U.S. patent application number 13/161753 was filed with the patent office on 2011-10-06 for load condition controlled power strip.
This patent application is currently assigned to IGO, INC.. Invention is credited to Richard G. DuBose, Michael D. Heil, Walter Thornton.
Application Number | 20110241443 13/161753 |
Document ID | / |
Family ID | 41446501 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110241443 |
Kind Code |
A1 |
DuBose; Richard G. ; et
al. |
October 6, 2011 |
LOAD CONDITION CONTROLLED POWER STRIP
Abstract
In accordance with various aspects of the present invention, a
method and circuit for reducing power consumption of a power strip
is provided. In an exemplary embodiment, a power strip is
configured for reducing or eliminating power during idle mode by
disengaging an outlet from power input. A power strip may include
two or more outlets and two or more outlet circuits, with AC power
input connected to the outlets through the outlet circuit(s), which
may include a current transformer, a control circuit, and a switch.
The current transformer secondary winding provides an output power
level signal proportional to the outlet load. If behavior of the
current transformer secondary winding indicates that the outlet is
drawing substantially no power from the AC power input, the switch
facilitates disengaging of the current transformer primary from the
outlet.
Inventors: |
DuBose; Richard G.;
(Scottsdale, AZ) ; Thornton; Walter; (Phoenix,
AZ) ; Heil; Michael D.; (Scottsdale, AZ) |
Assignee: |
IGO, INC.
Scottsdale
AZ
|
Family ID: |
41446501 |
Appl. No.: |
13/161753 |
Filed: |
June 16, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12860636 |
Aug 20, 2010 |
7964995 |
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13161753 |
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12180411 |
Jul 25, 2008 |
7800252 |
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12860636 |
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61076532 |
Jun 27, 2008 |
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Current U.S.
Class: |
307/126 |
Current CPC
Class: |
H02J 9/005 20130101;
Y04S 20/20 20130101; Y02B 70/30 20130101 |
Class at
Publication: |
307/126 |
International
Class: |
H02J 3/00 20060101
H02J003/00 |
Claims
1. A power strip configured to reduce power during idle operation
of an electronic device, said power strip comprising: a plurality
of outlets configured to transmit power to the electronic device;
an outlet circuit configured to receive power from an alternating
current (AC) line input and transmit power to a first outlet of
said plurality of outlets; a control circuit configured to receive
an output power level signal and control the connection between
said first outlet and the AC line input; and a reconnection device
configured to override said control circuit and reengage said first
outlet and the AC line input, and wherein said reconnection device
is further configured to disengage said first outlet and the AC
line input.
2. The power strip of claim 1, wherein said outlet circuit
comprises: a current measuring system configured to monitor current
from the AC line input, wherein said current measuring system
provides the output power level signal; wherein said outlet circuit
disengages transmitting power to said first outlet in response to
said first outlet drawing substantially no power.
3. The power strip of claim 1, further comprising a green mode
switch configured to select an operating mode of said first outlet,
wherein said operating mode is at least one of a normal mode and a
green mode.
4. The power strip of claim 1, wherein said reconnection device is
located remotely from said power strip.
5. The power strip of claim 1, wherein said reconnection device is
configured to override a single control circuit.
6. The power strip of claim 1, wherein said reconnection device is
configured to override a plurality of control circuits.
7. A power strip configured to efficiently provide power to an
electronic device, said power strip comprising: a plurality of
outlets configured to provide power to said electronic device; and
a control circuit configured to control the coupling of said
plurality of outlets to an alternating current (AC) line input;
wherein said control circuit decouples said plurality of outlets in
response to the current drawn by said plurality of outlets being
below a threshold level, such that said plurality of outlets is
effectively disengaged from the AC line input.
8. The power strip of claim 7, further comprising a reconnection
device configured to override said control circuit and re-engage
said plurality of outlets to the AC line input.
9. The power strip of claim 7, wherein said threshold level is a
percentage of a determined approximate low power level of said
electronic device, and wherein said percentage of said determined
approximate low power level is at least one range of approximately
100-105%, approximately 100-110%, and approximately 110-120%.
10. The power strip of claim 7, wherein said plurality of outlets
comprises a first outlet with a first threshold level and a second
outlet with a second threshold level, wherein said first threshold
level is different from said second threshold level.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/860,604, now U.S. Pat. No. 7,964,994, filed
on Aug. 20, 2010, and entitled "LOAD CONDITION CONTROLLED POWER
STRIP," which application is a continuation of U.S. patent
application Ser. No. 12/180,407, now U.S. Pat. No. 7,795,759, filed
Jul. 25, 2008, and entitled "LOAD CONDITION CONTROLLED POWER
STRIP", which is a non-provisional of U.S. Provisional Application
No. 61/076,527, filed Jun. 6, 2008, and entitled "LOAD CONDITION
CONTROLLED POWER STRIP", all of which are hereby incorporated by
reference.
FIELD OF INVENTION
[0002] The present invention relates to reducing power consumption
in electronic devices. More particularly, the present invention
relates to a circuit and method for disengaging an outlet in a
power strip from a power input when idle load conditions are
present.
BACKGROUND OF THE INVENTION
[0003] The increasing demand for lower power consumption and
environmentally friendly consumer devices has resulted in interest
in power supply circuits with "green" technology. For example, on
average, a notebook power adapter continuously "plugged in" spends
67% of its time in idle mode. Even with a power adapter which
conforms to the regulatory requirement of dissipating less then 0.5
watts/hour, this extended idle time adds up to 3000 watt hours of
wasted energy each year per adapter. When calculating the wasted
energy of the numerous idle power adapters, the power lost is
considerable.
[0004] Power strips are used to multiply the number of AC outlets
available from a single AC socket. In an office or home
environment, a computer, monitor, printer, scanner, and other
electronic devices are often connected to the same power strip.
When not in use, these connected devices will often be left on and
go into self-imposed idle modes that typically consume less than 1
watt per device. Even though each is consuming standby power, the
total power delivered by the power strip can be as much as the
number of outlets used times the idle power, perhaps as great as 6
watts or more. This multiplicity of wasted idle power can be
reduced or eliminated if the power strip can learn or be programmed
to sense the idle condition of each outlet and turn that outlet off
if idle conditions are present.
SUMMARY OF THE INVENTION
[0005] In accordance with various aspects of the present invention,
a method and circuit for reducing power consumption of a power
strip during idle conditions is provided. In an exemplary
embodiment, a power strip is configured for reducing or eliminating
power during idle mode by disengaging at least one outlet from a
power input. A power strip may include one or more outlets and one
or more outlet circuits, with AC power input connected to the
outlets through the outlet circuit(s). The outlet circuit may
include a current transformer, a control circuit, and a switch. The
secondary winding of the current transformer provides an output
power level signal that is proportional to the load at the outlet.
In an exemplary embodiment, if behavior of the secondary winding of
the current transformer indicates that at least one outlet is
drawing substantially no power from the AC power input, the switch
facilitates disengaging of the primary circuit of the current
transformer from such outlet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] A more complete understanding of the present invention may
be derived by referring to the detailed description and claims when
considered in connection with the Figures, where like reference
numbers refer to similar elements throughout the Figures, and:
[0007] FIG. 1A illustrates a block diagram of an exemplary load
condition controlled power strip;
[0008] FIG. 1B illustrates another block diagram of an exemplary
load condition controlled power strip in accordance with an
exemplary embodiment;
[0009] FIG. 2 illustrates a block diagram of an exemplary load
condition controlled power strip in accordance with an exemplary
embodiment;
[0010] FIG. 3 illustrates a circuit diagram of an exemplary control
circuit for use within an exemplary load condition controlled power
strip in accordance with an exemplary embodiment;
[0011] FIG. 4 illustrates a block diagram of an exemplary load
condition controlled power strip in accordance with an exemplary
embodiment; and
[0012] FIG. 5 illustrates a schematic diagram of an exemplary
control circuit for use within an exemplary load condition
controlled power strip in accordance with an exemplary
embodiment.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION
[0013] The present invention may be described herein in terms of
various functional components and various processing steps. It
should be appreciated that such functional components may be
realized by any number of hardware or structural components
configured to perform the specified functions. For example, the
present invention may employ various integrated components, such as
buffers, current mirrors, and logic devices comprised of various
electrical devices, e.g., resistors, transistors, capacitors,
diodes and the like, whose values may be suitably configured for
various intended purposes. In addition, the present invention may
be practiced in any integrated circuit application. However for
purposes of illustration only, exemplary embodiments of the present
invention will be described herein in connection with a sensing and
control system and method for use with power strip circuits.
Further, it should be noted that while various components may be
suitably coupled or connected to other components within exemplary
circuits, such connections and couplings can be realized by direct
connection between components, or by connection through other
components and devices located thereinbetween.
[0014] In accordance with various aspects of the present invention,
a power strip configured for reducing or eliminating power during
idle mode by disengaging power input from at least one outlet is
disclosed. In an exemplary embodiment, and with reference to FIG.
1A, a power strip 100 comprises two or more outlets 120 and two or
more outlet circuits 130. In another exemplary embodiment (not
shown), power strip 100 comprises a single outlet 120 and a single
outlet circuit 130. In yet another exemplary embodiment, and with
reference to FIG. 1B, power strip 100 comprises at least one outlet
120 coupled with outlet circuit 130 and at least one outlet 120
directly connected to an AC line input 110.
[0015] In an exemplary embodiment, and with reference to FIG. 2,
power strip 100 comprises AC line input 110 connected to outlet
circuit 130, which in turn is connected to outlet 120. The outlet
circuit 130 comprises a current measuring system 231, a control
circuit 232, and a switch 233. In an exemplary embodiment, current
measuring system 231 comprises a current transformer 231 having a
primary circuit and a secondary winding for illustration purposes.
However, current measuring system 231 may also comprise a resistor
with a differential amplifier, a current sensing chip, a
Hall-effect device, or any other suitable component configured to
measure current as now known or hereinafter devised. Current
transformer 231 provides an output power level signal that is
proportional to the load at outlet 120. Furthermore, switch 233
connects the primary circuit of current transformer 231 to outlet
120.
[0016] Furthermore, in one embodiment, AC line input 110 is a
standard 3 wire grounded plug and cord set that connects to the
body of power strip 100. However, AC line input 110 can be suitably
configured in any AC power input configuration or replaced with any
other input power configuration. The AC line input 110 is connected
in parallel to a number of similar outlet circuits 130 that lie
between the AC line input 110 and outlets.sub.1-N 120. Furthermore,
AC line input 110 may be connected to a 110 volt or 220 volt power
source in an exemplary embodiment.
[0017] In an exemplary embodiment, control circuit 232 may comprise
at least one of, or a combination of: a latching circuit, a state
machine, and a microprocessor. In one embodiment, control circuit
232 monitors the condition of the secondary winding of current
transformer 231 and controls the operation of switch 233.
Furthermore, in an exemplary embodiment, control circuit 232
receives a low frequency or DC signal from current transformer 231.
The low frequency signal, for example, may be 60 Hz. This low
frequency or DC signal is interpreted by control circuit 232 as the
current required by the load at outlet 120.
[0018] Control circuit 232 can comprise various structures for
monitoring the condition of the secondary winding of current
transformer 231 and controlling the operation of switch 233. In an
exemplary embodiment, with reference to FIG. 3, control circuit 232
includes a current sensor 301 and a logic control unit 302. Current
sensor 301 monitors the output of a current measuring system, such
as for example, the secondary winding of current transformer 231,
which is an AC voltage proportional to the load current. Also,
current sensor 301 provides a signal to logic control unit 302. In
one embodiment, the signal may be a DC voltage proportional to the
current through current sensor 301. In another embodiment, the
signal may be a current proportional to the current through current
sensor 301. In another exemplary embodiment, and with momentary
reference to FIG. 4, outlet circuit 130 of the power strip
comprises a logic control unit 302 that is in communication with,
and controls, more than one current transformer 231 and more than
one switch 233.
[0019] In an exemplary embodiment, logic control unit 302 is
powered by an energy storage capacitor. Logic control unit 302 may
briefly connect the storage capacitor to AC line input 110 in order
to continue powering logic control unit 302. In another embodiment,
logic control unit 302 may be powered by a battery or other energy
source. This energy source is also referred to as housekeeping or
hotel power; it functions as a low auxiliary power source. In one
embodiment, auxiliary power is taken from AC line input 110. For
further detail on similar current monitoring, see U.S. Provisional
Application 61/052,939, hereby incorporated by reference.
[0020] In an exemplary embodiment, logic control unit 302 is a
microprocessor capable of being programmed prior to, and after
integration of power strip 100 in an electronic device. In one
embodiment, a user is able to connect to logic control unit 302 and
customize the parameters of power strip 100. For example, a user
may set the threshold level and a sleep mode duty cycle of power
strip 100. Data from power strip 100 could be transmitted
regarding, for example, the historical power consumption and/or
energy saved. The bidirectional data transfer between power strip
100 and a display device may be achieved through a wireless signal,
such as for example, an infra-red signal, a radio frequency signal,
or other similar signal. The data transfer may also be achieved
using a wired connection, such as for example, a USB connection or
other similar connection.
[0021] In accordance with an exemplary embodiment, control circuit
232 may further comprise a power disconnect 303 in communication
with logic control unit 302. Power disconnect 303 is configured to
isolate logic control unit 302 from AC line input 110 and reduce
power loss. While isolated, logic control unit 302 is powered by
the storage capacitor or other energy source and logic control unit
302 enters a "sleep" mode. If the storage capacitor reaches a low
power level, power disconnect 303 is configured to reconnect logic
control unit 302 to AC line input 100 to recharge the storage
capacitor. In an exemplary embodiment, power disconnect 303 is able
to reduce the power loss from a range of microamperes of leakage to
a range of nanoamperes of leakage.
[0022] In another exemplary embodiment, control circuit 232
receives a control signal that is impressed upon AC line input 110
by another controller. The control signal may be, for example, the
X10 control protocol or other similar protocol. Control circuit 232
may receive the control signal through the secondary winding of
current transformer 231, from a coupled AC line input 110, or any
other suitable means configured to couple AC line input 110 to
control circuit 232 as now known or hereinafter devised. This
control signal may come from within power strip 100 or may come
from an external controller. The control signal may be a high
frequency control signal or at least a control signal at a
frequency different than the frequency of AC line input 110. In an
exemplary embodiment, control circuit 232 interprets the control
signal to engage or disengage switch 233. In another embodiment, an
external controller may transmit a signal to turn power strip 100
to an "on" or "off" condition.
[0023] In an exemplary embodiment, if behavior of the secondary
winding of current transformer 231 indicates that outlet 120 is
drawing substantially no power from AC line input 110, switch 233
facilitates or controls disengaging of the primary circuit of
current transformer 231 from outlet 120, i.e., switch 233
facilitates the disengaging of a power source from outlet 120. In
an exemplary embodiment, the secondary winding of current
transformer 231 is monitored for an AC waveform at the AC line
frequency, where the AC waveform has an RMS voltage proportional to
the load current passing through the primary circuit of current
transformer 231 to outlet 120. In another embodiment, the AC
waveform is rectified and filtered to generate a DC signal before
being received by control circuit 232. The DC signal is
proportional to the load current passing through the primary
circuit of current transformer 231 to outlet 120.
[0024] In one embodiment, the phrase "substantially no power" is
intended to convey that the output power is in the range of
approximately 0-1% of a typical maximum output load. In an
exemplary embodiment, switch 233 is configured to control the
connection of the primary circuit of current transformer 231 to
outlet 120 and comprises a switching mechanism to substantially
disengage the primary circuit of current transformer 231 from
outlet 120. Switch 233 may comprise at least one of a relay,
latching relay, a TRIAC, and an optically isolated TRIAC.
[0025] By substantially disabling the primary circuit of current
transformer 231, the power consumption at outlet 120 is reduced. In
one embodiment, substantially disabling outlet 120 is intended to
convey that the output signal of the secondary winding of current
transformer 231 has been interpreted by control circuit 232 as
sufficiently low so that it is appropriate to disengage switch 233
and remove power from outlet 120.
[0026] In another exemplary embodiment, outlet circuit 130 further
comprises a reconnection device 234, which is configured to enable
the closure of switch 233 through logic control unit 302. The
closure of switch 233 reconnects outlet 120 to the primary circuit
of current transformer 231 and AC line input 110. In an exemplary
embodiment, reconnection device 234 comprises a switch device that
may be closed and opened in various manners. For example,
reconnection device 234 can comprise a push button that may be
manually operated. In one embodiment, the push button is located
near outlet 120 on power strip 100, for example, on the same
surface of power strip 100 as outlet 120 or on an adjacent side of
power strip 100 to outlet 120. In another exemplary embodiment,
reconnection device 234 is located remote to power strip 100 to
allow a user to re-enable power to an outlet of power strip 100
without having direct contact with power strip 100. In another
embodiment, reconnection device 234 is affected remotely by signals
traveling through AC line input 110 that control circuit 232
interprets as on/off control. In yet another embodiment,
reconnection device 234 is controlled by a wireless signal, such as
for example, an infra-red signal, a radio frequency signal, or
other similar signal.
[0027] In accordance with another exemplary embodiment, switch 233
is automatically operated on a periodic basis. For example, switch
233 may automatically reconnect after a few or several minutes or
tens of minutes, or any period more or less frequent. In one
embodiment, switch 233 is automatically reconnected frequently
enough that a battery operated device connected to power strip 100
will not completely discharge internal batteries during a period of
no power at the input to the connected device. After outlet 120 is
reconnected, in an exemplary embodiment, outlet circuit 130 tests
for, or otherwise assesses, load conditions. If the load condition
on outlet 120 is increased above previously measured levels, outlet
120 will remain connected to the primary circuit of current
transformer 231 until the load condition has returned to a selected
or predetermined threshold level indicative of a "low load". In an
exemplary embodiment, the determination of load conditions at
re-connect are made after a selected time period had elapsed, for
example after a number of seconds or minutes, so that current
inrush or initialization events are ignored. In another embodiment,
the load conditions may be averaged over a selected time period of
a few seconds or minutes so that short bursts of high load average
out. In yet another exemplary embodiment, power strip 100 comprises
a master reconnection device that can re-engage all outlets 120 to
AC line input 110.
[0028] In an exemplary method of operation, power strip 100 has
switch 233 closed upon initial power-up, such that power flows to
outlet 120. When load conditions at outlet 120 are below a
threshold level, control circuit 232 opens switch 233 to create an
open circuit and disengage outlet 120 from the AC power signal.
This disengaging effectively eliminates any idle power lost by
outlet 120. In one embodiment, the threshold level is a
predetermined level, for example approximately one watt of power or
less flowing to outlet 120.
[0029] In an exemplary embodiment, different outlets 120 may have
different fixed threshold levels such that devices having a higher
power level in idle may be usefully connected to power strip 100
for power management. For example, a large device may still draw
about 5 watts during idle, but would never be disconnected from AC
line input 110 if the connected 120 had a threshold level of about
1 watt. In various embodiments, certain outlets 120 may have a
higher threshold levels to accommodate high power devices, or lower
threshold levels for lower power devices.
[0030] In another embodiment, the threshold level is a learned
level. The learned level may be established through long term
monitoring by control circuit 232 of load conditions at outlet 120.
A history of power levels is created over time by monitoring and
may serve as a template of power demand. In an exemplary
embodiment, control circuit 232 examines the history of power
levels and decides whether long periods of low power demand were
times when a device connected at outlet 120 was in a low, or
lowest, power mode. In an exemplary embodiment, control circuit 232
disengages outlet 120 during low power usage times when the period
of low power matches the template. For example, the template might
demonstrate that the device draws power through outlet 120 for
eight hours, followed by 16 hours of low power demand.
[0031] In another exemplary embodiment, control circuit 232
determines the approximate low power level of the electronic device
connected at outlet 120, and sets a threshold level to be a
percentage of the determined approximate low power level. For
example, control circuit 232 may set the threshold level to be
about 100-105% of the approximate low power level demand. In
another embodiment, the threshold demand may be set at about
100-110% or 110-120% or more of the approximate low power level
demand. In addition, the low power level percentage range may be
any variation or combination of the disclosed ranges.
[0032] Having disclosed various functions and structures for an
exemplary power strip configured for reducing or eliminating power
during idle mode by disengaging power input, a detailed schematic
diagram of an exemplary power strip circuit 500 can be provided in
accordance with an exemplary embodiment of the present invention.
With reference to FIG. 5, in an exemplary embodiment of power strip
500, outlet circuit 130 comprises current transformer 231, current
sensor 301, logic control unit 302, power disconnect 303,
reconnection device 234, and switch 233.
[0033] In one embodiment, current transformer 231 and current
sensor 301 combine to measure the current in AC line input and
convert said current to a proportional DC voltage that can be read
by logic control unit 302. Furthermore, switch 233 may comprise a
latching relay that provides a hard connect/disconnect of AC line
input 110 to outlet 120 after a command from logic control unit
302. Switch 233 alternates between open and closed contacts.
Furthermore, switch 233 holds its position until reset by logic
control unit 302, and will hold position without consuming any
power in the relay coil K1.
[0034] In an exemplary embodiment, logic control unit 302 comprises
a microcontroller that receives input of the current in the AC
line, controls the state of switch 233 and reads or otherwise
assesses the state or position of the contacts of reconnection
device 234 and switch 233. In addition, logic control unit 302
learns and stores the power profile for an electronic device
connected to outlet 120. In another exemplary embodiment, outlet
circuit 130 further comprises reconnection device 234, which is
activated to turn on outlet 120 when outlet circuit 130 is first
connected to AC line input 110 or when full power is needed
immediately at outlet 120.
[0035] In an exemplary embodiment, power disconnect 303 comprises a
network of transistors Q1, Q2, Q3 which are used to condition AC
line input 110 to a safe level suitable for logic control unit 302
and isolate logic control unit 302 from AC line input 110. In
another embodiment, power disconnect 303 comprises relays in
addition to, or in place of, the transistors of the prior
embodiment.
[0036] Initial plug-in of power strip 500 involves connecting power
strip 500 to an AC power source. In an exemplary method, upon
initial plug-in of power strip 500 to a power source, all circuits
of outlet circuit 130 are dead and switch 233 is in the last
position set by logic control unit 302. This initial condition may
or may not provide power to outlet 120. When all the circuits are
dead, there is no current flow into outlet circuit 130. This is due
to the isolation provided by power disconnect 303 and reconnection
device 234 in a normal, open position. In an exemplary embodiment,
power disconnect 303 comprises transistors Q1, Q2, Q3 and capacitor
C3. In this state, only leakage current will flow through
transistors Q1, Q2 and the leakage current will be on the order of
approximately tens of nanoamperes. Furthermore, current transformer
231 provides dielectric isolation from primary side to secondary
side so that only small leakage current flows due to the
inter-winding capacitance of current transformer 231.
[0037] With continued reference to FIG. 5, in an exemplary
embodiment and for illustration purposes, a user may reconnect the
circuit using reconnection device 234 to establish a current path
through diode D1, zener diode Z1, resistor R4, reconnection device
234 and zener diode Z3. Diode D1 serves to half-wave rectify the AC
line to drop the peak to peak voltage in half. Zener diode Z1
further reduces the voltage from diode D1, for example to about 20
volts. Zener diode Z3 and resistor R4 form a current limited zener
regulator that provides an appropriate DC voltage at the VDD input
to logic control unit 302 while reconnection device 234 is held. In
addition, capacitor C2 smoothes the DC signal on zener diode Z3 and
provides storage during the contact bounce of reconnection device
234. Capacitor C2 is sized to provide sufficient storage during the
start-up time of logic control unit 302, and capacitor C2 in
combination with resistor R4 provides a fast rising edge on the VDD
input to properly reset logic control unit 302. Furthermore, diode
D5 isolates capacitor C2 from capacitor CS so the rise time
constant of capacitor C2 and resistor R4 is not affected by the
large capacitance of capacitor CS. When capacitor CS is powering
logic control unit 302, the current of capacitor CS passes through
diode D5.
[0038] In an exemplary method, if reconnection device 234 is
activated for a few milliseconds, logic control unit 302 is
configured to initialize and immediately set up to provide its own
power before reconnection device 234 is released. This is
accomplished from voltage doubler outputs VD1-VD3 and ZG1 of logic
control unit 302. First, output ZG1 is driven high to turn on
transistor Q2. With transistor Q2 on, a current path is established
through resistor R3 and zener diode Z2 providing a regulated
voltage at the drain of transistor Q1. This regulated voltage is
similar to that produced by zener diode Z3 and is appropriate for
the VDD input of logic control unit 302. Second, after the voltage
on zener diode Z2 has stabilized for a few microseconds, logic
control unit 302 outputs VD1-VD3 begin switching to produce a gate
drive signal to turn on transistor Q1. The signals produced by
outputs VD1-VD3 and components including capacitor C3, transistor
Q3, capacitor C4, diode D3 and diode D4 produce a voltage at the
gate of transistor Q1 that is about twice the voltage on input VDD
of logic control unit 302. This voltage doubling turns transistor
Q1 on hard. Once transistor Q1 is on, the voltage at zener diode Z2
charges capacitor CS. In an exemplary embodiment, capacitor CS is a
large storage capacitor that is used to power logic control unit
302 when reconnection device 234 is not being activated. After
capacitor CS has been charged for a few milliseconds, outputs
VD1-VD3 and ZG1 return to a rest state and transistors Q1 and Q2
are turned off. In this embodiment, logic control unit 302 is
operating off the stored charge in capacitor CS and not drawing
power from AC line input 110. When reconnection device 234 is no
longer active, capacitor CS will continue to power logic control
unit 302.
[0039] If outlet 120 is idling and drawing substantially no power,
logic control unit 302 may be able to disengage from drawing power
and enter a "sleep" mode. In an exemplary method, and with further
reference to FIG. 5, when logic control unit 302 is operating from
the stored energy in capacitor CS, a timing function is enabled in
logic control unit 302 that uses capacitor C5 to perform the timing
function. Capacitor C5 is briefly charged by the CAPTIME output of
logic control unit 302 and over time capacitor C5 discharge rate
will mimic the decay of the voltage on capacitor CS. Once capacitor
C5 voltage at input CAPTIME reaches a low level, logic control unit
302 will set the state of outputs VD1-VD3 and ZG1 to again recharge
capacitor CS from the AC line. This process repeats over and over
so power is never lost to logic control unit 302. The recharge
process takes only milliseconds to operate, depending on the size
of capacitor CS.
[0040] Furthermore, in an exemplary method, when logic control unit
302 is not busy recharging capacitor CS, switching relay K1, or
measuring power drawn from outlet 120, logic control unit 302 is
operating in a deep sleep mode that stops all, or substantially
all, internal activity and waits for capacitor C5 to discharge.
This sleep mode consumes very little power and allows the charge on
storage capacitor CS to persist for many seconds. If reconnection
device 234 is activated during the sleep mode, logic control unit
302 will resume normal operation and set or reset relay K1.
Alternatively, if capacitor C5 voltage falls too low, logic control
unit 302 will again recharge capacitor CS and then return to sleep
mode.
[0041] While an electronic device is in an idle mode, power strip
100 may continue to monitor for changes in the power drawn by the
electronic device. In an exemplary method, while logic control unit
302 continuously goes in and out of sleep mode to re-power itself,
logic control unit 302 will also periodically test the power being
drawn from outlet 120. The period of power testing is much greater
than that of capacitor CS charging and, for example, may be only
tested every ten or more minutes. In accordance with an exemplary
method, there are at least three possible outcomes from the result
of power testing: 1) the device is operating and the switch is not
in standby condition, 2) the device is not operating but the switch
is not in a standby condition, or 3) the switch is in a standby
condition.
[0042] For the outcome when the device is operating and the switch
is not in a standby condition, relay K1 has been previously set to
deliver power to outlet 120 and power testing shows an appreciable
load current is being drawn by the electronic device connected. An
"appreciable load" may be defined by some fixed value programmed
into logic control unit 302, or it may be the result of a number of
power tests and be the typical load current for this electronic
device. A power test result here will be interpreted as normal
conditions and logic control unit 302 will go back into sleep mode
cycling until another time period, such as ten minutes, has passed
when the power test will be made again. In another exemplary
embodiment, the duration of the sleep mode cycling is determined by
a user. For example, a user may set the sleep mode duration to be
one, two, or five minutes and may do so using a dial, a digital
input, a push button, keypad or any other suitable means now know
or hereinafter devised.
[0043] For the outcome when the device is not operating but the
switch is not in a standby condition, relay K1 has been previously
set to deliver power to outlet 120 and power testing shows a
negligible load current being drawn by the device connected. The
"negligible load" may be some fixed value programmed into logic
control unit 302, or it may be the result of a number of power
tests and be the typical minimum found for this electronic device.
In either case the action taken by logic control unit 302 will be
to set relay K1 to an open condition by using logic control unit
302 outputs RELAY1-RELAY3 to energize relay coil K1. The state of
relay K1 is determined by logic control unit 302 testing for the
presence of resistor R5, since logic control unit 302 may not know
the previous state of relay K1, for example, starting from power
off state.
[0044] For the outcome when the switch is in a standby condition,
that is, relay K1 has been set to remove power from outlet 120,
logic control unit 302 must set relay K1 to a closed condition to
allow AC power to be applied to the outlet. In an exemplary method,
once relay K1 is set, a period of time is allowed to elapse before
the power testing is done. This delay allows for the electronic
device attached to outlet 120 to initialize and enter a stable
operating mode. Power measurements may now be made over some period
of time to determine if the electronic device is in a low or high
power state. If a high power state is determined, relay K1 remains
set. If a low power state is determined, relay K1 is reset to open
condition and power is again removed from outlet 120. Also, logic
control unit 302 will again begin sleep mode cycling and power
testing after a determined time period, for example, every ten
minutes.
[0045] If a user wants to operate a device that is connected to
outlet 120 and that outlet is turned off, in an exemplary
embodiment, activating reconnection device 234 will immediately
wake logic control unit 302 from sleep mode. Since the wake up was
from the activation of reconnection device 234 and not due to power
testing or capacitor CS recharging, logic control unit 302 will
immediately set relay K1 to closed position to power the electronic
device connected to outlet 120.
[0046] In addition to the embodiments described above, various
other elements may be implemented to enhance control and user
experience. One way to enhance user control is to allow a user to
select the operating mode of an outlet. In an exemplary embodiment,
power strip 100 further comprises a "Green Mode" switch that
enables or disables the "green" mode operation. The green mode
switch may be a hard, manual switch or it may be a signal to logic
control unit 302. "Green" mode operation is the disengaging of
outlet 120 from AC line input 110 when substantially no load is
being drawn at outlet 120. A user may use the green mode switch to
disenable green mode operation on various outlets when desired. For
instance, this added control may be desirable on outlets that power
devices with clocks or devices that need to be instantly on, such
as a fax machine.
[0047] In one embodiment, power strip 100 includes LED indicators,
which may indicate whether an outlet is connected to the power line
and drawing a load current. The LED indicators may indicate whether
an outlet is active, that is, power is drawn by an electronic
device and/or the outlet has power available even if an electronic
device is not connected. In addition, a pulsing LED may be used to
show when power testing is being done or to indicate the
"heartbeat" of sleep mode recharging.
[0048] In another embodiment, power strip 100 comprises at least
one LCD display. The
[0049] LCD display may be operated by logic control unit 302 to
indicate the load power being provided to outlet 120, for example
during times of operation. The LCD may also provide information
about the power saved or power consumed by operating power strip
100 in or out of a "green" mode. For example, LCD may display the
sum total of watts saved during a certain time period, such as the
life of power strip 100 or in a day.
[0050] Various embodiments may also be used to enhance the
efficient use of the power strip and/or individual outlets in the
power strip. One such embodiment is the implementation of a
photocell or other optical sensor monitored by logic control unit
302. The photocell determines whether light is present in the
location of power strip 100 and logic control unit 302 can use this
determination to disengage outlet 120 depending on the ambient
light conditions. For example, logic control unit 302 may disengage
power output 120 during periods of darkness. In other words, the
power strip may be turned off at night. Another example is devices
do not need power if located in a dark room, such as an unused
conference room in an office. Also, the power outputs may be turned
off when the ambient light conditions exceed a certain level, which
may be predetermined or user determined.
[0051] In another embodiment, power strip 100 further comprises an
internal clock. Logic control unit 302 may use the internal clock
to learn which time periods show a high power usage at outlet 120.
This knowledge may be included to determine when an outlet should
have power available. In an exemplary embodiment, the internal
clock has quartz crystal accuracy. Also, the internal clock does
not need to be set to an actual time. Furthermore, the internal
clock may be used in combination with the photocell for greater
power strip efficiency and/or accuracy.
[0052] The present invention has been described above with
reference to various exemplary embodiments. However, those skilled
in the art will recognize that changes and modifications may be
made to the exemplary embodiments without departing from the scope
of the present invention. For example, the various exemplary
embodiments can be implemented with other types of power strip
circuits in addition to the circuits illustrated above. These
alternatives can be suitably selected depending upon the particular
application or in consideration of any number of factors associated
with the operation of the system. Moreover, these and other changes
or modifications are intended to be included within the scope of
the present invention, as expressed in the following claims.
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