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Claims  |
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We claim:
1. A programmable wall switch for controlling the time for turning on and
for turning off a light which comprises:
means for producing from the AC power line a selected DC voltage;
microprocessor means powered by said DC voltage, for turning on a light at
any one of several selected times and for turning off said light at any
one of an additional corresponding several selected times, said
microprocessor means including means for incrementing said one of several
selected times and one of said additional corresponding selected times by
random amounts; and
means, responsive to signals from said microprocessor means, for displaying
the time.
2. A programmable wall switch according to claim 1 wherein said switch
includes control means for generating a signal and for supplying said
signal to said microprocessor means thus allowing for manually overriding
the operation of said light, through said microprocessor means, at any of
several selected times of said switch, to provide a function programmed
into said switch.
3. A programmable wall switch according to claim 2 wherein said means for
displaying comprises means for electronically displaying the time and for
electronically displaying the functions programmed into the programmable
wall switch at selected times.
4. A programmable wall switch according to claim 1 wherein said means for
incrementing comprises:
means employing a routine that takes the count of a selected counter and
adds that count to the time to determine the time for turning on said
light which results in a time randomly selected within a selected time
period after said one of several selected times; and
means employing a routine that takes the count of a selected counter and
adds that count to the time to determine the time for turning off said
light at a time within a range of time after said one of said additional
corresponding several selected times, thereby to create a randomness in
said turning on and turning off of said light which simulates the presence
of occupants.
5. A programmable wall switch according to claim 1 wherein said
microprocessor means for turning on a light at any one of several selected
times and for turning off the light at any one of an additional
corresponding several selected times and said means for reducing the load
current supplied to said light to one-half the load current applied during
normal operation comprises
means for programming said light to turn on, turn off or dim up to a
selected number of times per day.
6. A programmable wall switch according to claim 5 wherein said means for
programming is capable of programming said light to turn on, off or dim up
to eight times per day.
7. A programmable wall switch according to claim 6 including means for
indicating on said means for displaying that said microprocessor means for
producing a first output signal and for producing a second output signal
have been programmed to cause said light to turn on, turn off or dim more
than the allowed number of times per day.
8. A programmable wall switch according to claim 5 or 6 wherein said means
for programming is capable of programming said light in any selected
sequence to turn on, to dim and to turn off including the ability to turn
said light fully on, then to dim said light and then to turn said light
fully on again, and the ability to turn said light off, then dim and then
off again.
9. A programmable wall switch according to claim 1 wherein said means for
displaying the time includes, in addition, means for displaying an indicia
that the power has failed and the structure needs to be reprogrammed.
10. A programmable wall switch according to claim 1 including
means for reviewing the times at which said microprocessor means for
producing a first output signal and for producing a second output signal
and said means for reducing the load current are programmed to operate so
as to determine the sequence of activities programmed into said
programmable wall switch.
11. A programmable wall switch according to clam 1 including electronic
means for indicating that said switch is in the program mode.
12. A programmable wall switch according to claim 11 including
means for turning on said light prior to the setting of said programmable
wall switch in the program mode, thereby to allow the user to view the
wall switch as the wall switch is being programmed.
13. A programmable wall switch according to claim 1 including means for
manually overriding the setting of said programmable wall switch to turn
on, turn off or dim the light as desired.
14. A programmable wall switch according to claim 1 including
means for modifying the status of the program at any one or more of the
preset times.
15. Structure as in claim 1 wherein said means for generating said signal
at each zero crossing of the AC power line comprises
means for generating a first pulse having a first portion of a leading edge
rising coincident with a first portion of a leading edge of a positive
half cycle of a power signal on said AC power line, said first pulse then
leveling off at a maximum voltage for the remainder of the positive half
cycle of said power signal on said AC power line, and having a sharp drop
in voltage to a minimum voltage point, coincident with what would be the
zero voltage point of the trailing edge of said positive half cycle of
said power signal, even if said trailing edge is not generated, said first
pulse then remaining at said minimum voltage point for the duration of the
negative half cycle of said AC line signal.
16. A programmable wall switch for controlling the time for turning on and
for turning off a light which comprises:
means for producing from the AC power line a selected DC voltage;
microprocessor means powered by said DC voltage, for turning on a light at
any one of several selected times and for turning off said light at any
one of an additional corresponding several selected times;
said programmable wall switch including wall switch means for turning on
said light, in response to the application of power to said programmable
wall switch following absence or interruption of power which must then be
turned off by occupant;
means, responsive to signals from said microprocessor means, for displaying
the time;
means for generating a signal at each zero crossing of the AC power line
and for supplying to said microprocessor means; and
means responsive to signals from said microprocessor means for reducing the
load current supplied to said light to one-half the load current applied
during normal operation, thereby to reduce the amount of current supplied
to said light thus to save power, to extend the life of said light and to
more realistically simulate human occupancy.
17. A programmable wall switch for controlling the time for turning on and
for turning off a light which comprises:
means for producing from the AC power line a selected DC voltage;
microprocessor means powered by said DC voltage, for turning on a light at
any one of several selected times and for turning off said light at any
one of an additional corresponding several selected times;
means, responsive to signals from said microprocessor means, for displaying
the time, said means for displaying the time includes, in addition, means
for displaying an indicia that the power has failed and that the structure
needs to be reprogrammed;
means for resetting the real time displayed on said means for displaying,
said means for resetting comprising means for resetting at a first rate
said real time and in response to said means for resetting being activated
for greater than a first selected time, for accelerating the rate at which
said real time is changed;
means for generating a signal at each zero crossing of the AC power line
and for supplying said signal to said microprocessor means; and
means responsive to signals from said microprocessor means for reducing the
load current supplied to said light to one-half the load current applied
during normal operation, thereby to reduce the amount of current supplied
to said light thus to save power, to extend the life of said light and to
more realistically simulate human occupancy. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to light switches and in particular to a light
switch which is capable of being programmed by the user to turn on in
response to selected times, as well as to provide automatic dimmer
control.
2. Prior Art
The use of timers for turning on and off lights to simulate the occupancy
of rooms and homes is well-known. Numerous patents have issued describing
such structures. Thus, U.S. Pat. No. 3,979,601 issued Sept. 7, 1976
dicloses a combination dimmer and timer switch mechanism which is capable
of turning on and off the power to a receptacle in accordance with a
predetermined time switch. U.S. Pat. No. 4,151,515 issued Apr. 24, 1979
discloses a similar structure which not only reduces energy consumption by
turning lights off after business hours but also cycles lights in a
predetermined manner to discourage burglaries. These structures are
limited in that the pattern set for one day repeats on adjacent days
unless the system is reset daily. Accordingly, the very system designed to
give the appearance of occupancy can, by its precise repetitiveness,
indicate that the building is not occupied.
In addition, occupants of buildings typically do more than merely turn on
and off lights. Accordingly, prior art programmable switches have been
limited in their ability to accurately simulate the occupancy of a
building.
SUMMARY OF THE INVENTION
This invention overcomes certain of the disadvantages or prior art timed
switches by providing a swith which is user-programmable and capable not
only of controlling a light but, in addition, of automatically dimming the
light in accordance with a program, whether or not a building is occupied.
The programmable switch of this invention possesses several functions such
as time-keeping, dimmer control, power supply and power control, and
provides user inputs and an LCD display.
In accordance with this invention, a user-programmable module is provided
which is, in the preferred embodiment, microprocessor controlled and which
includes a real time display. The system provides a program interval
between an ON signal and an OFF signal of 30 minutes with a variable
ON/OFF capability to make the ON/OFF commands appear random. The system is
structured so that the settings can be reviewed by the user and the
program modified or cleared as desired. The system is also structured to
operate either in the manual or automatic mode with a manual override
being provided. The system is capable of acting as a dimmer and provides a
display which indicates system status (such as load, ON/OFF/DIM and
programming). The display also indicates AM and PM.
As a feature and for ease of installation and maintenance, no grounding is
provided and an air gap switch is provided to turn off the module and
lamps for installation and service.
As a further feature, the switch is designed to maintain memory and program
in power failure for at least 50 milliseconds minimum, thereby removing
the sensitivity of prior art programmed switches to temporary power
failures of a type all too common.
As a special feature of the invention, the display shows "PF" when the
switch installed or after power failure. PF is deleted and time is
displayed when real time is set.
An ON/OFF switch, preferably air gap, is provided to isolate power from the
unit when OFF. Program memory and real time are cleared when the switch
has been turned OFF for approximately one second. The switch has three
positions: OFF, manual and automatic.
A time-set button is also provided for setting the real time and advancing
times for ON/OFF/DIM programming.
Of particular utility is a command button which is used to manually turn a
light ON/OFF/DIM, to enter ON/OFF/DIM commands during programming, and to
dim the light to one-half intensity when pressed and held for greater than
a selected time, typically two seconds. The particular dimming method used
is selected to minimize radio frequency interferece. The module replaces
an ordinary single pole wall switch and uses a standard outlet box and
wall switch plate. Power and timekeeping base are derived from the line
signal (typically sixty (60) hertz and 110 volts).
This invention will be more fully understood in conjunction with the
following detailed description taken together with the attached drawings.
DESCRIPTION OF THE DRAWINGS
FIGS. 1a and 1b illustrate the system diagram for the switch;
FIG. 1c shows the relationship between FIGS. 1a and 1b;
FIG. 2a illustrates the normal triac triggering waveform and FIG. 2b
illustrates the waveform associated with the zero crossing circuit in
accordance with this invention;
FIG. 3 illustrates a waveform generated by the skip cycle method of dimming
the light to one-half its normal intensity to avoid radio frequency
interference; and
FIG. 4 shows the relationship of FIGS. 4a, 4b, 4c and 4d; and
FIGS. 4a, 4b, 4c and 4d illustrate software flow charts used with this
invention.
DETAILED DESCRIPTION
The overall system is illustrated in FIGS. 1a and 1b. The system as shown
in FIG. 1a divided into four main blocks together with ancillary
components and certain command and input switches. Thus, block 101
illustrates the three position slide switch 10 capable of assuming
automatic, manual and OFF positions. Block 102 illustrates the novel
synchronous rectifier and regulator of this invention suitable for
producing a fixed output voltage of about 9.5 volts required to drive the
selected microprocessor 103. Microprocessor 103 in the preferred
embodiment comprises the four bit TMS 1000 manufactured by Texas
Instruments. This specification is not meant to be limiting. Other
embodiments will become obvious to those skilled in the art.
Microprocessor 103 produces output signals which are then used to control
the state of display driver 104 which drives display 105. Display 105 is,
in the preferred embodiment, a liquid crystal display.
The circuitry of regulator 102 is shown in detail in FIG. 1 a. An input
signal which typically comprises the AC line signal of 60 cycles and 115
volts (hereinafter called the "AC power line") is applied across lines 12
and 13 through the lamp load 51 and switch 101 and then through diode D2
(1N4003) to zener diode Z2, (BZX-83C91) normally rated at about 91 volts.
Zener diode Z2 is back-biased relative to ground and its cathode is
conneced to V.sub.SS bus 11 (held at about nine volts) to which are
connected one terminal of resistor R2 and the collectors of transistors T2
and T3 (shown as NPN transistors).
As the signal on line 13 rises, current flows through diode D2 and resistor
R2 to the base of transistor T2, thereby turning on transistor T2. The
emitter current from transistor T2 then flows to the base of transistor
T3, thereby turning on transistor T3. Resistor R7 (470K ohms) is used to
shunt the ICBO leakage current around transistor T3 to avoid temperature
induced thermal runaway. The emitter current from transistor T3 charges
capacitor C2. When capacitor C2 reaches the desired voltage level of about
9.5 volts relative to ground V.sub.DD (bus 12), zener diode Z3 (BZX-83C11)
breaks down and thereby limits the voltage to which capacitor C2 is
charged to 9.5 volts. Zener diode Z3 breaks down at approximately 9.5
volts plus two voltage drops across two forward-biased PN junctions, or at
about 10.7 volts. FIG. 2a shows the voltage level C2 on capacitor C2 at
which zener diode Z3 breaks down. The current through resistor R2 also
passes through zener diode Z3 as well as maintaining the charge on
capacitor C2 at about 9.5 volts. As the input voltage continues to rise,
ultimately the voltage across zener diode Z2 breaks down zener diode Z2.
Z2 is selected to break down at about 91 volts. Accordingly, when Z2
breaks down, the voltage drop across resistor R3 turns on transistor T1
through base resistor R1. T1 then saturates, thereby dropping its
collector voltage substantially close to ground. Thus, transistors T2 and
T3 are shut off. Capacitor C2 maintains the voltage at approximately 9.5
volts for the remainder of the cycle. Capacitor C2, which is 470
microfarads, serves as the power source for the microprocessor and
discharges current of about 10 milliamps into the microprocessor. Circuit
102, called a synchronous rectifier, is activated once each cycle of the
input signal.
The synchronous rectifier 102 is self-starting (that is, has no lock up
modes) and charges capacitor C2 fairly rapidly with current from
transistors T2 and T3. Capacitor C2 is fully charged each cycle before
triac TR1 is turned on (TR1 is turned on at most once per cycle of the
line signal on lead 13) thus ensuring that capacitor C2 is fully charged
once each cycle regardless of the state of triac TR1. The microcomputer
103 is programmed to ensure that triac TR is not turned on before
capacitor C2 is charged to about 9.5 volts. Thus, the voltage on capacitor
C2 drops no more than 300 millivolts between charging cycles but during
the initial part of the power cycle the current from transistors T2 and T3
rapidly replenishes that charge which has been drawn from capacitor C2 to
run the microprocessor. The power circuit typically reaches 90 volts in
about 800 microseconds or 0.80 milliseconds. Because the cycle time of a
60 cycle current is 16.67 milliseconds, the circuit is on only for less
than about 1/20th of the total cycle time. Accordingly, very little heat
is dissipated in the circuit. Because this unit is mounted in a wall
socket box, there is no efficiency way to remove heat from this container
and thus a low duty cycle for the power supply is important.
Another circuit used in the structure of this invention and shown in FIG.
1a within the boundary 102 extends the pulse normally generated in a zero
crossing triggering circuit used for triggering a triac for substantially
a half cycle (as shown in FIG. 2b). This circuit takes the positive half
cycle of the waveform on line 13 (FIG. 1a) and uses this information to
generate a full cycle of timing information. The input signal on line 13
typically comprises a 115 VAC, 60 cycle line signal. The signal is applied
through diode D2, resistor R2 and resistor R5 to the input of diode D8
(FIG. 1a). On the positive half cycle, diode D8 is forward-biased, thereby
charging capacitor C1. The signal on capacitor C1 increases to a peak
magnitude of about 10.5 volts as controlled by the breakdown voltage of
zener diode Z3. Capacitor C1 stores this peak amplitude. Typically, C1 is
about 0.01 microfarads. The input line voltage (which is AC) continues to
increase in the first quarter of the cycle and then drops in the second
quarter of the cycle and for the last half of each cycle goes negative. As
the input line voltage drops, diode D8 becomes reverse-biased, thereby
trapping on capacitor C1 the charge previously stored on this capacitor.
As the input voltage drops toward zero volts, diode Z4 (which is connected
through diode D3 and resistor R6 (100K ohms) to the non-grounded plate of
capacitor C1 and thus is reverse biased once the voltage on C1 is above
the voltage on line 13) will break down when the voltage on capacitor C1
is above the voltage on line 13 by the breakdown voltage of the zener
diode Z4. This is designed to occur just after the input voltage on line
13 goes negative. When this occurs, the charge stored on capacitor C1
discharges through zener diode Z4 back to the signal source. Diode D1
(connected between V.sub.DD (zero volts) and the non-grounded side of
capacitor C1) the forward-biases to clamp the non-grounded plate of
capacitor C1 to a voltage slightly beneath ground. Diode Z4 stays broken
down until the input signal on line 13 goes positive at which time diode
D8 again conducts in its forward-biased direction until capacitor C1 is
again charged to the breakdown voltage of zener diode Z3 during the next
cycle of input current. Note that diode D3 is connected to present a low
impedance when the voltage on the non-grounded plate of C1 is above the
voltage on line 13 and a high impedance otherwise. The voltage on the
positive plate of capacitor C1 as a function of time is shown in FIG. 2b.
This figure illustrates how two zero crossings are produced each cycle of
the signal on line 13 using only the information contained in the first
half of each cycle.
During normal operation of the light 51 (i.e. during the times when the
light is to have substantial current flowing through it so as to turn on
the light), triac TR1 is turned on by a pulse from microprocessor 103 in a
well-known manner once each cycle just after zener diode Z2 breaks down,
thereby to provide a low impedance path for the load current from the
voltage source (line 13) through triac TR1.
When it is desired to dim the load, the pulse which turns on triac TR1 is
delayed one-half (1/2) cycle (i.e., the turning on of triac TR1 is
"skipped" for one-half (1/2) cycle) thereby to allow power to flow through
the load only during one-half of each cycle. Consequently, the light
intensity can be varied from full ON to one-half (1/2) ON. This variation
provides an extra degree of live-in authenticity (particularly when this
dimming is randomly programmed in microprocessor 103), saves energy and
extends light bulb life. This technique generates the waveform shown in
FIG. 3 wherein the solid line indicates the portion of time during which
triac TR1 is off thereby generating a positive half-cycle of voltage
across the regulator circuit and the dashed line indicates when triac TR1
is turned on during the negative half-cycle thereby to allow current to
flow through the load. Another advantage of this technique is that the
even harmonics of power flowing through the load substantially eliminate
the radio frequency interference associated with standard prior art
dimming circuits. Skipping more than every other half cycle causes flicker
in the light and thus is to be avoided.
As a feature of this invention, triac TR1 triggers about 800 microseconds
after the zero crossing of the signal on line 13. The TMS1000
microprocessor 103 sees the zero crossing approximately 100 microseconds
after it has occurred. The TMS1000 is then programmed to trigger triac TR1
about 700 microseconds after it sees the zero crossing. The triac TR1
triggers after zener diode Z2 breaks down. However, the triggering of
triac TR1 is not related to the breakdown of zener diode Z2.
A parallel RC network comprising capacitor C3 and resistor R8 is added in
the line between the "01" and "00" output leads from microcomputer 103
and triac TR1. Until the system power turns on and a "INIT" pulse has been
generated, it is not desired to have triac TR1 turn on. Thus, capacitor C3
and resistor R8 provide a differentiator so that triac TR1 is prevented
from being held on if the state of the 00 and 01 output leads from
microprocessor 103 is "on" when microprocessor 103 is turned on. If this
occurs triac TR1 is held on only for eight milliseconds and the circuit
thereafter operates correctly.
The capacitor C5 together with internal circuity in the TMS1000 creates a
delay of about one second during start-up to allow microprocessor 103 to
be properly reset during the power-up portion of the operation of the
system. Capacitor C6 and resistor R9 form a standard RC oscillator for
providing clock signals to microprocessor 103. Resistors R10, R11 and R12
are standard pull-down resistors. Diodes D6 and D7 clamp the sensed input
voltage to either V.sub.DD or V.sub.SS. D5 in conjunction with capacitor
C7 stretches the zero crossing signal so the microcomputer 103 can sense
its state even if triac TR1 has ben turned on.
The system of this invention is suitable primarily for turning on an
incandescent lamp rather than an appliance because the triac TR1 creates a
net DC voltage which would heat any motor used to run a typical appliance.
Accordingly, the circuit is primarily suitable mainly for an incandescent
light or a similar type structure. Note that the timing circuit does not
use the voltage drop across the load element but rather a voltage spike to
charge the capacitance C2 and thereby provide the drive voltage to run the
microcomputer. The lamp 51 is in series with the load created by the
structure of circuit 102, microcomputer 103, liquid crystal display driver
circuit 104 and liquid crystal display 105. The current continuously flows
through lamp 51 in accordance with this invention but at such a low level
then triac TR1 is not triggered on as to prevent lamp 51 for lighting. The
combination of the capacitor C2 and load 51 creates a time constant which
must be carefully sized to allow the voltage across capacitor C2 to reach
9.5 volts. Thus, zener diode Z3 controls the height of the voltage across
capacitor C2 while the width of the voltage pulse before triac TR1 turns
on is controlled by the line voltage on line 13 before zener diode Z2
breaks down thereby turning on transistor T1. As the lamp 51 increases in
impedance reflecting a lower wattage rating, the time constant associated
with the circuit as shown in FIG. 1a increases. The system shown in FIG.
1a can work with an incandescent light bulb as low as 40 watts. Otherwise,
the system takes too long to charge capacitor C2 to the desired operating
voltage of microprocessor 103.
The programmable wall switch of this invention has two modes of operation,
manual and automatic. In the automatic mode, the switch turns lights on
and off at the preprogrammed times. In the manual mode, it operates as a
regular light switch without disturbing the previously inserted program.
The wall switch can even be operated manually when it is in the automatic
mode.
The programmable wall switch can be programmed to turn lights ON, DIM or
OFF up to eight (8) times per day. By programming in DIM as well as ON and
OFF settings, the house containing the programmable wall switch appears
even more lived in while the owners are away than with a standard prior
art type automatic switch.
The programmable wall switch has a variable time feature further described
below in connection with the Software Program, that turns the lights on
and off at varying times up to ten minutes after the program time. This
creates a randomness in the turning on and off of lights which further
heightens the appearance of occupancy and thus further discourages any
intruder who may be observing a house containing the wall switch.
If power fails, the programmable wall switch of this invention will lose
its memory. When the power is restored, the wall switch will turn the
light on until the occupant turns it off. The display will read "PF" after
a power failure. Whenever a light bulb controlled by the programmable wall
switch burns out, the programmable wall switch loses its memory and the
display will go blank. This reflects the fact that the power for operating
the display and the programmable wall switch of this invention is derived
from a current which passes through an incandescent light bulb. However,
the current pulse which is used to power this light exists for only a very
short interval (typically about 800 microseconds) and therefore the total
average current over a given cycle when the light is off is very small. As
the wattage on the blub decreases, this average current becomes smaller.
Whenever a light bulb connected in series with the programmable wall switch
of this invention is changed, the pre-position slide switch 101 must be
placed in the OFF position so that there is no power to the socket. After
changing the light bulb the programmable wall switch of this invention
must be reprogrammed.
As a feature of this invention, the regulator for supplying power to
operate the microprocessor is charged during the first fractional portion
of each cycle of line current before the triac TR1 is turned ON each cycle
to activate the load 51. Accordingly, the line current is used to supply
power to the microprocessor and timer. Because the microprocessor is
located in the normal light switch receptacle or box, | | |
