Note: Descriptions are shown in the official language in which they were submitted.
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WILD ANIMAL DETERRENT DEVICE AND METHOD
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to a laser light producing device for
deterring attacks by
wild animals, and a method of using the device to prevent wild animal attacks.
Description of the Related Art
[0003] There are only a handful of non-lethal animal deterrent devices,
primarily pepper spray or
synthetic sprays. An example of a chemical based deterrent is disclosed in
U.S. Patent No.
4,097,607 to Larson, which is drawn to a capsaicin based chemical compound to
deter animals
from entering specified areas. There are also a number of devices that attempt
to use loud noises
to deter animals, see for examples U.S. Patent No. 5,892,446 to Reich, which
is a mounted
device to deter animals from entering a fixed location.
[0004] There are a wide variety of laser "dazzler" technology patents, which
use high intensity
laser light to temporarily blind a target, or cause eye irritation that causes
the target to turn away
from the light source. The terms "dazzle," "dazzling," and "dazzled" as used
herein refers to the
use of laser light to cause eye irritation. The existing dazzler inventions
are primarily used in
military or crowd control situations. Virtually all dazzler technology is
designed to increase the
intensity and or distance of the laser light to be able to "dazzle" a
potential human target at a
long distance from the light source. Examples include U.S. Patent No.
7,040,780 to Diehl; U.S.
Patent No. 7,232,240 to Kosnik et al.; and U.S. Patent No. 7,239,655 to
Casazza. These devices
create a high intensity laser light that causes eye irritation, or even
damage, and prevents a
person from looking directly at the light source. In military use this can
prevent an enemy from
aiming a weapon, and in non-military use it can deter people from approaching
the light source.
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The animal deterrent described herein uses analogous technology to prevent an
animal from
approaching or attacking the user of the device.
[0005] Laser-based dazzling technology has existed for several decades.
Virtually all
development has been in the field of military countermeasures, and designed
with the intent of
disabling an enemy so that he cannot effectively aim a weapon at the user.
Such devices are
expensive, usually weapon-mounted apparatus designed to cast a narrow, intense
beam of light
in the direction of a line of sight for a weapon, such as a rifle or cannon.
Laser dazzlers have
been fitted to rifles, tanks and armored personnel carriers, employing a
narrow beam divergence.
There have, also, been experiments with crowd control. The vast majority of
improvements on
this technology has been directed at increasing the intensity of the beam to
allow its use at
increased distances.
Background of the Invention
[0006] Large animals, such as bear, elk, moose, buffalo, cattle, wild cats and
dogs, can harm
humans through predatory attack, defense of territory, young or food, and by
offensive actions
attributable to numerous other motivations. In the past humans typically
protected themselves
with a firearm, but such action is now tightly restricted or banned, and in
many places is
considered unacceptable. People need the ability to quickly and effectively
defend themselves by
non-lethal means, using methods that are effective, yet do not permanently
harm an offending
animal in recognition of practical, legal, economic and ethical
considerations. An effective,
general-purpose deterrent should be easy to carry, quick to access, simple to
use, repeatable, yet
inexpensive. Such a deterrent would enable humans and other animals to co-
exist in habitats that
otherwise might become human-occupied only. The remainder of this discussion
will refer to
bears as the example target animal, because this species generates the
greatest need for
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deterrence. The device, however, will work equally well with any aggressive
animal.
[0007] Only one generally-accepted, non-lethal class of bear attack deterrent
currently exists.
These are chemical-based aerosol sprays that generally use a chili pepper
derived oleoresin
capsicum: brand names include Counter Assault, Frontiersman, Guard Alaska,
Mace and UDAP.
There are several problems associated with this type of deterrent. The maximum
range of an
aerosol spray is 25 to 35 feet under ideal conditions. The spray usually is in
a narrowly confined
stream so that it can reach these distances. Wind can impair properly aiming
the spray and it can
also shorten the useful range. Wind can also blow the chemical into the user's
face, disabling the
user instead of the animal. Total operating duration of conventional aerosol
sprays is typically 6
to 9 seconds before the container is exhausted. This means that the spray can
be used only once.
And finally the deterrent does not work on all animals.
[0008] Many locations around the world prohibit visitors into wilderness
habitats from carrying
lethal deterrents or deterrents that can cause permanent injury to an
offending animal. Other
practical considerations exist for areas that do allow carriage of lethal
deterrents, such as
firearms. Many people cannot afford or do not know how to use firearms. Misuse
of firearms
can wound and enrage an animal, transforming it from a potential threat into a
deadly one. The
potential for accidents with deadly weapons also exist, where those who would
protect
themselves instead find themselves the victim of their own defense. For these
reasons, an
economical, simple to use, one-hand operable, non-injurious, all-weather
deterrent device with a
long operational duty cycle is needed.
SUMMARY OF THE INVENTION
[0009] The present invention, referred to herein as the bear dazzler, is drawn
to an inexpensive,
hand held laser device that creates an eye irritant that will force an animal
to turn away from the
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user, and will therefore deter an animal attack. The laser device will include
a diverging lens to
create a broad beam, of between 5 and 30 degrees, so that the user can point
the device in the
general direction of the animal and will not have to aim the beam precisely.
[0010] The bear dazzler is about the size of a small conventional flashlight
and so is easy to
carry. It uses conventional, well known laser technology, so is relatively
inexpensive. The beam
divergence allows it to be pointed in the general direction of an animal and
eliminates the need to
be precisely aimed. It is also unaffected by the wind. Finally, with
conventional batteries and
conventional laser technology the bear dazzler has a typical operable life of
an hour and a half.
The bear dazzler is designed for easy storage and removal, and easy use. The
activation switch is
located on the side of the housing so that it can be easily activated. The
beam spread means that
the user does not need to precisely aim the device. This is a benefit since it
may be difficult to
properly aim during an animal encounter due to relative movement of the user
and the animal or
due to the user's anxiety.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011 ] FIG I is a perspective view of one embodiment of the bear dazzler.
[0012] FIG 2 is an exploded view, showing the main components of the bear
dazzler.
[0013] FIG 3 is a cross section view of one embodiment of the bear dazzler
showing the internal
components of the bear dazzler.
[0014] FIG 4 is a perspective view of the end cap.
[0015] FIG 5 is a cross section view of the battery compartment.
[0016] FIG 6 is a cross section view of the electric control compartment.
[0017] FIG 7 is an exploded view of the electric control mechanism.
[0018] FIG 8 is a cross section of the nose cap with the laser and lens
assembly.
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[0019] FIG 9 is a perspective cut away of the lens assembly.
[0020] FIG 10 is a cross section detail of the ball lens within the lens
assembly.
[0021] FIG 11 is a cross section detail of the double convex lens within the
lens assembly.
[0022] FIG 12 is a perspective view of the cold weather version of the bear
dazzler.
[0023] FIG 13 is a detailed cross section of the end cap of the cold weather
version.
[0024] FIG 14 is a perspective view of the laser insert of the cold weather
version.
[0025] FIG 15 is a cross section view of the laser insert of the cold weather
version.
[0026] FIG 16 is a cross section of the connection cable between the end cap
and the laser insert.
[0027] FIG 17 is a depiction of the spread and footprint of the beam.
[0028] FIG 18 is a depiction of the effective range and beam spread of the
bear dazzler.
DETAILED DESCRIPTION OF THE INVENTION
[0029] Detailed embodiments of the present invention are disclosed herein. It
is to be
understood that the disclosed embodiments are merely exemplary of the
invention, and that there
may be a variety of other alternate embodiments. The figures are not
necessarily to scale, and
some features may be exaggerated or minimized to show details of particular
components.
Therefore, specified structural and functional details disclosed herein are
not to be interpreted as
limiting, but merely as a basis for teaching one skilled in the art to employ
the varying
embodiments of the present invention.
[0030] Referring now to FIG 1, the Bear Dazzler 10 is cylindrical and
resembles a small, hand-
held flashlight. It consists of a housing 100 with battery compartment 120,
electronics
compartment 130, nose cap 140 with a laser 400 and a lens assembly 150 mounted
therein. There
is an end cap 110 that closes the housing 100 at the battery compartment 120,
and a front cap 160
which closes the housing 100 at the other end at the nose cap 140. The housing
100 is made from
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anodized aluminum, and can be produced in any desired color. In one embodiment
the main
components of the housing 100 (battery compartment 120, electronics
compartment 130 and
nose cap 140) are made from a single piece of material, but in the preferred
embodiment, as
shown in more detail in FIG 2, the components are separate and attached. As
seen in FIG 2, there
is an end cap 110 that attaches by means of corresponding threaded attachment
to the battery
compartment 120, which is threadedly attached to the electronics compartment
130, which
screws onto the nose cap 140 which has an incorporated heat sink 144, and
which is closed at the
end by a front cap 160. In the preferred embodiment the entire housing 100 is
just over six inches
in length, and the battery compartment 120 and electronics component 130 is
approximately
three-quarters of an inch in diameter. The nose cap 140 is slightly larger in
diameter. The
specific dimensions of the bear dazzler 10 can vary according to the type of
battery 200 used,
and the thickness of the material used for the housing 100.
[0031 ] As shown in FIG 2, each component is conventionally attached by a
threaded connection,
wherein one component has internal, or female threading and the corresponding
component has
external, or male threading. Each connection further includes an appropriate
sized O-ring, which
creates a water tight seal when the components are screwed together. The O-
rings are not shown
in FIG 2, but the use of appropriate sized 0-rings to create water tight seals
in similar
components is well known.
[0032] As seen in the cross section of FIG 3, there is a conventional Diode
Pumped Solid State
(DPSS) laser 400 within the nose cap 140. DPSS lasers are known in the art,
and the laser of the
bear dazzler is a conventional, off the shelf laser. Laser technology is
rapidly changing: the bear
dazzler works with existing laser technology, but will work with future
technology as well.
Recent developments in laser diodes are such that it is anticipated that a
laser diode will soon be
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usable for the bear dazzler 10. A lens 500 within the lens assembly 150
controls the spread, or
divergence angle, of the laser beam. There is a battery 200 in the battery
compartment 120 which
powers the laser 400, and a multi-mode electronic switch 300 within the
electronics compartment
130, which controls the power supplied by the battery 200 to the laser 400.
These components
are electronically connected in the standard and well known manner.
[0033] As depicted in FIG 5, the battery compartment 120 is a hollow cylinder
made of anodized
aluminum wherein the central opening forms the battery compartment 120. The
battery
compartment 120 is closed on one end with a screw-threaded end cap 110 with
lanyard loop 112,
which is depicted in FIG 4. The lanyard loop 112 allows the use of a lanyard
to connect the bear
dazzler 10 to a belt or back-pack or other outdoor hiking equipment in a
manner common and
well known among hikers and campers. The end cap 110 has a male threaded
portion 113 that
contains a groove 115 to retain an O-ring 114 to create a water tight seal
when in position in the
battery compartment 120. The diameter of the end cap 110 varies with the
diameter of the battery
compartment 120. The end cap 110 is a machined cylinder of anodized aluminum
and is fitted on
the interior 118 with a metal compression spring 220 which provides passive
electrical bonding
between the battery terminal 210 and the assembled Bear Dazzler housing 100.
[0034] The battery compartment 120 is sized to hold a battery 200 or battery
pack as required by
the power needs of the associated laser 400. In the most preferred embodiment
the battery 200 is
a single model 11865 (2,400 mAh, 3.7 VDC) rechargeable battery. In an
alternate embodiment
the battery 200 is a battery pack comprising six AA batteries in two 3-cell
plastic battery
assemblies that are sized to fit end to end within the battery compartment
120. Similar battery
compartments are standard in flashlights and other small battery powered
devices, and it is
known to use either single batteries or multi-battery packs to power similar
devices.
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[0035] The end cap 110 fits into a female thread 122 at the cap end 121 of the
inside wall 128 of
the battery compartment 120, through a polished neck 126 which accepts the end
cap O-ring 114
to provide a watertight seal. The aperture end 123 of the battery compartment
120 has a male
thread 124 and retaining groove 125 with an 0-ring 126. Metal to metal contact
provides
electrical conductivity and bonding between housing components. The aperture
end 123 of the
compartment is machined with an internal ledge to prevent the battery from
directly transmitting
force to the electronics compartment 130 if the unit is dropped. Similar
battery compartments
and configurations are common in standard flashlights and are known in the
art.
[0036] The electronics compartment 130 is shown in detail in the cross section
view of FIG 6
and the exploded view of FIG 7. The electronics compartment 130 is anodized
aluminum
electronics module. It is necessary that the electronics compartment 130
always be a thermally
conductive metal, such as aluminum, regardless of the composition of other
components of the
housing 100. The electronics compartment 130 is hollow with a raised saddle
131 having an
opening 132 with a circumferential internal groove 133 sized to hold a
rubberized switch cover
134 and held in place by a snap ring 135. The snap ring 135 holds the
rubberized switch cover
134 in place to create a water tight seal within the opening 132. There is an
electronic switch
mechanism 300 sized to be housed within the electronics compartment 130. As
best seen in the
exploded view of FIG 7, the electronic switch mechanism consists of a plastic
carrier 305 having
a carrier top 301 and a carrier bottom 302, with a circuit board 310 attached
between. There is a
plunger opening 307 in the carrier top 301. There is a push button switch 311
mounted on the
circuit board 310. When the circuit board 310 is mounted within the plastic
carrier 305, the
plunger opening 307 is aligned with the push button switch 311. A plunger 320
is movably
mounted within the plunger opening 307 such that it will activate the push
button switch 311
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when pressed. When the plastic carrier 305 is inserted within the electronics
compartment 130
the plunger opening 307 is aligned with the opening 132 such that the plunger
320 sits within the
opening 132 and is covered by the switch cover 134, such that the user can
press the switch
cover 134 to depress the plunger 320 to activate the push button switch 311.
The purpose of the
raised saddle 131 is to prevent inadvertent pushing of the switch cover 134
and inadvertent
activation of the device. In an alternate embodiment the switch cover 134 is
protected by a safety
cover latch. In an alternate embodiment, shown in FIG 1 and 3, there is a
raised latch 135, which
protects the switch and switch cover 134 from inadvertent activation. In that
embodiment the
latch 135 must be flipped up so that the user 8 can activate the dazzler 10 by
means of the witch
311.
[0037] Power from the battery 200 to the laser 400 is regulated by the
electronics controller
module 300 through pulse codes taken from user operation of the on-off switch
311. The
electronic controller module 300 is in electronic connection with the battery
200 in the
conventional manner. There is a battery spring 230 that contacts the battery
200 and transfers
power to the circuit board contact 312. There is an laser connector 340
mounted on the circuit
board 310, which connects to the laser lead 410 to allow power from the
battery 200 to flow to
the laser 400, as controlled by the controller module 300. In the preferred
embodiment of the
controller module 300, four modes of operation are possible: (1) off; (2)
steady on; (3) periodic
cyclic strobe; and (4) randomized strobe. In the preferred embodiment the
periodic strobe can
vary between 6 and 12 flashes per second, and in the randomized strobe the
flashes will be
controlled in a random manner and will flash between 6 and 16 flashes per
second. Laser output
is always at maximum power. Each mode will continue while the unit is powered
unless
changed by the user or the power source fails. There is no automatic cutoff or
mode change. In
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continuous mode, the amp-hour capacity of the battery will enable the DPSS
module to
continuously deliver 1.5 hours of performance. Pulsing the laser can further
disorient the target
animal and will also extend the service life of the battery. The user 8
controls the mode of
operation by pressing the switch cover 134, which activates the plunger 320
and in turn activates
the switch 311 as follows: one press within a three second period, and the
beam comes on in
continuous mode and will remain in continuous mode even if the switch 311 is
not again pressed;
two presses within a three second period generates the periodic strobe effect;
three presses within
a three second period generates the randomized strobe; holding the switch 311
down for three
seconds turns the unit off if the unit is on in any mode. Similar electronic
control circuitry is well
known in the art. The circuitry described herein is for the preferred
embodiment, but other
common on-off and multi-mode switches could be used.
[0038] The nose cap 140 screws onto the electronics compartment 130 by means
of appropriate
corresponding threading, and is sealed by means of an appropriately sized O-
ring. The nose cap
140, when secured, is flush with the electronics module compartment 130. As
shown in FIG 8,
there is a Diode Pumped Solid State laser 400 mounted within the nose cap 140
by means of
external threads on the laser 400 and corresponding threads in the nose cap
140. There is an
electric laser lead 410 that connects to the control module 300 as described
above to provide
power to the laser 400. As noted, in an alternate embodiment a laser diode can
be used. The laser
400 will be described in detail below. The nose cap 140 includes a thick
cylindrical block of
aluminum which acts as a heat sink 144. The heat sink 144 can include
wraparound vanes 145
for heat dissipation. In the most preferred embodiment the diameter of the
heat sink 144 is one
and one half (1.5) inches, and the grooves are 3 mm deep and 2 mm wide, with 3
mm ribs
created therebetween.
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[0039] The lens assembly 150 is attached to the end of the laser 400. In the
preferred
embodiment the laser 400 has external threading, and the lens assembly has
corresponding
threading to allow the lens assembly 150 to screw onto the laser 400. In
alternate embodiments
the lens assembly 150 can be manufactured as an integral component of the
laser 400. The lens
assembly 150 will typically be a small cylindrical shaped structure that is co-
axial with the laser
400. As seen in detail in FIGS 9, 10 & 11, the lens assembly 150 has a lens
assembly aperture
151 and a lens recess 152 sized to accommodate the diverging lens 500. The
lens 500 is held into
place within the lens recess 152 by means of two appropriately sized 0-rings
157, one on the
inside and the other on the outside of the lens 500. The lens assembly
aperture 151 is positioned
to allow the laser beam 410 to project into the diverging lens 500. The lens
recess 152 has
internal threading, and there is a lens assembly mounting ring 155 with
external threading sized
to screw into the internal threading of the lens recess 152 such that the
mounting ring 155 is
screwed into the recess and presses against the outer 0-ring 157 to hold the
lens 500 in place. In
an alternate embodiment, shown in FIG 11, there is a double convex lens as the
diverging lens
510. In all other regards, the structure and operation of the device is the
same with the double
convex lens 510 instead of the ball lens 500.
[0040] The windowed aperture front cap 160 has a threaded sleeve which accepts
an 0-ring seal
from the nose cap 140. The front cap 160 is best seen in FIGS 2 & 3. The front
cap 160 contains
a centered, machined recess 161 into which a clear acrylic or glass window
disc 162 is fitted and
sealed into place. The external end of the front cap 160 contains a deeply
machined inwardly
beveled cone to protect the clear window from damage if the unit is dropped,
yet makes cleaning
the window easy. In an alternate embodiment the diverging lens 500 cold
replace the aperture
window.
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[0041 ] There is a cold weather version of the bear dazzler 10, depicted in
FIGS 12, 13, 14, 15 &
16, which consists of a pocket unit 700 and a hand unit 800 which is
operatively connected by a
connecting cable 900. The cold weather version allows the bear dazzler 10 to
be worn under a
coat or other clothing and close to or against the user's body. Most lasers
must heat up to be
effective, and when worn against the body, body heat will keep the battery 200
and laser 400
operating with no cold startup latency or degraded performance. The laser beam
410 is
transmitted fiber-optically to a hand held unit 800 which electrically
controls the bear dazzler 10
and diverges the resulting beam of laser light 410.
[0042] The pocket unit 700 consists of the battery compartment 120, closed by
the end cap 110,
a modified electronics compartment 130, a modified nose cap 147 with the
internal laser 400.
Instead of the end cap 160, there is a transfer cap 710 which houses a fiber
optic cable 910 that is
aligned axially with the laser 400, such that the beam 410 will flow through
the fiber optic cable
910. The flow of light through a fiber optic cable is well known. The hand
unit 800 has a hand
unit housing 820 that is similarly sized and shaped to resemble the housing
100 of a standard
bear dazzler 10. The hand unit 800 contains a hand control switch 810 which is
connected to the
circuit board 310 of the control module 300 by means of an electronic control
cable 920. The
electronic control cable 920 is a binary wire as is common for use in similar
switching
mechanisms. The electronic control cable 920 attaches to the circuit board 310
at the cold
weather connection point 390. The hand control switch 810 is operated in the
same fashion as the
main on-off switch 311 of the standard bear dazzler as described above. As
best seen in FIG 15,
the lens assembly 150 is mounted at the terminus of the fiber optic cable 910
at the end of the
hand unit 800. There is a conduit 900 connecting the pocket unit 700 with the
hand unit 800. The
conduit 900 is a tube of appropriate length, which in the preferred embodiment
is about 1 meter.
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As seen in the perspective cut away view of FIG 16, the conduit 900 houses the
fiber optic cable
910 and the electronics control cable 920.
[0043] As seen in FIGS 8 & 9, the lens assembly 150 is mounted at the end of
the laser 400, and
sits within the nose cap 140. In the most preferred embodiment the lens
assembly 150 thread
mounts to the output end of the laser 400, but could be mounted by other
conventional means or
could be manufactured as an integral part of the laser 400 assembly. The lens
assembly holds a
diverging lens 500, which in the preferred embodiment is a simple fiber-optic
terminating ball
lens 500. In an alternate embodiment the diverging lens could be a double
convex lens 510.
Either type of diverging lens provides beam divergence of between 5 to 30
degrees depending on
the version of bear dazzler 10 used. In the most preferred embodiment the beam
divergence is 15
degrees, and in alternate embodiments the beam divergence is between 10 and 30
degrees.
[0044] The laser 400 is an off-the-shelf Diode Pumped Solid State (DPSS) laser
module
commonly used for small laser devices such as astronomical or surveyor laser
pointers. The laser
400 has an output wavelength of 532 nm, which appears as a lime-green in the
visual spectrum
and is often referred to simply as a green laser, and has a power output in
the 100 to 500 mw
range, as product variations demand, with a most preferred power output of 200
mw. A 555 nm
wavelength would be the most preferred wavelength because it centers on the
eye's most
sensitive reception curve. The internal components of the DPSS laser 400 are
well known in the
art and relatively standard. They are described herein for reference purposes
only to help explain
how the device works.
[0045] A laser beam, like every light source, will diverges from the point of
emission, but it is
the nature of laser beams to have a very low angle or degree of divergence.
This very low angle
of divergence is ideal for most standard prior art dazzlers, which require a
high beam intensity at
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long distances. The bear dazzler 10 requires a lower intensity and is only
used at a medium
distances of generally less than 50 feet (or about 15 meters) and requires a
much larger beam
divergence angle. This allows the user to project the beam only in the general
direction of a
target animal without the need to aim precisely. This larger divergence, or
beam spread, is
accomplished by means of the diverging lens 500. There are a wide variety of
diverging lenses
available, but the bear dazzler uses either a ball lens, shown in FIG 10, or a
double convex lens,
shown in FIG 11. The ball lens is the most preferred option because it is
easier to construct the
desired apparatus and hold the ball lens 500 within the lens assembly 150.
[0046] The beam divergence angle is controlled by the focal length of the
lens. For a ball lens
the focal length is a factor of the diameter of the ball. As the diameter of
the ball decreases the
divergence angle of the beam increases. Table 1 depicts the association for
beam divergence
angles of between 10 and 30 degrees and the associated ball lens diameter and
double convex
lens focal length.
Table 1
Beam Double
Divergence Convex Lens Nominal Ball
Angle Focal Length Focal Nominal Diameter Nominal
in Degrees in mm Length Diameter in mm Diameter
9.0 9.0 6.0 11.2 10.0
6.0 6.0 6.0 7.5 8.0
4.5 4.5 4.5 5.6 6.0
3.6 4.5 5.0
3.0 3.0 3.0 3.7 4.0
[0047] The preferred embodiment uses a glass ball lens. In the most preferred
embodiment the
lens is an Edmund Optics N-BK7 Ball lens, made of fused silica, but other
similar ball lenses
would work as well. In the preferred embodiment the beam divergence angle with
the most
appropriate properties was between 5 and 30 degrees, with a beam divergence
angle of 15
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degrees as the most preferred embodiment.
[0048] The beam divergence angle controls both the intensity of the beam and
the diameter of
the beam at a distance from the bear dazzler. As can be appreciated, there
needs to be a sufficient
intensity to cause an animal to look away, as well as a large enough beam
diameter at a distance
to easily acquire a target animal. The dazzler effect is well known and
described in a number of
prior art patents. See, e.g. U.S. Patent No. 5,685,636 to German. The dazzler
produces a light
beam of sufficient brightness that it is uncomfortable for the target person
or animal to look at
the beam. This causes the target to look away. This process is referred to in
the prior art as being
dazzled.
[0049] The actual intensity of a laser beam striking an object depends on the
object's distance
from the laser and the laser's divergence and energy profile. For a continuous
wave laser of the
type used in the bear dazzler, the intensity I (which is typically measured in
watts/Cm2 or
milliwatts/cm2) can be calculated by dividing the power rating by the area of
the beam spread,
which is also called the beam footprint. For example, for an ideal laser
operating continuously,
having a conical divergence pattern and an even distribution of intensity
throughout the beam
(i.e., no "hot spots"), the intensity I is provided by the equation:
I=P/n(x=tan(a/2)) 2 ; where P is
the laser power (typically measured in watts), x is the distance from the
laser, and a is the laser
beam divergence angle. For pulsed lasers, which operate with a pulse duration
and frequency, the
intensity is also a function of the pulse rate and energy density (typically
measured in Joules) per
pulse, as will be understood by those of ordinary skill in the art. Ideally,
the intensity of the bear
dazzler is tailored such that the maximum intensity In,ax does not exceed the
Maximum
Permissible Exposure (MPE) threshold, as set forth in, for example, the ANSI
Z136.1-1993
guidelines, within the intended effective zone of the device. Although it is
often preferred to
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impose the MPE limit on the present invention, it may be desirable to exceed
the MPE under
some circumstances, such as when the target poses a particularly high threat,
or when it is highly
unlikely that the target will be within the range in which the intensity
levels exceed the MPE. In
situations where a dangerous animal is in close proximity (depicted as Zone A
in FIG 18) the
only choice to avoid injury or even death to the person will be to impose
potential harm to the
eye of the animal. Although this is clearly an undesirable situation, there
may be cases where it is
unavoidable. At 200 mw power output, the Maximum Permissible Exposure (MPE)
distance is
less than two meters, making this the safety zone within which the bear
dazzler 10 should not be
used.
[0050) The standard laser 400 uses a light of the green visible frequency,
which is generally the
most efficient light to produce, and it is well known in the laser arts to
produce this particular
type of light. This green is a highly visible color, and also a color that the
human eye is both
highly attuned and sensitive to. A few studies of bears have indicated that
bears have similar
optical physiology to humans, so it is believed that green is also be highly
sensitive to bears.
Field tests have been conducted with green lasers and have produced acceptable
results. It is
possible, and within the concept of this invention, for other types of lasers,
that is other colors, to
be used. While the most preferred embodiment uses green lasers, it is to be
understood that other
color lasers could also be used. It is possible that other animals are more
sensitive to other colors,
and where appropriate to the desired animal, those colors will be used.
[0051] The eye damage danger thresholds, or Maximum Permissible Exposure
(MPE), are set
out it Table 2a and 2b. Tables 2a & 2b set out the intensity of the light I in
Watts per meter
squared (W/m). The intensity is a product of the power of the beam P. the
divergence angle a,
and the distance D: I = 4nP/ (aD)2. The intensities in bold are over the MPE.
The chart shows the
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intensity as a factor of the divergence angle of the beam and the distance, or
range in meters,
away from the beam source. As can be seen, a beam with a 5 degree spread or
divergence angle
can have an unacceptable intensity of just over six meters, or about twenty
feet. This means that
in some situations it could be possible for eye damage to occur at that range
if this beam
divergence angle is used. Beam divergence angles of 10 degrees and over have a
much more
appropriate safe range. The most preferred beam divergence angle is 15
degrees, and as can be
seen in Table 2 that means there is potential eye damage at just over two
meters, or
approximately six feet. If a bear or wild animal is at that close proximity to
a human there is an
equal chance of harm to the human. The dazzler 10 is safe at any distance over
2 meters, and the
15 degree beam divergence angle indicates that the dazzler is safe beyond two
meters. Table 2a
shows the intensity for distances of one to ten meters, and Table 2b, which is
a continuation of
the data from Table 2a, shows the intensity for distances of eleven to twenty
meters. The bolded
intensity numbers in Table 2a represent intensities that exceed MPE.
Power Range
in in
W Meters
Angle
in
m W Degrees 1 2 3 4 5 6 7 8 9 10
Intensity
200 5 42.08 10.52 4.68 2.63 1.68 1.17 0.86 0.66 0.52 0.42 in W/m
200 10 10.52 2.63 1.17 0.66 0.42 0.29 0.21 0.16 0.13 0.11
200 15 4.68 1.17 0.52 0.29 0.19 0.13 0.10 0.07 0.06 0.05
200 20 2.63 0.66 0.29 0.16 0.11 0.07 0.05 0.04 0.03 0.03
200 25 1.68 0.42 0.19 0.11 0.07 0.05 0.03 0.03 0.02 0.02
200 30 1.17 0.29 0.13 0.07 0.05 0.03 0.02 0.02 0.01 0.01
Table 2a
Power Range
n in
W Meters
mW Angle 11 12 13 14 15 16 17 18 19 20
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in
Degrees
Intensity
200 5 0.35 0.29 0.25 0.21 0.19 0.16 0.15 0.13 0.12 0.11 in W/m
200 10 0.09 0.07 0.06 0.05 0.05 0.04 0.04 0.03 0.03 0.03
200 15 0.04 0.03 0.03 0.02 0.02 0.02 0.02 0.01 0.01 0.01
200 20 0.02 0.02 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01
200 25 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.00
200 30 0.01 0.01 0.01 0.01 0.01 0.00 0.00 0.00 0.00 0.00
Table 2b
[0052] The degree of the beam divergence angle of the bear dazzler 10 will
have a direct bearing
on the maximum operable distance and effective range of the bear dazzler. This
will be a product
of the intensity, as described above, but also of the diameter of the beam and
the ease with which
the beam can be directed at and fall upon a target animal. FIG 17 shows the
patter of a typical
beam of light, or of the beam 410 produced by the diverging lens 500 of the
bear dazzler 10. One
of the main characteristics of a laser beam is that there is generally very
little beam divergence,
or spread of the beam. This means that a standard laser beam can be projected
to great distances
without the footprint of the beam changing appreciably. The bear dazzler 10
uses a diverging
lens 500, as explained above, to cause the beam 410 to spread. A beam of light
will cast a light
upon a surface, and the pattern that this light creates upon the surface is
known as the footprint.
The footprint 430 of the beam 410 of the bear dazzler 10 is a product of the
divergence angle
created by the lens, and the distance of the object from the dazzler 10. Table
3 shows the
diameter of the footprint 430 at selected distances from the dazzler 10.
Table 3
Beam Range
Divergence in
Angle in Meters
Degrees From
Dazzler
1 2 3 4 5 6 7 8 9 10
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0.09 0.18 0.26 0.35 0.44 0.53 0.61 0.70 0.79 0.88 Diameter
0.18 0.35 0.53 0.70 0.88 1.05 1.23 1.40 1.58 1.75 of
0.26 0.53 0.79 1.05 1.31 1.58 1.84 2.10 2.36 2.63 footprint
0.35 0.70 1.05 1.40 1.75 2.10 2.45 2.80 3.15 3.50 in
0.44 0.88 1.31 1.75 2.19 2.63 3.06 3.50 3.94 4.38 meters
0.53 1.05 1.58 2.10 2.63 3.15 3.68 4.20 4.73 5.25
[0053] Typically the maximum effective distance is approximately 10 meters or
about thirty feet.
With a lens having a ten degree divergence or beam spread the beam footprint
430 will be 1.75
meters in diameter, or about five feet wide, at ten meters from the dazzler
10. This should be
sufficient to fairly easily aim the bear dazzler to ensure that the beam will
shine upon the face
and into the eyes of the bear or other target animal. Most animals have eyes
that are less than one
foot apart. Bears and most predators, like wolves or large cats, have eyes
that face forward,
giving the animal binocular vision. When the animal is facing the dazzler 10
it will appear as a
single dot of light. Other large and potentially dangerous animals, such as
bison or moose in
North America, have eyes positioned on the side of the head. In either case
the width of the beam
will be sufficient to fall upon both eyes of an animal in the target range,
and the intensity will be
sufficient to cause eye irritation and to induce the animal to turn look away
from the light. When
most animals look away from an object they also turn away, so the result is
that when the bear
dazzler causes eye irritation the animal will turn away.
[0054] With a beam divergence of 30 degrees, the beam footprint 430 will be
5.25 meters or
about 17 feet wide at 30 feet (10 meters) distance from the dazzler 10. This
means that it will be
significantly easier to aim the dazzler with a 30 degree beam divergence
angle. But because the
intensity will be lower with a higher beam divergence angle this means that
the effective range
will be comparably shorter. A larger divergence angle makes the dazzler easier
to aim but
decreases the effective range. Conversely, a lower beam divergence angle
increases the operable
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deterrent distance of the dazzler, but it makes the dazzler slightly harder to
aim. There is a trade-
off between effective range and ease of aim. As a result the beam divergence
angle of 15 degrees
in most preferable.
[0055] The beam divergence angle allows the user to be able to only have to
point the dazzler in
the general direction of the animal to be effective and to hit both eyes. With
a standard, non-
diverged laser beam it would be necessary to precisely point the laser into
the animal's eye, and
it would be possible to only hit one eye at a time at an operable distance.
Standard dazzlers have
a small beam spread with a desired useful distance of hundreds, if not
thousands of feet, and so
would hit both eyes of a bi-focal animal (like a human or a bear) at between
(hundreds and
thousands of feet), which would be well beyond the operable range necessary
for a hiker
encountering a bear. The optimal range of the bear dazzler is between ten and
twenty yards. It is
desirable to keep the bear at least ten yards, or about thirty feet, away.
[0056] The method of use of the bear dazzler 10 is depicted in FIG 18. The
bear dazzler 10
produces a laser light in a diverged beam 410 that has sufficient intensity to
temporarily disorient
and unsettle a bear 8 (or other target animal) by depriving it of effective
sight, much like the
effect of looking into a photo flash. When the user 8 encounters a situation
where a bear 5
approaches or the user 8 wishes to move a bear 5 out of an area, the light
beam 410 from bear
dazzler 10 is aimed at the bear's head and face. Even if bright sunlight
prevents the user 8 from
seeing the beam 410, the beam 410 should be generally aimed in the appropriate
direction of the
bear 5. The breadth of the beam 410 will adequately cover the target area even
if the bear dazzler
is not precisely aimed. This is important since it will often be difficult to
precisely aim in a
stressful situation such as an encounter with a potentially dangerous animal.
As the bear 5 draws
nearer to the bear dazzler 10, the beam becomes increasingly intense, as
defined by the inverse
CA 02783218 2012-07-05
square law of light, as defined above. At the point where the bear 5 loses
compelling visual
acquisition, it will turn away. If the bear 5 makes additional approaches,
repeat the application
as necessary, until the animal tires and departs.
[0057] The bear dazzler 10 can be used in conjunction with other techniques
such as silence,
standing still, advancing while the bear 5 is dazzled, individuals grouping
together to appear
larger and/or employing body movements and noise or yelling to appear more
formidable. The
temperament of the bear 5 and circumstances of the encounter will determine
the correct
approach.
[0058] The diagram of FIG 18, depicts the user 8 standing at the bottom of the
figure, and
projects the bear dazzler beam 410 at the approaching bear 5. There are three
defined zones:
Zone A is the Maximum Permissible Exposure (MPE) safety zone. If the bear 5 is
within zone A,
a prolonged gaze into the bear dazzler 10 could result in permanent injury to
the retina of the
animal. Specifically the light can create a permanent dark spot in the field
of vision. The MPE
threshold distance from the bear dazzler 10 is under 2 meters or 6.7 feet,
depending on the beam
divergence angle. Zone B is the effective zone. An animal 5 in this zone is
disoriented and
thwarted from further approach. Zone C is the detection zone. It extends from
the Zone B
effectiveness threshold to an indefinite distance. An animal 5 in this zone
will detect the Bear
Dazzler but will not be appreciably affected by it. The dazzler will appear to
the animal as a
point of light, but not produce a beam 410 of sufficiently intensity to cause
the animal to turn
away. Preliminary field tests indicate that the effective range of the bear
dazzler 10 is
approximately 10 meters, or thirty feet using a 15 degree beam divergence.
[0059] The present invention is well adapted to carry out the objectives and
attain both the ends
and the advantages mentioned, as well as other benefits inherent therein.
While the present
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invention has been depicted, described, and is defined by reference to
particular embodiments of
the invention, such reference does not imply a limitation to the invention,
and no such limitation
is to be inferred. The depicted and described embodiments of the invention are
exemplary only,
and are not exhaustive of the scope of the invention. Consequently, the
present invention is
intended to be limited only be the spirit and scope of the claims, giving full
cognizance to
equivalents in all respects.
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