Note: Descriptions are shown in the official language in which they were submitted.
~43~33
BACKGROUND OF INVENTION:
Field of Invention
The present invention relates to a swi-tching
system and a method of remote switching an elec-trically
operated device and wherein the switching system is
operated by using calling signals generated by a telphone,
and more particularly, but not exclusively, using sound
calling signals.
Description of Prior Art
Various types of electrical or mechanical
switching devices are remotely operated by various methods
such as transmitting specific signals recognized by a
receiver to connect an electrical source to a device via a
switch, or else by transmitting coded signals, or by
generating specific sounds recognizable by a receiver
system. However, most of these systems require a speci~ic
transmitter device and receiver device, and are very
limited as to their operating range, that is to say, the
transmitter and receiver must be located within the
predetermined distance. Usually, this distance is fairly
short, such as for starting ignition systems of auto
mobiles, etc. Another disadvantage of such prior art
systems is that these are quite costly because of the need
of transmit-ters and receiver systems.
It is also known, particularly wi-th the use of
alarm systems, to protect an enclosure, to automatically
generate a specific code signal on a telephone line upon
detection of an alarm condition, such code signal is
connected to a central control station where an alarm code
can be identified by decoding the signal. These signals
are usually transmitted autornatically with an automatic
1-
~2~7~32~
dialing system as soon as an alarm condition is detected.
A disadvantage of these systems is that -they are also
costly in that the subscriber must pay a service charge
for the use of the telephone lines as well as the usual
cost of the call if a long distance call.
SUMMARY OF INVENTION:
It is a feature of the present invention to
provide a switching system for switching an electrically
operated device and wherein the switching system is
operated by remote control using the calling signals
generated by a telephone.
Another feature of the present invention is to
provide a switching system for switching an electrically
operated device by dialing a specific telephone number and
causing a predetermined first series of repetitive calling
signals to take place followed by a dialing of a second
: .
series of repetitive calling signals.
Another feature of the present invention is to
provide a switching system which utilizes telephone lines
without the transmission of voice signals along the
- telephone transmission link whereby there is no cost to
- the user for the use of a long distance telephone link.
Another feature of the present invention is to
~` provide a switching system which is remotely operated by
the use of the signals generated by a telephone regardless
if the telephone is utilized in a party-line arrangement
where there are restrictions concerning the connection of
any device to the telephone wires, and irrespective of the
type of calling signals generated by the telephone device.
~- :
~ ~ - 2 - ~
.. - . . . .. ~ . . . . . . .
3~
Another fea-ture of the present inventlon is to
provide a low stand-by supply current derived from a serial
circuit connection without affecting the load to be switched
by the serial connection link.
Another feature of the present invention is to
provide a switching system which is remotely controled by
telephone signals and wherein the switching system is
provided with a detector circuit for identifying a specific
code of telephone calling sound signals before validating a
predetermined number of such calling sound signals to deter-
mine if a switching function is to be performed or not.
Another feature of the present invention is to
provide a method of~remotely switching an electrically
operated device by the use of sound signals generated by a
telephone.
According to the above features, from a broad
aspect, the present invention provides a switching system
for switching an elect~rically operated device and wherein
the switching system is operated by~remote control using
calling signals generated by a telephone. The switching
system comprises switch means to enable the electrically
operated device. ~rocessing circuit means are provided for
identifying the calling signals and operating the switching
means upon accepting a specific code of the calling signals
and validating a predetermined number of the calling signals.
The electrically operated device is a temperature condition-
ing device. The switching system further comprises an
ambient temperature measuring ci~rcuit for sensing a tempera-
ture in an enclosure and feeding temperature information
signals to the processing circuit means for storage therein.
` ' '`''~
~L~7~
The ambient temperature measurlng circuit has two comparators
each connected to a respective -temperature~responsive trans-
ducer generating an output voltage signal~represen-tative of
the ambient temperature of the t~ransducer. One of the
comparators has a low temperature reference level and the
other a high temperature level ~hereby to feed temperature
control signals to the processing ci~rcuit means for storage
therein. The stored temperat~re information signals are
~retalned in the processing circuit means for a predetermined
period of time. The stored temperat~re information signals
are averaged by the processing circuit means when a command
signal is~received over the telephone. The processing means
when~receiving the specific code enables the switching
system to switch "on" a heating or cooling system of the
temperature conditioning device dependent on the average
value of the stored temperature information signals, to
maintain the temperature in the enclosure at a predetermined
low or high temperature~range.
According to a further broad aspect of the present
invention, the switching system is operated by calling sound ;
signals generated by the telephone.
According to another aspect of the present inven-
tion there is provided a switching system wherein the system
further comprises an ambient temperature measuring circuit
for sensing the temperature in one or more enclosures, and
feeding temperature information signals to the processing
ci~rcuit means whereby to control one or more temperature
conditioning devices.
~2~7~32~3
Another aspect of the present invention is to
~reduce energy loss by unnecessary operation of air condi-tion-
ing systems, such as heaters or air cooling devices, which
are often operated in an envi~ronment which is not occupied,
such as is the case with a second~residence or cottage.
A still further aspect of the present invention is
to provide a switching system which can be automatically
operated to actuate an ai~r conditioning device for a
predetermined time before a person is to occupy the space
where the ai~r is being conditioned.
Another aspect of the present invention is to
provide a switching system for switching a temperature
conditioning device by the use of long dis-tance telephone
lines without transmitting voice signals on the lines and
without unhooking the telephone receiver being called, and
wherein the temperature is automatically regulated.
According to a further broad aspect of the present
invention there is provided a method of~remote switching an
elect~rically operated device, the method comprising the
following steps: (i) calling a prede-termined telephone
number of a telephone coupled to a switching system having
processing circuit means to identifying a code of calling
signals and validating a predetermined number of calling
signals; (ii) causing the telephone to generate a first
series of repetitive calling signals followed by a delay
period and a second series of~repetitive calling signals to
cause the processing ci~rcuit means to validate the calling
signals, each of the calling signals comprising a sound and
signal followed by a period of silence, the sound signal and
period of silence constituting a period; the step of validat-
ing a predetermined number of the calling signals further
comprising: (a) measuring a time lapse of the sound signal
,~
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- 4a -
~27~3~
in a period to dete~rmine if it lies within a predetermined
time lapse; (b) accepting a sound signal within the ti.me
lapse and~rejecting othe~rs; (c) measuring the duration of
the period of silence; and (d) storing only validated
periods where the sound signal and following period of
silence fall within predetermined time limits; and (iii)
automatically switching the electrically operated device to
cause it to operate whereby to regulate temperature in a
sensed enclosure dependent upon an average value of stored
sensed temperature signals and upon validating a predeter-
mined number of the calling signals.
BRIEF DESCRIPTION OF DRAWINGS:
A preferred embodiment of the present invention
will now be described with~reference to the accompanying
drawings in which:
FIGURE 1 is a block diagram showing a specific
appli.cation of the switching system of the present invention;
FIGURE 2 is a further block diagram showing another
application of the switching system of the present invention;
FIGURES 3A, 3B, 3C, 3D and 3E are pulse signals
illustrating the manner in which the pulses are detected and
validated, and illustrating the presence of differen-t noise
signals thereon;
FIGURE 4 is an illustration of the calling signal
code;
FIGURE 5 is a temperature graph showing the opera- -
tion of the switching system of the present invention for .
controlling temperature conditioning device(s);
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FIGURE 6 is an interconnecting block diagram
showing the interconnection of the various schema-tic
diagrams illustrated in Figures 7 to 14 and forming -the
system of the present invention;
FIGURE 7 is a schematic diagram of the audio
detector circuit;
FIG~RE 8 is a schematic diagram of the
tempera-ture measuring circuit;
FIGURE 9 is a schematic diagram of the
converter;
FIGURE 10 is a schematic diagram of the
automatic filter;
FIGURE 11 is a schematic diagram of the voltage
regulator;
FIGURE 12 is a pin block diagram of the
microprocessor;
FIGURE 13 is a schematic diagram illustrating
the triac switch and protective mechanical switches;
FIGURE 14 is a schematic diagram of the
converter circuit which feeds the control signal to the
triac; and
FIGURE 15 is a schematic diagram of the signal
pulse visual detec-tor~
DESCRIPTION OF PREFERRED EMBODIMENTS:
Referring now to Figures 1 and 2 there is shown
two specific applications of the switching system 10 of
the present invention. As herein shown, the switching
system of the present invention is connected across the
existing -thermostat 11 of a heating or air conditioning
system, and may be connected, as shown in Figure 1, to
power relays 12 which interconnect various electric heat-
-- 6 --
~7~ 8
lng elements 13 to the electrical power distributed by theswitches 14 in a distribution panel 15. Thus, the switch-
ing system 10 can connect electrical power to any one of
the electric base board heaters 13 upon detection of
specific coded signals, as will be described later. As
shown in Figure 2, the switching system is connected to
the various functions of a heat pump and can operate all
functions or individual ones, as may be selected by the
switching system. As herein shown, the switching system
10 is connected to the heating, cooling, the fan and the
damper functions of the heat pump. . .
Before describing the specific co~struction of
the switching system 10 of the present invention, we will
firstly describe how the switching system is remotely
controlled by the use of local or long distance telephone
lines without transmitting voice signals along these
lines, but by utilizing the calling sounds generated by a
telephone being called by a user in a predetermined
manner. Firstly, it is necessary for the user to adjust
the switching system of the present invention to make sure
that it receives the telephone signals generated by his
telephone. This is done by placing a function switch on - .
the system to an "absence" position, and making the
telephone operate so that the user can determine visually
and/or audibly if the switching system is receiving the
telephone calling signals. The particular embodiment
herein described deals with calling sound signals
generated by a telephone~ although the invention is not
restricted thereto and can also process other types o~
signals that may be generated by a telephone.
~7~3?~8
We will now describe the method util~ied to
remotely command the switching system to switch an elec-
trically operated device. In accordance with communica-
tions regulations, in at least parts of North America, the
minimum time interval of a ringing sound or a silent sound
between two ringing sounds is 1 second, and a ringing
sound between two silence periods must be inferior to 5
seconds. This specification is fairly well respected when
one considers private telephone lines, as is quite common
nowadays. However, with party-type telephone lines this
regulation is not always followed. Accordingly, in order
for the switching system of the present invention to
operate with either private lines or party lines, the
system must be able to recognize different calling
signals, and therefore must analyze the sound period as
well as the period of silence in the signals. Herein we
consider the sum of -the sound period and the silence
period which follows as being "a period". This period
will be analyzed as having a duration time of 7 seconds
maximum, that is to say, 5 seconds maximum for the delay
between two silence periods and 1 second maximum for the
silence period and a l-second tolerance~ This period is
illustrated in Figure 3A.
The switching system of the present lnvention
utilizes a microprocessor circuit (see Figure 12), as will
be described later, to measure the duration time of a
ringing or calling sound 16 and the duration time of the
silence 17. If both these time periods meet certain
predetermined conditions, they will be stored and later
counted as a single "period". If not, they will be simply
rejected by the system. It is by analyzinq the "periods"
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3~
and by counting those that are rated as valid that the
processing circuit will make a decision to control various
circuits associated therewith to effect a required
predetermined function. Accordingly, the switching system
10 will effect a function when th~ validated "periods"
fall within a predetermined count or range.
In order for the microprocessor to analyze the
calling signals 16 and 17 generated by the telephone
device, the user must call a specific telephone number and
make the telephone ring a code, as shown in Figure ~. The
code illustrated consists of six ring periods 16', termi-
nated for a predetermined period of time 17', and then the
same telephone number is called again and a second series
of telephone rings 16" are caused to take place. The
microprocessor will not consider the last calling sound
generated by the telephone in both series of rings, as
that period will be followed by a very long period o
silence unless, and very unlikely, another person happens
to call a short time after the code of calling signals has
been effected. The time delay between both series of
rings must be in the range of from between 7 seconds to 90
seconds. Otherwise the command will not ta~e place. The
second series must be~ completed wi-thin the 90 seconds.
The program or memory of the microprocessor can accumulate
up to nine calling signals, and accordingly af-ter storing
nine calling signals the microprocessor can compare them,
and it is only those signals 16 and 17 falling within 9/10
of a second, when compared between themselves, tha-t will
be considered as validated "periods". The "periods" whlch
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have time lapses outside the required range will be
discarded. If the number of valid "periods" fall wi-thin
the range of ~hree to seven "periods", the call will be
validated as a "command" signal.
It is to be understood that the apparatus or
system of the present invention operates in an environment
which sometimes can have sounds or noises generated in the
environment, such as household appliances i.e, refrige-
rators, door bells, the cracking of wood within the walis
of a house, animals in close proximity, cars, immediate
neighbors, etc. All oE this random noise has very little
chance of repeating itself within a short period of time
or in an organized manner, but can be produced, while the
telephone is generating calling signals to form a
"co~and" signal. However, this random noise can produce
a problem for the system and must be eliminated. Figures
3B to 3C illustrate the various effects of such noise.
If the noise occurs between two ringing sounds,
the processing circuit will eliminate all noise signals
having a duration time which is less than 9/10 of a second
as with the calling signals. Also~ in view of the above
mentioned characteristics of the "period" that we are
measuring, all sound signals having a duration of more
than 6 seconds will also be eliminated (5 seconds being
the maximum time of a sound signal plus one 1 second
silence and tolerance). In any event, parasitic noise can
occur between two ringing periods 16 or during the silence
interval 17. As shown in Figure 3B, when a noise signal
20 occurs before a ringing period 18 it can lengthen the
actual ringing period 18, and shorten the preceding
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.
silence period lg, see reference numeral 19. If the noise
signal 20 has a duration time which is superior to -the
programmed tolerance of a system, both periods 18 and 19
will be rendered invalid.
As shown in Figure 3C, if the parasitic noise
signal 21 occurs during a ringing period 16, it will have
no effect on the decision being taken by the processing
circuit. If a parasitic noise signal 22 occurs imme-
diately after the ringing period 16, as shown in Figure
3D, it will prolong the duration or lapse time oE the
ringing period and reduce the duration time o~ the silence
period 23 that follows. In this particular instance, the
"period" will be considered as a valid "period". If a
parasitic noise signal 24 is spaced between two ringing
periods, as shown in Figure 3C, it reduces the preceding
sound period 17 and renders it invalid if, and only if,
the duration of the parasitic noise signal 24 is superior
to 9/10 of a second and thus treated as a ringing period.
The noise period 2~ will also be rendered invalid by the
second ringing period 16' when the silence period is
evaluated as invalid.
In conclusion, there is only one case where the
microprocessor can be affected in its decision, and that
is when a noise signal takes place very closely in front
of a ringing period 16, as shown in Figure 3B. However,
this is a very unlikely occurrence, but if it should
arise, there will still be three other valid "periodsl' for
the reason that the microprocessor would have eliminated
two "periods" due to this parasitic noise and the last
"period" automatically. .The three remaining 'Iperiods'' are
sufficient for the calliny "command" code to be validated
-- 11 --
to cause -the switching system to effec-t a switching opera-
tion. The microprocessor has a program with four func-
tions, and namely tc store period signals, to calculate
the number of period slgnals, to calculate if the valid
periods constitute a command signal, and to effect the
command.
The particular application of the system
described herein is associated wi-th a temperature condi-
tioning device, and namely resistive heating elements,
whereby to control the temperature in one or more areas
being controlled by the switching system. Figure 5 is a
temperature graph illustrating the manner in which the
temperature is controlled. In the absence of a command
signal, the temperature is maintained within a low tempe-
rature range 25 of between 6 and 8C. As soon as the
temperature goes above 8C, the heating system is cut off,
and once it falls below 6C, it is energized. As soon as
a command signal is detected and validated, the heating
-
system is turned "on" and the temperature is caused to
rise to a high temperature range, herein set at 20C which
is the high temperature limi-t of the system. This is
illustrated at 26 in Figure 5. Once the 20C is reached
the system is "shut off" and turned "on" again as soon as
the temperature falls below 18C. This control process
continues on for a predetermined period of time, herein a
2-hour period 28, and after this period lapse the heating
elements are no longer energized and the temperature
starts falling. The end of the period 28 is shown at 27
and the temperature drops down to its low level tempera-
ture control range 25, as illustrated at 26. If the
occupant enters the space being heated within the delay
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period 28, before the end of the cycle 28, he can then
place the switching system function switch to an
"occupant" position, and with the use of the local thermo-
stat select a desired temperature so that the thermostat
can take over the control of the temperature hea-ting
device. ~-
Two truth Tables are utilized to monitor the
positive and negative variations in the ambient tempera-
ture with each truth table taking into account the
2-differentials mentioned above and acting sometimes on
the rise and sometimes on the fall of the temperature.
These two truth Tables are set forth hereinbelow.
TEMP LT HT TEMP LT HT
1 1 20
18 1 0 18
8 1 o 8 1 0
6 0 0 6 1 0
O O O~ ~ O O O
It can be observed that when the temperature is 0C. a 1
condition does not appear in both truth Tables, and this
is referred to as an impossible condition. If such a
condition is read by the computer, the heating or air
conditioning load would automatically be switched off.
Not only does the program permit the reading of the tempe-
rature sensed by both comparators, it also stores the
information by a last-in/first-out method keeping only
temperature readings of the last twelve hours. When the
program then analyzes the sounds emitted by the telephone
generates a "command" signal to the control clrcuit of the
program, the program will effect an averaging of the
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~2~3~3
stored temperature information signal, and will take a
dicision as to whether it should actuate a heating device
or an air cooling device. This decision is taken after
considering the following three variables:
(a) after analyzing the series of ringing sounds of
the -telephone;
(b) after analyzing the average temperature stored
in the processor; and
(c) after analyzing the actual temperature to
determine if it is hot, cold or very cold.
This last decision i5 taken from analyzing the
signal at the output of the compara-tors; and if the tempe-
rature is inferior to 6C., the temperature is considered
very cold, and if it varies between 8 and 18C~, it is
considered cold; and lf it is superior to 20C., it is
considered hot. As a security measure, the program will
shut off the load supply as soon as-it detects an error or
an impossible condition. It can be appreciated that with
the above established condition the microprocessor can
decide if the electrical elements being controlled should
be energized or deenergi7.ed. When considering the control
- of heating or air conditioning devices, the following
switching decisions are made:
HEATING
SWITCHED OFF SWITCHED ON
1-impossible condition 1-cold ambient temperature
2-ambient average temperature 2-delay period started and
- and the delay is terminated average ambient tempera-
3-hot ambient temperature ture and average cold
temperture
3~heating already energized
and average ambient
temperature
- - 14 -
iL2~
P~IR CONDITIONING
SWITCHED OFF SWITCHED ON
l-impossible condition l-ho-t ambient -temperature
2-cold ambient tempera-ture and ho-t average -tempera~
3-slightly warm ambient ture and delay has just
temperature terminated
4-delay terminated 2-hot ambient temperature
and delay has initiated
3 average cold temperature
and delay initiated when
condition 2 has been met
It is pointed out -that the air conditioning is
not energzied or switched on when the ambient temperature
is above 20C. It is necessary that the 2-hour delay be
expired. However, the heater is energized or switched on
as soon as the temperature goes under 6C., and this is
done for safety reasons to prevent water pipes from freez-
ing, and to protect materials sensitive to low
temperatures.
The specific construction of the switching
sys-tem 10 of the present invention will be described in
detail with reference to Figures 7 to 15. Figure 6 is
simply a block diagram showing the interconnection of the
various circuits of Figures 7 to 15 which constitute the
switching system 10 of the present invention.
Referring now to Figure 7, there is shown the
specific construction of the audio detector circuit 30.
It consists of a receiver device, herein a microphone 31,
which receives the sound signals 33 from a telephone
receiver device 32. A voltage supply 34 is applied to the
terminals of the microphone 31 through resistances 35 and
36 and the signal at the output 37 of the microphone 31 is
then filtered by capacitor 38 in order to obtain a voltage
signal substantially free of noise~ Such a signal is
desired for amplification through high gain amplifiers.
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~Z~ 3X~3
This weak intensity signal is coupled to the preamplifier
circuit 39. Transistor 42 is biased by resistors 40 and
41 and connected to the base of transistor 42. The
operating potential and the gain of transistor 42 is
established by the feedback resistor 43 connected to -the
base/collector of the transistor. The maximum current
that will pass through the collector/emitter of the
transistor is determined by resistor 44.
A high gain amplifier 45 is connected to the
output of a preamplifier and it operates by a simple
polarity supply. The coupling between the preamplifier
and the high gain amplifier 45 is effected through
capacitor 46. Resistor 47 connected in series with
capacitor 46 limits the level of -the high frequency noise
generated by the components of the circuit. The gain of
the amplifier 45 is fixed by resistor 48 and input resis-
tance 47. The level at the input is established by
resistors 49 and 50 connected to the non-inverted input 51
of the operational amplifier ~5. Thus, the output signal
will be dependent upon this potential.
In order to establlsh comparison means it is
necessary to treat the audio signal to make it compatible
to a DC voltage. Accordingly, the level of the signal at
the output of the operational amplifier is establlshed by
capacitor 52 and diode 53 whereby the AC signal at the
output 54 of the operational amplifier 45 will be above
0.7 Vdc as set by diode 53. The signal is then integrated
by diode 55, resistor 56, and capacitor 57. Capacitor 58
eliminates noise in the signal created by the change of
state of the diodes 55 and 53~ Resistor 56 and capacitor
57 eliminates all pulse signals having a duration time
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~27~32!3
which is inferior to the time constant of this RC circuit.
Also, when capacitor 57 is charged, and there are no pulse
signals, it will discharge itself in resistor 59. Thus,
the circuit provides a pulse having a duration time which
is longer than the RC time constant of resistor 56 and
capacitor 57, and which will have a minimal time duration
equal to -the time constant of resistor 59 and capacitor
57. Resistor 60 connects the signal to the inverted input
61 of operational amplifier 62. This resistance 60
corrects -the input current as a function of the type and
characteristic of the operational amplifier 62. The
reference is established by resistors 63 and 6~ Feedfack
resistor 65 establlshes the hysteresis o~ the ampli~ier
with resistors 63 and 6~. Thlls, in the absence oE pulse
signals o~ levels superior to the reference signal, the
output of the comparator will be maintained high. Each
time that an input pulse exceeds the reference signal, the
output 66 will be switched to a low level and the
reference will drop down to a low hysteresis -through
resistor 65. It is only after the input signal at the
input 61 falls below this reference signal that the signal
on the output 66 will reset at a high level.
Referring no~ to Figure 8, there is shown the
construction of the temperature measuring circuit 70. It
consists of a temperature transducer 71 of a type well
known in the art, wherein a 10 mV output signal is
provided for every degree Fahrenheit sensed by the trans-
ducer 71. The output 72 of this transducer is connected
to the input 73 and 74 of comparators 75 and 76, respec-
tively. The operation of comparator 75 is set at a high
level by resistors 77 and 78. The reference voltage Erom
.
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~27~
the resistors 77 and 78 as well as from the sensor 71 are
fed to the compara-tor75 through resistors 75' and 75",
respectively, which corrects the input currents of the
comparator 75 dependent on the type of operational
amplifier used for the comparator. Capacitor 79 filters
any noise that could be present in this reference signal.
The hysteresis for the operational amplifier 75 is estab~
lished by feedback resistor 80. Thus, the output of
comparator 75 will be maintained at a low level as long as
the ouput voltage of the transducer 71 does not exceed the
reference level of the operational amplifier. When the
OUtp~lt s~gnal of the transducer exceeds the reference
signal, the signal at the output 81 of the comparator 75
will rise to its high level until the output signal of the
transducer drops below the reference level, less the
hysteresis. Diode 82' comple-tes the coupling of the
- resistor 24 to the input 73 of the operational amplifier.
~ The other comparator 76 or operational ampliEier
;. acts as a low level comparator. The reference and sensor
voltages are connected to the comparator through resistors
82 and 83 respectively, and this circuit operates
similarly to the other comparator, but for low level or
low temperature detection. Capacitor 84 suppresses the
noise on this reference signal. The hysteresis or
circuit is herein connected to the other terminals of the
operational amplifier, in reverse, and is provided by a
voltage divider constituted by resistors 85, 86 and 87.
The output of the comparator 76 will be mainiained high
until the output signal at the output 72 of the transducer
71 becomes inferior -to the reference level. If the output
of the transducer 71 becomes inferior to this reference
- 18 -
~27~3%~3
the signal on the output 88 of the comparator 76 will be
placed at a low level, and will increase to a high level
only when the output signal of the transducer rises to a
level which is superior to the reference level plus the
hysteresis. The result of the control action of the low
level comparator is shown at 25 in Figure 5. The control
of the high level comparator is shown in the same Figure
in the region between reference numerals 26 and 27.
Referring now to Figure 9~ there will be
descibed the cons-truction of the converter circuit 90
forming part of the power supply. As herein shown, the
converter is provided by a diode bridge consisting of four
diodes 91 whereby to convert the AC voltage into a DC
voltage. The alternating voltage is tapped from the
output connections 92 and 92' across a triac, as will be
described with reference to Figure 13. The negative side
of the diode bridge constitutes the ground potential for
the circuit, and the positive output is connected to the
input of an automatic filter circuit, as shown in Figure
10 . ,
Because there are two possible supplies across
the triac device, dependent on the state of the switching
system, it is important to maintain the system supply
voltage to the lowest possible current level whereby not
to consume much power when the system is in a switching
mode. Accordingly, care must be taken not to introduce
large filtering capacitors in the power supply. In this
automatic filter circuit 93 a small capacitance 9~ will
provide the minimum necessary filtration when the system
is in a non-switching mode. However, when the system is
in a switching mode where the voltage across the converter
-- 19 --
~2~ 2~3
bridge 90 is of the order of 7V DC, it is necessary to
filter -this voltage signal in a more serious manner
whereby to maintain a constant supply output voltage of
4.2 V DC. In order to achieve this filtration, a circuit
95 is provided to detect the potential drop at the output
of the diode bridge, and to provide a large capacitance
across capacitor 94 . Resistors 96 and 97 form a voltage
divider the value of which is calculated so that
transistor 98 conducts when the potential at the output of
the bridge 90 falls below 10 V DC. Resistor 99 limits the
current in the collector/emitter of transistor 98 and
supplies the base/emitter current necessary for the
conduction of transistor 100 which in turn polarizes the
base of transistor 101. This polarizing current is set by
resistor 102. Transistor 101 now acts as a swi-tch and
connec-ts capacitance 103 in parallel with capacitance 94,
thus increasing the filtering capacity of the circuit 95.
Diode 104 provides the supplementary 0.7 ~ DC and improves
the charging of capacitance 103 when placed in operation.
Referring now to Figure 11, there is shown the
regulator output circuit 105 of the power supply. It
comprises an asymmetric circuit connection of transistor
106, resistor 107, transistor 108, and resistor 109, which
circuit assures a stable current for the reference voltage
established by resistors 110~ 111 and transistor 112.
Transistor 112 corrects and maintains the potential
between the emitter and ground connection of transistor
113 by modifying the current on the base of transistor
113. Resistors 114, 115 and 116 constitute a correction
circuit which provides for a constant potential in either
of the two modes of operation oE the switching system. A
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~2~7~3;~3
variable potentiometer could also be pl~ced between
resistors llO and lll to correct the le~el of the output
voltage. The capacitors 117 and 118 prevent the circuit
from oscillating.
As can be observed from the above circuit
descriptions, the power supply circuit is connected to the
power switching circuit. Also, as seen from the load
supply, the load and the power supply circuit are
connected in series. The only location in the circuit
where a supply can be obtained i5 across the switching
element, herein the triac or switching relay. Accord-
ingly, there are two modes of supply and that is when the
triac conducts high voltage supply and when it does not
conduct a low voltage supply. However, in conditions
where the triac does not conduct, the current supply
should be maintained as low as possible in order not to
actuate the load, herein the elect~ically operated device
which lS connected in series with the triac. Thus, the
power supply circuit and the construction of its filter is
. .
an important part of the system of the present invention.
Referring now to Figure 12, there is shown the
pin circuit connections of the microprocessor~controller
circuit 120. This controller includes the programs to
analyze the telephone sound signal and to analyze the
temperature control signals of the temperature control
circuit 70. It is also provided with a clock circuit 121
including a crystal oscillator 122 and two small capaci-
tances 123 and 124. The oscillator generates a frequency
of 3.57~45 mHz. This frequency was selected in the light
of a low current consumption of the system taking into
consideration that the execution speed of the system need
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~27~2~3
not be very high for the intende~ applications of the
system. An initializing circuit is formed by capacitor
125 and an internal resistance (not shown) to generate a
pulse when the system is switched to "on". ~n inlet port
will be utilized to effect the transaction between the
various control circuits or signal generators.
Referring now to Figures 13 and 1~, there will
be described the construction of the switching circuit
130. As previously described, the switching circuit is
comprised of a triac 131 that will switch the necessary
charge or voltage supply for the operation of power relays
12, as shown in Figure 1. This switching voltage of 7
volts is connected across the output terminals 30, 132
which connect to the power relays. A capacitor 133
filters the noise in the electrical supply line and that
generated by the switching devices. The triac 131 is
controlled by the microcontroller I20, and more particu-
larly by the control voltage on the output line 134. This
control voltage is connected to the trigger 131' of the
triac tnrough the voltage rectifier formed by the diode
bridge 135 which is connected between the trigger connec-
tion 131' and the connection 136 of the triac. Thus, when
a signal is applied to the base of transistor 137 to
polarize it, and if the potential between the terminal 136
and the trigger is superior to the voltage of the Zener
diode 136, a pulse will be placed on the trigger of the
triac to place it in conduction until the end of the
cycle. The triac will conduct again for the second cycle
to create a voltage of 7.5 V AC at its terminals, which
potential will be connected also to the power supply, and
namely to the input of the converter 90. This voltage is
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~.~7~3Z13
also supplied across the terminals 132 to actuate the
power relays 12 (s~e Figure 1). Switch 160 is a high
temperature cut-out switch which will open once the tempe-
rature rises above 35C. Switch 161 is a low tempera-ture
protection switch which will close when the temperature
falls below 5C. and close the switching circuit to
energize the heating device.
Referring more particularly to Figure 13, it can
be seen that the switching circuit is also provided with a
mode switch 138 having a "presence" posi-tion 139 and an
"absence" position 140. As can be seen, the switch is
provided with a double armature each having the two posi-
tions 139 and 140. In the "presence" position 139, the
switching arm 142 will disconnect the switching system of
the present invention and connect to the thermostat 145.
The switching arm 141 will disconnect the triac from the
terminals 132 and thus the power relays. In the "absence1'
position 140, switch arm 142 will switch out the thermo-
stat and switch in the power system. Switch arm 141 will
connect the triac or the command signal line to the power
relays. In the "presence" posi-tion, the temperature
control is provided by the thermostat 145, while in the
"absence" position it is automatically provided by the
microprocessor/controller.
As shown in Figure 15, the circuit also
comprises a visual detector circuit 150 which is comprised
essentially by a light emitting diode 151 connected to the
output line 66 of the audio detector circuit 30. The
light emitting diode is controlled by a transistor 152,
the base of which controls the passage of current through
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32~
the light emitting diode of which the cathode 151' is
connected to the output 66 of the audio detec-tor 30.
Resistor 154 controls the current in the collector/emitter
o~ the transistor 152 and in the diode 151.
Summarizing briefly the operation of the switch-
ing system of the present invention, it comprises essen-
tially in positioning the telephone in close proximity to
the switching device of the present invention whereby the
switching device receives audible sound signals emitted by
the telephone device. The distance between the apparatus
and the telephone device is detected by the LED 151, and
this distance may vary by either increasing the intensity
oE the sound signals generated by the telephone or posi-
tioning the device closer to the telephone. The operation
of the system consists in calling the telephone number
associated with the device and making the telephone ring a
code including a predetermined number of rings, herein si~
rings Eollowed by a second series of telephone ring
signals generated after a pred~termined time delay after
the first series of ringing calls. In this particular
application, a minimum time delay of 5 seconds is
necessary. The switching system has a processing circuit
for identifying this code of calling signals and validat-
ing a prede-termined number of these calling signals.
After a predetermined number of these signals are
vaLidated the microprocessor automatically switches on an
elec rically operated device, such as base board heaters
or a heat pump, etc. to cause it to operate. A tempera-
ture sensing circuit is associated with the microprocessor
and sends information signals to the processor whereby the
processor may control the temperature in the environment
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~2'74~2t3
of the device to maintain the temperature at a predeter-
mined low temperature range or a predetermined high tempe~
rature range. The high temperature range, in the parti~
cular application described, can be m~intained Eor a
predetermined period of time af-ter a calling signal has
been validated.
It is within the àmbit of the present invention
to cover any obvious modlfications of the preferred
embodiment described herein, provided such modifications
fall within the scope of the appended claims. For
example, it is conceived that the switching system of the
present invention can have industrial applications, and in
such applications it is also conceived that the ambient
noise may be sufficient to make it difficult for the
apparatus to detect audible telephone sounds from the
noise. In such an application a direct connection can be
made -to the telephone line in orde~ to detect the signals
generating the audible sound. This direct electrical
connection would also include an electrical signal
detector capable of generating a square pulse signal
wherein the high level of the signal would represent the
time of the calling sound, and the low level would
represent the time lapse of t~e silence period. The
,
switching system of the present system can also be
commanded by DTMF signals or by pulses. Therefore~ the
microcontroller may be provided with a DTMF decoder t a
pulse detector to detect pulses created by the rotation of
a wheel of a standard telephone, a sound generator, a
sound signal detector as described hereinabove, or by an
lnterface having a plurality of channels with command
signals. A program can be de~eloped to accommodate such
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~27~3~
modifications and may comprise password signals for
programming -the system from a remote position, a personal
identification code, an address code for the loads, for
selecting a switching mode, or a selected synch signal or
flip-flop circuit,. for obtaining stored information, for
programming the system, or for controlling the various
associated circuits such as a temperature control circuit.
Thus, various modifications to the system as herein
described are possible within the scope of the p.resent
invention.
~; ' ~
.
`~ ' ,
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