U.S. patent application number 13/232827 was filed with the patent office on 2012-03-08 for automatic darkening filter with automatic power management.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Ingvar Sundell.
Application Number | 20120057240 13/232827 |
Document ID | / |
Family ID | 37054480 |
Filed Date | 2012-03-08 |
United States Patent
Application |
20120057240 |
Kind Code |
A1 |
Sundell; Ingvar |
March 8, 2012 |
AUTOMATIC DARKENING FILTER WITH AUTOMATIC POWER MANAGEMENT
Abstract
A protective automatic darkening filter (ADF) includes automatic
power management capabilities. The ADF includes a power management
control unit that controls power to the ADF based on whether or not
the ADF is currently in use. In one embodiment, to determine
whether the ADF is in use, the power management control unit
includes a motion sensor that senses movement of the ADF and
controls power to the ADF based on the sensed movement.
Inventors: |
Sundell; Ingvar; (Leksand,
SE) |
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
37054480 |
Appl. No.: |
13/232827 |
Filed: |
September 14, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12614648 |
Nov 9, 2009 |
8042958 |
|
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13232827 |
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11157038 |
Jun 20, 2005 |
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12614648 |
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Current U.S.
Class: |
359/601 |
Current CPC
Class: |
A61F 9/067 20130101 |
Class at
Publication: |
359/601 |
International
Class: |
G02B 27/00 20060101
G02B027/00 |
Claims
1. An automatic darkening protective shield, comprising: a
switchable filter mounted in the protective shield, the switchable
filter capable of changing from a light state to a dark state in
response to a control signal; a switchable filter control unit
capable of applying the control signal to the switchable filter in
response to detected incident light when the filter control unit is
in an ON state but not when the filter control unit is in an OFF
state; and a power management control unit comprising a sensor that
senses movement of the switchable filter, the power management unit
transmitting an activation signal to the switchable filter control
unit if the sensed movement satisfies a threshold condition,
causing the switchable filter control unit to enter into the ON
state, but if the threshold condition is not satisfied, the power
management control unit allows the switchable filter control unit
to remain in or enter the OFF state, wherein a user is not required
to control power to the automatic darkening protective shield prior
to use.
2. The protective shield of claim 1, wherein the sensor detects at
least one of motion, acceleration, tilt, shock and vibration.
3. The protective shield of claim 1, wherein the sensor is
positioned within the switchable filter.
4. The protective shield of claim 1, wherein the OFF state
comprises a low or no power mode.
5. The protective shield of claim 1, wherein the sensor is at least
one of a two-axis accelerometer or a three-axis accelerometer.
6. The protective shield of claim 1, wherein the sensor senses
movement of the protective shield and generates and transmits
signals indicative of movement via a signal conditioning
filter.
7. The protective shield of claim 1, wherein the sensor is a
passive device.
8. The protective shield of claim 1, wherein the power management
control unit deactivates the switchable filter when an OFF
condition is satisfied.
9. The protective shield of claim 8, wherein the OFF condition
includes at least one of absence of a detected welding light for a
defined period of time, absence of sensed movement for a defined
period of time, and absence of other user activity for a defined
period of time.
10. A method of controlling a state of a switchable filter, said
switchable filter capable of changing from a light state to a dark
state in response to a control signal, the method comprising:
sensing movement of an automatic darkening protective shield; and
if the sensed movement satisfies a threshold condition, putting the
switchable filter into an ON state, in which it changes from a
light state to a dark state in response to detected levels of
incident light; or if the sensed movement does not satisfy the
threshold condition, putting the switchable filter into or
retaining it in an OFF state, in which it does not change from a
light state to a dark state in response to detected levels of
incident light; wherein a user is not required to control power to
the automatic darkening protective shield prior to use.
11. The method of claim 10, further comprising generating signals
indicative of movement of the automatic darkening protective shield
and conditioning said signals.
12. The method of claim 10, further comprising deactivating the
switchable filter when an OFF condition is satisfied.
13. The method of claim 12, wherein deactivating the switchable
filter when an OFF condition is satisfied further comprises
deactivating the switchable filter upon absence of movement for a
predefined period of time.
14. The method of claim 13, wherein the predefined period of time
is within a range of 1 minute to 10 minutes.
15. The method of claim 10, wherein the sensed movement is sensed
by at least one of a two-axis accelerometer or a three-axis
accelerometer.
16. A power management method for controlling a switchable filter,
the method comprising multiple states, wherein: a first state is an
idle state or an OFF state; the system changes from the first state
to a second state in response to a movement event, and waits during
a first time period; if the system senses a second movement event
during a second time period, the system changes to a third state,
wherein the third state is an ON state; if the system does not
sense a second movement event during the second time period, the
system returns to the first state; and if the system does not sense
a movement event for a third period of time while in the third
state, the system returns to the first state.
17. The method of claim 16, wherein the first time period is within
a range of 0.5 seconds to 3 seconds.
18. The method of claim 16, wherein the second time period is
within a range of 0.5 seconds to 3 seconds.
19. The method of claim 16, further comprising deactivating the
switchable filter if no movement is sensed during a predetermined
period of time.
20. The method of claim 19, wherein the predetermined period of
time is within a range of 1 minute and 10 minutes.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Ser. No.
12/614,648, filed Nov. 9, 2009, now allowed; which is a divisional
of U.S. Ser. No. 11/157,038, filed Jun. 20, 2005, the disclosure of
which is incorporated by reference in its entirety herein.
[0002] The present invention pertains to an automatic darkening
liquid crystal protective shield or filter that can be used on a
welding helmet to filter light incident from a welder's torch.
BACKGROUND
[0003] Automatic darkening liquid crystal protective shields, also
known as automatic darkening filters, or ADFs, are often used for
applications like welding where protection from intense levels of
incident light is desired. A typical ADF includes electronic
control circuitry, powered by a battery, which causes the filter to
change from a light (clear or transparent) state when not subjected
to the glare of the welding arc to a dark (nearly opaque) state
upon exposure to such glare. This enables a welder to perform a
welding operation and also perform tasks outside the welding area
without removing the protective shield. The ADFs may be constructed
from a combination of polarizing filters and layers of liquid
crystal elements. Examples of such filters are described in U.S.
Pat. Nos. 6,097,451 and 5,825,441, both to Hornell and Palmer.
SUMMARY
[0004] The present invention provides a protective automatic
darkening filter (ADF) that includes automatic power management.
The ADF includes a power management control unit that controls
power to the ADF based on whether or not the ADF is currently in
use. In one embodiment, to determine whether the ADF is in use, the
power management control unit includes a motion sensor that senses
movement of the ADF and controls power to the ADF based on the
sensed movement.
[0005] In one embodiment, the invention comprises an automatic
darkening filter comprising an ADF helmet, a switchable filter
mounted in the ADF helmet that changes from a light state to a dark
state in response to a control signal, a switchable filter control
unit that generates and sends the control signal to the switchable
filter in response to information indicative of presence of
incident light, and a power management control unit that senses
movement of the ADF and that controls power to the ADF based on the
sensed movement.
[0006] In another embodiment, the invention comprises a method
comprising sensing movement of an automatic darkening filter and
controlling power to the automatic darkening filter based on the
sensed movement.
[0007] The term "automatic darkening filter" (ADF) means a
protective device including a helmet and a switchable filter
designed to protect a user's eyes from excessive glare in an
environment such as welding or in other environments where there is
the potential for damage to the human eye from excessively bright
light. The term "automatic power management" means automatically
controlling power to a device without affirmative user action (such
as pressing an ON/OFF button or other power control switch). The
term "switchable filter" means a filter capable of changing from a
light state to a dark state in response to a control signal. The
term "switchable filter control unit" means a unit that generates
and sends the control signal to the switchable filter in response
to information indicative of presence of incident light. The term
"motion sensor" means a sensor that senses any of a number of
parameters indicative of movement, such as position, acceleration,
tilt, shock and/or vibration. The term "power source" means any
device or mechanism by which electrical power may be supplied, such
as batteries, power supplies, generators, capacitors, fuel cells,
AC power source, or any other type of electrical power supply. The
term "power management control unit" means a unit that senses
movement of the ADF and that controls power to the ADF based on the
sensed movement.
[0008] The details of one or more embodiments of the invention are
set forth in the accompanying drawings and the description below.
Other features, objects, and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of an example automatic
darkening filter (ADF) helmet 10 having automatic power
management.
[0010] FIG. 2 is an exploded view of an example embodiment of an
ADF lens construction 20.
[0011] FIG. 3 is a block diagram of the switchable filter 30 of
FIG. 2 and control electronics 42 of an ADF with automatic power
management.
[0012] FIGS. 4A-4C are timing diagrams showing four system states
for an example ADF with automatic power management.
[0013] FIG. 5 is a flowchart illustrating an example process for
providing automatic power management in an ADF.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0014] FIG. 1 is a perspective view of an example automatic
darkening filter (ADF) helmet 10 of the type with which the present
invention may be used. ADF helmet 10 includes an auto-darkening
filter lens 20 supported in a helmet shell 12. The auto-darkening
filter lens 20 may be mounted in the helmet shell 12 so that it is
directly in front of the wearer's eyes when the helmet is worn by
the user. In one embodiment, lens 20 is replaceable. Lens 20 may
take the form of a rectangular (or other shaped) frame or housing.
Examples of helmet shells may be seen, for example, in U.S. Pat.
Nos. 6,185,739, 5,533,206, 5,191,468, 5,140,707, 4,875,235, and
4,853,973. ADF helmet 10 may also have clean air supplied to their
interior and thus may include a face seal to separate a breathing
zone from the ambient air. An example of such a face seal is shown
in U.S. patent application Ser. Nos. 10/987,512, 10/987,641,
10/988,789, 29/217,155, 29/217,153, 29/217,154, 29/217,107,
29/217,156.
[0015] FIG. 2 shows an exploded view of an example auto-darkening
filter lens 20. In this embodiment, auto-darkening filter lens 20
includes a switchable filter 30 mounted between two replaceable
protection plates 22 and 24. Switchable filter 30 is capable of
changing from a light state to a dark state and is controlled by
control electronics mounted within ADF helmet 10. In the embodiment
shown in FIG. 2, switchable filter 30 is a laminate of seven
different layers: a UV/IR filter 31, three polarizers 32, 34, and
36, two liquid crystal elements 33 and 35, and a cover glass 37.
UV/IR filter 31 continually blocks harmful radiation, whether the
lens is ON, OFF, light or dark. Aided by control electronics
(described below), liquid crystal elements 33 and 35 act as
shutters that detect and react to a welding arc by instantly
shading the lens. Examples of suitable switchable filters are
described in U.S. Pat. Nos. 6,097,451 and 5,825,441, and in
copending and commonly assigned U.S. patent application to
Magnusson et al., filed Mar. 11, 2005.
[0016] In one embodiment, first and second liquid crystal elements
33 and 35 are low twist liquid crystal cells. The liquid crystal
cells 33 and 35 are provided with connectors (not shown) by which a
control voltage may be applied. Also, in some embodiments, the
polarization orientations of the first polarizer 24 and the third
polarizer 32 are substantially perpendicular to the polarization
orientation of second polarizer 56 as described in the above
referenced U.S. Pat. No. 5,825,441. In other embodiments, the
polarization orientation of at least one of the first polarizer 24
or the third polarizer 32 is offset from substantially
perpendicular to the polarization orientation of second polarizer
56 as described in the above referenced U.S. patent application to
Magnusson et al., filed Mar. 11, 2005. Although a particular
switchable filter construction is shown and described in FIG. 2,
switchable filter 30 may also take other forms as known in the art,
and the invention is not limited in this respect.
[0017] FIG. 3 is a block diagram of an ADF referred to generally by
reference numeral 40. ADF 40 includes switchable filter 30,
switchable filter control unit 50, and power management control
unit 60. Switchable filter control unit 50 includes a light sensor
54 and a filter controller 52. Filter controller 52 controls the
degree of shade provided by switchable filter 30 in response to a
level of incident light detected by light sensor 54. To do this,
filter controller 52 receives signals from light sensor 54
indicative of the detected level of incident light and generates a
corresponding filter control signal, such as a voltage. Filter
controller 52 applies these filter control signals to switchable
filter 30, thus controlling the degree of shade provided by
switchable filter 30 in response to detected levels of incident
light. For example, when light sensor 54 detects the presence of a
welding arc or other source of incident light, filter controller 52
may generate and apply a corresponding control voltage to liquid
crystal elements 33 and 35 of switchable filter 30 (see FIG. 2).
The control voltage causes switchable filter 30 to darken and
protect the user from the glare of the welding arc. The magnitude
of the control voltage, and thus the degree of shade provided, may
be relative to the intensity of the incident light. In the absence
of a welding arc or other source of incident light from which the
user should be protected, filter controller 52 may reduce or
eliminate the control voltage to liquid crystal elements 33 and 35,
thus causing the filter 30 to become more transparent. The
switchable filter 30 thus protects the user while performing a
welding operation and allows them to perform other tasks outside
the welding area without removing the protective helmet.
[0018] Power management control unit 60 provides ADF 40 with
automatic power management capabilities. Namely, power management
control unit 60 controls power to ADF 40 based on whether ADF 40 is
currently in use. For purposes of the present invention, power
management control unit 60 infers use of ADF 40 from sensed
movement. Power management control unit 60 may sense such movement
when, for example, a user picks up or puts on ADF 40 in preparation
to perform a welding operation. Power management control unit 60
senses movement of ADF 40 and controls power to ADF 40 based on the
sensed movement.
[0019] Power management control unit 60 continually monitors
whether ADF 40 is in use and activates or deactivates ADF 40
accordingly. When ADF 40 is not in use, power management control
module 60 deactivates ADF 40. When deactivated, ADF 40 operates in
a low (or no) power, quiescent mode or OFF state. Detection of user
activity, such the movement sensed when a user picks up the welding
helmet, causes ADF 40 to automatically "wake up" or activate and
enter an active mode. On the other hand, power management control
unit 60 deactivates ADF 40, returning ADF 40 to the quiescent mode,
when the signals received from motion sensor 68 indicate that no
user initiated activity has been detected for a specified period of
time.
[0020] In the embodiment shown in FIG. 3, power management control
unit 60 includes a power source 66, such as a battery, a motion
sensor 68, a signal conditioning filter 62 and a power controller
64. Power controller 64 and motion sensor 68 operate together to
provide the automatic power management capabilities of ADF 40.
Motion sensor 68 senses movement of ADF 40 and generates and
transmits signals indicative of movement to power controller 64 via
signal conditioning filter 62. Signal conditioning filter 62
removes any of these signals that are due to small temporal
external vibrations. Signal conditioning filter 62 passes other
signals that may be associated with some user activity for analysis
by power controller 64.
[0021] Power controller 64 includes control logic that analyzes
signals originating from motion sensor 68 to determine whether any
sensed movements satisfy a preselected threshold condition. The
threshold condition corresponds to a minimum level of sensed
movement that may result from a user activity. Power controller 64
controls power to ADF 40 based on the sensed motion. If the
threshold condition is satisfied, power controller 64 generates and
transmits an activation signal to the switchable filter control
unit 50. This activation signal essentially "wakes up" ADF 40,
causing it to enter the ON state. When activated, ADF 40 provides
full auto-darkening protection, switching from light to dark states
in response to the presence or absence of detected ambient light as
described above.
[0022] Motion sensor 68 may sense any of a number of parameters
indicative of movement, such as position, acceleration, tilt, shock
and/or vibration, and it shall be understood that the invention is
not limited in this respect. In one embodiment, motion sensor 68 is
a fully passive device that does not require any power when ADF 40
is in the OFF state. Examples of such passive sensing devices may
include, for example, a mechanical vibration/movement sensor
consisting of a loosely connected electrical contact (e.g. one or
two gold plated balls), a two-axis or three-axis accelerometer
(e.g. a fully integrated silicon device), or any other type of
known sensor that senses motion, tilt, shock, vibration, and/or
other information indicative of movement. In other embodiments,
motion sensor 68 may be a low power sensor that draws a minimum
amount of current in the OFF state.
[0023] Although motion sensor 68 may be any one of several types of
vibration/movement sensors, in one embodiment, the signal of
interest is the mechanical acceleration of motion sensor 68. This
acceleration signal could be in a form such as a discriminated
binary indicator of any omni directional acceleration component
exceeding a given threshold. In other embodiments, the acceleration
signal could take on a more complex form, such as a three axis
accelerometer with separate absolute acceleration values for each
axis.
[0024] Power controller 64 may be conceptually represented as a
state machine that is activated at the detection of a first
vibration event (i.e., movement sensed by motion sensor 68). Four
example system states S0-S3 may be described as follows: [0025] S0
Idle and OFF, waiting for a vibration event. [0026] S1 Vibration
event detected at time to, wait until time t1. [0027] S2 Any
vibration event satisfying the threshold condition in time frame of
t2-t1 moves the system to state S3, the ON state. Otherwise, the
system returns to state S0. [0028] S3 ON. After a period of system
inactivity, e.g. no vibration, the system returns to state S0.
[0029] FIGS. 4A-4C show timing diagrams illustrating movement from
state to state for states S0-S3 described above. The top row of
FIGS. 4A-4C shows vibration events indicated generally by reference
numerals 70, 76 and 82, respectively. The middle row shows system
states S0-S3 indicated generally by reference numerals 72, 78 and
84, respectively. The bottom row shows status of the ADF (e.g., ON
or OFF) indicated generally by reference numerals 74, 80 and 86,
respectively.
[0030] FIG. 4A illustrates a short lived vibration event, indicated
generally by reference numeral 70, that does not result in
activation of the system into the ON-state. While in state S0
(OFF/deactivated), a small (short duration) vibration event occurs
at time t0, causing the system to move to state S1. Once in state
S1, the system waits until time t1. During state S1 (time frame
t1-t0) the vibration event continues. At time t1, the system moves
to state S2 and looks for a vibration event during time frame
t2-t1. Because there is no vibration event during state S2 (time
frame t241) the system is not activated and returns to state S0 at
time t2.
[0031] In FIG. 4B, a larger (longer duration) vibration results in
activation of the system into the ON state, state S3. In this case,
the vibration event indicated by reference numeral 76 occurs at
time t3 in state S2. Since time t3 occurs within the t2-t1 time
frame (in other words, before time t2) the system is activated and
enters state S3, the ON state.
[0032] In FIG. 4C, the system is ON (state S3) at time t0 as
indicated by reference numeral 86. While in the ON state S3, the
system continually monitors movement of the automatic darkening
filter. If no movement is sensed during a predefined period of
time, power management control unit 60 assumes that the automatic
darkening filter is not in use and deactivates ADF 40. In FIG. 4C,
the predefined period of time is time frame t4-t0. Because no
vibration event is sensed during the t4-t0 time frame, the power
management control unit 60 deactivates the system and returns it to
state S0, the OFF state.
[0033] In some embodiments, depending upon the environment, time
frame t1-t0 may be anywhere within a range of 0.5 seconds to 3
seconds, for example. Time frame t2-t1 may be anywhere within a
range of 0.5 to 3 seconds, for example. Time frame t440 may be
anywhere within a range of 1 minute to 10 minutes, for example. It
shall be understood, however, that these time frames may be
modified, and that other time frames lying outsides the listed
ranges may also be appropriate, depending upon the type of use
and/or the particular environment in which the ADF is to be used,
among other factors. The invention is therefore not limited in this
respect.
[0034] FIG. 5 is a flowchart illustrating an example process by
which power management control unit 60 automatically manages power
to ADF 40. The process will be described beginning in the OFF state
(S0) (90), although it shall be understood that the process may
also be described at any point.
[0035] In the OFF state, S0 (90), power controller 64 analyzes
signals originating from motion sensor 68 for a vibration event
(91). If no vibration event that satisfied the threshold condition
is detected, the system remains in the OFF state, S0 (90). If a
vibration even that satisfied the threshold condition is detected
(91), the system moves to state S1 and waits until a first time t1
(92). After time t1 has elapsed, the system moves to state S2 (93).
Power controller 64 then analyzes signals received from motion
sensor 68 for a vibration event during time frame t2-t1 (94). If no
vibration is detected during this time frame, power controller 64
assumes that the original detected vibration was not correlated
with a user initiated activity and returns to the OFF state, S0
(90).
[0036] If, on the other hand, a vibration event that satisfies the
threshold condition is detected during time frame t2-t1 (94), power
controller assumes that the movement corresponds to user initiated
activity and the device moves to the ON state, S3 (95). Once in the
ON state, power controller 64 analyzes signals received from motion
sensor for vibration events. As long as vibration events that
satisfy the threshold condition continue to occur, the system will
remain in the ON state, S3. However, whenever an OFF condition is
satisfied (96), power controller 64 assumes that the device is no
longer in use and returns the system to the OFF state, S0 (90).
[0037] Examples of appropriate OFF conditions (96) may include, for
example, absence of a detected welding light for a defined period
of time, absence of sensed movement for a defined period of time,
no other user activity (such as operation of the ADF user controls)
for a defined period of time, or other appropriate condition
indicative that the ADF is not currently being used. For example,
if no vibration event satisfying the threshold condition is
detected for a specified period of time, power controller 64 may
assume that ADF 40 is no longer in use and may return the system to
the OFF state, S0. This specified time period may be set, for
example, anywhere between 1 minute and 10 minutes. The specified
time period may be determined and set by the manufacturer or may be
settable by the user, and may be chosen to provide an appropriate
length of time for the environment in which the ADF is used.
[0038] Power controller 64 and/or filter controller 52 may be
embodied as a computer-readable medium that includes instructions
for causing a programmable processor to carry out the methods
described above. A "computer-readable medium" includes but is not
limited to read-only memory (ROM), random access memory (RAM),
non-volatile random access memory (NVRAM), electrically erasable
programmable read-only memory (EEPROM), flash memory, a magnetic
hard drive, a magnetic disk or a magnetic tape, a optical disk or
magneto-optic disk, a holographic medium, or the like. The
instructions may be implemented as one or more software modules,
which may be executed by themselves or in combination with other
software. A "computer-readable medium" may also comprise a carrier
wave modulated or encoded to transfer the instructions over a
transmission line or a wireless communication channel.
[0039] The invention may also be embodied as one or more devices
that include logic circuitry to carry out the functions or methods
as described herein. The logic circuitry may include a processor
that may be programmable for a general purpose or may be dedicated,
such as microcontroller, a microprocessor, a Digital Signal
Processor (DSP), an Application Specific Integrated Circuit (ASIC),
a field programmable gate array (FPGA), and the like.
[0040] One or more of the techniques described herein may be
partially or wholly executed in software. For example, a
computer-readable medium may store or otherwise comprise
computer-readable instructions, i.e., program code that can be
executed by a processor to carry out one of more of the techniques
described above.
[0041] The invention described herein has several advantages. For
example, because the ADF automatically activates when the helmet is
picked up, the user need not take any special measures to get the
system ready for use. In addition, the control circuitry ensures
that the system is activated when needed, reducing the risk that
the user forgets to turn on the ADF and does not receive active
protection. The system may also save electrical energy (e.g.,
battery life) by powering down the device when not in use and
activating the device only when needed. Because of the lower energy
consumption, smaller and lighter batteries may also be used.
[0042] All of the patents and patent applications cited above,
including those cited in the Background Section, are incorporated
by reference into this document in total.
[0043] Various embodiments of the invention have been described.
These and other embodiments are within the scope of the following
claims.
* * * * *