Note: Descriptions are shown in the official language in which they were submitted.
~114~42
BACKGROUND OF THE INV~NTION
Fiel.d of the Invention:
The present inventlon relates to building heating
and air conditioning thermostats of the type usually mounted
on a wall to control the ambient air temperature.
Description of the Prior Art:
llistorically, building heating and air condition-
ing control has been performed b~ wall mounted thermostats.
Such thermostats can be readily read to ascertain the
actual temperature and a sliding scale or rotary dial is
manipulated to alter the desired temperature. A te~.nperature
sensing element closes electrical contacts to turn on the
heating or air conditioning unit when a predetermined
, temperature differential exists between actual te~pera'~lr~
and desired temperature. The furnace or air conditioner is
cut off by opening the contacts once actual temperature
achieves the desired temperature to within a predetermined
smaller tolerable limit.
With increasing concerns for energy conservation
, , .
,~ 20 brought about by a progressive diminution of energy resources,
more sophisticated temperature control systems have been
made. For example, U. S. Patent 3,948,441 describes a wall
; mounted thermostat in which provision is afforded to set
~ time variable thermostat settings such as a lower night
J~: 25 temperature and a higher daytime temperature as the. desired
temperatures. A clock is provided so that the targe~ or
desired temperature is autor.latically adjusted to the appro-
priate settil~g depending upon the time o day. The systeM
described in the aoresaid patent provides for ~he l:imer or
~:
,
42 `-
clock mechanis~l to be isola~ed from the line voltage an.d
driven only from a rechargeable battery source. The bat~ery
source itself is charged a~ a very low rate by 24 vol~, 60
cycle current during the time the thermos~at is off. This
arrangement permits a thermostat having only two wires for
control purposes to be retrofitted with a time variable
: energy saving thermostat that uses the same two wires for
two purposes, i.e., battery charging and thermostatic con-
trolling of the heating system. Generally, because conven-
tional wall thermostats use coiled bimetal strips fo~ open-
ing and closing electrical contacts to relays or contactors
; associated with the heating and air conditioning devices,
sensitivity and thermal inertia are limiting factors to eff-
3~ orts to achieve better control.
~i~ 15 In another current thermostat employing a digital
clock, temperature sensilg is provided by an epoxy-coated
thermistor operated in a linear voltage versus temperature
~ ,
: ;~ circuit. Comparison with referen.ce settings in electronic
amplifiers causes the appropriate heating or cooling element
20~ to~be energized as conditions demand. Timing for relative
temperature shifts between two alternative temperature
levels is derived from a 60 hertz low voltage line obtained
from an~existing low voltage supply line. The return path
is~through an~inactive heating/cooling relay element, or
~through an active relay element via a transformer in the
case of a heat-only system.
; SU~D$ARY OF THE INVENTION
The present invention provides a control to regu~
: ;late ambient alr conditions which has the capability of
~ $;~
: . . . .
li~4~42
responding to and be~te~ controlling primarily the ~ernpera-
ture ccmfort level. This flexi.bility and accuracy is ach-
ieved by providing increased levels of sophistication through
use of computational capabi.lity and special techniques for
initiating necessary controL signals. The computational
capability is ~r~vided by an arithmetic logic unit, a random
access memory with stored arithmetic coeffi.cients, a read
only memory with program storage and associated ranclom logic
ftmctions for proper control of the above elements. All of
these elements are packaged into a unitary thermostat suit-
able for wall mounting which additionally contains a re-
chargeable battery power supply for powering ~he elements, a
quartz crystal time base for supplying system timing, a dis-
play with drivers, selector switches, a temperature senscr
and at least one power switch.
The invention provide.s an ambient air temperature
regulating thermostat which may be wall mounted in place of
a conventional thermostat and which may be sensitiv~ to a
~ nu~ber of different conditions to effectuate temperature
1 ~20 control. In addition to regulating ambient air temperature
.,~ to different settings at daytime and at night to conserve
~ ~ energy, the present invention is also able to predict within
'~ ~ each cycle the time at which the target temperature will be
reached, and to shut off the furnace or air conditioning
unit prior to this time. Heated or cooled air already pre-
~ent in the heating or cooling system prior to shut off is
circulated in the space to be heated or cooled, thus allow-
~ ing the system to "coast" to the desired setting without
'~ overshooting the target temperature, Furthermore, a temper-
ature signal accumulating or aver3ging delay is built into
,
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~,
.
1~4042
the syst:en~ so ~lla~ momentary a~r drafts do not activa~e un-
necessary heating or cooling. Such air drafts frequently
occur as a result of people movirlg through a room past a
temperature control lmit, doors opening and closing ~ irregtl-
lar convection currents from fireplaces and so forth.
Random access memory of the present invention stores sensed
temperature information and the arithme~ic logic unit per-
forms averaging calculations to ascertain whether or not
activation of a heating or cooling system is truly necessary.
The invention also provides a temperature regulat-
ing system which utilizes a rechargeable direct current
power source that may b,? recharged from a conventional two
wire thermostat system.
~ Still further, the invention provides a temperature,~ 15 regulation system with a digital display and with a keyboard
input with which to effectuate manual commands. The digital
display may take the fol~m of a liquid crystal display or
light emitting diode display or a display from other similar
, ~
technology. The display is made possible due to the contin-
uous provision of power from the battery. A keyboard input
allows commands to be digitized at their source and in a
manner familiar to many people. A single keyboard provides
a universal input for multiple manual commands to the therm-
ostat.
A binary coded decimal slide switch shall be the
input means ~or either temperature set back or set forward
with numbers provided as to the degrees of change. Both
tlmes and temperatures can thereby be read into the control
system of the present invention from a single input keyboard.
. ~ ~
Furthermore, selection of output devices and override
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.
i~4~42
controls are also provided in the form of slide switches.
An ambient air regul.ating system can thereby be directed to
heat, to cool, or to be sllut of entirely. Similarly, a
fan can be turne~ on continuously or the system can be dir-
ected to selectively operate the fan only during heating andcooling periods.
An additional feature of the invention is to have
a built in minimum time duration of a temperature differential
to prevent hunting by the system or too frequent operation
thereof but at the same time achieve superior controlling.
This prevents aggravation of recurrent cycling noise, reduces
equipment wear and is especially important in preserving air
conditioner compressor life.
` It is to be understood that all of the operating
parameters of the system can be adjusted at the factory.
That is the system may be designed to maintain a temperature
', with two degree Farenheit differential preferred. Also the
. control may be required to maintain a minimum cyclical per-
.
iod of operation. That is, a heat pump may be forced to
operate for at least ten minutes, and stay off for at least
fi~e minutes. The specific values of all such settings of
. ~:
these factors are engineering considerations and the pre- -
ferred values can be varied as desired.
~r~ The improved control circuitry of the invention
25~ is adaptable to ascertain information as to whether or not
the heating or cooling system employed is operating at an
energy output sufficient to return actual temperature to
the desired temperature setting, and to vary the energy
output accordingly. When heating or cooling cycles do not
change temperature in the direction desired, the energy
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.
, .
1~14~)42
output is too low and hc~nce may be increased. This may be
achieved by a multistage energy level system. In such a sys-
tem, or exa~lple, a two s~age system, the control c~n from
init:ial operation at one level of heating or cooling output
determi.ne that ~he other level of heating or cooling output
is more desireable to obtain proper cycle timing. Thereafter,
the system will operate at the other output stage until, from
stored data, the arithmetic logic unit determines that the
system should revert to the initial rate of heating or cool.-
ing. One possible criterion for changing s~ages of operationmay be by a determination of tempera~ure gradient with time
to ascertain whether or not actual temperature moves toward
desired temperature. If it does, the furnace or air con-
ditioner may be operated at a lower stage of energy output.
If it does not, a higher stage of energy is indicated.
Stages of operation may be graduated in incremental adjust-
ments, or the energy output control may be modulated on a
continuous sliding scale, depending upon the manner of ad~
justmen~ chosen and environmental equipnent used.
A further optional feature of the invention is
the flexibility to compensate for humidity variations in
regulating heat output. The level of humidity in air eff-
ects the degree of comfort achieved by maintaining a parti-
cular temperature. By way of example, a temperature of 72F
may be quite comfortable at 40% relative humidity. This same
degree of comfort may be achieved by a somewhat lower tem-
perature where the h~nidity is 80%, or a somewhat higher
temperature may be required to achieve the same level of
comfort with very dry air. The flexibility of the present
invention provides a capability to accept data from a
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04Z
humidi~y sensor and ~o modify ~he desired tempera~ures.
That is, and cc,ntinuing, with tlle :Eolegoing exalllple, if a
temperature of 72 as a desirecl temperatllr~ i.s mamlally
registered into the system using the keyboard, the control
circuitry can treat this as the desired temperature at a
prese~ standard of 40% relative hulnidity. If the humidity
xises to 80~/OJ instead of maintaini.ng a temperature of 72,
the system might ~egulate heat generation to maintain a
lower temperature until the hurnidity again drops. The
converse wculd be true should ~he humidity fall.
The system is also flexlble enough ~o accon~lodate
dead band heating and cooling in a system employing both a
furnace and an air conditioner. Should the ambient air tem-
perature rise, for eY~ample, to a temperature above 72, an
overriding signal could be generated to prevent the furnace
from being turned on. A tenlperatUre band might exist, for
example, between 72 and 74 F in which activation of both
the furnace and air conditioning unit would be inhibited.
~either the furnace nor the air conditioner would be turned
on while the temperature remained within this narrow dead
band range. Above 74 the inhibit signal would be rernoved
from the air cor.ditioner, but would remain in effect with
respect to the furnace. By the same token, below 72 the
air conditionin~ unit would be inhibited while activation of
the furnace is permitted. This manner of operation is
optional and the function, as achieved with conventional
thermostat controls, is explained in U. S. Patents 3,040,807
and 3,961,237.
111404;~ :
DESCRIPTION OF TH~ DR~WINGS
Fig. 1 illustrates the control panel of one embodi-
ment of the invention wi~h the cover closed on the keyboard.
Fig. 2 is similar to Fig. 1 wi~h the cover open.
Fig. 3 is a block diagram illustrating the manner
of operation of the embodiment of Fig. 1.
With reference to Figs. 1 and 2, the face 10 of a
control unit for the air temperature regulation sys~em of
the invention is depicted having a display 12, a keyboard 16
and selector switches 13. A cover plate 11 hinged along its
lower edge and hides the keyboard 16 and some of the selector
switches 13 from view when closed, as in Fig. 1, but when
opened as in Fig. 2, allows access to the keyboard 16 and
all of the selector switches 13 and displays written operat-
ing instructions printed on the i.nterior surface thereofwhen display or alteration of settings is desired. The
configuration of the regulating apparatus 10 is such that it
may be conveniently mounted in any wall thermostat mounting
location or on upright stanchions that are provided for this
purpose in some buildings.
An electronic display 12 of four digit positions
and a designation of A.M. and P.M. is provided in the upper
left hand portion of the face 10 o the regulator. The dis-
play 12 is shown as a light emitting diode display which
could be activated as desired but a liquid crystal display
could alternatively be selected so as to draw as little
power as possible to display a continuously observable image
of numbers designating temperature in degrees. Temperature
may be calibrated in the internal electronics of the system to
present a two digit display in either Farenheit or Centigrade
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ll~ Z
de~,~ees. J~CD, gas discl~arge or o~her conventional c~lectrorllc
displays mi~llt be elllployed in place o~ tl~e L~D display.
~lile the display 12 n~ay always be i.lluminated un-
- l~ss ~he l;eyl~oard ~6 is ac~uated, it mu~t l~c ~ppreci~ted
that tllis need not be the case. For example, ~he selec~or
switches labelled ROOM TEMP alld TE]~P SET are provided and
the displ~y 12 remains blank ~o conserve energy unless one
of them is depressed. Depresslon of the ROOM TEMP button
activates the display 1~ and causes it to display the curr~nt
temperature of the room in which the control unit is located.
Dis~lay may be in either degrees Farenheit or degrees Centi-
grade. Depression of the TEMP SET button, on the other
hand, causes the display 12 to register the normal room
temperature maintained by the control unlt of the invention.
The set back temperature may be determined from a slide
switch 17 ~-hich may be adjusted to provide a deviation from
the normal room temperature setting of between plus and
minus 10. Again, the control unit may be arranged to
operate on the basis o~ either degrees Farenheit or degrees
Centigrade. Accordingly, one may ascertai.n ~he alternative
or set back temperature by depressing the TEMP SET button,
observing the display 12, and mentally calculating the
difference according to the setting of the slide switch 17.
The other selector switches 13, visible in Fig. 2,
also perform predetermined functions. The switches labeled
S~T TII~ 1 and RESET TIME 1 are used to control respectively
the times within a 24-hour period at which the control unit
of the invention first ceases to maintain the normal desir~d
room temperature and begi.ns to maintain an of~set or setback
temperature as determined by the setting of the slide switch
_ g _
4~
17 for a prescril3ed operatiIl~ per;oc3 and the tirne at the t:erm-
inatiol~ o~ that p~riod whe~n control reverts to the norlllal
temperature. In some ln6tances it will be desirable for the
control unlt to maintain the setback temperature throughout
discontin~lous period~s of a 24-hour day. Accordingly, the
selector switch~s l~beled SET TIM~ 2 and RESET Tl~ 2 are
provided ~o designate the second commencement and cessation
of mai.l~tc-nance of the setback temperature by the control
unit of the invention within a 24-hour period.
Depression of the SET TIME 1 button which the con-
trol unit first begins to maintain the setback temperature
setting. This time appears in LED or LCD display 12. ~e-
pression of the RESET TII~E 1 button similarly calls from
. mernory the time thereafter at which the control unit of the
inventi.on will cease maintaining the setback temperature set-
, ting determined by the slide switch 17, and will instead re-
; vert to maintenance of the normal temperature. This time
likewise appears as at display 12 in response to depression
of the RESET 'l'IME 1 button. In a similar manner, depression
of the SET TIME 2 button causes the displa~ 12 to provide an
image of a clock reading of a subsequent time during the day
at which the control unit will again resume maintenance of
the setbaclc room temperature. The time at which control
according to that setback temperature will again cease is
registered on display 12 by depression of the RESET TIME 2
button. Depression of the CLOCK button provides a visual
display at 12 of the current time. Depression of the CLEAR
button clears the memory of the time or temperature last
appearing on the display 12. Changes in normal room temper-
~ 30 ature setting are achieved by first depressing ei~her the
:
- 1 0 -
404Z
`,:
SET TIME 1 or SET TIl~I' 2 but~ons, and thereaf~er depression
o~ selected ones of the keys in the keyboard 16 design~tlng
a new normal room temperature. Changes in the secondary or
set baclc ~emperature are achieved by manipulation of the
slide swi~ch 17.
The control panel face lO is also equipped with a
sli.de swi~ch 19 which may be utilized to alternatively oper-
ate either a furnace or an air conditioner by movement to
the HEAT or COOL position respectively. When in ~he OFF
position, the slide switch 19 prevents operation of either
the furnace or the air conditioner.
The slide switch 21 is provided to control oper-
ation of a fan. The fan can be turned on continuously by
¦ movement of the switch 21 to the ON position. Air circula-
~l; 15 tion and low level cooling can thus be achieved with a min-
. imum power consumption. Alternatively, the slide switch 21
l can be moved to the AUTO position in which the fan is cycled
l off and on with the air conditioner operation. When the
: switch 21 is in the ON position and when switch 19 is in
20 ~ the~ HEA T ~position, the fan will not be operable under the
control of the central processor 24. Rather, the fan will
. ~ be operated directly from the furnace in response to a
bonnet temperature sensor.
It~should be appreciated that other types of con-
z5~ trol functions can be provided for~the control unit of theinvention by using various slide or rotary switches in a
similar manner.
Fig. 3 illustrates the operational components of
the ~tèmperature~control system according to the present
30~ invention. In addition to the control panel face 10, a
- 11 -
~ O~Z
main cen~r,~l procesxing unit 24 is provided to perform ~he
arithmetic computat]ons and to effectuate the necessary en-
coding, decoding, storage and other data manipulation func-
tions re~uired for temperature con~rol. The cen~ral pro-
cessor 24 may take the form of a programmRble microcomputer,or alterna~ively it may be a dedicated custom designed in-
tegrated circuit pack.~ge. In either event ~ bec~use of size
and performance considerations, the ccntral processor 24
must be entirely electronic and must function without elec-
tro-mechanical components. Different integrated circuit
forms such as TTL, MOS, C-MOS, P-MOS and other integrated
circuit logic may be employed. The most desirable integrated
i circuits should exhibit low power requirements for the semi~
conductor circuitry utilized One suitable form of micro-
computer which may be employed as the central processor 24
, is the PPS-4/1 Microcomputer manufactured by Rockwell Inter-
national Corporation. This microcomputer, with minor modi-
fication, can be arranged to perform the functions of the
central processor 24.
20 ;~ The electronic clock circuit indicated at 30 may
or may not be included as an integral part of the central
processor 24, but in either event supplies clock pulses to a
counter arrangement that divides down the output of a uni-
form pulse source. The raw clock pulse source is a 3.579545
;25~ ~megahertz quartz crystal oscillator indicated at 28. The
l output of the crystal oscillator 28 is divided down through
;flip-flop circuits OL counter chips in the clock counter
array 30~to provide an integral hertz output on line 29 for
use~by the central processor 24. This output is tested by
30~ the ~entral processor 24 and if the signal is found to be
- 12 -
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~ ~ .. , . . , . ~
1114~)4Z
true, a current ~ime r~gister secti.on of the r~nd.om access
memory 36 is updated. In thls way a continuous recor(l of
the current time is ma.in~ai.ned at a known location within
the random access memory 36.
The touch panel switches of ~he keyboard 16 are
configured in a matrix format. A particular switch column
is selected by one of the five digit select lines 58 which
are connected to a multiplexer circuit 53, including appro-
priate drivers and receivers. Information concerning acti~.-
ation of any switches in a row of switches is determined
through one o~ four row select line 59 and transmitted to
an accumulator 34 in the central processor 24 where a test
is made to determine if a switch is being activated,
From the multiplexer 53 a signal is transmitted
sequentially upon each of the column select lines 58 to the
' touch panel 16 under the control of the instruction decoder
', 52, which also provides a corresponding signal to the accu- :
mulator 34. By sampling the receiver 75, the accumulator
, 34 is able to determine, for the particular column select
: 20 line 58 enabled, which, if any, of the row selec~ lines 59
is enabled, The accumulator 34 is thereby able to identify
depressed keys in the keyboard 16, As governed by instruc-
tion decoder 52 and the data address register 60, the accu-
~;~ mulator writes infonnation from the keys of the keyboard 16
into the random access memory 36,
In response to activation of particular ones of ~`
the selector switches 13, the central processor 24 performs
. ; an appropriate servicing routine, The inputs from the touchpanel 16 are required to complete the servicing routine if
: 30 the temperature switching times or the desired normal
13 -
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~il4Q42
tempcrature are ~o be altered.
Depression of any one of the selector switche~ 13,with the exception of the CLE~R switch, results in an image
- a~ the display 12. Outputs from the random access memory 36
to produce images on ~he display 12 are assembled in the
accumulator 34 and dispatched to a 16 by 8 decode matrix
circuit 63, which converts the tilne and temperature signals
to be displayed from the binary coded decimal form in which
they are stored to a seven segment code. The seven segme~.t
codes are transmitted to a pair of data buffers 65 and 67
where the proper digit segments are latched prior to select-
in~ and latching ~he associated digit in the display 12 by
activation of one of the cathode drivers 61 from one of the
column select lines 58. The segment code is trans~erred
from the buffer 65 and 67 to a pair of driver and receiver
circuits 69 and 71, and then in amplified form on seven
parallel inputs collectively indicated at 73 to annode
drivers 64.
The display 12 is multiplexed at the same rate as
is the keyboard switch matrix. The numbers for display are
~ selected one position at a time, although the persistence
j illumination of the LED's or LCD's in the display 12 allows
all of the numbers in the display to be viewed concurrently.
The scanning cycle is continued repeatedly during normal
operation of the control unit of the invention.
The address register 60 provides the accumulator
34 with information as to the locations within the random
access memory 35 and the read only memory 62 where informa-
tlon is to be re~d or written. This allows the accumulator
34 to draw permanent coefficients from the read only memory
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~il4042
62 to calcula~.e telllperature change rates to de~ermille which
stage o heating or cooling shoulcl be utili.zed to perform
calculations to anticipate when a desired temperature will
be reached, and to shut off heating or cool;ng in advance
so that there is no overshoo~ of this tempera~ure. The
provision of coefficients by read only memory 62 through the
instruction decoder 52 allows the accumulator to perform
averaging functions to prevent the system from being actuated
in response to transiell~ drafts from air currents. Other
means can be used to achieve the averaging function such as
an R-C ~ilter or some other hardware filtering arrangement.
This form~ a means for suppressing response to misleading
transistory excursions of sensed temperature from average
actual zone temperature. The address register 60 also pro-
vides the accumulator with address identification informa-
tion to allow the accumulator to draw information from the
random access memory 36 and pass this information through
driver circuitry 64 for display in LED or liquid crystal
display 12, as previously explained. An arithmetic logic
unit 66 and a carry flip-flop ~2 are also necessary to per-
form the temperature differential and averaging calculations
necessary for the control functions to be performed
The arithmetic logic unit 66 and the carry flip-
flop 42 are used in conjunction with accumulator 34 to de-
termine the predicted time of return of the actual temper-
ature to the desired temperature in response to operation
o~ the furnace contact 87, the air conditioner contacter 85
and fan contacter 78, all denoted generically as a thermal
pump 83, and for responsively terminating generation of an
30 ~ actuating signal on line 70. The thermal pump 83 may be
:~
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.
~ 1114~42
any device for hea~i.ng or coollng ambient air in a closed
envi.ronmen~ and includes such devlces as central ~urnaces,
air conditioners and heat yumps. To terminate a signal on
line 70 a ~emperature gradient is derived from a thermister
92 during provision of the signal on line 104. The predicted
time at which actual temperature will coincide with desired
temperature at the rate of incremental temperature gradient
is calculated by the arithmetic logic unit 66 and the carry
flip-flop 42. This interval is stored in the random access
memory 36 and is continuously updated until a predetermined
interval prior to the calculated predicted time. The signal
70 is then immediately terminated to compensate for thermal
inertia of the thermal pump 83.
. The drive signal for controlling the physical
activation and deactivation of the heating and air condition-
ing units is provided on line 70. A common output control is
provided for both heating and cooling. The control circuit
consists of both an SCR 74, an associated gate drive trans-
istor 72 and a diode bridge 73. The SCR 74 is used for both
heating and cooling by means of the two pole slide switch 19,
depicted in Fig. 3 and also visible in the lower right hand
-portion of the control unit face 10 in Figs. 1 and 2. One
side of the contacts of the slide switch 19 connects the pro-
per actuator control circuit for the air conditioner con-
tacter 85, the furnace contacter ~7 or the fan contacter 7~,
to the SCR 74 while the other side of the contacts provides
a logic signal to the central processor 24, either on line
82 for heating or on line 89 for cooling.
When the proper temperature setpoint is reached,
~30 the centFal processor 24 latches line 70 to 7.5 volts. Thi.s
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-. - , , ~ , . ; -: .
..
-- 1i14(~4Z
voltage provi.dcs drive current ~o the base of gatc dri.-ve
transi.stor 72 which in tu-L-n drive.l, tl~e ~ate of SC~ 74. The
diode bridge 72 is used to provide full wave rectified v
age ~or operating the SCR 74 and gate drive ~ransis~or 72.
The ~igna]. on line 70 is transmitted t~ the base
of the transi~tor 72 which provides the necessary amplifica-
tion to gate ~he SCP~ 74. Gating of the SCR 74 opens and
closes the transformer secondary circuit indicated generally
at 76 which i.s conventionally a step-down loop of 24 volts
A.C. derived ~rom the 115-120 volt, 60 cycle power source 78
acting through the transformer 80. Opening and closi.ng of
the seco~dary loop 76 provid~s power to the air c~nditioner
and furnace contacters 85 and 87 respectively. When the con-
tacter 85 closes a circuit to the furnace, the thermal pump
83 is operated in the heating cycle and when the contacter
87 closes a circuit to the air conditioner the thermal pump
83 is operated in the cooling cycle.
While three lines 70, 82 and 89 are employed between
the central processor 24 and the SCR control circuitry, it
should be noted that only two line would be necessary to
interconnect the transformer secondary loop 76 with the cen- -
tral processor 24 in a system employing a thermal pump 83
designed only for heating. This allows the temperature regu-
lating circuit of the present invention to be utilized with
conventional two wire thermostat connection lines for use
with existing furnace installations which do not also include
central air conditioning.
A further feature of the invention is the provision
of power from the secondary loop 76 to the central processor
24 on the clock circuit 30 at all times whether or not the
- 17 -
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~1404Z
SCR 74 i.s conductin~,. In the operation o the invention, .~
trickle charge to rechar~e the recharga~le battery 90 which
powers the central processor 24 is derived from the elec-
trical current tap 81 from the secondary loop 76 of the
5 trans~ormer 8~. Power is supplied on the current tap 8~, -
which draws current of a very low level, for exa1nple, about
4 miliamps. The current from the transformer 80 is recti-
fied by diode bri.dge 72 and passed through a diode 84 and a
resistor o8 to charge a conventi.onal nickel-cadmium recharg
able battery 90, A zener diode 105 acts as a transient cir-
cuit protector. In addition, the current from diode 84 is
passed at all times to power the clock circuit 30, and to
the central processor 24.
A thermistor circuit 92 is comprised of fixed and
variable resistors 94 and 96 respectively, a capacitor 98,
' and amplifiers lO0. The output of the thermistor circuit
92 is conne.cted as a data input source on line 104 to the
accu~ulator 34 of the central processor 24 through an in-
terrupt circuit 103 and an instruction decoder circuit 52.
2~0 The thermistor circuit 92 may be located anywhere within
the~area of temperature regulation but is most convenien~ly
located directly beneath or behind the face lO of the con-
trol unit. In some applications, a coiled nickel resistance
wi~re may~be substituted for the the~rmistor circuit 92 in
2s~ order~to nchieve more linear temperature signaling charac-
teristics. The variable resistor 96 of the thermistor cir-
cuit~9~2 der;ives actual anmbient temperature information and
transmits~ a signal indicative of the actual temperature on
Iine~104~to the accumulator 34, where it is translated into
3o~ b~inàry~ form~
18 -
' ' ' ~ '; ' ' ' " '." :'' ' . . ~ , : , .', . "' . ' ' ' ' .
~114~4Z
If the accumula~or 34, in cycling ~hrough a rou~
tine o~ temperature checks, ascertain~ that the actual te-n-
perature, as ~ransmittecl ~o it on lJne 104 is at sufficient
variance with the desired temperature stored ~n a location
in the random access memory 36 identified by the clocl; 30,
the accumulator 34 sends a signal on line 70 to gate driver
transistor 72 to gate the SCR 74. Prior to initiation of
any signal QM line 70, however, the system first ascertains
that the temperature deviation is not a result of a transient
draft. This function is achieved by sampling the output of
actual temperature on line 104 over an interval determined
by the cloc~ circuit 30. A comparison is performed on the
two temperatures obtained using parameters derived from the
read only memory 62. If the calculations carried out by the
arithmetic logic unit 66 and the carry flip-flop 42 show
that an average minimum threshold temperature deviation does
exist, a signal is initiated on line 70 to gate the SCR 74.
The embodiment of the invention depicted in Fig. 3
ill~strates but a single stage of operation for a furnace
and a single stage of operation for an air conditioner with-
in the thermal pump 83. It should be understood, however,
that the system depicted in Fig. 3 could be modified to pro-
vide a second control signal line in which a signal is pro-
vided on a line parallel to the line 70. The one of the
29 parallel control signal lines actuated could be determined
in accordance with the results of a temperature gradient
calculation, again possibly performed by the arithmetic
logic unit 66 and the carry flip-flop 42. If the calculated
temperature gradient derived from temperature sensed by
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~ 30 thermistor circuit 92 were to show that the operation of
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the thermal l)ump 83 had failed to Inove actual temperature
toward desired temperature, the signa:L on one of the con~rol
li.nes could be provided to operate a higher energy contac~or,
instead of the lower energy contactor wll;ch would otherwise
be actuated by a signal on thc other parallel control llne
in such a two stage contactor system. This would dri~e the
furnace or air conditioning unit to provide energy at a
greater rate than would occur if the temperature gradient
calculations were to show the tem~erature increasing in the
case of heating, or decreasing in the case of air condition-
ing, in response to signals from the thermistor circuit 92.
The clock 30 causes the accumulator 34 to access
different areas of the random access memory 36 at different
times of the day in order to determine the desired tempera-
ture. Thus, the accumulator 34 will compare average actualtemperature from ~he thermis~or circuit 92 with the regular
desired temperature stored in random access memory 36 fol-
lowing the time designated. Conversely, once the designated
sét back time has been reached, the accumulator 34 will per-
form its comparisons on the lower set back desired tempera-
ture designated by the slide switch 17 and stored in those
areas of the random access memory 36 corresponding to the
times of day falling after the designated set back time and
before the regular desired time designated.
Operation of the control unit of the in~ention is
carried out in accordance with the instructions on the in-
side of the cover plate ll, visible in Fig, 2. An occupant
of the room in which the control unit is located may easily
perform certain inquiries to determine temperature inorm-
ation. Depression of the ROOM TEMP selector switch 13 will
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cause the accl1mula~0r 34 to access the P~M 36 and provide
the current room temperature, at a clesignati.on F for Faren--
hei~ or C for Centigrade, ~o a~pear on the display 12. The
image of th~ curren~ numerical reading of the temperatllre
rem2ins for a ~e~ momen~s for a time determined internally
by the central processor 12. To ascertain what ~he normal
temperature setting is, one need merely depress the TEMP SET
selector swit~h 13. A similar image will appear on the dis-
play l~ to provide i.nformation as to what the normal temper-
ature setting is, During periods when the control unit ismaintaining ambient temperature at the normal desired tem-
perature, the two temperatures appearing in response to de-
pression of the ROOM TEMP and TEMP SET selector switches 13
should be very close, and usually will be identical. During
periods when the control unit maintains the ambient air at
the set back temperature, as determined by the s~lector
switch 17, the readings in response to depression of the
ROOM TEMP selector switch and the TEMP SET selector switch
should differ by exactly the amount specified by switch 17.
By opening the cover 11, one can perform further
inquiries and al~er time and temperature settings. The
clock 30 of Fig. 3 should be set to accurately maintain the
correct time within the random access memory 36. To ascer-
tain the time stored as the current time in random access
~emory 36, one need merely depress the CLOCK selector s~itch
13. In response thereto, the accumulator 34 will read the
;~ current time from the random access memory 36 and provide a
visual image of a clock reading, including a suffix A for A.M.
~;~ or P for P.~l. on the display 12. If this reading is incorrect,
the CLEAR select switch 13 should be depressed. This removes
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the previously stored reading from the random acces~ memory
36. It i.s then necessary to reset the accurate time by the
sequential depression of the proper nu~erical keys iII tlle
keyboard 16, followed by depression of the AM or PM key.
When this has been done, the display 12 will automatically
register the new current time. The CLOCK selector switch 13
is depressed a second time, thus terminating the sub-routine.
To inquire of the control unit as to the earliest
time of day at which temperature will be controlled according
to the setback temperature setting, determined by the switch
17, th~ SET TIME 1 switch is depressed. This will access
rom the random access memory 36 the earliest time within a
24-hour day at which the control unit will begin to maintain
the normal desired temperature and will begin ~o maintain
the set back ternperature. If this is, in fact, the desired
time at which the setback temperature is to be maintained,
the SET TIME 1 button is again depressed and the image of
. the clock reading of the setback temperature disappears from
`, the display 12. If one would thereafter like to change the
¦ 20 time at which set back temperature will commence, the clear
~ switch is depressed instead of depressing the SET TIME 1
il switch a second time. This clears the previously set com-
mencement time. Following depression of the CLEhR switch, a
new time is entered by depressing numerical keys in the
keyboard 16 in the proper order, followed by depression of
the AM or PM designation key. This enters the altered
comtnencement time of the setback temperature in the random
access memory 36. This new ~ime then appears on the display
12. ~Thereater, the SET TIME 1 button is depressed again to
store the in~ormation entered.
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The R~SET TIME 1 button al~ers the cessation t;,m~
of the first interval within a 24-hour day during which am-
bient temperclture is main~ai~ned at the set baclr tempera~ure
set:ti,ng. Alt-eration of ~he rese~ tiTne of the firs-t set back
temperature interval is achieved in much the same way as
alteration of the con~lencement of that interval. That is,
the RESET TIME 1 switch is depressed, thereby providing an
image on the display 12 at which the first set back tempera-
ture interval is to terminate. To change this time, the
CLEAR switch is depressed and thereafter a new time designa-
; tion is entered on the keyboard 16. This new time designa-
tion appears on the display 12, and if it i5 corr~ct, that
time is stored as the new reset time by again depressing the
~; RESET TIME 1 button.
Similarly, a second time interval durin~ the day
I , can be altered. By way of example, a typical normal temper-
'l ature setting might be 72 E, while a set back temperature
,l might be 68 F. A preferable time interval for the set back
temperature setting might well be from 8:00 A.M. to 5:00 P.M.
These times could be designated using the SET TIME 1 and
R~SET TI~ 1 switches respectively. A second interval of the
day during which the set back setting of 68 might be desired
could be from 10 P.M. to 6:30 A.M. The SET TIME 2 and RESET
TII~E 2 switches can respectively be used to establish these
~Z5 time demarlcations. If the normal temperature is to be 72,
' the slide switch 17 is set on -4 since 68 is 4 less than
,l' ~ 72. To change the time of the second set back temperature
~ interval from commencement at 10 P.M. and termination at
,-, 6:30 A.M. to commencement at 11:15 P.M. and termina~ion at
~ 30 7:00 A.M., the following steps are taken. The SET TIME 2
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switcl is de~ressed, theJ~by ~roducing an j.mage o 3.000P onthc di.splay l.~. The clear switch is depl-essed ~o remove
this ima~e. The keys l,1,1,5 and PM in th.e keyboard 16 are
then <lepressed ir) tha~ orde~. ~. corresponding i.mage 1115
appea~s on the dlspl.ay 12. The SET TIME 2 switch is dep~e~sed
to store this as ~he new com~lencement time for the secolld
set back temperature in~erval. The r~ESET TIME 2 button is
then depressed, thereby producing an image 630A on ~he
display 12. This lmage ls removed by depression of the
clear switch. The new desired time is entered by sequen-
tially depressing the buktons 7,0,0 and ~M in that order to
pro~uce a corresponding image 700A i~ ~he display 12. The
RESET TIME 2 switch is again depressed, thus stor.il~g this
time as the termination time of the second normal tempera~ure
interval
If it is desired to change the normal temperature
setting, the TEMP SET switch is depressed, thus providing an
image of the normal desired temperature on the display 12
If this temperature is 72 F, and it is desired to chan~e
20 the normal desired temperature to 74 F, the CLEAR switch is
; depressed following depression of the TEMP SET swi~ch. This ~:
clears the image from display 12. The numerical keys 7 fol- -.
lowed by 4 are depressed in that order on the keyboard 16.
The new norma.l desired temperature 74 F appears on the dis-
play 12. This information is locked in storage by again de-
pressing the TEMP SET switc1.l which removes the image from
the display 12. If the slide switch 17 remains at the -4
setting, the secondary or set back temperature will no
: longer be 68 F, but instead will be 70 F, since 70 is 4
less than 74.
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~ ~ 4042
It should be unders1:ood th~-~t llumerous additional
features can easlly be incorporale~ i.nto the prcse~nt inven-
~ion ~o~ exampl.e, a llumidi~y sensor can adclitionally be
eml)loyed to al~er the norml3. desired telnperature in rcsponse
lo hu~lidi.~y deviati~ns. Also, it is possible to arrang~ the
de~rice s~ that there is an automa~ic change over from air
conditionin~ to heating upon reaching a predetermined tem-
perature, wlth a dead band within which neither heating nor
cooling will occur so that alt-ernative cycling between heat-
ing and cooling cannot result In additi.on, an outside tem-
perature sensor can be employed to adjust various parameters
of the dcvice, including the normal desiled temperature.
Also, as previously no~ed, multiple stages of heating and
cooling can be employed, ~ypically through the use of par
allel connected SCR's or triacs. In such multiple stage
operation, failure of the system to effectuate the desired
temperature change, either heating or cooling, in response
to a signal on line 70, would advance the system to a higher
stage of energy operation. That is, the energy output,
either heating capability or cooling capability would be
increased.
A further desirable feature might be a manual
emer~ency bypass. That is, if ambient temperature conditions
fall an unacceptable level due to some llialfunction of the
control unit or some other event, the control provided by
the control system of the invention could be overridden and
controlled by a simple single temperature control. This
feature could be used to prevent freezing of water pipes and
other adverse consequences
30:.: It is to be understood that numerous other
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variations and modifications of the system will become
readily apparent to those slcilled in the art. Accordingly,
the invention should not be construed as limited to ~he em-
bodiments disciosed hcrein, but rather is defi.ned in the
5 c~ aims appended hereto .
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