U.S. patent application number 12/189670 was filed with the patent office on 2009-05-14 for portable radiometry and imaging apparatus.
This patent application is currently assigned to FLIR SYSTEMS, INC.. Invention is credited to Michael W. Burke, Stewart W. Evans, Scott A. Foster, Raul Krivoy, John R. Rae, Charles C. Warner.
Application Number | 20090121135 12/189670 |
Document ID | / |
Family ID | 22781837 |
Filed Date | 2009-05-14 |
United States Patent
Application |
20090121135 |
Kind Code |
A1 |
Warner; Charles C. ; et
al. |
May 14, 2009 |
PORTABLE RADIOMETRY AND IMAGING APPARATUS
Abstract
Systems, including devices and methods, for infrared imaging,
and more particularly to systems for infrared imaging.
Inventors: |
Warner; Charles C.; (Forest
Grove, OR) ; Foster; Scott A.; (Portland, OR)
; Evans; Stewart W.; (Keizer, OR) ; Krivoy;
Raul; (Beaverton, OR) ; Burke; Michael W.;
(Tualatin, OR) ; Rae; John R.; (Lake Oswego,
OR) |
Correspondence
Address: |
KOLISCH HARTWELL, P.C.
200 PACIFIC BUILDING, 520 SW YAMHILL STREET
PORTLAND
OR
97204
US
|
Assignee: |
FLIR SYSTEMS, INC.
Wilsonville
OR
|
Family ID: |
22781837 |
Appl. No.: |
12/189670 |
Filed: |
August 11, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11048105 |
Jan 31, 2005 |
7411193 |
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12189670 |
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|
09561266 |
Apr 27, 2000 |
6849849 |
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11048105 |
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|
09210167 |
Dec 11, 1998 |
6255650 |
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09561266 |
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Current U.S.
Class: |
250/330 |
Current CPC
Class: |
G02B 2027/0123 20130101;
G02B 2027/0138 20130101; G02B 2027/0118 20130101; G02B 2027/0112
20130101; G02B 27/017 20130101; G02B 23/125 20130101 |
Class at
Publication: |
250/330 |
International
Class: |
H01L 31/00 20060101
H01L031/00 |
Claims
1. A method of producing thermal images, comprising: providing a
portable device adapted to produce images of scenes adjacent to a
user using an infrared camera; programming the portable device to
identify portions of scenes within a first selected temperature
range; using the portable device to produce a first thermal image
of a first scene, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in a color range that is
visually distinct from all other portions of the first image;
reprogramming the portable device to identify portions of scenes
within a second selected temperature range different than the first
selected temperature range; and using the portable device to
produce a second thermal image of a second scene, wherein the
portions of the second image corresponding to the portions of the
second scene within the second selected temperature range are
displayed in a color range that is visually distinct from all other
portions of the second image; wherein the step of using the
portable device to produce a first thermal image includes using the
device for a rescue operation.
2. The method of claim 1, wherein the step of using the portable
device to produce a second thermal image further includes using the
device for a fire fighting operation.
3. The method of claim 1, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in the same color range as
the portions of the second image corresponding to the portions of
the second scene within the second selected temperature range.
4. The method of claim 1, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in a different color range
as the portions of the second image corresponding to the portions
of the second scene within the second selected temperature
range.
5. A method of producing thermal images, comprising: providing a
portable device adapted to produce images of scenes adjacent to a
user using an infrared camera; programming the portable device to
identify portions of scenes within a first selected temperature
range; using the portable device to produce a first thermal image
of a first scene, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in a color range that is
visually distinct from all other portions of the first image;
reprogramming the portable device to identify portions of scenes
within a second selected temperature range different than the first
selected temperature range; and using the portable device to
produce a second thermal image of a second scene, wherein the
portions of the second image corresponding to the portions of the
second scene within the second selected temperature range are
displayed in a color range that is visually distinct from all other
portions of the second image; wherein the step of using the
portable device to produce a first thermal image includes using the
device for a fire fighting operation.
6. The method of claim 5, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in the same color range as
the portions of the second image corresponding to the portions of
the second scene within the second selected temperature range.
7. The method of claim 5, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in a different color range
as the portions of the second image corresponding to the portions
of the second scene within the second selected temperature
range.
8. A method of using a portable device adapted to display thermal
images of scenes adjacent to a user using a thermal camera,
comprising: programming the portable device to have a first set of
system parameters that cause the portable device to display
portions of thermal images corresponding to portions of scenes
within a first selected temperature range in a color range that is
visually distinct from all other portions of the image;
reprogramming the portable device to have a second set of system
parameters that cause the portable device to display portions of
thermal images corresponding to portions of scenes within a second
selected temperature range in a color range that is visually
distinct from all other portions of the image; and using the
portable device programmed to have the first set of system
parameters to display a first thermal image of a first scene;
wherein the step of using the portable device to produce a first
thermal image includes using the device for a rescue operation.
9. The method of claim 8, wherein the step of using the portable
device to produce a second thermal image includes using the device
for a fire fighting operation.
10. The method of claim 8, further comprising using the portable
device reprogrammed to have the second set of system parameters to
display a second thermal image of a second scene.
11. The method of claim 10, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in the same color range as
the portions of the second image corresponding to the portions of
the second scene within the second selected temperature range.
12. The method of claim 10, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in a different color range
as the portions of the second image corresponding to the portions
of the second scene within the second selected temperature
range.
13. A method of using a portable device adapted to display thermal
images of scenes adjacent to a user using a thermal camera,
comprising: programming the portable device to have a first set of
system parameters that cause the portable device to display
portions of thermal images corresponding to portions of scenes
within a first selected temperature range in a color range that is
visually distinct from all other portions of the image;
reprogramming the portable device to have a second set of system
parameters that cause the portable device to display portions of
thermal images corresponding to portions of scenes within a second
selected temperature range in a color range that is visually
distinct from all other portions of the image; and using the
portable device programmed to have the first set of system
parameters to display a first thermal image of a first scene;
wherein the step of using the portable device to produce a first
thermal image includes using the device for a fire fighting
operation.
14. The method of claim 13, further comprising using the portable
device reprogrammed to have the second set of system parameters to
display a second thermal image of a second scene.
15. The method of claim 14, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in the same color range as
the portions of the second image corresponding to the portions of
the second scene within the second selected temperature range.
16. The method of claim 14, wherein the portions of the first image
corresponding to the portions of the first scene within the first
selected temperature range are displayed in a different color range
as the portions of the second image corresponding to the portions
of the second scene within the second selected temperature range.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/048,105, filed Jan. 31, 2005, now U.S. Pat.
No. 7,411,193, which in turn is a continuation of U.S. patent
application Ser. No. 09/561,266, filed Apr. 27, 2000, now U.S. Pat.
No. 6,849,849, which in turn is a continuation of U.S. patent
application Ser. No. 09/210,167, filed Dec. 11, 1998, now U.S. Pat.
No. 6,255,650. These priority applications are each incorporated
herein by reference in their entirety for all purposes.
BACKGROUND ART
[0002] Fire fighting is extremely hazardous and demanding because
of extreme temperatures and obscurants that can blind or disable a
fire fighter from locating the fire's source or human beings at
risk within a burning building. When there are no visible flames,
e.g., when alcohol, hydrogen, hydrocarbons, etc. burn, there can be
lethally high temperatures caused by gases that burn without
visible ignition or flaming. Whether there are visible or invisible
flames, nevertheless there can be dense smoke or airborne
particulate that makes normal vision impossible. At night or in
dark locations, even without extremely high temperatures and even
without obscurants, vision is essential to containing a fire or
saving a life.
[0003] Conventionally, infrared (IR) vision subsystems for fire
fighters have been bulky and integrated with other fire fighting
protective equipment worn by fire fighters. They also typically
have required an umbilical cord to equipment worn on the body of
the fire fighter. Typically, IR equipment is connected with
protective body gear referred to herein as a bunker suit typically
including or augmented by self-contained breathing apparatus
(SCBA).
[0004] Other vision systems for fire detection are not designed for
hands-free operation as is required of a system used by
firefighters that must enter the scene of the fire. For example,
U.S. Pat. Nos. 5,422,484 and 5,726,632, the disclosures of which
are incorporated herein by reference, disclose various hand-held or
pedestal-mounted flame sensors.
[0005] So-called night vision systems relying on IR detection and
imaging often are useless in the presence within the detector's
field of view of such extreme temperatures that the location of a
human being or animal, for example, in a burning building goes
undetected by a display phenomenon called blooming whereby a
high-temperature gas cloud is represented by a color, e.g., white,
that tends to wash out critical detail such as a low-temperature
human form represented in another area of the display by a
different gray scale. Effectively, the high-temperature cloud
within view of the IR detector bleaches out needed detail in
another area of the display, such as that of a human form. For
example, the video systems of U.S. Pat. No. 5,200,827, the
disclosure of which is incorporated herein by reference, do not
address these problems unique to the firefighting and rescue
fields.
DISCLOSURE OF THE INVENTION
[0006] The present teachings relate generally to systems, including
devices and methods, for infrared imaging.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIGS. 1A and 1B are side elevations of the invented
apparatus, with FIG. 1A showing the apparatus in infrared (IR) mode
of deployment and with FIG. 1B showing the apparatus in a
tilted-back, direct-view mode of deployment.
[0008] FIGS. 2A and 2B are isometric views of the invention, with
FIG. 2A showing an exploded, partly assembled version and with FIG.
2B showing a fully assembled version, with certain portions of the
imaging apparatus's housing cut away to reveal certain interior
details.
[0009] FIG. 3 is an optical schematic diagram corresponding with
FIG. 1A illustrating the IR optical geometry of the invention.
[0010] FIGS. 4A and 4B are schematic diagrams respectively showing
an overhead and lateral view of a user and a camera head-mounted
camera, the views illustrating line-of-sight and focal axes and
their convergence in front of the user.
[0011] FIG. 5 is a block diagram of the opto-electronics within the
housing of the invented apparatus.
[0012] FIG. 6 is a flowchart illustrating the color mapping method
used in the invented apparatus for image enhancement.
[0013] FIGS. 7A and 7B are graphs that illustrate the color mapping
method used in the invented apparatus for image enhancement, with
FIG. 7A showing an entire palette mapped, and with FIG. 7B showing
a detail of a portion of FIG. 7A.
DETAILED DESCRIPTION
[0014] Referring first to FIGS. 1A, 1B, 2A and 2B, a preferred
embodiment of the invented wrap-around, head-up display apparatus
is indicated generally at 10. Apparatus 10 may be seen to include a
left arching region 12, a right arching region 14 and a forward
arching region 16 that hovers preferably just above the user's eye
level on the face. Apparatus 10 preferably includes a lightweight,
preferably molded polymer housing with an interior void in which
are located all essential components including an IR (thermal)
optical engine 18 located adjacent forward region 16.
[0015] Optical engine 18 includes an un-cooled bolometric IR
detector array 20, preferably of the type described and illustrated
in commonly owned U.S. Pat. No. 5,554,849 entitled MICRO-BOLOMETRIC
INFRARED STARING ARRAY and issued Sep. 10, 1996, the disclosure of
which is incorporated herein by reference. Array 20 produces a
high-resolution, two-dimensional, temperature pixel image of a
scene within its field of view. The image produced by array 20 is
stored in a digital memory 22 managed by a microprocessor 24. Left
region 14 includes a battery subsystem 26 for integrally powering
all components.
[0016] Bolometric IR detector array 20, because it is un-cooled (by
which is meant it is not cryogenically cooled), produces only
slight heat itself, but nevertheless is sensitive to heat in the
ambient environment around it. Thus, an important contribution of
the invention is a fluid heatsink 28 for removing heat from
opto-electronics 30 including optical engine 18, array 20, memory
22 and processor 24. Opto-electronics 30 typically are subject to
extreme environmental heat that may be produced by a fire.
Accordingly, heatsink 28 is provided to ensure continuous,
long-term, accurate temperature profile detection and imaging by
the detector array despite the environmental extremes.
[0017] FIG. 1A shows apparatus 10 in its deployed position whereby
the user is blinded in a left eye and vision-enhanced in a right
eye, as described above. The choice of the right or left eye for
blinding and viewing is predetermined for each apparatus 10, but a
mirror-image version of apparatus 10 may be constructed for those
users that prefer blinding the right eye, and vision-enhancing the
left eye. All of the drawings and the discussion herein is for a
right-eye-enhanced embodiment.
[0018] FIG. 1B corresponds directly with FIG. 1A and shows the same
features as those described above but in a different orientation.
FIG. 1B shows apparatus 10 in a tilted-back or stowed position in
which the user is able to see relatively unobstructed and
unenhanced with the naked eyes when the vision-enhancement features
of apparatus 10 are not needed. The configuration of front region
16 of apparatus 10 wherein the lower edge 16a of region 16
terminates in a line just below eye-level makes it possible to tilt
apparatus 10 back toward the forehead ever so slightly to afford
the user a direct unenhanced and relatively unobstructed view, as
indicated.
[0019] This configuration of apparatus 10 may be preferable to
alternative arrangements whereby, for example, a visor section
flips up away from the frame on a hinge along the top or is
removable or whereby the left lens is rendered transparent for
direct viewing with the left eye or whereby the right and/or left
lens is rendered only translucent such that an IR image and direct
view are superimposed within the view of the user. The lens hinge
or removal configurations over which apparatus 10 is believed to
represent an improvement require a hinge or connection between the
active display surface and the frame, thus potentially disturbing
or destabilizing the optical path from the IR camera to the user's
eye.
[0020] The translucent display lens configuration over which
apparatus 10 distinguishes itself is known to cause eye-strain and
confusion in many users due to the superposition of often slightly
conflicting images. Confusion from superimposed images is
unavoidable, since the natures of infrared energy and visible
spectral energy are by definition different, and amorphous object
or target boundaries result in confusion when the different images
are superimposed. Often the infrared image will lag the direct
image, for example, as the user's head is turned. Invented
apparatus 10 avoids these problems by going against conventional
wisdom in head-up IR displays and provides the user with the option
of choosing to view a scene in either monocular IR or in binocular
direct view modes of operation by a simple tilt or rotate of the
apparatus about the user's ears.
[0021] Referring next to FIG. 3, the optical imaging technique used
in accordance with the invention is illustrated schematically.
Optical engine 18 may be seen in a slightly different form here to
include array 20, a preferably back-lit liquid crystal display
(LCD) 32 providing preferably at least 320.times.240 pixel
resolution with a minimum 6-bit gray scale, a partially (preferably
50%) reflective planar mirror or mirrored lens 34 that turns the
LCD image onto a focusing curved 100% reflective mirrored surface
36 that reflects the 50% intensity image back through 50%
reflective surface 34 into the firefighter's eye. The display
expanse may be viewed by looking through mirror 34 at focusing
mirror 36, providing an approximately 25% polychromatic spectral
energy efficiency, IR-representative field of view below which the
firefighter may view the scene directly as indicated. Optical
engine 18 also includes an IR camera unit 37 mounted as better
illustrated in FIGS. 7A and 7B to intercept a frontal infrared
scene along its focal axis.
[0022] The objective lens optical components within optical engine
18 preferably meet the F 1.3 optical standard in operation. The
objective lens preferably is a 1'' diameter lens having a 300
azimuth (horizontal) field of view for wide-angle scene imaging.
The lens also preferably is transmissive of IR energy in the 8 to
12 micron spectral bandwidth. The focus range of the lens is
preferably set to 2 to 24 feet for normal viewing, but may be
manually adjusted to 100 feet optimum focus distance.
[0023] Forward region 16 of apparatus 10 thus may be seen from
FIGS. 1A, 1B, 2A, 2B and 3 to include a curved display expanse
within and extending across an upper portion of a user's right eye
field of view and a `blind` or opaque expanse 38 within the user's
left eye field of view. The left eye of the user thus is preferably
covered, or `blinded.` By enabling through one eye an IR image of
the fire scene and through the other eye an obstructed or `blind`
view (as the parallax view resulting from a user's slightly
laterally separated eyes and the depth perception obtained as a
result of the parallax view are relatively unimportant in this
so-called night-vision environment), weight, power and cost are
saved without significant compromise of IR image.
[0024] Importantly, prior art difficulties with the user resolving
a visual image through one eye and an IR image through the other,
or resolving a visual image and an IR image through the same one or
more eyes, are avoided. Depth distortion whereby one image suggests
a foreground scene or shorter distance to an object and a different
superimposed image suggests a background scene or greater distance
to an object--a distortion of visual perception that is inherent in
superimposition vision systems--also is avoided.
[0025] Placement of the eyeglass forward region of apparatus 10
relative to the user's head and particularly the user's face such
that its bottom edge effectively cuts across the bridge of the nose
is an important feature of the invention. Configuring apparatus 10
to achieve this strategic placement permits the user normally to
view the fire scene monoscopically via LCD 32 and mirrored lens 36,
and, alternatively, to view the scene stereoscopically and unaided
beneath the eyeglass portion, by looking below the display expanse.
Such dual mode viewing is very easily accomplished by a momentary,
slight backward tilt of the user's head around which apparatus 10
wraps or by a momentary, slight backward tilt of the apparatus
relative to the user's head. This invented feature will be referred
to herein as bi-focality.
[0026] The dimension and configuration of the apparatus--and its
resulting automatic positioning relative to the elevation of the
user's eyes by its conformation with the bridge of the nose and the
ears such that it perches at a given elevation on the user's
face--results in bifocal operation, i.e., the dual mode operation
achieved by a slight tilting forward or backward of the head or the
slight tilting backward or forward of the apparatus. This is
perceived to represent a great advantage over prior art systems
that require the user's mind to resolve simultaneous inputs to
either eye (in a left-and-right bifurcated system) or both eyes (in
a head-up, see-through system), one of which is unaided vision and
the other of which is IR imaged vision, which superposition is
believed to be confusing and potentially hazardous.
[0027] FIGS. 2A and 2B show apparatus 10 in isometric view
corresponding generally with FIGS. 1A, 1B and 3, with identical
component parts identically designated by reference designators.
FIGS. 2A and 2B are exploded, partly assembled, and fully assembled
versions of apparatus 10, respectively. Also shown in FIGS. 2A and
2B are the internal configuration of various subsystems within a
housing of apparatus 10. The subsystems include battery subsystem
26, opto-electronics indicated generally at 40, and a clamshell
housing assembly, or simply housing, 42. Opto-electronics 40
include optical engine 18 and electronics, to be described in more
detail by reference to FIG. 5, most or all of which are mounted
within housing 42.
[0028] The subsystems listed above that form a part of apparatus 10
are operatively connected as suggested by FIGS. 2A and 2B. For
example, battery subsystem 26 provides regulated DC power to
opto-electronics 40 within housing 42 via one or more electrical
conductors 44 that route power and ground, as well as control and
communication signals between the two subsystems and more
particularly to electronics 46 of opto-electronics 40. Preferably,
battery subsystem 26 includes a Sanyo HR-4/3FAU or Panasonic
HHR-450AB01 battery.
[0029] Battery subsystem 26 may also include circuitry, not shown,
that monitors usage of battery 26 so that warning messages may be
produced if the remaining charge of battery 26 has dropped below a
certain level, or if battery 26 has been subjected to too many
charge cycles or excessive temperature. The interactive nature of
battery 26 is indicated in FIG. 5 by the control and communication
signal that leads to and from battery 26. The plurality of contacts
44 shown on battery subsystem 26 in FIG. 2A allow for the
transmission of the power, control and communication signals from
and to battery subsystem 26.
[0030] Battery subsystem 26 preferably is mounted to housing 42 in
such a manner that it can be easily and quickly removed for
maintenance, repair or replacement with a fresh, fully charged
battery subsystem. Finally, as seen from FIG. 2B, preferably
substantially all of opto-electronics 40--including the integral
display that enables a user to `see` though obscurants such as
smoke or to `see` in the absence of light--are contained within
housing 42. This holds true except for those insubstantial portions
that extend from the housing such as the forward region of optical
engine 18 including forward portions of IR camera unit 37.
[0031] A helmet clip 42C also may be seen from the drawings to
extend slightly forward and above the upper front edge of housing
42. Other quick release mechanisms may be used to attach apparatus
10 to a protective helmet of the type typically worn by
firefighters. A headband or strap B, shown in FIG. 1A, may be
attached to apparatus 10 for additional support, at eyelets 42E. It
is intended but not essential that apparatus 10 may be passed
between firefighters as needed, while the firefighters are fully
clothed in typical protective gear including hoods and gloves.
[0032] The preferred horseshoe shape of housing 42 is designed, in
part, to ease handling of apparatus 10 by a gloved hand. The
horseshoe shape is defined by left arching region 12 and right
arching region 14 (the legs of the horseshoe) interconnected by
front region 16. Legs 12 and 14 function as carrying handles for
apparatus 10, if needed. Legs 12 and 14 even allow a firefighter to
hold apparatus 10 in a viewing position without attaching apparatus
10 to a helmet or strapping it to a user's head. This may be
particularly useful if apparatus 10 is passed frequently between
firefighters in the midst of a fire, or if apparatus 10 or a
firefighter's helmet becomes dislodged or structurally damaged.
[0033] Opto-electronics 40 including electronics 46 will be
described now by reference to the schematic block diagram of FIG.
5, which, for completeness, also includes battery subsystem 26 and
external options to be described. Detector array 20 preferably is
mounted on a camera/buffer printed circuit board (PCB) 48 which
includes digital memory 22 for buffering digital scenery data
obtained by the optical engine. Optical engine 18 and battery
subsystem 26 counterbalance one another along the legs.
[0034] Heatsink, or phase change module, 28 may be mounted in close
physical proximity to detector 20 and other sensitive electronics
mounted on camera/buffer PCB 48 and microprocessor PCB 50, so as to
dissipate heat radiating therefrom and to maintain the detector and
the electronics within predefined limits compatible with proper
operation thereof. Preferably, heatsink 28 is placed far enough
back in leg 14 of housing 42 so that it counterbalances detector 20
along leg 14. Battery subsystem 26 in leg 12 further
counterbalances detector 20 along leg 12, while at the same time
offsetting the weight of heatsink 28 so that apparatus 10 is
balanced laterally as well, in a direction extending along forward
region 16.
[0035] Microprocessor 24 preferably is separately mounted on a
microprocessor PCB 50 located nearby so that timing, control, gain,
image data and power are shared between the PCBs. Optical engine 18
preferably includes an NUC shutter 52 and IR optics 54 and drive
and heat signals are routed to shutter 52 from camera/buffer PCB 48
as shown. An optional software development connector 56 may be
provided as shown in FIG. 5 that facilitates future software
development and upgrades that may be implemented in the form of
programmable read-only memory (PROM) that preferably is an integral
part of microprocessor 24.
[0036] Microprocessor PCB 50, with camera/buffer PCB 48 preferably
mounted thereon, is mounted on a printed circuit
motherboard/display board 58 and routes power, audio, control and
digital LCD video signals therebetween. Board 58 also mounts LCD
backlight electronics 60, LCD 32 and display optics 62 as shown.
Board 58 provides power and control via a power distribution board
64 to battery subsystem 26. Optionally, a video transmitter 66 or
video recorder 68 or both may be supported as external options to
apparatus 10 via a provided NTSC/PAL video (RS-170) input/output
port mounted on motherboard/display board 58. Other external
options may be provided, within the spirit and scope of the
invention. However, current implementation of these added options
may seriously limit the portability and exchangeability of
apparatus 10 between firefighters.
[0037] Battery subsystem 26 is an important contributor to the
portability and high functional density of apparatus 10. Battery
subsystem 26 includes a switch 70 and a light-emitting diode (LED)
72 for switching power on and off in apparatus 10 and for
indicating when power is on. These are battery save features of
apparatus 10 intended to extend its useful operating life without
the user having to replace the battery subsystem.
[0038] In accordance with a preferred embodiment of the invention,
battery subsystem 26 provides power conversion from battery voltage
to the regulated +3.3 volts direct current (VDC), .+-.5VDC,
.+-.12VDC required by opto-electronics 40. It also provides
sufficient holdover (internal capacitance) to support low-power
operation of apparatus 10 when the battery is unexpectedly removed.
The battery that forms a preferably lightweight, low-cost,
removable and rechargeable part of battery subsystem 26 when fully
charged provides a minimum of 1 hour's operation when new, and a
minimum of 40 minutes' operation after 500 charge/discharge cycles.
Importantly, the battery contacts disconnect prior to external
environmental exposure when installing and removing the battery
into and from housing 42 to avoid possible explosive atmospheric
exposure to electrical potential. This is accomplished via the
mechanical design of the mounting structure and seal
configurations.
[0039] Self-contained, sealed, liquid or plural-phase heatsink 28
may take any suitable form, but in accordance with the preferred
embodiment of the invention, may be thought of as a plural-phase
heatsink that by its solid/fluid character may be contained within
a finite volume over its operating curve. Importantly, only a
self-contained system enables a firefighter to easily employ and
deploy such a vision/display system in a fire without a restraining
umbilical, for example, to a separate coolant source. The use of a
high-temperature-range plural phase polymer as a heatsink material
avoids exhaust problems or the removal of high-temperature
by-products, e.g., the steam produced by heating water.
[0040] Heatsink 28 is low-mass including sealed container and
material contents, and provides for the thermal storage of 3100
calories of heat of fusion at a 65.degree. C. (149.degree. F.) to
75.degree. C. (167.degree. F.) melting point. Heatsink 28 in its
preferred embodiment utilizes organic paraffin, such as beeswax, or
n-hexatriacontane, C36H74. Organic paraffins typically have high
heats of fusion per unit weight, melt homogeneously, and do not
supercool.
[0041] One particular heatsink material believed to work well is
available from Le Technologies, Inc., Hillsboro, Oreg., as product
04000850. It includes approximately 80% or less modified paraffin
wax, CAS 64742-51-4, up to 25% amide wax, CAS 13276-08-9, up to 25%
ethylene vinyl acetate copolymer, CAS 24937-78-8, and up to 3%
antioxidant, CAS10081-67-1. Many other phase-change materials might
be used, including fatty acids, salt hydrates, fused salt hydrates,
and metallic eutectic compounds. Heatsink 28 is intended to
maintain the IR detector array hot side temperature below
80.degree. C. under all rated environmental conditions, at least
for a limited time.
[0042] The use of the invented liquid or plural-phase heatsink
permits apparatus 10 to operate usefully, depending upon the
ambient temperature of the environment in which it is used, over
varying periods of time. For example, apparatus 10 may be operated
indefinitely without interruption in ambient temperatures
-10.degree. C..ltoreq.T.sub.A.ltoreq.30.degree. C. (14.degree.
F..ltoreq.T.sub.A.ltoreq.86.degree. F.); up to 2 hours at
T.sub.A=40.degree. C. (104.degree. F.); one hour at
T.sub.A=50.degree. C. (.about.120.degree. F.); twenty minutes at
T.sub.A=80.degree. C. (176.degree. F.); ten minutes at
T.sub.A=100.degree. C. (212.degree. F.); five minutes at
T.sub.A=150.degree. C. (302.degree. F.); and two minutes at
T.sub.A=315.degree. C. (.about.600.degree. F.).
[0043] Other important features of the invention that complement
the self-contained, head-mount features of vision/display system 10
include its ergonomics and colorized display. Ergonomically
speaking, apparatus 10 is easily employed and deployed by simply
slipping it onto the face and over the ears, and perhaps by
securing it with a clip 42C and a band B that extends over the brim
or bill of the firefighter's helmet, as shown best in FIG. 1A, with
no connections to other equipment being required. Apparatus 10 is
dimensioned and configured to avoid interference with other gear
such as typically may be worn by users of apparatus, e.g., helmets,
respirator or gas masks, e.g., SCBA, and attire. Thus the size and
shape of apparatus 10 is designed for more than low weight or
volume, it also is sized and shaped to conform to and extend around
an average user's head and face at approximately eye level, while
not extending laterally around the head of the user any more than
is necessary or radially therefrom more than .about.3-inches.
[0044] The colorization of the IR display is of great benefit in
avoiding temperature extrema which tend to saturate the image
field. Apparatus 10 has a very wide thermal dynamic range that
enables it to accurately survey scenes having temperatures ranging
between 0.degree. C..ltoreq.T.sub.S.ltoreq.815.degree. C.
(32.degree. F..ltoreq.T.sub.S.ltoreq.1500.degree. F.). Where there
are present extreme temperature ranges, it is difficult in
monochrome or color display systems to differentiate extremely high
temperatures, e.g., a gaseous, flammable vapor that may be several
hundred degrees Centigrade, and relatively low temperatures, e.g.,
a living human being the surface temperature of which typically is
under forty degrees Centigrade.
[0045] Color coding temperature ranges, via microprocessor 24 in
cooperation with one or more image buffers in memory 22, may, for
example, represent dangerously high avoidance zones having
avoidance temperature ranges like fires, e.g.,
T.sub.S1.gtoreq.600.degree. C. in shades of red, intermediate
temperature ranges, e.g., 100.degree.
C..ltoreq.T.sub.S2.ltoreq.600.degree. C., in shades of gray and
relatively low target temperature ranges that might be rescue
targets like human beings, e.g., 25.degree.
C..ltoreq.T.sub.S3.ltoreq.100.degree. C. in shades of blue. This
preferred color coding allows a user to readily distinguish
hazardous temperature zones from `safe` target temperatures, which
may be targets of particular interest to the firefighter. The
representation of intermediate temperature ranges in the color
range of gray de-emphasizes those zones of the scene that are
normally of little interest to a firefighter, because the zones are
of too high a temperature to be a rescue target, and too low a
temperature to be a threat to the protective gear used by the
firefighter.
[0046] Some other neutral color may be used instead of or addition
to gray for the representation of the intermediate temperature
ranges, such as brown or copper. Similarly, some color other than
red or blue may be used for target and avoidance temperature
ranges, provided, preferably, that the color of the target and/or
avoidance portions are visually distinct from all other portions of
the color image. Red is believed to readily distinguish those
portions of the scene that are at a dangerously high temperature.
The novel color coding also avoids occurrences of monochrome or
polychromatic saturation of displays by which object profile and
character often are obscured.
[0047] Other inventive features briefly include the provision of
remote wireless monitoring via an optional pocket-sized, belt-worn
transmitter 66 operatively connected to an input/output port of the
microprocessor via suitable means such as a video cable and adding
radiometric, e.g., numerical temperature readout, capability to
apparatus 10. The latter feature requires calibration, which is
facilitated in accordance with the preferred embodiment of the
invention by the fact that bolometric detectors are relatively
easier to calibrate than are prior art ferro-electric detector or
cryogenically cooled elements. Apparatus 10 also preferably
provides a NTSC/PAL output port for the digital video signals to be
provided to an external display monitor.
[0048] The invented apparatus represents a step-wise decrease in
volume and weight in IR imaging systems, with the weight of
apparatus 10 under 4-pounds and the internal and external volume of
apparatus 10 under 80, e.g., 71, cubic inches and 120, e.g., 105,
cubic inches, respectively. Such is made possible, in part, by
forming housing 42 using a suitably durable but lightweight polymer
preferably via suitable injection molding techniques. Such volume
and weight, coupled with the increase in functionality, will be
referred to herein as high functional density. It involves
miniaturizing IR imaging systems to render them more
self-contained, portable, low-cost, etc., and results in a
significant utility improvement.
[0049] In accordance with a preferred embodiment of the invention,
apparatus 10 weighs less than 4-pounds, making it extremely
portable and comfortably wearable by a user. This extremely low
weight renders apparatus 10 comfortably worn, and transported and
stored on the person of the user or a vehicle or storage area, and
makes it easily ported among users. In other words, apparatus 10 by
virtue of its extremely low weight is as easy to deploy and stow
and handle as a piece of clothing or accessory, yet it is extremely
valuable as a firefighting or surveillance tool. Such low weight is
achieved in accordance with the invention by a combination of
component selection, especially in the selection of low-weight
batteries, heatsinks and optical elements, and a preferably
integrally molded clam-shell type housing requiring little or no
hardware to seal its contents against environmental extremes such
as salt or fresh water spray or airborne contaminants.
[0050] Another aspect of the invention is the color or other coding
of images whereby temperature-representing pixels are classified
into selected temperature ranges and color coded to represent
particular ranges for visual image enhancement, e.g., to highlight
visually those portions of the scene that may contain a living
human being whose temperature is within a certain relatively low
predefined range and/or to visually diminish a flaming background
whose temperature is within a certain relatively high predefined
range. This concept is not limited to fire fighting, but is broadly
applicable to IR imaging wherein a broad range of temperatures is
expected and wherein an important feature within a field of view
might otherwise be masked from view by color saturation due to the
prevalence of extreme temperatures around the target object. For
example, it may be useful in temperature-condition monitoring, law
enforcement and television broadcast. This aspect of the invention
will be referred to herein as a high-contrast ratio visual image
enhancement method.
[0051] FIGS. 6, 7A and 7B illustrate the preferred technique by
which color mapping is accomplished in apparatus 10 in accordance
with the invention. It is noted in this connection that monochrome
displays lend themselves to shape identification, whereas
polychrome displays lend themselves to temperature identification.
Thus, the invention in its preferred embodiment uses a combination
of monochrome and color displays in which normal temperature ranges
are presented on LCD 30 in monochrome to facilitate feature ID and
extreme temperature ranges might be presented thereon in polychrome
to facilitate temperature ID. In this way, background may be
presented in gray-scale and highlights of particular interest may
be presented in color. All such temperature zone identification,
isothermal boundary imaging and color coding readily are
accomplished by software and firmware operating within
self-contained microprocessor 24.
[0052] A gray-scale image in the present invention is created on
LCD 32 by mapping the image in pixels, with any particular pixel
being produced on the screen by equal levels of the red, green and
blue portions of an RGB multicolor signal. The luminance produced
by the combined RGB signal for each pixel is modulated as a
function of the temperature of each portion of the sensed scene.
This is done by firmware in microprocessor 24, preferably using
histogram-equalization image processing. Examples of such histogram
equalization used in connection with machine vision systems are
found in U.S. Pat. Nos. 5,083,204 and 5,563,962, the disclosures of
which are incorporated herein by reference.
[0053] Preferably, IR camera unit 37 is radiometrically calibrated
so that the image on LCD 30 accurately represents the thermal
profile of the scene within the field of view of IR camera unit 37,
and not just a relative temperature as found in prior art devices.
Optionally, the calibrated signal from unit 37 is further processed
to highlight selected temperature ranges in a selected color. A
unique aspect of this highlighting is that the signal is mapped so
that the highlighting within the selected temperature range is
within a range of the selected color, as described below.
[0054] The graphs in FIGS. 7A and 7B illustrate how the
highlighting is mapped to the displayed image. The RGB luminance as
a function of temperature is represented in FIGS. 7A and 7B as
three linear regions, each a linear function of temperature. This
linear representation is a gross simplification, particularly when
histogram equalization and automatic gain control is used, but it
clarifies the color mapping routine of the present invention. The
luminance of the red and green signals of the RGB signal have been
shifted slightly so that it is easier to distinguish the individual
R, G, and B signals.
[0055] Within a particular temperature range, such as near human
body temperature, or at extreme temperatures (above 550.degree. C.
in FIG. 7A), the equalized mapping of the RGB portion of the signal
is shifted to favor one color, with compensating decreases in the
corresponding portions of the RGB signal. The preferred color
highlighting is to emphasize one of the base components of the RGB
signal, such as blue for the human target zone, and red for the
extreme temperature zone. The highlighting of the human temperature
zone in shades of blue is shown in detail in FIG. 7B.
[0056] The luminance of the highlighted portions of the image are
maintained relative to the non-highlighted portions adjacent in
temperature range to the highlighted temperature range by the
compensation discussed above. However, luminance highlighting in
addition to the described color highlighting may be added, by
changing the compensation routine. For example, by increasing the
blue portion of the RGB signal as desired within the selected
temperature range, without making any compensation to the red or
green portions of the RGB signal, the relative luminance will be
increased within the selected temperature range, and the portions
of the image in the selected temperature range will be highlighted
in ranges of blue.
[0057] It is intended that the color highlighting of the present
invention may be applied to various or multiple temperature ranges
as the situation requires or allows. For firefighting and other
life-threatening activities, it may be safer to highlight only a
few key portions of the image, such as those representing a human
target and excessive heat. Other highlighted temperature ranges may
be identified based on a particular activity such as fire control,
in which the image might be highlighted to show different levels of
combustion, or such as fire cleanup, in which the image might be
highlighted to show dangerous hotspots within walls or other
structure.
[0058] The software and firmware within microprocessor 24 provides
other advantages. Preferably the firmware upon the application of
power automatically uses default settings for many operating
parameters of apparatus 10, with such default settings stored in
non-volatile memory such as read-only memory (ROM). Such
permanently stored default settings preferably include control
settings for image temperature range, and display brightness. The
firmware preferably indicates to the user normal operating
conditions including the elapsed time on the battery and the
battery charge level. The firmware preferably provides user
warnings of critical operating conditions such as failed power,
critical battery level (e.g., <5 operating minutes remaining)
and internal temperature alarm indicating that the opto-electronics
are operating above their nominal maximum operating
temperature.
[0059] Many of the system parameters may be reprogrammed. For
example, apparatus 10 may first be used for a rescue operation, and
then used for a fire control operation, in which case different
temperature ranges of the scene may be highlighted in the image.
Such a change might be accomplished by an external switch on
housing 42, not shown, which triggers different routines within the
firmware of apparatus 10. Currently, reprogramming is accomplished
by connecting a programming computer to the
power/control/communication contacts associated with battery
subsystem 26, or to software development connector 56.
[0060] Referring now to FIGS. 4A and 4B, a head-mounted camera such
as IR camera 37 of apparatus 10 and a head of a user wearing such
apparatus including the camera are shown schematically in overhead
and side views. The camera and its positioning and mounting within
housing 42 (not shown in the simplified schematic diagram but in
keeping with the teachings of the present application) of apparatus
10 achieves an important advantage over prior art portable thermal
imaging systems. A parallax problem exists in conventional systems
wherein the optical axis of the camera is parallel with the line of
sight of the user.
[0061] This problem results from the off-axis, asymmetric location
of the camera relative to the eye or centerline of the eyes of the
user. The problem is a serious one, especially in life-threatening
or hazardous situations such as firefighting. In the near field of
`view` through the camera, the user has difficulty handling objects
within arm's reach because the camera effectively misrepresents to
the user the object's location to the extent of the vertical and
lateral offset between the user's eyes and the camera's "eye." A
user thus tends to reach for an object imaged by the camera only to
grope for it where its position is falsely indicated, a few inches
typically from where the object actually is located in space.
[0062] Apparatus 10 solves this problem by providing convergence of
optical axis A defined by optical engine 18 (of which IR camera 37
is a part) and an axis describing the user's virtual or nominal
line of sight through the right eye that is viewing the scene on
LCD 32. This is accomplished by mounting optical engine 18 within
housing 42 such that the optical axis converges the nominal line of
sight to define a point of convergence F. In accordance with the
invention, the user's line of sight is actually to a virtual scene
produced for display on a mirrored lens within apparatus 10 but
that the user's nominal line-of-sight axis Au may be projected into
the scene, as illustrated, for purposes of explaining another
feature of the invention. Accordingly, FIGS. 4A and 4B illustrate a
virtual line of sight of the user and the focal point along such
virtual line of sight representing the effective focal path of the
user viewing a scene on such a display.
[0063] The angle of convergence is chosen such that convergence F
of the axes occurs at a nominal arm's length spaced away or in
front of the user's right eye, e.g., between 2- and 4-feet, and
typically approximately 3-feet away. This distance is indicated in
FIGS. 4A and 4B by a solid horizontal line 74 extending from the
point of convergence F and the user's eye. The angles of
convergence between the optical axis A and line of sight LOS in the
horizontal plane and in the vertical plane are indicated as 76 and
78 in FIGS. 4A and 4B, respectively.
[0064] Objects within the user's grasp will be found where
indicated by the image projected on LCD 32 because the camera is
targeting and imaging the object with the angular offset that
overcomes the above problem, typically in a range of between
approximately 4- and 10-degrees. In accordance with a preferred
embodiment of the invention, the optical axis of optical engine 18
is aimed down in a vertical plane by and angle of approximately
6-degrees and to the side in a horizontal vertical plane by and
angle of approximately 8-degrees by configuring housing 42 to mount
IR camera 37 at corresponding angles that converge approximately 3
feet in front of the user's right eye with the user's line of sight
from the right eye.
[0065] Users of apparatus 10 thus reach to grasp an object in front
of them based upon the image projected on LCD 32 and find the
object where they reach without difficulty and without groping as
with prior art systems in which the camera's optical axis and the
user's line of sight are parallel with one another. In the user's
very far field of view, objects' location are slightly offset
vertically and laterally as a result of the alignment of IR camera
37, but it is believed that there is little difficulty for a user
to proceed toward a distant object and locate the object readily
once the object is a few feet in front of the user. Thus the
invented solution to the prior art parallax problem surprisingly is
without disorientation when `viewing` a distant object.
[0066] The invention may include an apparatus and a method of
representing a thermal image in a portable device, as described
above. The steps of the method include generating an electronic
signal representative of a scene in front of a user using an
infrared camera, identifying target portions of the electronic
signal that represent portions of the scene that are within an
identified target temperature range, and mapping the electronic
signal to display a color image of the scene. Preferably, the
target portions of the electronic signal are mapped in a color
range that is visually distinct from all other portions of the
color image. The method may also include the steps of identifying
avoidance portions of the electronic signal that represent portions
of the scene that are above an identified avoidance temperature;
mapping the avoidance portions of the electronic signal to the
color image in a color range that is visually distinct from all
other portions of the color image, and mapping those portions of
the electronic signal that do not represent target and/or avoidance
portions to the color image in a neutral color range. Preferably,
this is done by producing a multicolor RGB signal representative of
the image, and emphasizing at least one color of the multicolor
signal. Other colors of the multicolor signal may be de-emphasized
so that the relative luminance of the target portions of the image
remain approximately equivalent to the relative luminance of
portions of the image that represent portions of the scene that are
near to the identified temperature target range.
[0067] The foregoing description of the preferred embodiment of the
invention has been presented for purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise form disclosed, and many modifications and
variations are possible in light of the above teaching. The
embodiment was chosen and described in order to best explain the
principles of the invention and its practical application to
thereby enable others skilled in the art to best utilize the
invention in various embodiments and with various modifications as
are suited to the particular use contemplated. It is intended that
the scope of the invention be defined only by the claims.
* * * * *