U.S. patent application number 13/449248 was filed with the patent office on 2013-10-17 for controller for optically-switchable windows.
This patent application is currently assigned to View, Inc.. The applicant listed for this patent is Stephen C. Brown. Invention is credited to Stephen C. Brown.
Application Number | 20130271813 13/449248 |
Document ID | / |
Family ID | 49324820 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130271813 |
Kind Code |
A1 |
Brown; Stephen C. |
October 17, 2013 |
CONTROLLER FOR OPTICALLY-SWITCHABLE WINDOWS
Abstract
This disclosure provides a window controller that includes a
command-voltage generator that generates a command voltage signal,
and a pulse-width-modulated-signal generator that generates a
pulse-width-modulated signal based on the command voltage signal.
The pulse-width-modulated signal drives an optically-switchable
device. The pulse-width-modulated signal comprises a first power
component having a first duty cycle and a second power component
having a second duty cycle. The first component delivers a first
pulse during each active portion of the first duty cycle, and the
second component delivers a second pulse during each active portion
of the second duty cycle. The first pulses are applied to a first
conductive layer and the second pulses are applied to a second
conductive layer. The relative durations of the active portions and
the relative durations of the first and second pulses are adjusted
to result in a change in an effective DC voltage applied across the
optically-switchable device.
Inventors: |
Brown; Stephen C.; (San
Mateo, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Brown; Stephen C. |
San Mateo |
CA |
US |
|
|
Assignee: |
View, Inc.
Milpitas
CA
|
Family ID: |
49324820 |
Appl. No.: |
13/449248 |
Filed: |
April 17, 2012 |
Current U.S.
Class: |
359/275 |
Current CPC
Class: |
G02F 1/163 20130101;
E06B 9/24 20130101; E06B 2009/2464 20130101 |
Class at
Publication: |
359/275 |
International
Class: |
G02F 1/163 20060101
G02F001/163 |
Claims
1. A window controller comprising: a command-voltage generator
configured to generate a command voltage signal; a
pulse-width-modulated-signal generator configured to generate a
pulse-width-modulated signal based on the command voltage signal,
the pulse-width-modulated signal configured to drive an
optically-switchable device on a substantially transparent
substrate, wherein: the pulse-width-modulated signal comprises a
first power component having a first duty cycle and a second power
component having a second duty cycle; the first power component is
configured to deliver a first pulse during each active portion of
the first duty cycle; the second power component is configured to
deliver a second pulse during each active portion of the second
duty cycle; and during operation, the first pulses are applied to a
first conductive electrode layer of the optically-switchable device
and the second pulses are applied to a second conductive electrode
layer of the optically-switchable device; wherein the relative
durations of the active portions of the first and second duty
cycles and the relative durations of the first and second pulses
are adjusted to result in a change in an effective DC voltage
applied across the optically-switchable device.
2. The window controller of claim 1, wherein the substantially
transparent substrate is configured in an IGU.
3. The window controller of claim 2, wherein the window controller
is located at least partially within a seal of the IGU.
4. The window controller of claim 2, wherein the
optically-switchable device is an electrochromic device formed on a
surface of the substantially transparent substrate and adjacent an
interior volume of the IGU.
5. The window controller of claim 4, wherein the electrochromic
device is entirely comprised of inorganic solid-state
materials.
6. The window controller of claim 1, wherein: the first duty cycle
has a first time period and a first voltage magnitude; the second
duty cycle has a second time period and a second voltage magnitude;
the first time period equals the second time period; and the first
voltage magnitude equals the second voltage magnitude.
7. The window controller of claim 6, further comprising first and
second inductors that couple the first and second power components
to the optically-switchable device, wherein the voltage applied
across the optically-switchable device resulting from the applied
first and second power components is effectively a DC voltage.
8. The window controller of claim 7, wherein: the active portion of
the first duty cycle comprises a first fraction of the first time
period; and the active portion of the second duty cycle comprises a
second fraction of the second time period.
9. The window controller of claim 8, wherein: the magnitude of the
voltage applied to a first conductive layer of the
optically-switchable device is substantially proportional to the
product of the first fraction and the first voltage magnitude; the
magnitude of the voltage applied to a second conductive layer of
the optically-switchable device is substantially proportional to
the product of the second fraction and the second voltage
magnitude; and the effective DC voltage applied across the
optically-switchable device is substantially equal to the
difference between the magnitude of the voltage applied to the
first conductive layer and the magnitude of the voltage applied to
the second conductive layer.
10. The window controller of claim 1, wherein the command-voltage
generator includes a microcontroller configured to generate the
command voltage signal.
11. The window controller of claim 10, wherein the microcontroller
generates the command voltage signal based at least in part on a
voltage feedback signal that is itself based on an effective DC
voltage applied across the optically-switchable device.
12. The window controller of claim 10, wherein the microcontroller
generates the command voltage signal based at least in part on a
current feedback signal that is itself based on a detected current
transmitted through the optically-switchable device.
13. The window controller of claim 10, further comprising a memory
device configured to store one or more drive parameters.
14. The window controller of claim 13, wherein the drive parameters
include one or more of a current outside temperature, a current
inside temperature, a current transmissivity value of the
electrochromic device, a target transmissivity value of the
electrochromic device, and a transition rate.
15. The window controller of claim 14, wherein the microcontroller
is further configured to modify the command voltage signal based on
one or more other input, feedback, or control signals.
16. The window controller of claim 15, wherein the microcontroller
modifies the command voltage signal based at least in part on a
voltage feedback signal that is itself based on a detected actual
level of the effective DC voltage applied across the
optically-switchable device.
17. The window controller of claim 15, wherein the microcontroller
modifies the command voltage signal based at least in part on a
current feedback signal that is itself based on a detected current
transmitted through the optically-switchable device.
18. The window controller of claim 15, wherein the window
controller further comprises one or more communication
interfaces.
19. The window controller of claim 18, wherein: the window
controller is configured to communicate with a network controller;
the network controller is configured to communicate and control a
plurality of window controllers; and the microcontroller is
configured to modify the command voltage signal based on input from
the network controller.
20. The window controller of claim 19, wherein: the window
controller or network controller is configured to communicate with
a building management system; and the microcontroller is configured
to modify the command voltage signal based on input from the
building management system.
21. The window controller of claim 19, wherein: the window
controller or network controller is configured to communicate with
one or more lighting systems, heating systems, cooling systems,
ventilation systems, power systems, and/or security systems; and
the microcontroller is configured to modify the command voltage
signal based on input from the one or more lighting systems,
heating systems, cooling systems, ventilation systems, power
systems, and/or security systems.
22. The window controller of claim 19, wherein: the window
controller is configured to communicate with one or more
photodetectors; and the microcontroller is configured to modify the
command voltage signal based on input from the one or more
photodetectors.
23. The window controller of claim 19, wherein: the window
controller is configured to communicate with one or more
temperature sensors; and the microcontroller is configured to
modify the command voltage signal based on input from the one or
more temperature sensors.
24. The window controller of claim 19, wherein: the window
controller or network controller is configured to communicate with
one or more manual user-input devices; and the microcontroller is
configured to modify the command voltage signal based on input from
one or more of the manual user-input devices.
25. A system comprising: a plurality of windows, each window
comprising an optically-switchable device on a substantially
transparent substrate; a network controller configured to control a
plurality of window controllers; a plurality of window controllers,
each window controller comprising: a command-voltage generator
configured to generate a command voltage signal; and a
pulse-width-modulated-signal generator configured to generate a
pulse-width-modulated signal based on the command voltage signal,
the command voltage signal being based at least in part and at
least at certain times on an input received from the network
controller, the pulse-width-modulated signal configured to drive a
respective one or more of the optically-switchable devices, one or
more communication interfaces that enable the window controller to
communicate with the network controller; wherein: the
pulse-width-modulated signal comprises a first power component
having a first duty cycle and a second power component having a
second duty cycle; the first power component is configured to
deliver a first pulse during each active portion of the first duty
cycle; the second power component is configured to deliver a second
pulse during each active portion of the second duty cycle; and
during operation, the first pulses are applied to a first
conductive electrode layer of the optically-switchable device and
the second pulses are applied to a second conductive electrode
layer of the optically-switchable device; wherein the relative
durations of the active portions of the first and second duty
cycles and the relative durations of the first and second pulses
are adjusted to result in a change in an effective DC voltage
applied across the optically-switchable device.
26. The system of claim 25, wherein each substantially transparent
substrate is configured in an IGU.
27. The system of claim 26, wherein one or more of the window
controllers are located at least partially within a seal of a
respective IGU.
28. The system of claim 26, wherein the optically-switchable device
is an electrochromic device formed on a surface of the
substantially transparent substrate and adjacent an interior volume
of the IGU.
29. The system of claim 25, wherein, for each window controller:
the first duty cycle has a first time period and a first voltage
magnitude; the second duty cycle has a second time period and a
second voltage magnitude; the first time period equals the second
time period; and the first voltage magnitude equals the second
voltage magnitude.
30. The system of claim 29, wherein each window controller further
comprises first and second inductors that couple the first and
second power components to the optically-switchable device, wherein
the voltage applied across the optically-switchable device
resulting from the applied first and second power components is
effectively a DC voltage.
31. The system of claim 30, wherein: the active portion of the
first duty cycle comprises a first fraction of the first time
period; and the active portion of the second duty cycle comprises a
second fraction of the second time period.
32. The system of claim 31, wherein: the magnitude of the voltage
applied to a first conductive layer of the optically-switchable
device is substantially proportional to the product of the first
fraction and the first voltage magnitude; the magnitude of the
voltage applied to a second conductive layer of the
optically-switchable device is substantially proportional to the
product of the second fraction and the second voltage magnitude;
and the effective DC voltage applied across the
optically-switchable device is substantially equal to the
difference between the magnitude of the voltage applied to the
first conductive layer and the magnitude of the voltage applied to
the second conductive layer.
33. The system of claim 25, wherein the command-voltage generator
of each window controller includes a microcontroller configured to
generate the command voltage signal.
34. The system of claim 33, wherein the microcontroller generates
the respective command voltage signal based at least in part on a
voltage feedback signal that is itself based on an effective DC
voltage applied across the respective optically-switchable
device.
35. The system of claim 33, wherein the microcontroller generates
the respective command voltage signal based at least in part on a
current feedback signal that is itself based on a detected current
transmitted through the respective optically-switchable device.
36. The system of claim 33, wherein each window controller further
comprises a memory device configured to store one or more drive
parameters.
37. The system of claim 36, wherein the drive parameters include
one or more of a current outside temperature, a current inside
temperature, a current transmissivity value of the electrochromic
device, a target transmissivity value of the electrochromic device,
and a transition rate.
38. The system of claim 37, wherein the microcontroller modifies
the command voltage signal based at least in part on a voltage
feedback signal that is itself based on a detected actual level of
the effective DC voltage applied across the respective
optically-switchable device.
39. The system of claim 37, wherein the microcontroller modifies
the command voltage signal based at least in part on a current
feedback signal that is itself based on a detected current
transmitted through the respective optically-switchable device.
40. The system of claim 33, wherein: the network controller is
configured to communicate with a building management system; and
the microcontroller of each window controller is configured to
modify the command voltage signal based on input from the building
management system.
41. The system of claim 33, wherein: the network controller is
configured to communicate with one or more lighting systems,
heating systems, cooling systems, ventilation systems, power
systems, and/or security systems; and the microcontroller of each
window controller is configured to modify the command voltage
signal based on input from the one or more lighting systems,
heating systems, cooling systems, ventilation systems, power
systems, and/or security systems.
42. The system of claim 33, wherein: each window controller is
configured to communicate with one or more photodetectors; and the
respective microcontroller is configured to modify the command
voltage signal based on input from the one or more
photodetectors.
43. The system of claim 33, wherein: each window controller is
configured to communicate with one or more temperature sensors; and
the respective microcontroller is configured to modify the command
voltage signal based on input from the one or more temperature
sensors.
44. The system of claim 33, wherein: the network controller is
configured to communicate with one or more manual user-input
devices; and the microcontroller of each window controller is
configured to modify the command voltage signal based on input from
one or more of the manual user-input devices.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The application is related to: U.S. patent application Ser.
No. 13/049,756 (Attorney Docket No. SLDMP007) naming Brown et al.
as inventors, titled MULTIPURPOSE CONTROLLER FOR MULTISTATE WINDOWS
and filed 16 Mar. 2011; U.S. patent application Ser. No. ______
(Attorney Docket No. SLDMP035) naming Brown as inventor, titled
CONTROLLING TRANSITIONS IN OPTICALLY SWITCHABLE DEVICES and filed
17 Apr. 2012; and U.S. patent application Ser. No. ______ (Attorney
Docket No. SLDMP042) naming Brown as inventor, titled CONTROLLER
FOR OPTICALLY SWITCHABLE WINDOWS and filed 17 Apr. 2012; all of
which are incorporated herein by reference in their entireties and
for all purposes.
TECHNICAL FIELD
[0002] This disclosure relates generally to optically-switchable
devices including electrochromic windows, and more particularly to
controllers for controlling and driving optically-switchable
devices.
DESCRIPTION OF THE RELATED TECHNOLOGY
[0003] Optically-switchable devices can be integrated with windows
to enable control over, for example, the tinting, transmittance, or
reflectance of window panes. Optically-switchable devices include
electrochromic devices. Electrochromism is a phenomenon in which a
material exhibits a reversible electrochemically-mediated change in
one or more optical properties when stimulated to a different
electronic state. For example, the electrochromic material can be
stimulated by an applied voltage. Optical properties that can be
reversibly manipulated include, for example, color, transmittance,
absorbance, and reflectance. One well known electrochromic material
is tungsten oxide (WO.sub.3). Tungsten oxide is a cathodic
electrochromic material that undergoes a coloration
transition--transparent to blue--by electrochemical action via
intercalation of positive ions into the tungsten oxide matrix with
concurrent charge balance by electron insertion.
[0004] Electrochromic materials and the devices made from them may
be incorporated into, for example, windows for home, commercial, or
other uses. The color, transmittance, absorbance, or reflectance of
such electrochromic windows can be changed by inducing a change in
the electrochromic material. For example, electrochromic windows
can be darkened or lightened in response to electrical stimulation.
For example, a first voltage applied to an electrochromic device of
the window may cause the window to darken while a second voltage
may cause the window to lighten. This capability can allow for
control over the intensities of various wavelengths of light that
may pass through the window, including both the light that passes
from an outside environment through the window into an inside
environment as well as potentially the light that passes from an
inside environment through the window out to an outside
environment.
[0005] Such capabilities of electrochromic windows present enormous
opportunities for increasing energy efficiency, as well as for
aesthetic purposes. With energy conservation being foremost in the
minds of many modern energy policy-makers, it is expected that the
growth of the electrochromic window industry will be robust. An
important consideration in the engineering of electrochromic
windows is how best to integrate them into new as well as existing
(e.g., retrofit) applications. Of particular importance is how best
to organize, control, and deliver power to the electrochromic
windows.
SUMMARY
[0006] According to one innovative aspect, a window controller
includes a command-voltage generator configured to generate a
command voltage signal. The window controller also includes a
pulse-width-modulated-signal generator configured to generate a
pulse-width-modulated signal based on the command voltage signal.
The pulse-width-modulated signal is configured to drive an
optically-switchable device on a substantially transparent
substrate. In some embodiments, the pulse-width-modulated signal
comprises a first power component having a first duty cycle and a
second power component having a second duty cycle. In some
embodiments, the first power component is configured to deliver a
first pulse during each active portion of the first duty cycle, and
the second power component is configured to deliver a second pulse
during each active portion of the second duty cycle. In some
embodiments, during operation, the first pulses are applied to a
first conductive electrode layer of the optically-switchable device
and the second pulses are applied to a second conductive electrode
layer of the optically-switchable device. In some embodiments, the
relative durations of the active portions of the first and second
duty cycles and the relative durations of the first and second
pulses are adjusted to result in a change in an effective DC
voltage applied across the optically-switchable device.
[0007] In some embodiments, the substantially transparent substrate
is configured in an IGU. In some embodiments, the window controller
is located at least partially within a seal of the IGU. In some
embodiments, the optically-switchable device is an electrochromic
device formed on a surface of the substantially transparent
substrate and adjacent an interior volume of the IGU.
[0008] In some embodiments, the first duty cycle has a first time
period and a first voltage magnitude, the second duty cycle has a
second time period and a second voltage magnitude, the first time
period equals the second time period, and the first voltage
magnitude equals the second voltage magnitude. In some embodiments,
the window controller also includes first and second inductors that
couple the first and second power components to the
optically-switchable device, the voltage applied across the
optically-switchable device resulting from the applied first and
second power components is effectively a DC voltage. In some
embodiments, the active portion of the first duty cycle comprises a
first fraction of the first time period, the active portion of the
second duty cycle comprises a second fraction of the second time
period, the magnitude of the voltage applied to a first conductive
layer of the optically-switchable device is substantially
proportional to the product of the first fraction and the first
voltage magnitude, the magnitude of the voltage applied to a second
conductive layer of the optically-switchable device is
substantially proportional to the product of the second fraction
and the second voltage magnitude, and the effective DC voltage
applied across the optically-switchable device is substantially
equal to the difference between the magnitude of the voltage
applied to the first conductive layer and the magnitude of the
voltage applied to the second conductive layer.
[0009] In some embodiments, the command-voltage generator includes
a microcontroller configured to generate the command voltage
signal. In some embodiments, the microcontroller generates the
command voltage signal based at least in part on a voltage feedback
signal that is itself based on an effective DC voltage applied
across the optically-switchable device. In some embodiments, the
microcontroller generates the command voltage signal based at least
in part on a current feedback signal that is itself based on a
detected current transmitted through the optically-switchable
device.
[0010] In some embodiments, the window controller also includes a
memory device configured to store one or more drive parameters. In
some embodiments, the drive parameters include one or more of a
current outside temperature, a current inside temperature, a
current transmissivity value of the electrochromic device, a target
transmissivity value of the electrochromic device, and a transition
rate. In some embodiments, the microcontroller is further
configured to modify the command voltage signal based on one or
more other input, feedback, or control signals. The window
controller of claim 15, wherein the microcontroller modifies the
command voltage signal based at least in part on a voltage feedback
signal that is itself based on a detected actual level of the
effective DC voltage applied across the optically-switchable
device.
[0011] According to another innovative aspect, a system includes: a
plurality of windows, each window including an optically-switchable
device on a substantially transparent substrate; a plurality of
window controllers such as those just described; and a network
controller configured to control the plurality of window
controllers. In some embodiments, each window controller is
configured to generate a command voltage signal based at least in
part and at least at certain times on an input received from the
network controller.
[0012] In some embodiments, the network controller is configured to
communicate with a building management system and the
microcontroller of each window controller is configured to modify
the command voltage signal based on input from the building
management system. In some embodiments, the network controller is
configured to communicate with one or more lighting systems,
heating systems, cooling systems, ventilation systems, power
systems, and/or security systems and the microcontroller of each
window controller is configured to modify the command voltage
signal based on input from the one or more lighting systems,
heating systems, cooling systems, ventilation systems, power
systems, and/or security systems.
[0013] Details of one or more embodiments or 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
[0014] FIG. 1 shows a depiction of a system for controlling and
driving a plurality of electrochromic windows.
[0015] FIG. 2 shows a cross-sectional axonometric view of an
example electrochromic window that includes two window panes.
[0016] FIG. 3 shows an example of a voltage profile for driving an
optical state transition in an electrochromic device.
[0017] FIG. 4 shows a depiction of an example plug-in component
including a window controller.
[0018] FIG. 5A shows a depiction of an example transistor
implementation of a pulse-width modulator circuit.
[0019] FIG. 5B shows a depiction of an equivalent H-bridge
configuration representation of the pulse-width modulator circuit
of FIG. 5A.
[0020] FIG. 5C shows voltage profiles for the configurations of
FIGS. 5A and 5B.
[0021] FIG. 6 shows an example 3-dimensional data structure
including drive parameters for driving an electrochromic
device.
[0022] Like reference numbers and designations in the various
drawings indicate like elements.
DETAILED DESCRIPTION
[0023] The following detailed description is directed to certain
embodiments or implementations for the purposes of describing the
innovative aspects. However, the teachings herein can be applied
and implemented in a multitude of different ways. Furthermore,
while the disclosed embodiments focus on electrochromic windows
(also referred to as smart windows), the concepts disclosed herein
may apply to other types of switchable optical devices including,
for example, liquid crystal devices and suspended particle devices,
among others. For example, a liquid crystal device or a suspended
particle device, rather than an electrochromic device, could be
incorporated into some or all of the disclosed embodiments.
[0024] Referring to FIG. 1 as an example, some embodiments relate
to a system, 100, for controlling and driving (e.g., selectively
powering) a plurality of electrochromic windows, 102. System 100,
adapted for use in a building, 104, is used for controlling and
driving a plurality of exterior facing electrochromic windows 102.
Some embodiments find particularly advantageous use in buildings
such as commercial office buildings or residential buildings. Some
embodiments can be particularly suited and adapted for use in the
construction of new buildings. For example, some embodiments of
system 100 are designed to work in conjunction with modern or novel
heating, ventilation, and air conditioning (HVAC) systems, 106,
interior lighting systems, 107, security systems, 108, and power
systems, 109, as a single holistic efficient energy control system
for the entire building 104, or campus of buildings 104. Some
embodiments are particularly well-suited for integration with a
building management system (BMS), 110. A BMS is a computer-based
control system that can be installed in a building to monitor and
control the building's mechanical and electrical equipment such as
HVAC systems, lighting systems, power systems, elevators, fire
systems, and security systems. A BMS consists of hardware and
associated firmware or software for maintaining conditions in the
building according to preferences set by the occupants or a
building manager or other administrator. The software can be based
on, for example, internet protocols or open standards.
[0025] A BMS is typically used in large buildings, and typically
functions at least to control the environment within the building.
For example, a BMS may control lighting, temperature, carbon
dioxide levels, and humidity within a building. Typically, there
are many mechanical or electrical devices that are controlled by a
BMS such as, for example, heaters, air conditioners, blowers, and
vents. To control the building environment, a BMS may turn on and
off these various devices according to pre-defined rules or in
response to pre-defined conditions. A core function of a typical
modern BMS is to maintain a comfortable environment for the
building's occupants while minimizing heating and cooling energy
losses and costs. A modern BMS can be used not only to monitor and
control, but also to optimize the synergy between various systems,
for example, to conserve energy and lower building operation
costs.
[0026] Some embodiments are alternatively or additionally designed
to work responsively or reactively based on feedback sensed
through, for example, thermal, optical, or other sensors or through
input from, for example, an HVAC or interior lighting system, or an
input from a user control. Some embodiments also can be utilized in
existing structures, including both commercial and residential
structures, having traditional or conventional HVAC or interior
lighting systems. Some embodiments also can be retrofitted for use
in older residential homes.
[0027] In some embodiments, system 100 includes a network
controller, 112. In some embodiments, network controller 112
controls a plurality of window controllers, 114. For example,
network controller 112 can control tens, hundreds, or even
thousands of window controllers 114. Each window controller 114, in
turn, can control and drive one or more electrochromic windows 102.
The number and size of the electrochromic windows 102 that each
window controller 114 can drive is generally limited by the voltage
and current characteristics of the load on the window controller
114 controlling the respective electrochromic windows 102. In some
embodiments, the maximum window size that each window controller
114 can drive is limited by the voltage, current, or power
requirements to cause the desired optical transitions in the
electrochromic window 102 within a desired time-frame. Such
requirements are, in turn, a function of the surface area of the
window. In some embodiments, this relationship is nonlinear. For
example, the voltage, current, or power requirements can increase
nonlinearly with the surface area of the electrochromic window 102.
For example, in some cases the relationship is nonlinear at least
in part because the sheet resistance of the first and second
conductive layers 230 and 238 (see FIG. 2) increases nonlinearly
with distance across the length and width of the first or second
conductive layers. In some embodiments, the relationship between
the voltage, current, or power requirements required to drive
multiple electrochromic windows 102 of equal size and shape is,
however, directly proportional to the number of the electrochromic
windows 102 being driven.
[0028] In the following description, each electrochromic window 102
will be referred to as an insulated glass unit (IGU) 102. This
convention is assumed, for example, because it is common and can be
desirable to have IGUs serve as the fundamental construct for
holding an electrochromic lite or pane. Additionally, IGUs,
especially those having double or triple pane window
configurations, offer superior thermal insulation over single pane
configurations. However, this convention is for convenience only
because, as described below, in many implementations the basic unit
of an electrochromic window can be considered to include a pane or
substrate of transparent material, upon which an electrochromic
coating or device is deposited, and to which associated electrical
connections are coupled to power the electrochromic coating or
device.
[0029] FIG. 2 shows a cross-sectional axonometric view of an
embodiment of an IGU 102 that includes two window panes, 216. In
various embodiments, each IGU 102 can include one, two, or more
substantially transparent (e.g., at no applied voltage) window
panes 216 as well as a frame, 218, that supports the panes 216. For
example, the IGU 102 shown in FIG. 2 is configured as a double-pane
window. One or more of the panes 216 can itself be a laminate
structure of two, three, or more layers or panes (e.g.,
shatter-resistant glass similar to automotive windshield glass). In
each IGU 102, at least one of the panes 216 includes an
electrochromic device or stack, 220, disposed on at least one of
its inner surface, 222, or outer surface, 224: for example, the
inner surface 222 of the outer pane 216.
[0030] In multi-pane configurations, each adjacent set of panes 216
can have a volume, 226, disposed between them. Generally, each of
the panes 216 and the IGU 102 as a whole are rectangular and form a
rectangular solid. However, in other embodiments other shapes
(e.g., circular, elliptical, triangular, curvilinear, convex,
concave) may be desired. In some embodiments, the volume 226
between the panes 116 is evacuated of air. In some embodiments, the
IGU 102 is hermetically-sealed. Additionally, the volume 226 can be
filled (to an appropriate pressure) with one or more gases, such as
argon (Ar), krypton (Kr), or xenon (Xn), for example. Filling the
volume 226 with a gas such as Ar, Kr, or Xn can reduce conductive
heat transfer through the IGU 102 because of the low thermal
conductivity of these gases. The latter two gases also can impart
improved acoustic insulation due to their increased weight.
[0031] In some embodiments, frame 218 is constructed of one or more
pieces. For example, frame 218 can be constructed of one or more
materials such as vinyl, PVC, aluminum (Al), steel, or fiberglass.
The frame 218 may also include or hold one or more foam or other
material pieces that work in conjunction with frame 218 to separate
the window panes 216 and to hermetically seal the volume 226
between the panes 216. For example, in a typical IGU
implementation, a spacer lies between adjacent panes 216 and forms
a hermetic seal with the panes in conjunction with an adhesive
sealant that can be deposited between them. This is termed the
primary seal, around which can be fabricated a secondary seal,
typically of an additional adhesive sealant. In some such
embodiments, frame 218 can be a separate structure that supports
the IGU construct.
[0032] Each pane 216 includes a substantially transparent or
translucent substrate, 228. Generally, substrate 228 has a first
(e.g., inner) surface 222 and a second (e.g., outer) surface 224
opposite the first surface 222. In some embodiments, substrate 228
can be a glass substrate. For example, substrate 228 can be a
conventional silicon oxide (SO.sub.x)-based glass substrate such as
soda-lime glass or float glass, composed of, for example,
approximately 75% silica (SiO.sub.2) plus Na.sub.2O, CaO, and
several minor additives. However, any material having suitable
optical, electrical, thermal, and mechanical properties may be used
as substrate 228. Such substrates also can include, for example,
other glass materials, plastics and thermoplastics (e.g.,
poly(methyl methacrylate), polystyrene, polycarbonate, allyl
diglycol carbonate, SAN (styrene acrylonitrile copolymer),
poly(4-methyl-1-pentene), polyester, polyamide), or mirror
materials. If the substrate is formed from, for example, glass,
then substrate 228 can be strengthened, e.g., by tempering,
heating, or chemically strengthening. In other implementations, the
substrate 228 is not further strengthened, e.g., the substrate is
untempered.
[0033] In some embodiments, substrate 228 is a glass pane sized for
residential or commercial window applications. The size of such a
glass pane can vary widely depending on the specific needs of the
residence or commercial enterprise. In some embodiments, substrate
228 can be formed of architectural glass. Architectural glass is
typically used in commercial buildings, but also can be used in
residential buildings, and typically, though not necessarily,
separates an indoor environment from an outdoor environment. In
certain embodiments, a suitable architectural glass substrate can
be at least approximately 20 inches by approximately 20 inches, and
can be much larger, for example, approximately 80 inches by
approximately 120 inches, or larger. Architectural glass is
typically at least about 2 millimeters (mm) thick and may be as
thick as 6 mm or more. Of course, electrochromic devices 220 can be
scalable to substrates 228 smaller or larger than architectural
glass, including in any or all of the respective length, width, or
thickness dimensions. In some embodiments, substrate 228 has a
thickness in the range of approximately 1 mm to approximately 10
mm.
[0034] Electrochromic device 220 is disposed over, for example, the
inner surface 222 of substrate 228 of the outer pane 216 (the pane
adjacent the outside environment). In some other embodiments, such
as in cooler climates or applications in which the IGUs 102 receive
greater amounts of direct sunlight (e.g., perpendicular to the
surface of electrochromic device 220), it may be advantageous for
electrochromic device 220 to be disposed over, for example, the
inner surface (the surface bordering the volume 226) of the inner
pane adjacent the interior environment. In some embodiments,
electrochromic device 220 includes a first conductive layer (CL)
230, an electrochromic layer (EC) 232, an ion conducting layer (IC)
234, a counter electrode layer (CE) 236, and a second conductive
layer (CL) 238. Again, layers 230, 232, 234, 236, and 238 are also
collectively referred to as electrochromic stack 220. A power
source 240 operable to apply an electric potential across a
thickness of electrochromic stack 220 effects the transition of the
electrochromic device 220 from, for example, a bleached or lighter
state (e.g., a transparent, semitransparent, or translucent state)
to a colored or darker state (e.g., a tinted, less transparent or
less translucent state). In some other embodiments, the order of
layers 230, 232, 234, 236, and 238 can be reversed or otherwise
reordered or rearranged with respect to substrate 238.
[0035] In some embodiments, one or both of first conductive layer
230 and second conductive layer 238 is formed from an inorganic and
solid material. For example, first conductive layer 230, as well as
second conductive layer 238, can be made from a number of different
materials, including conductive oxides, thin metallic coatings,
conductive metal nitrides, and composite conductors, among other
suitable materials. In some embodiments, conductive layers 230 and
238 are substantially transparent at least in the range of
wavelengths where electrochromism is exhibited by the
electrochromic layer 232. Transparent conductive oxides include
metal oxides and metal oxides doped with one or more metals. For
example, metal oxides and doped metal oxides suitable for use as
first or second conductive layers 230 and 238 can include indium
oxide, indium tin oxide (ITO), doped indium oxide, tin oxide, doped
tin oxide, zinc oxide, aluminum zinc oxide, doped zinc oxide,
ruthenium oxide, doped ruthenium oxide, among others. First and
second conductive layers 230 and 238 also can be referred to as
"transparent conductive oxide" (TCO) layers.
[0036] In some embodiments, commercially available substrates, such
as glass substrates, already contain a transparent conductive layer
coating when purchased. In some embodiments, such a product can be
used for both substrate 238 and conductive layer 230 collectively.
Examples of such glass substrates include conductive layer-coated
glasses sold under the trademark TEC Glass.TM. by Pilkington, of
Toledo, Ohio and SUNGATE.TM. 300 and SUNGATE.TM. 500 by PPG
Industries of Pittsburgh, Pa. Specifically, TEC Glass.TM. is, for
example, a glass coated with a fluorinated tin oxide conductive
layer.
[0037] In some embodiments, first or second conductive layers 230
and 238 can each be deposited by physical vapor deposition
processes including, for example, sputtering. In some embodiments,
first and second conductive layers 230 and 238 can each have a
thickness in the range of approximately 0.01 .mu.m to approximately
1 .mu.m. In some embodiments, it may be generally desirable for the
thicknesses of the first and second conductive layers 230 and 238
as well as the thicknesses of any or all of the other layers
described below to be individually uniform with respect to the
given layer; that is, that the thickness of a given layer is
uniform and the surfaces of the layer are smooth and substantially
free of defects or other ion traps.
[0038] A primary function of the first and second conductive layers
230 and 238 is to spread an electric potential provided by a power
source 240, such as a voltage or current source, over surfaces of
the electrochromic stack 220 from outer surface regions of the
stack to inner surface regions of the stack, with relatively little
Ohmic potential drop from the outer regions to the inner regions
(e.g., as a result of a sheet resistance of the first and second
conductive layers 230 and 238). In other words, it can be desirable
to create conductive layers 230 and 238 that are each capable of
behaving as substantially equipotential layers across all portions
of the respective conductive layer along the length and width of
the electrochromic device 220. In some embodiments, bus bars 242
and 244, one (e.g., bus bar 242) in contact with conductive layer
230 and one (e.g., bus bar 244) in contact with conductive layer
238 provide electric connection between the voltage or current
source 240 and the conductive layers 230 and 238. For example, bus
bar 242 can be electrically coupled with a first (e.g., positive)
terminal 246 of power source 240 while bus bar 244 can be
electrically coupled with a second (e.g., negative) terminal 248 of
power source 240.
[0039] In some embodiments, IGU 102 includes a plug-in component
250. In some embodiments, plug-in component 250 includes a first
electrical input 252 (e.g., a pin, socket, or other electrical
connector or conductor) that is electrically coupled with power
source terminal 246 via, for example, one or more wires or other
electrical connections, components, or devices. Similarly, plug-in
component 250 can include a second electrical input 254 that is
electrically coupled with power source terminal 248 via, for
example, one or more wires or other electrical connections,
components, or devices. In some embodiments, first electrical input
252 can be electrically coupled with bus bar 242, and from there
with first conductive layer 230, while second electrical input 254
can be coupled with bus bar 244, and from there with second
conductive layer 238. The conductive layers 230 and 238 also can be
connected to power source 240 with other conventional means as well
as according to other means described below with respect to window
controller 114. For example, as described below with reference to
FIG. 4, first electrical input 252 can be connected to a first
power line while second electrical input 254 can be connected to a
second power line. Additionally, in some embodiments, third
electrical input 256 can be coupled to a device, system, or
building ground. Furthermore, in some embodiments, fourth and fifth
electrical inputs/outputs 258 and 260, respectively, can be used
for communication between, for example, window controller 114, or
microcontroller 274, and network controller 112, as described
below.
[0040] In some embodiments, electrochromic layer 232 is deposited
or otherwise formed over first conductive layer 230. In some
embodiments, electrochromic layer 232 is formed of an inorganic and
solid material. In various embodiments, electrochromic layer 232
can include or be formed of one or more of a number of
electrochromic materials, including electrochemically cathodic or
electrochemically anodic materials. For example, metal oxides
suitable for use as electrochromic layer 232 can include tungsten
oxide (WO.sub.3), molybdenum oxide (MoO.sub.3), niobium oxide
(Nb.sub.2O.sub.5), titanium oxide (TiO.sub.2), copper oxide (CuO),
iridium oxide (Ir.sub.2O.sub.3), chromium oxide (Cr.sub.2O.sub.3),
manganese oxide (Mn.sub.2O.sub.3), vanadium oxide (V.sub.2O.sub.5),
nickel oxide (Ni.sub.2O.sub.3), and cobalt oxide (Co.sub.2O.sub.3),
among other materials. In some embodiments, electrochromic layer
232 can have a thickness in the range of approximately 0.05 .mu.m
to approximately 1 .mu.m.
[0041] During operation, in response to a voltage generated across
the thickness of electrochromic layer 232 by first and second
conductive layers 230 and 238, electrochromic layer 232 transfers
or exchanges ions to or from counter electrode layer 236 resulting
in the desired optical transitions in electrochromic layer 232, and
in some embodiments, also resulting in an optical transition in
counter electrode layer 236. In some embodiments, the choice of
appropriate electrochromic and counter electrode materials governs
the relevant optical transitions.
[0042] In some embodiments, counter electrode layer 236 is formed
of an inorganic and solid material. Counter electrode layer 236 can
generally include one or more of a number of materials or material
layers that can serve as a reservoir of ions when the
electrochromic device 220 is in, for example, the transparent
state. For example, suitable materials for the counter electrode
layer 236 include nickel oxide (NiO), nickel tungsten oxide (NiWO),
nickel vanadium oxide, nickel chromium oxide, nickel aluminum
oxide, nickel manganese oxide, nickel magnesium oxide, chromium
oxide (Cr.sub.2O.sub.3), manganese oxide (MnO.sub.2), and Prussian
blue. In some embodiments, counter electrode layer 236 can have a
thickness in the range of approximately 0.05 82 m to approximately
1 .mu.m. In some embodiments, counter electrode layer 236 is a
second electrochromic layer of opposite polarity as electrochromic
layer 232. For example, when electrochromic layer 232 is formed
from an electrochemically cathodic material, counter electrode
layer 236 can be formed of an electrochemically anodic
material.
[0043] During an electrochromic transition initiated by, for
example, application of an appropriate electric potential across a
thickness of electrochromic stack 220, counter electrode layer 236
transfers all or a portion of the ions it holds to electrochromic
layer 232, causing the optical transition in the electrochromic
layer 232. In some embodiments, as for example in the case of a
counter electrode layer 236 formed from NiWO, the counter electrode
layer 236 also optically transitions with the loss of ions it has
transferred to the electrochromic layer 232. When charge is removed
from a counter electrode layer 236 made of NiWO (e.g., ions are
transported from the counter electrode layer 236 to the
electrochromic layer 232), the counter electrode layer 236 will
transition in the opposite direction (e.g., from a transparent
state to a darkened state).
[0044] In some embodiments, ion conducting layer 234 serves as a
medium through which ions are transported (e.g., in the manner of
an electrolyte) when the electrochromic device 220 transitions
between optical states. In some embodiments, ion conducting layer
234 is highly conductive to the relevant ions for the
electrochromic and the counter electrode layers 232 and 236, but
also has sufficiently low electron conductivity such that
negligible electron transfer occurs during normal operation. A thin
ion conducting layer 234 with high ionic conductivity permits fast
ion conduction and hence fast switching for high performance
electrochromic devices 220. In some embodiments, ion conducting
layer 234 can have a thickness in the range of approximately 0.01
.mu.m to approximately 1 .mu.m.
[0045] In some embodiments, ion conducting layer 234 also is
inorganic and solid. For example, ion conducting layer 234 can be
formed from one or more silicates, silicon oxides, tungsten oxides,
tantalum oxides, niobium oxides, and borates. The silicon oxides
include silicon-aluminum-oxide. These materials also can be doped
with different dopants, including lithium. Lithium-doped silicon
oxides include lithium silicon-aluminum-oxide.
[0046] In some other embodiments, the electrochromic and the
counter electrode layers 232 and 236 are formed immediately
adjacent one another, sometimes in direct contact, without
separately depositing an ion conducting layer. For example, in some
embodiments, electrochromic devices having an interfacial region
between first and second conductive electrode layers rather than a
distinct ion conducting layer 234 can be utilized. Such devices,
and methods of fabricating them, are described in U.S. patent
application Ser. Nos. 12/772,055 and 12/772,075, each filed 30 Apr.
2010, and in U.S. patent application Ser. Nos. 12/814,277 and
12/814,279, each filed 11 Jun. 2010, all four of which are titled
ELECTROCHROMIC DEVICES and name Zhongchun Wang et al. as inventors.
Each of these four applications is incorporated by reference herein
in its entirety.
[0047] In some embodiments, electrochromic device 220 also can
include one or more additional layers (not shown), such as one or
more passive layers. For example, passive layers used to improve
certain optical properties can be included in or on electrochromic
device 220. Passive layers for providing moisture or scratch
resistance also can be included in electrochromic device 220. For
example, the conductive layers 230 and 238 can be treated with
anti-reflective or protective oxide or nitride layers. Other
passive layers can serve to hermetically seal the electrochromic
device 220.
[0048] Additionally, in some embodiments, one or more of the layers
in electrochromic stack 220 can contain some amount of organic
material. Additionally or alternatively, in some embodiments, one
or more of the layers in electrochromic stack 220 can contain some
amount of liquids in one or more layers. Additionally or
alternatively, in some embodiments, solid state material can be
deposited or otherwise formed by processes employing liquid
components such as certain processes employing sol-gels or chemical
vapor deposition.
[0049] Additionally, transitions between a bleached or transparent
state and a colored or opaque state are but one example, among
many, of an optical or electrochromic transition that can be
implemented. Unless otherwise specified herein (including the
foregoing discussion), whenever reference is made to a
bleached-to-opaque transition (or to and from intermediate states
in between), the corresponding device or process described
encompasses other optical state transitions such as, for example,
intermediate state transitions such as percent transmission (% T)
to % T transitions, non-reflective to reflective transitions (or to
and from intermediate states in between), bleached to colored
transitions (or to and from intermediate states in between), and
color to color transitions (or to and from intermediate states in
between). Further, the term "bleached" may refer to an optically
neutral state, for example, uncolored, transparent or translucent.
Still further, unless specified otherwise herein, the "color" of an
electrochromic transition is not limited to any particular
wavelength or range of wavelengths.
[0050] Generally, the colorization or other optical transition of
the electrochromic material in electrochromic layer 232 is caused
by reversible ion insertion into the material (for example,
intercalation) and a corresponding injection of charge-balancing
electrons. Typically, some fraction of the ions responsible for the
optical transition is irreversibly bound up in the electrochromic
material. Some or all of the irreversibly bound ions can be used to
compensate "blind charge" in the material. In some embodiments,
suitable ions include lithium ions (Li+) and hydrogen ions (H+)
(i.e., protons). In some other embodiments, however, other ions can
be suitable. Intercalation of lithium ions, for example, into
tungsten oxide (WO.sub.3-y(0<y.ltoreq..about.0.3)) causes the
tungsten oxide to change from a transparent (e.g., bleached) state
to a blue (e.g., colored) state.
[0051] In particular embodiments described herein, the
electrochromic device 220 reversibly cycles between a transparent
state and an opaque or tinted state. In some embodiments, when the
device is in a transparent state, a potential is applied to the
electrochromic stack 220 such that available ions in the stack
reside primarily in the counter electrode layer 236. When the
magnitude of the potential on the electrochromic stack 220 is
reduced or its polarity reversed, ions are transported back across
the ion conducting layer 234 to the electrochromic layer 232
causing the electrochromic material to transition to an opaque,
tinted, or darker state. In certain embodiments, layers 232 and 236
are complementary coloring layers; that is, for example, when ions
are transferred into the counter electrode layer it is not colored.
Similarly, when or after the ions are transferred out of the
electrochromic layer it is also not colored. But when the polarity
is switched, or the potential reduced, however, and the ions are
transferred from the counter electrode layer into the
electrochromic layer, both the counter electrode and the
electrochromic layers become colored.
[0052] In some other embodiments, when the device is in an opaque
state, a potential is applied to the electrochromic stack 220 such
that available ions in the stack reside primarily in the counter
electrode layer 236. In such embodiments, when the magnitude of the
potential on the electrochromic stack 220 is reduced or its
polarity reversed, ions are transported back across the ion
conducting layer 234 to the electrochromic layer 232 causing the
electrochromic material to transition to a transparent or lighter
state. These layers may also be complementary coloring.
[0053] FIG. 3 shows an example of a voltage profile for driving an
optical state transition in an electrochromic device (e.g.,
electrochromic device 220). The magnitude of the DC voltages (e.g.,
supplied by power source 240) applied to an electrochromic device
220 may depend in part on the thickness of the electrochromic stack
and the size (e.g., surface area) of the electrochromic device 220.
A voltage profile 300 can include the following sequence of applied
voltage or current parameters for driving electrochromic device 220
from a first state to a colored state, and from a colored state to
a bleached state: a negative ramp 301, a negative hold 303, a
positive ramp 305, a negative hold 307, a positive ramp 309, a
positive hold 311, a negative ramp 313, and a positive hold 315. In
some embodiments, the voltage remains constant during the length of
time that the device remains in its defined optical state, e.g., in
negative hold 307 or positive hold 315. Negative ramp 301 drives
the device to the colored or opaque state (or an intermediate
partially transparent state) and negative hold 307 maintains the
device in the transitioned-to state for a desired period of time.
In some embodiments, negative hold 303 may be applied for a
specified duration of time or until another condition is met, such
as a desired amount of ionic charge being passed sufficient to
cause the desired change in coloration, for example. Positive ramp
305, increases the voltage from the maximum magnitude negative
voltage (e.g., negative hold 303) to the smaller magnitude negative
voltage (e.g., negative hold 307) used to hold the desired optical
state. By performing a first negative ramp 301 (and a first
negative hold voltage 303 at this peak negative voltage) to
"overdrive" electrochromic device 220, the inertia of the ions is
overcome more rapidly and the desired target optical state is
reached sooner. The second negative hold voltage 307 effectively
serves to counteract the voltage drop that would otherwise result
from the leakage current. As the leakage current is reduced for any
given electrochromic device 220, the hold voltage required to hold
the desired optical transition can approach zero.
[0054] In some embodiments, positive ramp 309 drives the transition
of the electrochromic device from the colored or opaque state (or
an intermediate less transparent state) to the bleached or
transparent state (or an intermediate more transparent state).
Positive hold 315 maintains the device in the transitioned-to state
for a desired period of time. In some embodiments, positive hold
311 may be applied for a specified duration of time or until
another condition is met, such as a desired amount of ionic charge
being passed sufficient to cause the desired change in coloration,
for example. Negative ramp 313, decreases the voltage from the
maximum magnitude positive voltage (e.g., positive hold 311) to the
smaller magnitude positive voltage (e.g., positive hold 315) used
to hold the desired optical state. By performing a first positive
ramp 309 (and a first positive hold voltage 311 at this peak
positive voltage) to "overdrive" electrochromic device 220, the
inertia of the ions is overcome more rapidly and the desired target
optical state is reached sooner. The second positive hold voltage
315 effectively serves to counteract the voltage drop that would
otherwise result from the leakage current. As the leakage current
is reduced for any given electrochromic device 220, the hold
voltage required to hold the desired optical transition can
approach zero.
[0055] The rate of the optical transition can be a function of not
only the applied voltage, but also the temperature and the voltage
ramping rate. For example, since both voltage and temperature
affect lithium ion diffusion, the amount of charge passed (and
hence the intensity of the ionic current peak) increases with
voltage and temperature. Additionally, because voltage and
temperature are interdependent, this implies that a lower voltage
can be used at higher temperatures to attain the same transition
rate as a higher voltage at lower temperatures. This temperature
response can be exploited in a voltage-based switching algorithm as
described below. The temperature is used to determine which voltage
to apply in order to effect rapid transitioning without damaging
the device.
[0056] In some embodiments, electrical input 252 and electrical
input 254 receive, carry, or transmit complementary power signals.
In some embodiments, electrical input 252 and its complement
electrical input 254 can be directly connected to the bus bars 242
and 244, respectively, and on the other side, to an external power
source that provides a variable DC voltage (e.g., sign and
magnitude). The external power source can be window controller 114
itself, or power from building 104 transmitted to window controller
114 or otherwise coupled to electrical inputs 252 and 254. In such
an embodiment, the electrical signals transmitted through
electrical inputs/outputs 258 and 260 can be directly connected to
memory device 292, described below, to allow communication between
window controller 114 and memory device 292. Furthermore, in such
an embodiment, the electrical signal input to electrical input 256
can be internally connected or coupled (within IGU 102) to either
electrical input 252 or 254 or to the bus bars 242 or 244 in such a
way as to enable the electrical potential of one or more of those
elements to be remotely measured (sensed). This can allow window
controller 114 to compensate for a voltage drop on the connecting
wires from the window controller 114 to the electrochromic device
220.
[0057] In some embodiments, the window controller 114 can be
immediately attached (e.g., external to the IGU 102 but inseparable
by the user) or integrated within the IGU 102. For example, U.S.
patent application Ser. No. 13/049,750 (Attorney Docket No.
SLDMP008) naming Brown et al. as inventors, titled ONBOARD
CONTROLLER FOR MULTISTATE WINDOWS and filed 16 Mar. 2011,
incorporated by reference herein, describes in detail various
embodiments of an "onboard" controller. In such an embodiment,
electrical input 252 can be connected to the positive output of an
external DC power source. Similarly, electrical input 254 can be
connected to the negative output of the DC power source. As
described below, however, electrical inputs 252 and 254 can,
alternately, be connected to the outputs of an external low voltage
AC power source (e.g., a typical 24 V AC transformer common to the
HVAC industry). In such an embodiment, electrical inputs/outputs
258 and 260 can be connected to the communication bus between
window controller 114 and the network controller 112 as described
below. In this embodiment, electrical input/output 256 can be
eventually (e.g., at the power source) connected with the earth
ground (e.g., Protective Earth, or PE in Europe) terminal of the
system.
[0058] As just described, although the voltages plotted in FIG. 3
are expressed as DC voltages, in some embodiments, the voltages
actually supplied by the external power source are AC voltage
signals, In some other embodiments, the supplied voltage signals
are converted to pulse-width modulated voltage signals. However, as
described below with reference to FIG. 4, the voltages actually
"seen" or applied to the bus bars 242 and 244 are effectively DC
voltages. The frequency of the oscillations of the applied voltage
signal can depend on various factors including the leakage current
of the electrochromic device 220, the sheet resistance of the
conductive layers 230 and 238, the desired end or target state
(e.g., % T), or a critical length of a part (e.g., the distance
between bus bars 242 and 244). Typically, the voltage oscillations
applied at terminals 246 and 248 are in the range of approximately
1 Hz to 1 MHz, and in particular embodiments, approximately 100
kHz. The amplitude of the oscillations also can depend on numerous
factors including the desired level of the desired intermediate
target state. However, in some example applications, the amplitude
of the applied voltage oscillations can be in the range of
approximately 0 volts (V) to 24 V while, as described below, the
amplitude of the DC voltage actually applied to bus bars 240 and
242 can be in the range of approximately 0.01 V and 10 V, and in
some applications, in the range of approximately 0.5 V and 3 V. In
various embodiments, the oscillations have asymmetric residence
times for the darkening (e.g., tinting) and lightening (e.g.,
bleaching) portions of a period. For example, in some embodiments,
transitioning from a first less transparent state to a second more
transparent state requires more time than the reverse; that is,
transitioning from the more transparent second state to the less
transparent first state. As will be described below, a controller
can be designed or configured to apply a driving voltage meeting
these requirements.
[0059] The oscillatory applied voltage control allows the
electrochromic device 220 to operate in, and transition to and
from, one or more intermediate states without any necessary
modification to the electrochromic device stack 220 or to the
transitioning time. Rather, window controller 114 can be configured
or designed to provide an oscillating drive voltage of appropriate
wave profile, taking into account such factors as frequency, duty
cycle, mean voltage, amplitude, among other possible suitable or
appropriate factors. Additionally, such a level of control permits
the transitioning to any intermediate state over the full range of
optical states between the two end states. For example, an
appropriately configured controller can provide a continuous range
of transmissivity (% T) which can be tuned to any value between end
states (e.g., opaque and bleached end states).
[0060] To drive the device to an intermediate state using the
oscillatory driving voltage, as described above, a controller could
simply apply the appropriate intermediate voltage. However, there
are more efficient ways to reach the intermediate optical state.
This is partly because high driving voltages can be applied to
reach the end states but are traditionally not applied to reach an
intermediate state. One technique for increasing the rate at which
the electrochromic device 220 reaches a desired intermediate state
is to first apply a high voltage pulse suitable for full transition
(to an end state) and then back off to the voltage of the
oscillating intermediate state (just described). Stated another
way, an initial low frequency single pulse (low in comparison to
the frequency employed to maintain the intermediate state) of
magnitude and duration chosen for the intended final state can be
employed to speed the transition. After this initial pulse, a
higher frequency voltage oscillation can be employed to sustain the
intermediate state for as long as desired.
[0061] As described above, in some particular embodiments, each IGU
102 includes a plug-in component 250 that in some embodiments is
"pluggable" or readily-removable from IGU 102 (e.g., for ease of
maintenance, manufacture, or replacement). In some particular
embodiments, each plug-in component 250 itself includes a window
controller 114. That is, in some such embodiments, each
electrochromic device 220 is controlled by its own respective local
window controller 114 located within plug-in component 250. In some
other embodiments, window controller 114 is integrated with another
portion of frame 218, between the glass panes in the secondary seal
area, or within volume 226. In some other embodiments, window
controller 114 can be located external to IGU 102. In various
embodiments, each window controller 114 can communicate with the
IGUs 102 it controls and drives, as well as communicate to other
window controllers 114, network controller 112, BMS 110, or other
servers, systems, or devices (e.g., sensors), via one or more wired
(e.g., Ethernet) networks or wireless (e.g., WiFi) networks, for
example, via wired (e.g., Ethernet) interface 263 or wireless
(WiFi) interface 265. Embodiments having Ethernet or Wifi
capabilities are also well-suited for use in residential homes and
other smaller-scale non-commercial applications. Additionally, the
communication can be direct or indirect, e.g., via an intermediate
node between a master controller such as network controller 112 and
the IGU 102.
[0062] FIG. 4 shows a depiction of an example plug-in component 250
including a window controller 114. In some embodiments, window
controller 114 communicates with network controller 112 over a
communication bus 262. For example, communication bus 262 can be
designed according to the Controller Area Network (CAN) vehicle bus
standard. In such embodiments, first electrical input 252 can be
connected to a first power line 264 while second electrical input
254 can be connected to a second power line 266. In some
embodiments, as described above, the power signals sent over power
lines 264 and 266 are complementary; that is, collectively they
represent a differential signal (e.g., a differential voltage
signal). In some embodiments, line 268 is coupled to a system or
building ground (e.g., an Earth Ground). In such embodiments,
communication over CAN bus 262 (e.g., between microcontroller 274
and network controller 112) may proceed along first and second
communication lines 270 and 272 transmitted through electrical
inputs/outputs 258 and 260, respectively, according to the CANopen
communication protocol or other suitable open, proprietary, or
overlying communication protocol. In some embodiments, the
communication signals sent over communication lines 270 and 272 are
complementary; that is, collectively they represent a differential
signal (e.g., a differential voltage signal).
[0063] In some embodiments, plug-in component 250 couples CAN
communication bus 262 into window controller 114, and in particular
embodiments, into microcontroller 274. In some such embodiments,
microcontroller 274 is also configured to implement the CANopen
communication protocol. Microcontroller 274 is also designed or
configured (e.g., programmed) to implement one or more drive
control algorithms in conjunction with pulse-width modulated
amplifier or pulse-width modulator (PWM) 276, smart logic 278, and
signal conditioner 280. In some embodiments, microcontroller 274 is
configured to generate a command signal V.sub.COMMAND, e.g., in the
form of a voltage signal, that is then transmitted to PWM 276. PWM
276, in turn, generates a pulse-width modulated power signal,
including first (e.g., positive) component V.sub.PW1 and second
(e.g., negative) component V.sub.PW2, based on V.sub.COMMAND. Power
signals V.sub.PW1 and V.sub.PW2 are then transmitted over, for
example, interface 288, to IGU 102, or more particularly, to bus
bars 242 and 244 in order to cause the desired optical transitions
in electrochromic device 220. In some embodiments, PWM 276 is
configured to modify the duty cycle of the pulse-width modulated
signals such that the durations of the pulses in signals V.sub.PW1
and V.sub.PW2 are not equal: for example, PWM 276 pulses V.sub.PW1
with a first 60% duty cycle and pulses V.sub.PW2 for a second 40%
duty cycle. The duration of the first duty cycle and the duration
of the second duty cycle collectively represent the duration,
t.sub.PWM of each power cycle. In some embodiments, PWM 276 can
additionally or alternatively modify the magnitudes of the signal
pulses V.sub.PW1 and V.sub.PW2.
[0064] In some embodiments, microcontroller 274 is configured to
generate V.sub.COMMAND based on one or more factors or signals such
as, for example, any of the signals received over CAN bus 262 as
well as voltage or current feedback signals, V.sub.FB and I.sub.FB
respectively, generated by PWM 276. In some embodiments,
microcontroller 274 determines current or voltage levels in the
electrochromic device 220 based on feedback signals I.sub.FB or
V.sub.FB, respectively, and adjusts V.sub.COMMAND according to one
or more rules or algorithms to effect a change in the relative
pulse durations (e.g., the relative durations of the first and
second duty cycles) or amplitudes of power signals V.sub.PW1 and
V.sub.PW2 to produce the voltage profiles described above with
respect to FIG. 3. Additionally or alternatively, microcontroller
274 can also adjust V.sub.COMMAND in response to signals received
from smart logic 278 or signal conditioner 280. For example, a
conditioning signal V.sub.CON can be generated by signal
conditioner 280 in response to feedback from one or more networked
or non-networked devices or sensors, such as, for example, an
exterior photosensor or photodetector 282, an interior photosensor
or photodetector 284, a thermal or temperature sensor 286, or a
tint command signal V.sub.TC. For example, additional embodiments
of signal conditioner 280 and V.sub.CON are also described in U.S.
patent application Ser. No. ______ (Attorney Docket No. SLDMP035)
naming Brown as inventor, titled CONTROLLING TRANSITIONS IN
OPTICALLY SWITCHABLE DEVICES and filed 17 Apr. 2012.
[0065] Referring back, V.sub.TC can be an analog voltage signal
between 0 V and 10 V that can be used or adjusted by users (such as
residents or workers) to dynamically adjust the tint of an IGU 102
(for example, a user can use a control in a room or zone of
building 104 similarly to a thermostat to finely adjust or modify a
tint of the IGUs 102 in the room or zone) thereby introducing a
dynamic user input into the logic within microcontroller 274 that
determines V.sub.COMMAND. For example, when set in the 0 to 2.5 V
range, V.sub.TC can be used to cause a transition to a 5% T state,
while when set in the 2.51 to 5 V range, V.sub.TC can be used to
cause a transition to a 20% T state, and similarly for other ranges
such as 5.1 to 7.5 V and 7.51 to 10 V, among other range and
voltage examples. In some embodiments, signal conditioner 280
receives the aforementioned signals or other signals over a
communication bus or interface 290. In some embodiments, PWM 276
also generates V.sub.COMMAND based on a signal V.sub.SMART received
from smart logic 278, as described below. In some embodiments,
smart logic 278 transmits V.sub.SMART over a communication bus such
as, for example, an Inter-Integrated Circuit (I.sup.2C)
multi-master serial single-ended computer bus. In some other
embodiments, smart logic 278 communicates with memory device 292
over a 1-WIRE device communications bus system protocol (by Dallas
Semiconductor Corp., of Dallas, Tex.).
[0066] In some embodiments, microcontroller 274 includes a
processor, chip, card, or board, or a combination of these, which
includes logic for performing one or more control functions. Power
and communication functions of microcontroller 274 may be combined
in a single chip, for example, a programmable logic device (PLD)
chip or field programmable gate array (FPGA), or similar logic.
Such integrated circuits can combine logic, control and power
functions in a single programmable chip. In one embodiment, where
one pane 216 has two electrochromic devices 220 (e.g., on opposite
surfaces) or where IGU 102 includes two or more panes 216 that each
include an electrochromic device 220, the logic can be configured
to control each of the two electrochromic devices 220 independently
from the other. However, in one embodiment, the function of each of
the two electrochromic devices 220 is controlled in a synergistic
fashion, for example, such that each device is controlled in order
to complement the other. For example, the desired level of light
transmission, thermal insulative effect, or other property can be
controlled via a combination of states for each of the individual
electrochromic devices 220. For example, one electrochromic device
may be placed in a colored state while the other is used for
resistive heating, for example, via a transparent electrode of the
device. In another example, the optical states of the two
electrochromic devices are controlled so that the combined
transmissivity is a desired outcome.
[0067] As described above, in some embodiments, microcontroller
274, or window controller 114 generally, also can have wireless
capabilities, such as wireless control and powering capabilities.
For example, wireless control signals, such as radio-frequency (RF)
signals or infra-red (IR) signals can be used, as well as wireless
communication protocols such as WiFi (mentioned above), Bluetooth,
Zigbee, EnOcean, among others, to send instructions to the
microcontroller 274 and for microcontroller 274 to send data out
to, for example, other window controllers 114, network controller
112, or directly to BMS 110. In various embodiments, wireless
communication can be used for at least one of programming or
operating the electrochromic device 220, collecting data or
receiving input from the electrochromic device 220 or the IGU 102
generally, collecting data or receiving input from sensors, as well
as using the window controller 114 as a relay point for other
wireless communications. Data collected from IGU 102 also can
include count data, such as a number of times an electrochromic
device 220 has been activated (cycled), an efficiency of the
electrochromic device 220 over time, among other useful data or
performance metrics.
[0068] Window controller 114 also can have wireless power
capability. For example, window controller 114 can have one or more
wireless power receivers that receive transmissions from one or
more wireless power transmitters as well as one or more wireless
power transmitters that transmit power transmissions enabling
window controller 114 to receive power wirelessly and to distribute
power wirelessly to electrochromic device 220. Wireless power
transmission includes, for example, induction, resonance induction,
RF power transfer, microwave power transfer, and laser power
transfer. For example, U.S. patent application Ser. No. 12/971,576
(Attorney Docket No. SLDMP003) naming Rozbicki as inventor, titled
WIRELESS POWERED ELECTROCHROMIC WINDOWS and filed 17 Dec. 2010,
incorporated by reference herein, describes in detail various
embodiments of wireless power capabilities.
[0069] In order to achieve a desired optical transition, the
pulse-width modulated power signal is generated such that the
positive component V.sub.PW1 is supplied to, for example, bus bar
244 during the first portion of the power cycle, while the negative
component V.sub.PW2 is supplied to, for example, bus bar 242 during
the second portion of the power cycle. As described above, the
signals V.sub.PW1 and V.sub.PW2 are effectively DC signals as seen
by electrochromic device 220 as a result of, for example, the
inductance of series inductors 312 and 314 (see FIGS. 5A and 5B)
within PWM 276, or of various other components of window controller
114 or electrochromic device 220 in relation to the frequency of
the pulse-width modulated power signals V.sub.PW1 and V.sub.PW2.
More specifically, referring now to FIG. 5C, the inductance is such
that the inductors 312 and 314 effectively filter out the highest
frequency components in the voltages V.sub.TEC and V.sub.ITO, the
voltages applied to the first and second conductive layers 230 and
238, respectively, and thus the effective voltage V.sub.EFF applied
across the bus bars 242 and 244 is effectively constant when the
first and second duty cycles are constant.
[0070] In some cases, depending on the frequency (or inversely the
duration) of the pulse-width modulated signals, this can result in
bus bar 244 floating at substantially the fraction of the magnitude
of V.sub.PW1 that is given by the ratio of the duration of the
first duty cycle to the total duration t.sub.PWM of the power
cycle. Similarly, this can result in bus bar 242 floating at
substantially the fraction of the magnitude of V.sub.PW2 that is
given by the ratio of the duration of the second duty cycle to the
total duration t.sub.PWM of the power cycle. In this way, in some
embodiments, the difference between the magnitudes of the
pulse-width modulated signal components V.sub.PW1 and V.sub.PW2 is
twice the effective DC voltage across terminals 246 and 248, and
consequently, across electrochromic device 220. Said another way,
in some embodiments, the difference between the fraction
(determined by the relative duration of the first duty cycle) of
V.sub.PW1 applied to bus bar 244 and the fraction (determined by
the relative duration of the second duty cycle) of V.sub.PW2
applied to bus bar 242 is the effective DC voltage V.sub.EFF
applied to electrochromic device 220. The current IEFF through the
load--electromagnetic device 220--is roughly equal to the effective
voltage VEFF divided by the effective resistance (represented by
resistor 316) or impedance of the load.
[0071] In some embodiments, the relative durations of the first and
second duty cycles--the durations of the V.sub.PW1 and V.sub.PW2
pulses, respectively--are based on V.sub.COMMAND. In some
embodiments, in order to generate the two opposing polarity signals
V.sub.PW1 and V.sub.PW2, PWM 276, and IGU 102 generally, is
designed according to an H-bridge configuration 294. In some
embodiments, PWM 276 is constructed using four transistors 296,
298, 300, and 302 powered by a supply voltage V.sub.SUPPLY as shown
in FIG. 5A. Transistors 296, 298, 300, and 302 can be, for example,
metal-oxide-semiconductor field-effect transistors (MOSFETs). In
some implementations, transistors 296 and 300 are n-type MOSFET
transistors while transistors 298 and 302 are p-type MOSFET
transistors. In some implementations, during a first portion of
operation, the gate of transistor 296 receives signal A, while the
gate of transistor 302 receives its complement such that when
signal A is high is low, and thus, transistors 296 and 302 are
conducting while transistors 298 and 300 are not. In this
configuration, current from V.sub.SUPPLY is transferred through
transistor 296, through the load, including electromagnetic device
220, through transistor 302 and ultimately to ground. This results
in a power signal pulse V.sub.PW1 during this portion of operation.
Similarly, in some implementations, during a second portion of
operation, the gate of transistor 300 receives signal B, while the
gate of transistor 298 receives the complement of signal B, and
thus, transistors 300 and 298 are conducting while transistors 296
and 302 are not. In this configuration, current from V.sub.SUPPLY
is transferred through transistor 300, through the load, including
electromagnetic device 220, through transistor 298 and ultimately
to ground. This results in a power signal pulse V.sub.PW2 during
this portion of operation.
[0072] FIG. 5B shows a depiction of an equivalent H-bridge
configuration representation 294 in which switches 304, 306, 308,
and 310 represent transistors 296, 298, 300, and 302. Based on
V.sub.COMMAND, H-Bridge 294 synchronously transitions from a first
state (represented by solid arrows), to generate the first duty
cycle (V.sub.PW1 pulse), to a second state (represented by dotted
arrows), to generate the second duty cycle (V.sub.PW2 pulse). For
example, in the first state the switches 304 and 310 can be closed
(e.g., transistors 296 and 302 are conducting) and switches 306 and
308 can be open (e.g., transistors 298 and 300 are not conducting).
Similarly, in the second state switches 306 and 308 can be closed
(e.g., transistors 298 and 300 are conducting) and switches 304 and
310 can be open (e.g., transistors 296 and 302 are not conducting).
As described above, in some embodiments, the first and second duty
cycles of the pulse-width modulated signals V.sub.PW1 and V.sub.PW2
are not symmetric; that is, neither the first nor the second duty
cycle is a 50% duty cycle. For example, in the case of a 100 kHz
signal, V.sub.PW1 could be pulsed for more than half the time
constant t.sub.PWM (e.g., more than 5 micro-seconds (.mu.s))
followed by V.sub.PW2 being pulsed for less than half the time
constant t.sub.PWM (e.g., less than 5 .mu.s), and so on resulting
in a first duty cycle of greater than 50% and a second duty cycle
of less than 50%. As a result, even when the magnitudes of
V.sub.PW1 and V.sub.PW2 are equal and remain constant, the
effective voltage at the load (e.g., electrochromic device 220) can
be changed from the static DC voltage generated across the load
when the duty cycles are symmetric (e.g., (V.sub.PW1-V.sub.PW2)/2).
Thus, by varying the duty cycles such that they are non-symmetric,
a voltage ramp (e.g., ramps 301, 305, 309, or 313) can be applied
across the electrochromic device 220. It is this DC voltage that
drives the additional ion transfer that causes the optical
transitions in electrochromic device 220. Additionally, the duty
cycles also can be varied such that a static DC voltage is
developed to compensate, for example, for ions trapped in
defects.
[0073] This method--pulse-width modulation--of applying the DC
voltage across electrochromic device 220 provides increased
protection from damage as compared to, for example, devices that
simply use a battery or other DC voltage source. DC voltages
sources such as batteries can result in initial current spikes that
can permanently damage the electrochromic device 220 in the form
of, for example, defects that trap ions. Furthermore, by adjusting
the relative durations of the pulses V.sub.PW1 and V.sub.PW2 of
each duty cycle based on the command signal V.sub.COMMAND, the
command signal V.sub.COMMAND can be used to change the applied DC
voltage at the electrochromic device 220 (e.g., to produce ramps
301, 305, 309, and 313) continuously without changing the magnitude
of the supply voltage V.sub.SUPPLY.
[0074] Additionally, in some embodiments, the transistors 296, 298,
300, and 302 (or switches 304, 306, 308, and 310) can be configured
at certain times to all be insulating (or open) enabling certain
embodiments of electrochromic device 220 to hold at a desired
optical state without an applied voltage. In some embodiments, this
configuration can be used to save energy by not drawing power from
V.sub.SUPPLY, which is typically the main electrical power for the
building 104. In such a configuration, the electrochromic device
220 could be left floating. In some other embodiments, in this
configuration, the electrochromic device 220 could receive power
from another source to hold the desired optical state, such as
from, for example, a photovoltaic cell on or within the IGU 102.
Similarly, in some embodiments, the transistors 296, 298, 300, and
302 (or switches 304, 306, 308, and 310) can be configured at
certain times to all be conducting (or closed) and shorted to
ground enabling a discharge of electrochromic device 220. In such
embodiments, appropriately sized resistors can be arranged within
the H-bridge configuration 294 between each transistor or switch
and ground to ease or to make more graceful the discharge of the
electrochromic device 220.
[0075] In some embodiments, microcontroller 274 is programmed to
darken or lighten (e.g., change the % T of) the windows on various
sides, surfaces, or zones of a building 104 at certain times of day
as well as according to certain times of year, according to certain
conditions or in response to other feedback, or based on manual
input. For example, microcontroller 274 can be programmed to darken
east-facing IGUs 102 at 9:00 am for 1 hour during winter months
while at the same time lightening west-facing IGUs. As another
example, microcontroller 274 can be programmed to darken an IGU 102
based on light intensity detected outside by a photodetector. In
some such embodiments, microcontroller 274 can be programmed to
continue to darken the IGU 102 as long as light detected inside by
a second photodetector remains above a threshold amount of interior
light intensity, or until a lighting system 107 or network
controller 112 transmits an input command to window controller 114
commanding the window controller 114 to stop tinting such that the
lighting system can remain off or at a lower energy operational
level while enabling workers to have enough ambient light or other
light to continue working. As another example, microcontroller 274
can be programmed to darken an IGU 102 based on a manual input from
a user, for example, in his or her own office relative to a
baseline % T commanded by network controller 112.
[0076] In some embodiments, the drive or device parameters for a
given IGU 102 are stored within the IGU 102, in the frame 218, or
in an internal or external electrical connection assembly wired to
the frame or IGU. In particular embodiments, the drive and device
parameters for the IGU 102 are stored within the plug-in component
250. In some particular embodiments, the drive and device
parameters are stored within non-volatile memory device 292, which
may be included within or be external to window controller 114 or
plug-in component 250, but which, in particular embodiments, is
located within IGU 102. In some embodiments, upon inserting and
connecting plug-in component 250 into IGU 102 or upon powering or
otherwise activating window controller 114, memory device 292
transfers or loads the drive or device parameters to a fast dynamic
memory (e.g., a random access memory (RAM), DRAM, NVRAM, or other
flash memory) location within microcontroller 274 for quick access
by microcontroller 274. In some embodiments, window controller 114
can periodically poll for memory device 292, and when window
controller 114 detects memory device 292, it can transfer the drive
parameters to the RAM or other faster memory location within
microcontroller 274. In some embodiments, memory device 292 can be
a chip (e.g., computer chip having processing or logic capabilities
in addition to storing capabilities) designed according to the
1-WIRE device communications bus system protocol. In some
embodiments, memory device 292 can include solid state serial
memory (e.g. EEPROM (E.sup.2PROM), I.sup.2C, or SPI), which can
also be programmable memory.
[0077] In some embodiments, the drive parameters can be used by
microcontroller 274 in conjunction with one or more voltage
profiles, current algorithms, or voltage and current operating
instructions for transitioning electrochromic device 220 from a
first optical state to a second optical state. In some embodiments,
microcontroller 274 uses the drive parameters to calculate or
select a voltage profile (e.g., a portion of voltage profile 300)
and, using the voltage profile, to generate the associated command
voltages V.sub.COMMAND to achieve the calculated or selected
voltage profile. For example, in some embodiments, a voltage
profile can be selected from a number of pre-determined profiles
(e.g., stored or loaded within microcontroller 274 or other
suitable accessible memory location) based on one or more of a
multitude of drive parameters including, for example, a current
temperature outside, a current temperature inside, a % T of the
first or current optical state, a % T of the second or desired
optical state, or a desired transition or ramp (e.g., ramp 301 or
309) rate, as well as various initial driving voltages, holding
voltages, among other parameters. Some drive parameters, such as %
T and ramp rate, can be generated prior to manufacture of the
device, for example, based theoretically or empirically on a number
of device parameters including, for example, the size, shape,
thickness, age, or number of cycles experienced by electrochromic
pane 216. In some embodiments, each voltage profile can, in turn,
be determined theoretically or empirically prior to manufacture of
the device based on the drive and device parameters.
[0078] In some embodiments, microcontroller 274 calculates
V.sub.COMMAND values during operation of IGU 102 based on the
selected voltage profile and drive parameters. In some other
embodiments, microcontroller 274 selects discrete V.sub.COMMAND
values previously calculated and stored based on the selected
voltage profile and drive parameters. However, as described above,
in some cases V.sub.COMMAND can additionally be modified according
to one or more other input or feedback signals, such as signals
V.sub.CON, V.sub.FB, or I.sub.FB, for example, based on input from
temperature sensors or photodetectors, voltage feedback from
electrochromic device 220 or PWM 276, or current feedback from
electrochromic device 220 or PWM 276. For example, as the outside
environment becomes brighter, the microcontroller 274 can be
programmed to darken the electrochromic device 220, but as the
electrochromic device 220 darkens the temperature of the device can
rise significantly as a result of the increased photon absorption
and, because the tinting of the electrochromic device 220 is
dependent on the temperature of the device, the tinting could
change if not compensated for by, for example, modifying
V.sub.COMMAND in response to a signal, such as V.sub.CON, V.sub.FB,
or I.sub.FB. Furthermore, in some cases, the voltage profiles
themselves stored in the microcontroller 274 or memory device 292
can be modified temporarily (e.g., in RAM) or
permanently/perpetually (e.g., in memory device 292) based on
signals received from, for example, network controller 112.
[0079] In some embodiments, the drive and device parameters stored
within a given IGU 102 can be transmitted, for example via CAN
communication bus 262, to network controller 112 periodically, in
response to certain conditions, or at other appropriate times.
Additionally, in some embodiments, drive parameters, voltage
profiles, current algorithms, location or zone membership
parameters (e.g. at what location or in what zone of the building
104 is this IGU 102 and controller 114), digital output states, and
generally various digital controls (tint, bleach, auto, reboot,
etc.) can be transmitted from network controller 112 to window
controller 114 and microcontroller 274 as well as to memory device
292 for storage and subsequent use. Network controller 112 also can
be configured to transmit to microcontroller 274 or memory device
292 information relating to a location of the IGU 102 or building
104 (e.g., a latitude, longitude, or region parameter), a time of
day, or a time of year. Additionally, the drive or device
parameters can contain information specifying a maximum voltage or
current level that can safely be applied to electrochromic device
220 by a window controller 114. In some embodiments, network
controller 112 can be programmed or configured to compare the
actual current being output to a particular IGU 102 and
electrochromic device 220 to the current expected to be output to
the IGU 102 based on the device or drive characteristics (e.g.,
transmitted from the memory device 292 to the microcontroller 274
and to the network controller 112), or otherwise determine that
they are different or different beyond a threshold range of
acceptability, and thereafter signal an alarm, shut off power to
the IGU 102, or take some other action to, for example, prevent
damage to the electrochromic device 220. Furthermore, memory device
292 also can include cycling or other performance data for
electrochromic device 220.
[0080] In some embodiments, the drive parameters are organized into
an n-dimensional data array, structure, or matrix. FIG. 6 shows an
example 3-dimensional data structure 600 of drive parameters for
driving an electrochromic device 220. Data structure 600 is a
3-by-4-by-4 matrix of elements 624. A voltage profile is associated
with each element 624. For example, matrix element (0, 3, 3) is
associated with voltage profile 626 while matrix element (1, 0, 1)
is associated with voltage profile 628. In the illustrated example,
each matrix element 624 is specified for three drive parameters
that define the element 624 and thus the corresponding voltage
profile. For example, each matrix element 624 is specified for a
given temperature range value (e.g., <0 degrees Celsius, 0-50
degrees Celsius, or >50 degrees Celsius), a current % T value
(e.g., 5%, 20%, 40%, or 70%), and a target % T value (e.g., 5%,
20%, 40%, or 70%).
[0081] In some embodiments, each voltage profile includes one or
more specific parameters (e.g., ramp rate, target voltage, and
applied voltage duration) or a combination of one or more specific
parameters. For example, each voltage profile can include one or
more specific parameters for each of one or more profile portions
or zones (e.g., S1, S2, S3, S4) for making the desired optical
transition from the current % T, at a current temperature, to a
target % T at the same or a different temperature. For example,
voltage profile 626 contains parameters to transition a
electrochromic window from 70% T to 5% T, at a temperature less
than zero degrees Celsius. To complete this transition, voltage
profile 626 provides an initial ramp S1 (e.g., a rate in mV/s for a
specified time duration or to a specified target voltage value), a
first hold S2 (e.g., specified in V for a specified time duration),
a second ramp S3 (e.g., a rate in mV/s for a specified time
duration or to a specified target voltage value), and a fourth hold
S4 (e.g., a specified holding voltage to maintain the target % T).
Similarly, voltage profile 628 can provide a different initial ramp
S1 (e.g., a flatter voltage ramp), a different hold S2 (e.g., a
longer hold at this holding voltage), a different second ramp S3
(e.g., a shorter but steeper ramp), and a different fourth hold S4
(e.g., the holding voltage to maintain the target % T) based on the
different drive parameters associated with that element (in this
example, transitioning from 20% T to 70% T at a temperature of
between zero and fifty degrees Celsius).
[0082] Each voltage profile in the n-dimensional data matrix may,
in some implementations, be unique. For example, because even at
the same temperature, transitioning from 70% T to 5% T often cannot
be achieved by a simple reversal of the voltage profile used to
transition from 5% T to 70% T, a different voltage profile may be
required or at least desirable. Put another way, by virtue of the
device architecture and materials, bleaching is not simply the
reverse of coloring; devices often behave differently for each
transition due to differences in driving forces for ion
intercalation and deintercalation to and from the electrochromic
materials.
[0083] In other embodiments, the data structure can have another
number of dimensions n, that is, be more or less granular than
matrix 600. For example, in some embodiments, more drive parameters
can be included. In one embodiment, 288 drive parameters are used
including three temperature range values, four current % T values,
and four target % T values resulting in a 3-dimensional matrix
having 36 matrix elements and 72 corresponding voltage profiles,
each of which has one or more specific parameters (e.g., ramp rate,
target voltage, and applied voltage duration, or a combination of
one or more specific parameters) for each of one or more profile
portions or zones (e.g., S1, S2, S3, . . . ). In other embodiments,
the number of temperature bins or ranges of values can be increased
or decreased (e.g., 5 or more temperature range values), the number
of possible current % T values can be increased or decreased (e.g.,
there could be eight possible optical states such as 5% T, 15% T,
25% T, 35% T, 45% T, 55% T, 65% T, and 75% T), the number of
possible target % T values can be increased or decreased (e.g., to
match the possible current % T states), among other suitable
modifications. Additionally, the voltage profiles associated with
each element of the matrix may have more than four profile portions
or zones (e.g. S1-S8) with associated parameters. In some
embodiments, for example, 8 zones are permitted to be specified for
each voltage profile, 12 voltage profiles are permitted to be
specified for the current ambient temperature range, and 3 sets of
12 profiles are permitted to be specified for the 3 temperature
ranges specified. That combines to 288 parameters for the voltage
profile alone. Additional information also can be stored within
memory device 292.
[0084] Additionally, in some embodiments in which a single window
controller 114 controls and drives two or more IGUs 102, each IGU
102 can still include its own memory device 292. In such
embodiments, each memory device 292 transmits its drive parameters
to the single window controller 114 and window controller 114, and
particularly microcontroller 274, uses the drive parameters for the
IGU having the smallest size (and hence the lowest power
requirements) to calculate V.sub.COMMAND as an added safety to
prevent damage. For example, window controller 114 can include
logic to identify the IGU size (e.g., length, width, thickness,
surface area, etc.) or the IGU 102 can store size information
within memory that can then be read by controller 114, e.g., by
microcontroller 274. In some embodiments, the microcontroller can
compare the drive parameters for two coupled IGUs 102, determine
that incompatible IGUs have been connected based on the compared
drive parameters, and send an alarm to the BMS 110 or network
controller 112. In some embodiments, the microcontroller 274 can
use the drive parameters of the parallel-connected IGUs 102 to
determine a safe maximum current drive for the aggregate group to
further prevent damage to the IGUs.
[0085] Additionally, in some embodiments, each window controller
114 also can be configured to compensate for transmission losses
such as, for example, voltage drops across bus bars 242 or 244 or
down other transmission lines in between PWM 276 and bus bars 242
and 244. For example, because PWM 276 (or some other component of
window controller 114 or IGU 102) can be configured to provide
current feedback (e.g., I.sub.FB), microcontroller 274 (or some
other logic component of window controller 114) can be configured
to calculate the voltage drop caused by transmission losses. For
example, resistor R.sub.T in FIG. 4 models the transmission line
resistance while resistor R.sub.S in FIG. 4 models a series
resistance. R.sub.T and R.sub.S are inherent to the transmission
line or other system components. As current is supplied from the
window controller 114 it passes through R.sub.T, through IGU 102,
and through R.sub.S, before returning to the window controller 114
closing the loop. Because the current through R.sub.T, IGU 102, and
R.sub.S is known--by using I.sub.FB to set a fixed current output
of the PWM 276 (e.g. 1 Ampere)--and because the differential
amplifier 422 can be used to effectively measure the voltage drop
across R.sub.S, the values of R.sub.S and R.sub.T can be
calculated. For all intents and purposes, R.sub.T can be
approximated by R.sub.S. Now, during normal operation of the device
220, because the current demand through the IGU 102 is not
constant, knowing the effective resistance of the combination Rs+Rt
allows for dynamically adjusting the voltage output from the window
controller 114 so the developed voltage V.sub.ACTUAL at the
terminals of the IGU 102 can be calculated as
V.sub.ACTUAL=V.sub.TARGET+I.sub.ACTUAL*(R.sub.S+R.sub.T) or
V.sub.ACTUAL=V.sub.TARGET+2V(R.sub.S), where V(R.sub.S) is the
voltage drop across R.sub.S.
[0086] In one or more aspects, one or more of the functions
described may be implemented in hardware, digital electronic
circuitry, analog electronic circuitry, computer software,
firmware, including the structures disclosed in this specification
and their structural equivalents thereof, or in any combination
thereof Certain embodiments 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.
[0087] Various modifications to the embodiments 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. 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 devices as implemented. Additionally, as used
herein, "or" may imply "and" as well as "or;" that is, "or" does
not necessarily preclude "and," unless explicitly stated or
implicitly implied.
[0088] Certain features that are described in this specification in
the context of separate embodiments 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.
[0089] Similarly, while operations are depicted in the drawings in
a particular order, this does not necessarily mean that the
operations are required to 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.
* * * * *