Note: Descriptions are shown in the official language in which they were submitted.
CA 02633200 2008-06-20
PROGRAMMABLE THERMOSTAT WITH PREEMPTIVE SETPOINT
ADAPTATION BASED UPON DETECTION OF OCCUPANCY
This application claims priority based on U.S. Patent Application No.
11/926,950
entitled PROGRAMMABLE THERMOSTAT WITH PREEMPTIVE SETPOINT
ADAPTATION BASED UPON DETECTION OF OCCUPANCY filed October 29, 2007,
which is herein incorporated by reference.
FIELD OF THE INVENTION
This invention relates to the art of environmental control systems and more
particularly to the art of programmable thermostats. Additional related fields
of art include
electric heating, electric heaters, electric baseboard heaters, air-
conditioning system control,
thermostats, energy conservation, energy management, motion detectors, and
occupancy
sensors.
BACKGROUND OF THE INVENTION
Energy usage for environmental control, especially for heating or cooling, is
a major
expense in many homes and businesses. Even minor changes in environmental
control
procedures can result in significant energy savings. Typical approaches for
saving energy
include such procedures as manually turning off a heating or cooling system
when a room is
not used, or reducing the level of heating or cooling based upon some
algorithm of
programmed control in a thermostat. It is common in thermostats intended for
home use to
provide programmable features allowing for temperature settings that are
dependent upon the
time of day, and also upon the day of the week with the desired temperature
being set based
upon the user's prediction of needs for heating or cooling, or possibly to
shift energy usage to
a time of day or day of the week when energy costs are lower.
When a user programs a programmable thermostat, the prediction of need and the
setting of the programmed temperatures may be based upon the user's occupancy
predictions,
the typical use of a specific area or room, or to take into account lower cost
energy during
certain times of the day or on certain days of the week such as weekends It is
often true that
rooms or areas of certain office buildings or houses are unoccupied on certain
days, for
example weekends, which provides opportunity for potentially reducing energy
usage. It may
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also often be the case that a room or area is often unused or unoccupied
during certain periods
of a day or a room may be used only at night.
Prior art programmable thermostats for use in a home have provided for a user
of the
thermostat to input a user program which sets a desired temperature as the
thermostat's
setpoint temperature at or during user programmed times of the day, with
typical provision for
four periods of programming each day being common. Programmable thermostats
also may
provide for programmed settings that can be varied by the day of the week.
Typical programmable thermostats for home use however do not automatically
provide for unpredictable or varying patterns of occupancy, or patterns of
occupancy which
may change over periods of time such as days, weeks, months, or seasons. For
example, a
person coming home from work unexpectedly in the middle of the day may have to
manually
override the programmed thermostat settings in order to achieve a comfortable
environment.
Also, a thermostat programmed to provide a certain level of comfort at night
may waste
energy if nobody is at home for one night or a few nights, particularly if the
absence is
unexpected or if there is no opportunity for the previously programmed
settings to be
manually changed by the user.
In environments such as a motel or hotel room, further difficulties in
reducing energy
use are encountered. Varying desires of individual guests and unpredictable
patterns of
occupancy make it difficult to predict a pattern of temperature settings that
might be
acceptable to a guest or desirable for energy savings. For these reasons
programmable
thermostats are often not chosen for use in many motels or hotels.
It is also often true that completely turning off a heating or cooling system,
or
manually changing the temperature setting too far away from a comfortable
setting, makes the
recovery time for achieving comfort in a room too long to be acceptable. For
example, if the
heating system were to be turned completely off on a very cold day, and the
temperature in
the room fell to 45 degrees Fahrenheit, the time to heat a typical motel room
with a heat pump
to a comfortable level when the desired temperature was changed to 72 degrees
would be too
long to suit the desires of many discriminating guests. In this case it would
be advantageous
to strike a compromise between saving energy and maintaining a programmed
temperature.
Therefore, there is need for an improved programmable thermostat that would
provide opportunity for potentially lower energy usage and reduced need for
user interaction
while achieving lower energy usage.
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BRIEF SUMMARY OF THE INVENTION
The present invention provides an improved thermostat system and method
described
in an illustrated embodiment which incorporates a mechanism for detecting
occupancy in a
room or area in which a programmable thermostat is located with opportunity
for
programming that can reduce energy usage while still providing for comfort.
The inclusion of
a means for detection of occupancy in a programmable thermostat increases the
convenience
of operation by allowing a thermostat program to normally run in a mode
designed for saving
energy, and then to have that mode of normal operation preempted when
occupancy is
detected. This allows for reduced energy usage while still providing for
comfort, without
requiring manual override of the thermostat settings as a person enters a room
or area, and
without requiring that the person again interact with the thermostat when
departing. The user
programming for the unoccupied state can be optimized by the user for saving
energy more so
than just providing programming for comfortable temperatures during periods of
occupancy
as allowed by thermostats in the prior art.
DESCRIPTION OF THE DRAWINGS
The subject matter of the invention is particularly pointed out and distinctly
claimed
in the concluding portion of the specification. The invention, however, both
as to
organization and method of operation, may better be understood by reference to
the following
description taken in conjunction with the subjoined claims and the
accompanying drawing of
which:
FIG. 1 is a diagram showing space conditioning equipment controlled by a
programmable thermostat system which incorporates the teachings of the present
invention
that includes a programmable thermostat with input from a temperature sensor,
a display, a
user input panel for providing user input for programming, a thermostat
control unit
controlling operation of the thermostat system, and a motion detector serving
as an occupancy
detector providing an indication of occupancy to the thermostat control unit's
microprocessor
for the thermostat system;
FIG. 2 is a diagram showing a electric heater powered from house power
connected
through a programmable thermostat system that includes a programmable
thermostat with
input from a temperature sensor, a display, a user input panel providing for
user input in
programming the thermostat, a thermostat control unit controlling operation of
the overall
thermostat system, a triac device gated under control of the thermostat
control unit for gating
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house power through to an electric heater, and a motion detector serving as an
occupancy
detector providing an indication to the thermostat control unit of occupancy
in the room or
area in which the thermostat is mounted;
FIG. 3 is a diagram showing data on a touch sensitive display screen as might
be
used to provide user input describing a user's time-based normal thermostat
control sequence
intended by the user to be followed when no occupancy has been detected;
FIG. 4 is a diagram showing data on a touch sensitive display screen as might
be
used to provide user input specifying a preset comfortable room temperature to
be used by the
thermostat control program as the thermostat setting during periods of
occupancy in
accordance with the teachings of the present invention;
FIG. 5 is a diagram showing an example of data on a touch sensitive display
screen
as might be used to provide user input describing a user's time-based
comfortable thermostat
control sequence intended by the user to be followed when occupancy has been
detected in
accordance with teachings of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
In a room or area such as a house or motel room it would be advantageous to
reduce
the cost of cooling or heating the room or area by providing a programmed time-
based
thermostat control sequence designed for energy savings and running that
program as the
normal case as long as the room or area is unoccupied. Programmable
thermostats of the
prior art as typically used in homes have provided for four periods of
programming for each
day of the week, with allowance for a thermostat setting that is different
during each period of
programming. Some thermostats of the prior art have also had occupancy sensors
incorporated or attached to the thermostats, and allowed for invocation of a
specific setback
temperature at when no occupancy was determined.
The present invention improves over the prior art by providing in an
illustrated
embodiment, a programmable thermostat system for control of a heating or
cooling system
with provision for attachment or inclusion of an occupancy sensor which
provides an
indication of current occupancy to the thermostat system. A thermostat control
unit included
as part of the thermostat system in the illustrated embodiment provides for
user programming
that directly addresses the goal of energy savings during periods of no
occupancy which is
when the most energy can be conserved. Provision is made for automatic
preemption of a
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user's normal time-based thermostat control sequence when occupancy is
detected which
allows for using a programmed sequence during the unoccupied state with
potential for more
energy reduction than might be chosen if the override of the programmed
settings was not
automatic, or if the normal user programming were to be applied only while
occupied.
As an example of how energy savings may be achieved with specific teachings of
the
present invention it is helpful to illustrate with an example. For example, it
may be known by
the occupant of a house that a room in the basement is only occasionally used
during the
evening when people are watching television. The room is not used every night,
and the
starting and ending times for usage vary significantly. During the winter the
room is heated
with a baseboard heater that draws a significant amount of electricity because
the room is not
well insulated.
Without an occupancy sensor the user might choose a program that allows the
temperature of the room to be fairly cool during the day, a little warmer in
the early afternoon
in case someone comes home early, then nice and warm during the evening and
into the night
when someone might be watching television, and then once again fairly cool for
the rest of the
night when nobody is expected to be in the room.
With the programmable thermostat system having an occupancy sensor and
automatic preemption of the normal program when occupancy occurs, the user
might choose a
modified approach to programming the thermostat that achieves significant
energy savings
over the first approach. For example, the user might choose a significantly
lower temperature
during the early afternoon and evening than chosen with a thermostat of the
prior art knowing
that the baseboard heater can respond quickly if and when occupancy is
detected and heat the
room to a comfortable temperature. In a similar manner the user may choose to
allow the
room temperature to drift significantly colder during the night, and also
during the day when
nobody is expected to be home. This would result in significant energy savings
on days when
the room is unused or lightly used. The automatic occupancy response still
provides for
comfort without manually touching the thermostat settings if a person came
home during the
day to watch television for a short time and then potentially saves some
energy by lowering
the thermostat setting even if the person leaves without further thought about
the thermostat
or energy savings.
As another example, in a room or area which is a motel or hotel room it is
again
advantageous to reduce the cost of electrical heating by lowering the heat
applied during
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periods of non-use or no occupancy. Many motel and hotel rooms are unoccupied
during
much of the day. The power to an electric heater can be shut off when the room
is not
occupied, and turned on as needed when the room becomes occupied. In many
motel rooms
this is routinely done by having someone turn off the heater when a guest
leaves, and then
either a motel person turns on the heater when a guest arrives or is about to
arrive, or the guest
turns on the heater when he or she enters the room. A problem with having
motel or hotel
personnel turn off the heater is that this may mean that the heater stays on
for some period of
time after a guest has left before it is convenient to enter the room and
adjust the thermostat.
Another problem with switching the heater completely off during a period of no
occupancy is that the room may become too cold and it may take too long to
recover and heat
the room to a comfortable level when a guest arrives. The manual turning on or
off of the
heater also requires that task be done by people, who may forget or neglect to
do that, thus
potentially wasting energy that could have been saved. It is thus an
advantageous approach of
the present invention to provide a thermostat that automatically turns on the
heat when
occupancy of the room is detected. It is a further advantage of the present
invention to
provide for following a programmable thermostat control sequence during
periods of no
occupancy that provides less setback of the temperature during periods when
occupancy
might be expected. That is, the invention provides for programming which
anticipates
possible occupancy during periods of no occupancy. This allows for energy
savings to be
achieved while still providing reasonable response time in recovery during
periods when
occupancy is expected, but without wastefully changing the temperature
completely to the
temperature that would be invoked if occupancy were actually sensed.
Determination of occupancy or non-occupancy is not a completely trivial
subject but
is well known in the state of the art. For example, with a motion detector
device such as an
infrared motion detector for determining occupancy a timer might be required
to determine
how often an occupant has to physically move in order to keep the condition of
occupancy
satisfied. The sensing mechanism has to be sensitive enough to continue a
detection of
occupancy even when a person is sitting fairly still or sleeping. A motion
detector that detects
infrared signals as from body heat is one good choice for an occupancy sensor
because it
would be less likely to give a false signal due to curtains moving, for
example. However, a
false detection of no occupancy is not a fatal flaw with regards to operation
of the present
invention because when someone is in the room it is quite likely they will
eventually move
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enough to be noticed by a detector designed for that purpose. Even if they do
not move for a
time beyond that which might normally be expected and the control program
enters a state
where comfort is reduced, the system will still continue to run and recover
eventually when
occupancy is again detected. It is noted that the term occupancy sensor
throughout discussion
of the present invention is intended to refer to a device which automatically
senses occupancy
without any interaction with the device by a person or user of the thermostat.
An infrared
motion detector is an example of a good device for serving as an occupancy
sensor and
sensing occupancy of an area near to the device.
Electric heaters and electric baseboard heaters are heavy users of electricity
and
rooms in which these are installed can often be heated quite quickly when the
heater is turned
fully on as long as the room is not extremely cold, meaning that the recovery
time is quite
reasonable when occupancy is detected and a comfortable temperature is now
what is desired.
Air-conditioning compressors are also heavy users of electricity and
programming a
thermostat in control of these units to follow a program designed for reducing
energy usage
can provide significant energy and cost savings. In particular reducing usage
at night or
during periods of expected no occupancy can provide significant savings.
Electrical rates which vary based upon time of day or day of the week also
provide
opportunity for programming that saves energy and are particularly adaptable
to savings using
the teachings of the present invention. A thermostat control sequence might be
chosen which
changes the setpoint temperature (the desired conditioned space temperature)
significantly
based upon the time periods during which electricity is most expensive. During
peak periods a
much larger setback might be utilized during periods of no occupancy, in
comparison to the
setback that might be desired during periods of more moderate energy cost.
Thus, as just discussed, one improvement offered by the present invention is
to
utilize a detection of occupancy to invoke a preemption of a user's time based
normal
thermostat control sequence designed for maximum energy savings, in contrast
to the prior art
approach which provided for a detection of no occupancy causing an override of
what had
been a programmed temperature control sequence used during periods of detected
occupancy.
A second further improvement is to provide for two user programmed thermostat
control sequences, one for use when occupancy is not determined, and a second
for
preemptive use when occupancy is determined. This approach is a further
enhancement
which provides for user programmable comfort to be set during periods of
occupancy without
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impacting the savings that can be achieved during the normal unoccupied state.
For example,
a family room might be kept cool during the day when people are passing
through the room or
there is significant activity, and then kept just a little warmer while
occupied during the
evening when people might be just sitting and watching television, or doing
homework.
Detection of occupancy can be further enhanced by providing for an occupancy
sensor or multiple occupancy sensors which are remote to the thermostat unit
itself. For
example, a thermostat unit with an occupancy sensor mounted in a hallway might
not provide
as good an indication of occupancy anywhere in the house as would be provided
by a remote
occupancy sensing unit mounted in the kitchen. Using multiple remote occupancy
sensors
which can transmit signals to the thermostat unit may help the thermostat
system in more
accurately determining occupancy, for example in a large house with many rooms
served by
the same space conditioning equipment.
A further provision that may be utilized with the present invention for added
energy
savings is to provide as part of the thermostat user interface a way to
override the sensing of
occupancy. This can be accomplished by providing an additional user input
mechanism such
as a button on a thermostat's touch sensitive display screen that tells the
thermostat control
unit to override the occupancy detection for a defined period, with the period
being increased
if the button is touched multiple times. For example, if someone enters the
room and is
already comfortable with the current temperature, or if they plan to be in the
room for only a
short time, or if they are going in and out of the room but do not want a more
costly user
programmed thermostat control sequence to be invoked, they can touch the
occupancy
override button a few times and keep the thermostat either temporarily or
permanently in the
more economical mode. The user might also be provided with a way to select a
mode of
occupancy suspension which disables the occupancy sensor response until the
selection is
removed by the user. A first touch of the occupancy override button might
override the
occupancy detection for a period of 15 minutes, a second for 30 minutes, a
third for 1 hour
and so on with the largest time being the mode of occupancy suspension. After
that, another
push of the button would cycle back to the mode where occupancy detection is
again enabled.
A user might also select the mode of occupancy detection suspension by holding
the button a
significant amount of time more than one might normally hold a button such as
more than two
seconds.
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If multiple occupancy sensors are utilized to achieve a wider coverage and
better
detection of occupancy in the conditioned space, a means for disabling
occupancy detection
on any one or more or all occupancy sensors is a further enhancement to the
invention. The
choice of disablement might be implemented utilizing a user input mechanism on
the
occupancy sensor itself, or by selection through user input at the
programmable thermostat
itself.
Another further provision in the illustrated embodiment of the present
invention for
added energy savings is to utilize the occupancy sensor to determine, in
addition to
occupancy, a level of activity in the room or area near the occupancy sensor.
An occupancy
sensor implemented as a motion detector circuit will provide a signal of
occupancy whenever
movement is detected. The thermostat control program can determine the
frequency of any
movement being detected in the room or area and if the frequency of detected
movement is
high the control program might decide that the room is being used by active
people and that
the temperature required for comfort might be lower in comparison to what
would be needed
if the room were occupied but with little activity or motion by the occupants.
At a different
time of day such as at night, a low level of activity might provide indication
that the room is
occupied but the occupant is asleep and that the temperature might be reduced
while still
retaining comfort. The level of activity could be used to select an alternate
user provided
thermostat control sequence with temperature settings dependent not only on
the time of day
or day of week with occupancy consideration, but also with the level of
activity considered.
An alternative implementation would be to provide an adjustment based upon
level of activity
to an already provided thermostat control sequence as another set of
parameters provided as
part of the user input.
For energy savings, electric heaters provide added opportunity for energy
savings. In
many motel rooms and houses heating is provided by electric heaters which
produce heat
from electrical energy and which are powered from the house electrical system.
Oftentimes
these heaters are "baseboard" heaters, so named because they are mounted along
the
baseboard of the walls in a room. These heaters are a fairly large user of
electricity typically
drawing more than 1 kWatt of power and often several kWatts of power. The
electric heaters
are controlled by a thermostat which includes an electrical gating device such
as a mechanical
relay or electronic switch.
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A thermostat system for control of an electric baseboard heater utilizing the
teachings
of the present invention and a system which incorporates a thermostat, a triac
switching
device, a motion detector, a control program with a means for changing the
settings of the
control program provides for significant improvement over baseboard heaters of
the prior art.
The quick recovery time achievable by electric baseboard heaters allows for
user
programming during unoccupied periods to maximize energy savings, while still
providing
automatic recovery in a reasonable time when occupancy is detected.
DESCRIPTION OF THE ILLUSTRATED
EMBODIMENT(S) OF THE PRESENT INVENTION
Certain aspects of the illustrated embodiment will now be described in greater
detail
with reference to the figures of the drawings.
FIG. 1 is a diagram showing space conditioning equipment 100 controlled by a
programmable thermostat system that includes a programmable thermostat with
input from a
temperature sensor 130, a display illustrated as a liquid crystal display 110,
a user input panel
115 for providing user input for programming, a thermostat control unit 120
controlling
operation of the thermostat system, and a motion detector serving as an
occupancy detector
140 providing an indication of occupancy for the room in which the thermostat
is mounted to
the thermostat control unit's microprocessor for the thermostat system.
The space conditioning equipment 100 provides conditioned air to the room 170
which is in the conditioned space. The conditioning can be in the form of
heating or cooling
or with other conditioning such as for humidity. The temperature sensor 130
and the
occupancy sensor 140 provide input to the thermostat control unit.
The thermostat control unit 120 includes a microprocessor 121 for running a
thermostat control program contained in memory 122, a real time clock 123, an
input / output
unit, and other devices if or as necessary to support the microprocessor such
as a power
regulator and a timing crystal.
A display 110, which may be a liquid crystal display or other display type,
serves as
a mechanism for displaying various alphanumeric messages and icons which may
be used to
prompt the user for user programming and also for displaying system status,
room
temperature, the time of day and other items that might be of interest to the
thermostat system
user.
CA 02633200 2008-06-20
The user input panel 115 may be implemented as a touch screen detector as an
attachment or as part of the liquid crystal display, with buttons for touching
being displayed
on the liquid crystal display. The user input panel may also be buttons or
touch sensors
separate from the display, and may incorporate wheels, joystick type switches,
trackballs, or
other types of switches and sensors for user input.
The microprogram processor of the thermostat control unit generally performs
many
functions as part of its programming relating to maintenance of the display,
monitoring the
data inputs which come from the temperature sensor, and the motion detector,
and other
functions or threads necessary to implement the concepts of present invention,
and also in
general support of the functions of the thermostat system..
The microprogram processor has access to a real time clock 123 which is used
to
determine when to invoke temperature settings provided as programming by the
thermostat
user. The real time clock may be part of the microprocessor itself, or as
another device part of
the thermostat control unit. The real time clock may also be settable by the
microprocessor.
The occupancy sensor device 140 and temperature sensor device 130 in one
embodiment are contained within the housing of the thermostat system. In
another illustrated
embodiment either of these devices may be located external to the thermostat
system with
connections 141 and 131 respectively to the thermostat control unit.
If multiple occupancy sensors are in use, then a connection from each
occupancy
sensor to the thermostat control unit is provided. The connection of occupancy
sensors can be
by wire, by RF signal, or other wireless signal. The temperature sensor
connection would
typically be connected by wiring but could also be wireless if desired.
In this FIG. 1 illustration, the thermostat control unit sends signals over a
wire 160 to
the space conditioning equipment as control for the equipment. The thermostat
control unit
causes the space conditioning equipment to turn on heating or cooling to the
conditioned
space. The signal wire 160 might be replaced by a wireless type signal if
desired.
FIG. 2 is a diagram showing a electric heater 200 powered from house power 220
connected through a programmable thermostat system including an input to a
thermostat
control unit 120 from a temperature sensor 130, a display 110 which is a
liquid crystal
display, a user input panel 115 providing for user input in programming the
thermostat, the
thermostat control unit 120 including a microprocessor with a memory
controlling operation
of the overall thermostat system, a triac device 240 gated under control by a
control signal
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260 from the thermostat control unit and gating house power 220 through as
gated power 250
to the heating elements 201 of the electric heater 200, and a motion detector
serving as an
occupancy detector 140 providing an indication to the thermostat control unit
of occupancy in
the room or area in which the thermostat is mounted. The programmable
thermostat system
in FIG. 2 functions in manner similar to that shown in FIG. 1 but with
adaptation for
controlling an electric heater directly instead of sending signals to the
space conditioning
equipment. In FIG. 2, the space conditioning equipment being controlled is an
electric heater,
and the triac device 240 acts as an electronic switch with an input gating
signal for turning on
or allowing the house power through to the electric heater. The gating signal
to the triac
device 260 is an output from the thermostat control unit and used in manner
similar to the
signal wire 160 in FIG. 1 to turn on or off power to the electric heater'
heating elements.
FIG. 3 is a diagram showing data on a touch sensitive display screen 300 as
might be
used to provide user input describing a user's time based normal thermostat
control sequence
intended by the user to be followed when no occupancy has been detected, as
indicated by the
data on the programming status screen. In the illustration four periods of
programming 310
for each day are displayed but any number of periods could be provided. Days
of the week
320 for alternative programming can be selected. This style of programming is
for exemplary
purposes only. Other styles of methods of programming could be designed by one
knowledgeable in the state of the art without deviating from the teachings of
this present
invention.
FIG. 4 is a diagram showing data on a touch sensitive display screen as might
be
used to provide user input specifying a preset comfortable room temperature
400 to be used
by the thermostat control program as the thermostat setting during periods of
occupancy. In
one embodiment, this value of temperature is provided by the user of the
thermostat as the
temperature to be used as the set temperature for the thermostat when
occupancy is detected.
That is, this is the temperature that is used when the normal thermostat
sequence chosen
during periods of no occupancy is preempted.
FIG. 5 is a diagram showing data on a touch sensitive display screen 500 as
might be
used to provide user input describing a user's time based comfortable
thermostat control
sequence intended by the user to be followed when occupancy has been detected.
This user
input program is part of an alternate embodiment of the invention which
provides more
flexibility in programming than the illustrative single temperature shown in
FIG. 4. In this
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FIG. 5 illustration, the user input screen 500 for programming the second
thermostat control
sequence programmed for use during periods of detected occupancy is shown,
with the screen
as shown in FIG. 3 showing the user input screen 300 which might be used for
programming
to be used during periods of no occupancy.
It will be appreciated that the present invention is not in any limited by the
packaging of the devices. In addition, circuitry of the thermostat, the triac
device, the
thermostat control unit processing circuitry or other elements disclosed in
connection with
describing the invention may be changed without affecting the novel aspects of
the invention.
For example, the processing circuitry of the thermostat may be implemented in
an Field
Programmable Gate Array (FPGA) or gate array chip without departing from the
teachings of
the present invention. The triac may be contained in a package with processing
circuitry of its
own or in conjunction with the processing circuitry of the thermostat, or all
elements of the
invention could be combined and packaged as a unit. The occupancy sensor can
be a motion
detector mounted as part of package housing the thermostat or externally from
the thermostat
housing, but connected to the thermostat.
In addition the thermostat control unit and the microprogram processor may be
designed or packaged in many ways by a person knowledgeable in the state of
the art. For
example, the memory may be contained on the same silicon chip as the
microprogram
processor, and the input / output unit may be separate from the microprogram
processor or on
the same chip. Some parts of the memory may be flash memory, Read-Only Memory
(ROM)
memory, or Random Access memory (RAM) memory.
Thus, while the principles of the invention have now been made clear in an
illustrative embodiment, there will be immediately obvious to those skilled in
the art many
modifications of structure, arrangements, the elements, circuitry, materials,
and components,
used in the practice of the invention which are particularly adapted for
specific environments
and operating requirements without departing from those principles.
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