second light guide 1120
until light scattered by the object 140 enters the second light
guide 1120.
[0106] FIG. 12A shows an example of a plan view of another
implementation of a touch screen apparatus 1200 configured to
detect the presence and location of the contacting object 140. The
touch screen apparatus 1200 illustrated in FIG. 12A includes a
light source that is formed by a plurality of discrete light
emitters 940a to 940n that are configured to collimate light so
that the light propagates through the light guide 910 substantially
normal to the array of light sources 940a to 940n. In some
implementations, one light emitter can be included for each row of
pixels of the light-turning layer 912. Alternatively more or fewer
light emitters 940a to 940n can be included for each row of pixels
of the light-turning layer 912. The plurality of light sources 940a
to 940n can be positioned, for example, along an input edge of the
light guide 910. According to some implementations, the plurality
of light sources 940a to 940n can sequentially pulse light into the
input edge of the light guide 910 and pixels of the pixilated
light-turning layer 912 can redirect scattered light associated
with a touch event towards their correlated locations on the light
sensor 920. Alternatively or additionally to pulsing light, the
plurality of light sources 940a to 940n can be configured to emit
light having two or more different wavelengths. Light associated
with different light sources 940a to 940n can be differentiated at
least in part by wavelength according to some implementations.
[0107] The touch screen apparatus 1200 can include a light sensor
920 along an edge of the light guide 910 transverse to the edge of
the light guide 910 along which the plurality of light sources 940a
to 940n are positioned. It will be understood that other
arrangements of light sensor 920 can be utilized in other
implementations. For instance, the light sensor 920 can be
positioned along other edges of the light guide 910. In various
implementations, the light sensor 920 can be positioned along two
or more edges of the light guide 910. In some implementations, the
light sensor 920 can include a line array of light receiving
locations i.sub.t to i.sub.n. Each location i.sub.t to i.sub.n can
correspond to a column of pixels of the pixilated light-turning
layer 912, according to some implementations.
[0108] The touch screen apparatus 1200 can include the various
configurations of light guides 910 and/or 920 and the pixilated
light-turning layers 912 of FIGS. 10B and/or 11B. For instance, the
touch screen apparatus 1200 can include a single light guide 910
and a pixilated light-turning layer 912, for example, as shown in
FIG. 10B. In other implementations, the touch screen apparatus 1200
can include two light guides 910 and 920, an optical decoupling
layer 1110, and a pixilated light-turning layer 912, for example,
as shown in FIG. 11B.
[0109] FIG. 12B shows an example of selected light rays scattered
by an object 140 contacting the touch screen of FIG. 12A and
redirected by pixel P of the pixilated light-turning layer 912 to
correlated light receiving location i.sub.x on the light sensor
920. The location of a touch event can be determined based on which
correlated location of the light sensor 920 detects light scattered
by the object 140 and which light source 940a to 940n emits light
corresponding to the touch event that is detected. For instance,
which light source 940a to 940n is emitting light can be determined
based on the timing of the touch event in implementations in which
light sources 940a to 940n are configured to sequentially emit
light. As another example, which light source 940a to 940n is
emitting light can be determined based on the a wavelength of light
striking a receiving surface of the light sensor 920 in
implementations in which light sources 940a to 940n are configured
to emit two or more different wavelengths of light. Knowledge of
which of the light sources 940a to 940n emitted the scattered light
(determined based on the pulse timing and/or light wavelength) can
provide a coordinate along one axis and the correlated light
receiving location of the sensor 920 receiving the light can
provide a coordinate along an orthogonal axis, thereby allowing the
location of the touch event to be determined.
[0110] FIG. 12C shows an example of selected light rays scattered
by two objects simultaneously contacting the touch screen of FIG.
12A and redirected by a pixilated light-turning layer to a light
sensor. The touch screen apparatus 1200 can detect touch events
corresponding to a first object 140a and a second object 140b
simultaneously contacting a major surface of the light guide 910.
The touch screen 1200 can distinguish the first object 140a and the
second object 140b from hypothetical contact positions 140c and
140d. The touch screen apparatus 1200 can emit light from different
light sources 940a to 940n at different times and/or at different
wavelengths. One coordinate of the position of each touch can be
determined based on the different times and/or different
wavelengths. For instance, one light source 940a to 940n can emit
light that is scattered by the first object 140a and a different
light source 940a to 940n can emit light that is scattered by the
second object 140b. The position of each of the simultaneous touch
events can be determined based on the sensor location receiving
light directed by each object and the time at which the light
strikes the correlated locations on the light sensor 920 and/or the
wavelength of the light striking the correlated locations on the
light sensor 920.
[0111] FIG. 12D shows an example of a plan view of another
implementation of a touch screen apparatus 1300 configured to
detect the presence and location of a contacting object. In
addition to the features of the touch screen apparatus 1200 of
FIGS. 12A-12C, the touch screen apparatus 1300 of FIG. 12D can
include a second plurality of light emitters 941a to 941m
configured to provide collimated light such that the light
propagates through the light guide 910 substantially normal to the
second plurality of light emitters 941a to 941m. The second
plurality of light emitters 941a to 941m can include any
combination of features of the plurality of light emitters 940a to
940n, for example, as described in connection with FIGS. 12A-12C.
The second plurality of light emitters 941a to 941m can be
configured to emit light into a third edge of the light guide 910
that is different from the edge into which the plurality of light
emitters 940a to 940n are configured to emit light into the light
guide 910. In the implementation, illustrated in FIG. 12D, the
edges of the light guide 910 into which the plurality of light
emitters 940a to 940n and the second plurality of light emitters
941a to 941m are configured to emit light into are adjacent and
orthogonal to each other.
[0112] With continued reference to FIG. 12D, the touch screen
apparatus 1300 also includes light sensors 920a and 920b. The light
sensor 920a can be positioned along an edge of the light guide 910
that is disposed on an axis transverse to the edge of the light
guide 910 along which the plurality of light emitters 940a to 940n
are positioned. The light sensor 920b can be positioned along an
edge of the light guide 910 that is disposed on an axis transverse
to the edge of the light guide 910 along which the second plurality
of light emitters 941a to 941m are positioned.
[0113] According to some implementations, the plurality of light
sources 940a to 940n and the second plurality of light sources 941a
to 941m can sequentially pulse light into the input edge of the
light guide 910 and pixels of the pixilated light-turning layer 912
can redirect scattered light associated with a touch event towards
their correlated locations on the light sensor 920a and/or 920b.
For example, the plurality of light sources 940a to 940n and the
and the second plurality of light sources 941a to 941m can be
configured to emit light at different times and the light sensors
920a and 920b can be configured to be inactive or to ignore
received light when the light source facing it is emitting light.
Alternatively or additionally to pulsing light, the plurality of
light sources 940a to 940n and/or the second plurality of light
sources 941a to 941m can be configured to emit light having two or
more different wavelengths. In some implementations, the plurality
of light sources 940a to 940n can sequentially pulse light and the
second plurality of light sources 941a to 941m can emit light
having two or more different wavelengths. Having two pluralities of
light sources and two light sensors can increase the precision or
resolution of the touch screen 1300 in some implementations by
providing additional data points for determining the location of a
touch event. In some implementations, the first plurality of light
sources 940a to 940n can have a different number of light sources
than the second plurality of light sources 941a to 941m. In some
other implementations, n can equal m and the first plurality of
light sources 940a to 940n can have the same number of light
sources as the second plurality of light sources 941a to 941m.
[0114] The example touch screen apparatuses 1000, 1100, 1200, 1300
can alternatively or additionally use ambient light and/or light
from a display (for example, the display 930 of FIG. 9B) in
connection with detecting a touch event. For instance, ambient
light and/or light from the display can be injected into the light
guide 910. The light sensor 920 can be configured to detect the
absence of ambient light associated with an object 140 touching or
in close proximity to a major surface of the light guide 910. For
example, the object 140 can block ambient light and the pixilated
light-turning layer 912 can direct ambient light associated with
pixels that are not blocked by the object 140 to the light sensor
920. The light sensor 920 can then generate one or more signals
indicative of a sensor location that does not receive ambient
light. A touch event associated with the object 140 can be
determined based on the one or more generated signals.
[0115] FIG. 13 shows an example of light-turning pixels correlated
with locations on a light sensor. In some implementations, as
described herein, for an object contacting a light guide to be
detected, light scattered by the object may be repeatably
redirected only to one or more particular locations on an light
sensor. To later determine a position of the object, a mapping of
the two-dimensional location of the object to one or more specific
locations on the light sensor may be utilized.
[0116] In the touch screen apparatus 900, 1000, 1100, 1200, and/or
1300, various predefined correlations of light-turning pixels to
light receiving locations on the light sensor 920 can be used in
detecting the position of a touch event. According to some
implementations, predefined correlations of the light-turning
pixels to light receiving locations can include one or more pixels
having a similar sequence and/or relative spatial orientation to
one another as the light receiving locations on the light sensor.
Alternatively or additionally, as illustrated with pixels
P.sub.4-P.sub.6 and light receiving locations i.sub.4-i.sub.6, in a
predefined correlation of one or more light-turning pixels to light
receiving locations on the light sensor may not match a relative
location of one or more pixels in the light guide 910.
[0117] Referring to FIG. 13, a correlation between pixels and light
receiving locations is illustrated by arrows from pixels P.sub.1,
P.sub.2, P.sub.3, . . . P.sub.m to light receiving locations
i.sub.1, i.sub.2, i.sub.3, . . . i.sub.n on the light sensor 920.
In some implementations, there can be a one-to-one correspondence
between a pixel of the light-turning layer and a light receiving
location on the light sensor. In other implementations, more than
one location on the light sensors 920a or 920b can correspond to a
single pixel and/or more than one pixel can correspond to one
location on the light sensor 920a or 920b. With more than one light
receiving location mapped to a single pixel, a more accurate and/or
precise determination of a position of a touch event can be
detected in some implementations. With more than one pixel mapped
to a single light receiving location, a smaller light sensor 920a
or 920b can be used. A processor, such as the processor 21 of FIG.
15B, can be configured with specific executable instructions to
correlate a sensor location with the location of the object based
on a known correlation of sensor locations to pixels and/or
locations above a light guide.
[0118] FIG. 14 shows an example of a flow diagram illustrating a
process 1400 for determining a position of a touch event according
to some implementations. Light redirected from a pixel of a
pixilated light-turning layer to a sensor location can be received
at block 1402. The pixilated light-turning layer can correspond to
the light-turning layer 912 (FIGS. 9A-13) and the redirected light
can propagate through light guide 910 (FIGS. 9A-13) and/or 1120
(FIGS. 11A-11D) to reach the light sensor 920 (FIGS. 9A-13).
[0119] The light receiving location receiving the incident light
can be correlated with a location of the object at block 1404. The
light receiving can be mapped to at least one pixel of the
pixilated light-turning layer. According to certain
implementations, the light receiving location can be mapped to a
single pixel of the pixilated light-turning layer.
[0120] At block 1406, a position of the touch event can be
determined based on the mapping. For instance, the mapping of the
light receiving location to the at least one pixel of the pixilated
light-turning layer can be used to determine the position of the
touch event. The position of the touch event can be computed by any
suitable processor in communication with the light sensor. In some
implementations, the process 1400 can include causing a plurality
of light sources to sequentially emit light into the light guide
according to some implementations. In these implementations, the
correlation can be based on which light source of the plurality of
light sources emits light that is scattered by the object and
received by the light sensor. For instance, one coordinate of a
position of a touch event can be determined based on a time at
which a location of the light sensor receives light. The time can
be matched with when a particular light source emits light, which
in turn indicates at least one coordinate of a position of the
touch event. Another coordinate for the touch event can be
determined from the light receiving location receiving light.
[0121] The process 1400 can detect the position of two or more
simultaneous touch events. For example, light redirected from the
pixilated light-turning layer can be received at a second sensor
location. The second sensor location can be correlated with a
location of a second object in contact with the light guide. For
instance, the second sensor location can be mapped to at least one
pixel of the pixilated light-turning layer that is not mapped to
the first sensor location. A position of another touch event can be
determined based on mapping the second sensor location with the
location of the second object. In this way, positions of the touch
event and the other touch event that occur simultaneously can be
detected.
[0122] FIGS. 15A and 15B show examples of system block diagrams
illustrating a display device 40 that includes a plurality of
interferometric modulators. The display device 40 can be, for
example, a cellular or mobile telephone. However, the same
components of the display device 40 or slight variations thereof
are also illustrative of various types of display devices such as
televisions, e-readers and portable media players.
[0123] 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 can be formed from any of a variety of
manufacturing processes, 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. The
housing 41 can include removable portions (not shown) that may be
interchanged with other removable portions of different color, or
containing different logos, pictures, or symbols.
[0124] The display 30 may be any of a variety of displays,
including a bi-stable or analog display, as described herein. The
display 30 also can be configured to include a flat-panel display,
such as plasma, EL, OLED, STN LCD, or TFT LCD, or a non-flat-panel
display, such as a CRT or other tube device. In addition, the
display 30 can include an interferometric modulator display, as
described herein.
[0125] The components of the display device 40 are schematically
illustrated in FIG. 15B. The display device 40 includes a housing
41 and can include additional components at least partially
enclosed therein. For example, the 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 can provide power to all components as required by
the particular display device 40 design.
[0126] The network interface 27 includes the antenna 43 and the
transceiver 47 so that the display device 40 can communicate with
one or more devices over a network. The network interface 27 also
may have some processing capabilities to relieve, e.g., data
processing requirements of the processor 21. The antenna 43 can
transmit and receive signals. In some implementations, the antenna
43 transmits and receives RF signals according to the IEEE 16.11
standard, including IEEE 16.11(a), (b), or (g), or the IEEE 802.11
standard, including IEEE 802.11a, b, g or n. In some other
implementations, the antenna 43 transmits and receives RF signals
according to the BLUETOOTH standard. In the case of a cellular
telephone, the antenna 43 is designed to receive code division
multiple access (CDMA), frequency division multiple access (FDMA),
time division multiple access (TDMA), Global System for Mobile
communications (GSM), GSM/General Packet Radio Service (GPRS),
Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio
(TETRA), Wideband-CDMA (W-CDMA), Evolution Data Optimized (EV-DO),
1xEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access (HSPA),
High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet
Access (HSUPA), Evolved High Speed Packet Access (HSPA+), Long Term
Evolution (LTE), AMPS, or other known signals that are used to
communicate within a wireless network, such as a system utilizing
3G or 4G technology. The transceiver 47 can pre-process 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
can process signals received from the processor 21 so that they may
be transmitted from the display device 40 via the antenna 43.
[0127] In some implementations, the transceiver 47 can be replaced
by a receiver. In addition, the network interface 27 can be
replaced by an image source, which can store or generate image data
to be sent to the processor 21. The processor 21 can control the
overall operation of the 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 can send the processed data to the
driver controller 29 or to the 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.
[0128] The processor 21 can include a microcontroller, CPU, or
logic unit to control operation of the display device 40. The
conditioning hardware 52 may include amplifiers and filters for
transmitting signals to the speaker 45, and for receiving signals
from the microphone 46. The conditioning hardware 52 may be
discrete components within the display device 40, or may be
incorporated within the processor 21 or other components.
[0129] The driver controller 29 can take the raw image data
generated by the processor 21 either directly from the processor 21
or from the frame buffer 28 and can re-format the raw image data
appropriately for high speed transmission to the array driver 22.
In some implementations, the driver controller 29 can re-format 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 an 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. For example,
controllers 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.
[0130] The array driver 22 can receive the formatted information
from the driver controller 29 and can re-format the video data into
a parallel set of waveforms that are applied many times per second
to the hundreds, and sometimes thousands (or more), of leads coming
from the display's x-y matrix of pixels.
[0131] In some implementations, the driver controller 29, the array
driver 22, and the display array 30 are appropriate for any of the
types of displays described herein. For example, the driver
controller 29 can be a conventional display controller or a
bi-stable display controller (e.g., an IMOD controller).
Additionally, the array driver 22 can be a conventional driver or a
bi-stable display driver (e.g., an IMOD display driver). Moreover,
the display array 30 can be a conventional display array or a
bi-stable display array (e.g., a display including an array of
IMODs). In some implementations, the driver controller 29 can be
integrated with the array driver 22. Such an implementation is
common in highly integrated systems such as cellular phones,
watches and other small-area displays.
[0132] In some implementations, the input device 48 can be
configured to allow, e.g., a user to control the operation of the
display device 40. The input device 48 can include a keypad, such
as a QWERTY keyboard or a telephone keypad, a button, a switch, a
rocker, a touch-sensitive screen, or a pressure- or heat-sensitive
membrane. The microphone 46 can be configured as an input device
for the display device 40. In some implementations, voice commands
through the microphone 46 can be used for controlling operations of
the display device 40.
[0133] The power supply 50 can include a variety of energy storage
devices as are well known in the art. For example, the power supply
50 can be a rechargeable battery, such as a nickel-cadmium battery
or a lithium-ion battery. The power supply 50 also can be a
renewable energy source, a capacitor, or a solar cell, including a
plastic solar cell or solar-cell paint. The power supply 50 also
can be configured to receive power from a wall outlet.
[0134] In some implementations, control programmability resides in
the driver controller 29 which can be located in several places in
the electronic display system. In some other implementations,
control programmability resides in the array driver 22. The
above-described optimization may be implemented in any number of
hardware and/or software components and in various
configurations.
[0135] The various illustrative logics, logical blocks, modules,
circuits and algorithm steps described in connection with the
implementations disclosed herein may be implemented as electronic
hardware, computer software, or combinations of both. The
interchangeability of hardware and software has been described
generally, in terms of functionality, and illustrated in the
various illustrative components, blocks, modules, circuits and
steps described above. Whether such functionality is implemented in
hardware or software depends upon the particular application and
design constraints imposed on the overall system.
[0136] The hardware and data processing apparatus used to implement
the various illustrative logics, logical blocks, modules and
circuits described in connection with the aspects disclosed herein
may be implemented or performed with a general purpose single- or
multi-chip processor, a digital signal processor (DSP), an
application specific integrated circuit (ASIC), a field
programmable gate array (FPGA) or other programmable logic device,
discrete gate or transistor logic, discrete hardware components, or
any combination thereof designed to perform the functions described
herein. A general purpose processor may be a microprocessor, or,
any conventional processor, controller, microcontroller, or state
machine. A processor may also be implemented as a combination of
computing devices, e.g., a combination of a DSP and a
microprocessor, a plurality of microprocessors, one or more
microprocessors in conjunction with a DSP core, or any other such
configuration. In some implementations, particular steps and
methods may be performed by circuitry that is specific to a given
function.
[0137] In one or more aspects, the functions described may be
implemented in hardware, digital electronic circuitry, computer
software, firmware, including the structures disclosed in this
specification and their structural equivalents thereof, or in any
combination thereof. Implementations of the subject matter
described in this specification also can be implemented as one or
more computer programs, i.e., one or more modules of computer
program instructions, encoded on a computer storage media for
execution by, or to control the operation of, data processing
apparatus.
[0138] If implemented in software, the functions may be stored on
or transmitted over as one or more instructions or code on a
computer-readable medium. The steps of a method or algorithm
disclosed herein may be implemented in a processor-executable
software module which may reside on a computer-readable medium.
Computer-readable media includes both computer storage media and
communication media including any medium that can be enabled to
transfer a computer program from one place to another. A storage
media may be any available media that may be accessed by a
computer. By way of example, and not limitation, such
computer-readable media may include RAM, ROM, EEPROM, CD-ROM or
other optical disk storage, magnetic disk storage or other magnetic
storage devices, or any other medium that may be used to store
desired program code in the form of instructions or data structures
and that may be accessed by a computer. Also, any connection can be
properly termed a computer-readable medium. Disk and disc, as used
herein, includes compact disc (CD), laser disc, optical disc,
digital versatile disc (DVD), floppy disk, and blu-ray disc where
disks usually reproduce data magnetically, while discs reproduce
data optically with lasers. Combinations of the above should also
be included within the scope of computer-readable media.
Additionally, the operations of a method or algorithm may reside as
one or any combination or set of codes and instructions on a
machine readable medium and computer-readable medium, which may be
incorporated into a computer program product.
[0139] Various modifications to the implementations described in
this disclosure may be readily apparent to those skilled in the
art, and the generic principles defined herein may be applied to
other implementations without departing from the spirit or scope of
this disclosure. Thus, the claims are not intended to be limited to
the implementations shown herein, but are to be accorded the widest
scope consistent with this disclosure, the principles and the novel
features disclosed herein. The word "exemplary" is used exclusively
herein to mean "serving as an example, instance, or illustration."
Any implementation described herein as "exemplary" is not
necessarily to be construed as preferred or advantageous over other
implementations. Additionally, a person having ordinary skill in
the art will readily appreciate, the terms "upper" and "lower" are
sometimes used for ease of describing the figures, and indicate
relative positions corresponding to the orientation of the figure
on a properly oriented page, and may not reflect the proper
orientation of the IMOD as implemented.
[0140] Certain features that are described in this specification in
the context of separate implementations also can be implemented in
combination in a single implementation. Conversely, various
features that are described in the context of a single
implementation also can be implemented in multiple implementations
separately or in any suitable subcombination. Moreover, although
features may be described above as acting in certain combinations
and even initially claimed as such, one or more features from a
claimed combination can in some cases be excised from the
combination, and the claimed combination may be directed to a
subcombination or variation of a subcombination.
[0141] Similarly, while operations are depicted in the drawings in
a particular order, this should not be understood as requiring that
such operations be performed in the particular order shown or in
sequential order, or that all illustrated operations be performed,
to achieve desirable results. Further, the drawings may
schematically depict one more example processes in the form of a
flow diagram. However, other operations that are not depicted can
be incorporated in the example processes that are schematically
illustrated. For example, one or more additional operations can be
performed before, after, simultaneously, or between any of the
illustrated operations. In certain circumstances, multitasking and
parallel processing may be advantageous. Moreover, the separation
of various system components in the implementations described above
should not be understood as requiring such separation in all
implementations, and it should be understood that the described
program components and systems can generally be integrated together
in a single software product or packaged into multiple software
products. Additionally, other implementations are within the scope
of the following claims. In some cases, the actions recited in the
claims can be performed in a different order and still achieve
desirable results.
* * * * *