Note: Descriptions are shown in the official language in which they were submitted.
CA 02652218 2013-03-28
LED WORK LIGHT
TECHNICAL FIELD
The invention relates to work lights and components therefore, and to lenses.
More particularly,
it relates to LED work lights and components therefore, and to lenses for use
with LEDs.
BACKGROUND ART
Work lights, often known as "trouble lights", are widely used in automotive
repair shops and
other repair settings and construction settings. Such work lights are often in
a form that can
alternatively be handheld or hung from a suitable elevated object such as a
raised automobile
hood.
Incandescent work lights have been in use, but they have some drawbacks. One
drawback is that
work lights are all too often dropped or knocked down and fall onto a hard
surface, and this often
results in breakage of the bulb or its filament. An additional drawback of
incandescent work
lights is a safety hazard that results from the possibility of the bulb
breaking with its hot filament
in close proximity to flammable material such as spilled flammable liquid if
the work light
suffers a fall.
Fluorescent work lights exist and they have advantages over incandescent work
lights, namely
greater energy efficiency and a reduced hazard of igniting flammable materials
if they suffer a
fall. However, fluorescent work lights can experience breakage of their bulbs
if they suffer a
fall. Although breakage of an operating fluorescent bulb is not as likely to
ignite nearby
flammable materials as breakage of an incandescent bulb is, there is still a
slight chance that a
fluorescent bulb can ignite adjacent flammable materials if broken while
operating since
fluorescent lamps normally have hot filaments while they are operating. There
are fluorescent
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work lights that have impact cushioning means included to increase their
ability to survive falls,
but they still have a slight chance of experiencing breakage of their bulbs if
they fall onto a hard
surface.
LED work lights are better able to survive falls than are work lights that
have glass bulbs.
Furthermore, LEDs do not generally operate with parts hot enough to ignite
flammable materials,
so even falls that do result in breakage are less likely to cause fires than
are similar falls of work
lights that have glass bulbs.
The prior art has LED work lights. Many produce light that is insufficiently
intense or in the
form of an excessively narrow beam. It is possible to achieve adequately
intense light in an
0 adequately wide beam by using a large number of LEDs. However, a work
light having a
sufficient number of LEDs and sufficient power input to achieve adequately
intense light in an
adequately wide beam without overheating of the LEDs is generally large and
expensive.
As described further herein some features of some aspects of the invention
will address some of
the issues raised above. Other features and other aspects will address other
issues with existing
5 LED lights to provide alternatives or improvements thereto.
DISCLOSURE OF THE INVENTION
In a first aspect the invention provides an LED work light including a handle
section and a head
section and a structural tube. The structural tube extends through the head
section and the handle
section. The light further includes at least one LED mounted in the tube
within the head section,
:0 and power receiving means for the at least one LED to receive electrical
power. The light further
includes an LED board in the tube within the head section and the at least one
LED is attached to
the LED board,. The light further includes a heatsink in the tube within the
head section and the
LED board is fastened to the heatsink in a manner that achieves thermal
contact between the at
least one LED and the heatsink. The structural tube is transparent in the head
section for light
from the at least one LED to emit from the work light.
At least one of the at least one LED may include a plurality of LED chips
within a diffusing
dome. The at least one LED may comprise separate electrical terminals for each
chip. The chips
within each LED may be connected in series with each other.
The at least one LED may receive power from a boost converter. The entire
structural tube may
10 be transparent. The at least one LED may include a white LED.
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The LED work light may include a battery to supply power to the power
receiving means. The
battery may be rechargeable for recharging the battery. The LED work light may
include a
charging circuit for recharging the battery.
The may produce a beam that is at least about 40 degrees wide and about 100
degrees wide or
less.
A convex lens may be disposed forward of at least one of the at least one LED
to achieve a beam
having a width of at least above 40 and about 100 degrees or less.
The at least one LED may have a voltage drop of about 80-85% of the voltage of
the battery, and
current through the at least one LED may be controlled or limited by at least
one resistor. An
0 individual LED chip may be connected directly in parallel with at least
one other LED chip.
Individual LED chips may be connected together in a series-parallel manner.
At least one LED may include only one dropping resistor for each LED with only
some of the
LED chips connected in series with each other. All of the chips in at least
one of the at least one
LED may be connected in parallel with each other.
5 All of the chips in at least one of the at least one LED may be connected
together in a series-
parallel manner. At least one LED may be mounted to an opposite side of the
LED board from a
side of the LED board that faces a direction which light from the at least one
LED is directed
towards. At least one of the at least one LED may be a multichip LED.
The LED work light may include a convex lens associated with at least one of
the at least one
!O LEDs to concentrate the light from its associated LED into a beam that
is between about 40 to
100 degrees wide.
At least one of the at least one LED may be pressed against the heatsink by
the LED board. The
LED work light may receive electrical power from an external power source that
is designed to
provide limited output current if the power source is shorted.
The LED work light may include grounding means. The LED work light may receive
power
from the external power source through two conductors, and may include a
separate grounding
conductor. The LED work light may receive power from the external power source
through two
conductors, and one of the two conductors may also be used as a grounding
conductor.
In a second aspect the invention provides an LED work light including at least
one LED and a
;0 lens associated with the at least one LED, wherein at least one of the
at least one associated lens
has a curved surface that is nonhemispheric while a cross section of the
nonhemispheric surface
of the lens includes at least one circular arc and all arcs arcs circular.
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A lens associated with at least one of the at least one LED may be a convex
lens that
concentrates the light from its associated LED into a beam that is between
about 40 to 100
degrees wide. At least one lens may be a concavoconvex lens.
A convex surface of the at least one lens may be hemispheric and a concave
surface may be non-
hemispheric. The concave surface may be a cross section including a lens axis
with at least one
circular arc and without non-circular arcs.
The LED work light may include a single piece transparent lens assembly
including more than
one concavoconvex lens with a hemispheric convex surface and a non-hemispheric
concave
surface that has a cross section including a lens axis with at least one
circular arc and all arcs
0 being circular.
The LED work light may include magnets to allow the LED work light to be
attached to a
magnetic surface.
In a third aspect the invention provides an LED work light comprising a head
section, a handle
section, at least one LED within the head section, and a transparent shield.
The head section
5 includes transparent structural material that allows light from the at
least one LED to emit from
the head section. The transparent shield is suitable for protecting said
transparent structural
material from scratches and abrasions. The transparent shield is removable and
replaceable.
The transparent shield may be in the form of a tube that surrounds the head
section of the LED
work light. The transparent shield may bein the form of a circular tube. The
transparent shield
may be made of a plastic that is related to polyethylene. The transparent
shield may be made of
polyethylene terephthalate. The transparent shield may be made of
polytetrafluoroethylene. The
transparent shield may include a plurality of laminations with the laminations
removable one at a
time by means of removing an outermost lamination. The transparent shield may
include an
adhesive between respective laminations.
Z5 The LED work light may include at least one lens, each lens associated
with a respective one of
the at least one LED. The LED work light of claim 42, wherein the at least one
lens concentrates
light from its associated LED into a beam of width of between about 40 degrees
and about 100
degrees.
In a fourth aspect the invention provides an LED work light including a head
section,
30 a handle section, at least one LED within the head section, a lens
associated with each of the at
least one to concentrate the light from the at least one LED, and a
transparent shield suitable for
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protecting the lens associated with each of the at least one LED from
scratches and abrasions.
The transparent shield is removable and replaceable.
Sealing means may be used at the edges of the transparent shield. The sealing
means may
include a gasket. The sealing means may include an 0-ring. The sealing means
may include
part of a rubber cover. The rubber cover used for sealing means may be a
handle cover. The
rubber cover used for sealing means may include a cap at one end of a tubular
structure.
In a fifth aspect the invention provides an LED work light including a handle
section and a head
section and at least one LED mounted in the head section and means for the at
least one LED to
receive electrical power and further including magnets within the LED work
light to allow the
0 LED work light to be attached to a magnetic surface.
The LED work light may have a beam with a width that is between at least about
40 degrees and
about 100 degrees or less. The LED work light may include at least one lens to
concentrate light
from at least one LED into the beam. The LED work light may include a housing
of polygonal
shape to allow it to be attached to a magnetic surface so that light from the
LED work light is
5 directed from the LED work light at an angle from the surface that the
LED work light is
attached to.
The housing may have a shape of a partial octagon to permit the LED work light
to be attached
to a magnetic surface so that light from the LED work light is directed into a
direction 45 degrees
from the magnetic surface.
).,0 In a sixth aspect the invention provides an LED work light including a
head section and a handle
section and at least one LED of a type suitable for mounting onto a heatsink,
a heatsink that the
at least one LED is mounted onto, a structural plate disposed forwards of the
heatsink, and a hole
in the structural plate associated with each LED of the at least one LED.
The LED work light may include a lens mounted onto the structural plate in
front of and
associated with at least one of the at least one LED. The heatsink may be a
metal core printed
circuit board. The structural plate may be a printed circuit board.
In a seventh aspect the invention provides an LED work light including a head
section, a handle
section and a hook. The head section has an axis, and the LEDs are mounted
within the head
section such that the light output from the LEDs is directed from the head
section at an angle
30 from the axis of the head section. The transparent shield may be made of
polycarbonate.
BRIEF DESCRIPTION OF THE DRAWINGS
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For a better understanding of the present invention and to show more were
clearly how it may be
carried into effect, reference will now be made, by way of example, to the
accompanying
drawings which show the preferred embodiment of the present invention and in
which:
FIG. 1 is a cross sectional side view of a first example embodiment of a work
light,
FIG. 2 is a cross sectional side view of an example embodiment of a lens that
may be used in a
work light such as those described herein,
FIG. 3 is an exploded side view of an example embodiment of an LED light
source assembly that
may be used in a work light such as those described herein,
FIG. 4 is a diagrammatic illustration of a second example embodiment of a work
light,
0 FIG. 5 is a block diagram of an example power supply that may be used in
the work light
embodiments described herein,
FIG. 6 is a cross sectional side view of a third example embodiment of a work
light,
FIG. 7 is a cross sectional side view of a fourth example embodiment of a work
light,
FIG. 8 is a cross sectional side view of a fifth example embodiment of a work
light,
5 FIG. 9 is a diagrammatic illustration of an example embodiment of a
transparent shield that may
be used in a work light such as those described herein,
FIG. 10 is a frontal view of a second example embodiment of a shield that may
be used in a work
light such as those described herein,
FIG. 11 is a partially exploded perspective view of a sixth example embodiment
of a work light,
FIG. 12 is a cross sectional top view of an example variation of the sixth
embodiment,
FIG. 13 is an exploded side view of a second example embodiment of an LED
light source
assembly that may be used in a work light such as those described herein,
FIG. 14 is a cross sectional side view of a seventh example embodiment of a
work light,
FIG. 15 is a partially exploded perspective view of an eighth example
embodiment of a work
as light,
FIG. 16 is a first example circuit diagram of an embodiment of a circuit work
light, suitable for
use in embodiments of work lights described herein,
FIG. 17 is a second example circuit diagram of an embodiment of a circuit work
light, suitable
for use in embodiments of work lights described herein,
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FIG. 18 is a cross-sectional end view of an example head section of the work
light embodiment
of FIG. 1,
FIG. 19 is a cross-sectional end view of an alternative example head section,
FIG. 20 is a side cross-section of a portion of a tubular work light
illustrating an example
embodiment of a position sensing switch,
FIG. 21 is an example circuit employing a position sensing switch; the circuit
may be used in
work light such as, for example, the work light embodiments described herein,
and
FIG. 22 is a side cross-section of a portion of a tubular work light
illustrating an alternate
example embodiment of a position sensing switch.
0
MODES FOR CARRYING OUT THE INVENTION
Referring to FIG. 1, an LED work light 100, has a head section 101 and a
handle section 102.
The LED work light 100 has a transparent plastic tube 103 as a main structural
member, which is
common to both the head section 101 and the handle section 102. The plastic
tube 103 is
5 preferably polycarbonate but may alternatively be made of a different
plastic such as acrylic.
Other suitable transparent materials, plastic or non-plastic, may be utilized
for the tube 103. The
plastic tube 103 may have ridges and/or one or more grooves (not shown) to
hold.
The LED work light 100 has at least one LED 104. The LED work light 100 is
shown as having
two LEDs 104, although a different number of LEDs 104 can be used. LEDs 104
are preferably
mounted onto an LED board 106. The LED board 106 is preferably also a heatsink
and may be
made of metal core printed circuit board. Alternatively, an LED board 106 can
be made to have
useful heatsinking capability by attaching a conventional circuit board to a
metal heatsink such
as a piece of sheet metal. A conventional circuit board incorporated into a
heatsinking LED
board 106 may have large copper pads and a large number of thermal vias to
conduct heat away
Z5 from LEDs 104. In this description when referring to an LED, the LED
includes its package and
each LED chip within the package.
The LEDs 104 are multichip LEDs with diffusing domes and preferably have
separate electrical
terminals for each chip. Any of the LEDs 104 may be, for example, Citizen
Electronics of Japan
CL-652-8WN, which has 8 chips and 16 terminals and a diffusing dome
approximately 5
30 millimeters in diameter. This description will often reference the
Citizen Electronics LED as an
example of an LED that can be suitable for embodiments providing some of the
features and
functions described herein. It is to be understood that other LEDs having
different
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characteristics may be utilized to provide embodiments with some or all of the
features and
functions described herein. This LED has an essentially lambertian radiation
pattern, with a
nominal beam width of 120 degrees.
Preferably LEDs 104 produce essentially white light for most illumination
tasks that LED work
lights would be used for. The Citizen Electronics CL-652-8WN is a white light
LED. A
combination of white and colored LEDs can be used in an LED work light 100 to
adjust the color
balance or the color rendering properties of the light produced by the LED
work light 100. For
example, one or more red and one or more green LEDs can be used in addition to
white light
LEDs 104 to achieve either a high color rendering index or even exaggerated
color rendering.
0 One or more blue LEDs can be added to a combination of red, green and
white light LEDs to
achieve good or exaggerated color rendering while maintaining a high color
temperature typical
of most white LEDs. Any colored LEDs may or may not have multiple LED chips,
diffusing
domes or multiple electrical terminals. Other combinations of colour LEDs may
be used
including combinations having a single LED of a single colour.
5 Since most high power LEDs 104 have a beam width greater than 100
degrees, light from each
of the LEDs 104 is preferably concentrated by associated convex lenses 105
disposed forward of
their associated LEDs 104 in order to increase the intensity of the light
directed forward from the
LEDs 104. The convex LEDs 105 are a form of optic. Preferably the lenses 105
concentrate the
light from their associated LEDs 104 into a beam that is at least about 40
degrees wide and about
!O 100 degrees wide or less.
Alternatively, other optical devices such as reflectors can be used to
concentrate the light from
the LEDs 104 into a beam. Further alternatively, no optics can be used if LEDs
104 are obtained
that produce a suitable beam by themselves or that produce a sufficient
quantity of light without
being concentrated by any optics.
?,5 An advantage of having the LEDs 104 being multichip ones with diffusing
domes is that their
associated lenses 105 can sometimes be simple hemispheres without causing an
undesirable
bright ring at the edge of the beam. Use of hemispherical and most other
convex lenses with
LEDs having a single chip and a clear dome or clear body and with a radiation
pattern wider than
100 degrees such as many Lumileds LuxeonTM models tends to produce beams with
bright rings
30 at their edges. This can be solved by having a rear surface of a convex
lens being slightly
concave and with curvature of the concave surface being sharper towards the
edge of the
concave surface than toward the center of the concave surface. Depending on
the size of a lens
105 and other factors such as the size of the diffusing dome of an LED 104, a
hemispherical or
other planoconcave lens may or may not produce a beam with a bright ring at
its edge when
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concentrating the light from a multichip LED 104 having a diffusing dome. A
hemispherical
lens 105 made of acrylic and having a diameter of 0.5 to 0.75 inch has been
found to work if a
Citizen Electronics CL-652-8WN is being used as the LED 104. A hemispherical
acrylic lens 1
inch in diameter with the Citizen Electronics CL-652-8WN produces a beam that
has only a mild
and possibly tolerable bright ring at its edge.
Lenses 105, whether hemispherical or otherwise, are preferably made of acrylic
or
polycarbonate. Alternatively lenses 105 may be made of a different transparent
material such as
glass. Polycarbonate lenses can be made thinner than acrylic ones because
polycarbonate has a
higher refractive index than acrylic has. Making a thermoplastic lens thinner
can improve its
0 ability to be injection molded.
Even if an acrylic hemispherical lens 105 of a given diameter with a given LED
104 produces a
beam that lacks a bright ring at its edge, it may be preferable to use a
different shape lens 105.
For example, a polycarbonate concavoconvex lens can collect and concentrate
into a beam more
light from the LED 104 than a hemispherical lens.
5 The LED board 106 is shown as having circuitry 107 to ensure that the
current flowing through
the LEDs 104 is at a proper magnitude. The circuitry 107 may be one or more
resistors, linear
current regulators, switching current regulators or boost converters.
Alternatively, such circuitry
may be located elsewhere within the LED work light 100. Further alternatively,
it may be found
possible to power the LEDs 104 without such circuitry, such as in a case where
the LEDs 104
!O receive power from a battery 117 that has significant internal
resistance.
The LED board 106 preferably receives power from a battery 117 that are
contained within the
LED work light 100. Alternatively, the LED work light 100 may receive power
from an external
power source. Preferably the battery 117 is rechargeable. A rechargeable
battery 117 may be
nickel cadmium, NiMH, lead acid, lithium ion, or lithium polymer. As shown
made up of a
plurality of battery cells 117a; however, other battery 117 configurations are
possible as will be
evident to those skilled in the art.
If the LEDs 104 have chips that have a typical forward voltage drop of
sufficiently less than 3.6
volts, then each chip in the LEDs 104 can, for example, receive power through
a resistor in the
circuitry 107 from a battery 117 comprising three NiMH cells 117a. If in
addition the chips in
30 the LEDs 104 are connected in series pairs, then each series pair of LED
chips may, for example,
receive power through a resistor in the circuitry 107 from a battery 117
comprising six NiMH
cells 117a. If the forward voltage drop of an LED 104 is 80-85% of the voltage
produced by the
battery 117, then resistors in the circuitry 107 can be used to control the
amount of current
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flowing through an LED 104 with 80-85% of the power drawn from the battery 117
being
delivered to the LEDs 104, and such resistors will typically drop sufficient
voltage for the current
through the LEDs 104 to be adequately reliably at a proper magnitude.
Alternatively, a
switching current regulator (such as the one shown in FIG. 8 and associated
detailed description
of US Patent Application 11/083,086 on 18 March 2005 and published as
US20050265035A1 on
1 December 2005), or a boost converter (such as described in FIGS. 11-15 and
associated
detailed description of US Patent Application 10/885,031 on 7 July 2004 and
published as
US20050007777A1 on 13 January) may be used. A switching regulator or a boost
converter in
lieu of resistors for circuitry 107 can, for example, reduce losses in
circuitry 107; however, a
switching regulator or boost converter may not be economically warranted. If
the voltage drop
of an LED 104 is too close to the voltage produced by the battery 117 then
resistors may not
adequately control the magnitude of current flowing through the LEDs 104.
The LEDs 104 may have chips of sufficiently identical characteristics to
permit connecting the
chips in parallel or in a series-parallel manner without separate current
limiting means for each
chip or series combination thereof. This can simplify construction of the LED
work light 100 by
having each LED 104 having a single dropping resistor even if the chips in the
LED 104 are not
all in series with each other. At least one multichip LED by Citizen
Electronics is designed to
permit connecting the individual chips of the LED in parallel with each other
and to use only one
dropping resistor or other current limiting means to limit the current through
all of the chips.
Such a multichip LED can also have its chips connected together in a series-
parallel manner with
only one dropping resistor for the multichip LED.
White LEDs having Cree XT series chips or other LED chips with similarly low
voltage drop for
white LEDs can have voltage drops of 3.1-3.15 volts per chip at a current of
20-25 milliamps
through each chip.
The Citizen Electronics CL-652-8WN was found to have a voltage drop of 3.15
volts per chip
with 25 milliamps of current through each chip, which is approximately 84% of
the voltage of a
lightly loaded battery 117 comprising three NiMH cells 117a. Although the
Citizen Electronics
CL-652-8WN can safely receive more than 25 milliamps through each chip, its
light output can
be sufficient at a lower current that results in a lower voltage drop.
One advantage of multichip LEDs 104 that have separate terminals for each chip
is that the same
LEDs can be used in different versions of the LED work light 100 that have
different types of
circuitry 107. For example, the circuitry 107 may be changed from a set of
resistors to a boost
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converter, with the boost converter powering LEDs 104 if all of their chips
are connected in
series. Many boost converter circuits achieve the current limiting that is
typically necessary for
LEDs but only if the load voltage is either greater than or essentially equal
to the supply voltage,
and best utilized with several LED chips in series to achieve a relatively
high load
voltage.Another advantage of LEDs 104 that have multiple chips with separate
electrical
terminals is that the LEDs 104 can be used to replace different LEDs of
different voltage drops.
For example, an LED work light 100 having Lumileds of San Jose, California
LuxeonTMu 1
watt or 3 watt LEDs can have all chips in the LED 104 connected in parallel
with each other,
either directly or with current dividing resistors. Lumileds "Luxeon Vrm" LEDs
can be replaced
0 by LEDs 104 that have their chips connected into a parallel set of series
pairs, whether with or
without current dividing resistors.
For clarity, electrical connections from the battery to the switch and from
the switch to the
circuitry 107 are not shown; however, it is understood that appropriate
electrical connections
between the electrical components, for example by wires and printed circuit
board traces, are
5 provided.
The LED work light 100 is shown as having a separate charging board 108 with
charging
circuitry 109 to recharge the shown battery 117. Alternatively, the LEDs 104
and charging
circuitry 109 can be mounted onto the same board, preferably along with the
circuitry 107
typically required by the LEDs 104. If the charging circuitry 109 and the LEDs
104 are mounted
!O onto the same board, then the charging circuitry 109 may, if desired, be
mounted on the opposite
side of that board from the side that the LEDs 104 are mounted on.
Also included in the LED work light 100 are a switch 113 and a charging jack
114. The switch
113 is preferably a pushbutton switch; however, other switches may be used
such as for example
a toggle switch. The switch 113 and charging jack 114 are shown as being
mounted in a base
cap 115. As shown, the base cap may be mounted to the plastic tube 103 with
rivets 116. Other
mounting means may be used for the switch 113 or jack 114, or for the cap 115.
The switch 113 is shown as being mounted in the bottom of the LED work light
100.
Alternatively it may be mounted in a side surface of the LED work light 100 or
the top of the
LED work light 100.
;0 A handle cover 112 is shown as covering the handle section 102 of the
LED work light 100. The
handle cover 112 preferably also covers much of the base cap 115. The handle
cover 112 may
be made of rubber or another resilient material to protect from impact. The
handle cover 112 can
also provide a slip resilient grip surface. The handle cover 112 may have an
extension 118 to
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protect the switch 113 and charging jack 114 from impacts. The extension 118
can also be used
to rest the light 100 in an upright position.
The LED work light 100 is also shown as having a top cap 110 with a hook 111.
Preferably the
hook 111 can rotate within the top cap 110. The top cap 110 may be of a
material similar to that
of the handle cover 112 and liquid resistant when mounted to the tube 103. The
handle cover
112 and tube 103 can be in sufficiently close contact or sealed to be liquid
resistant.
Referring to FIG. 2, a lens 200 that may be used in the LED work light 100 of
FIG. 1 is shown.
The lens 200 may be similar to the lenses 105 of FIG. 1; however, the lens 200
is shown in
greater detail and with example mounting means.
0 The lens 200 is shown with a convex forward surface 201 and a rear
surface 202. The lens 200
is shown as being concavoconvex, having the rear surface 202 being concave. As
an alternative
example, a planoconvex lens may be used. A planoconvex lens may an aspheric
convex forward
surface 201.
The rear surface 202 of concavoconvex lens 200 is shown having a flat central
region 203 and a
5 curved outer region 204. Preferably the curved region 204 has its cross
section in a plane
containing the axis 206 of the lens 200 being a circular arc. This combination
of the flat central
region 203 and the curved outer region 204 is selected to approximate a curved
surface that is
less sharply curved towards its center and more sharply curved toward its
edge. While the lens
200 may work better if concave rear surface 202 is a single curve that
gradually sharpens toward
!O its edge (and such embodiments are included in the principles described
herein), making of a
mold for producing the lens 200 may be simplified by having all curves in the
lens 200
describable as circular arcs.
The convex forward surface 201 of the lens 200 is preferably a spherical
curve. The purpose of
having the convex forward surface 201 spherical is also to possibly simplify
making of a mold
used to produce the lens 200. Aspherical embodiments are included in the
principles described
herein.
The lens 200 is also shown as having holes 205 to permit mounting by means of
screws or rivets
or the like. The lens 200 may be otherwise mounted, for example, using epoxy.
Convex lenses other than the specific lens 200 may also be used as the lenses
105 in the LED
30 work light 100 of FIG. 1. For example, a single molded transparent piece
may have more than
one lens element. Such a molded lens assembly with more than one lens element
preferably has
each lens element having a hemispheric convex forward surface and a non-
hemispheric concave
rear surface with each rear surface having at least one circular arc and no
non-circular arcs in a
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cross section containing the axis of the lens element for reasons described
previously. Again,
other convex lenses may be used.
Referring to FIG. 3, an alternative example assembly of an LED board 306,
heatsink 108 LEDs
104, and lenses 200 is shown. Such an assembly differs from the arrangement
shown in FIG. 1
by having the LEDs 104 being placed against the heatsink 108 when the assembly
is assembled.
The LED board 306 differs from the LED board 106 of FIG. 1 by having holes to
allow the LED
board 306 to fit around the LEDs 104 in order to allow the LEDs 104 to
directly contact the
heatsink 108. Such an alternative assembly may, for example, be used in a
tubular LED work
light that is otherwise similar to the LED work light 100 of FIG. 1.
0 The LEDs are preferably soldered to the rear surface of the LED board
306. The light emitting
domes of the LEDs 104 protrude through holes 302 that are provided in the LED
board 306. The
LED board is fastened to the heatsink 108, such as with the shown screws 301.
The heatsink
may have tapped screw holes 303 for any screws 301. Alternatively, any screw
holes in the
heatsink 108 may be untapped and the screws 301 may screw into nuts. Further
alternatively,
5 other means of fastening the LED board 106 to the heatsink 108 such as
rivets may be used.
Fastening the LED board 306 to the heatsink 108 presses the rear surfaces of
the LEDs 104 to the
heatsink 108. Preferably the LED board 306 itself does not touch the heatsink
108.
Where desired, the LEDs 104 would be a type intended for mounting as shown.
The Citizen
Electronics CL-652-8WN is such an LED and has solder pad type terminals
towards the edge of
!O its forward surface to permit soldering to the LED board 106 in the
orientation shown.
As shown, any screws 301 or other fasteners used to fasten the LED board 106
to the heatsink
108 may also be fastening the lenses 200 to the LED board 106. As shown, the
lenses 200 would
actually be pressing against the LED board 106 in order to press the LEDs 104
against the
heatsink 108. Alternatively, the lenses 200 or different lenses may be mounted
by other means
such as glue or fasteners other than the ones used to fasten the LED board 106
to the heatsink
108.
A single LED board 306 is shown. Alternatively, more than one LED board 106
such as
individual LED boards 306 for each of the LEDs 104 may be used. Further
alternatively, the
LEDs 104 may be glued or otherwise fastened to the heatsink 108 in lieu of
having fastening
means fastening the LED board 306 to the heatsink 108.
Referring to FIG. 4, an LED work light 400 can be made like that of the LED
work light 100 of
FIG. 1 operating from electrical power received via a cable 401 from an
external power source
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402. The external power source 402 is shown as being of a "wall transformer"
type for
connection to a line power source, not shown.
The external power source 402 may have current limiting means such as current
regulation or a
resistor to minimize production of sparks if the cable 401 is inadvertently
severed and shorted.
This can permit use of the LED work light 400 in locations that are classified
as hazardous due to
presence or possible presence of flammable or explosive vapors or dust.
The LED work light 400 may lack a switch in order to minimize the possibility
of sparks.
Alternatively, the LED work light 400 may have a switch that is safe to use in
locations having
flammable or explosive vapors or dust. Further alternatively, a switch may be
mounted on the
0 external power source 402.
Any switch in the LED work light 400 may be a position sensing switch so that
the LED work
light 400 will shut off in response to being placed in a particular position.
Such a switch may be
a mercury switch. Such a switch may have a metal ball or a metal cylinder or
the like that rolls
onto contacts when the switch is in a particular position. Such a switch may
be a tilt switch, for
5 example a tilt switch designed for pinball machines. Such a switch may be
combined with
electronic circuitry to minimize the amount of current that the switch has to
conduct.
The LED work light 400 is shown as having three LEDs and associated lenses
403. Any number
of LEDs and associated lenses 403 may be used. The lenses 403 may be comprised
as convex
elements in a single piece of transparent material rather than having each
lens being a separate
!O piece of transparent material as shown in FIGS. 1, 2 and 3.
Referring to FIG. 5, the external power source 402 may comprise a transformer
501, a bridge
rectifier 502, a filter capacitor 503, a current regulator 504 and a voltage
regulator 505 as well as
input prongs 506 including a grounding prong 507 and an output cable 508.
Other arrangements
may be used to achieve an external power source 402 that is suitable for use
in hazardous
a5 locations. For example, a resistor may be used in lieu of the current
regulator 504.
The external power source 402 is shown as having three conductors in its
output cable 508. One
of these conductors is shown as connected to the grounding prong 507.
Alternatively, the output
cable 508 may have only two conductors, with one of the two conductors both
carrying output
current and being connected to the grounding prong 507. Further alternatively,
the output cable
30 may lack a conductor connected to any grounding prong 507 and may
further lack a grounding
prong 507, although it is preferable to have a grounding means to eliminate
accumulation of
static electricity on any LED work light 400 that is to be used in hazardous
locations.
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Referring to FIG. 6, an LED work light 100, similar to the LED work light 100
of FIG. 1, has
added to it a transparent plastic cover 119 in the form of a tubular sleeve.
The plastic cover 119
protects the transparent structural member 103, in this case a plastic tube,
from scratches and
abrasions. Since the plastic cover 119 does not have the structural
requirements of the
transparent plastic structure 103 being protected, the transparent plastic
cover 119 can be made
of a type of plastic selected for resistance to scratching and scraping. The
transparent plastic
cover 119 may be made of polyethylene terephthalate. Should a suitably
transparent and
otherwise usable form of another polyethylene-related plastic be usable, then
the transparent
plastic cover can be made of such a plastic, for example polyethylene,
polypropylene or
0 polytetrafluoroethylene. Alternatively, the transparent plastic cover 119
may be made of a non-
polyethylene-related plastic such as polycarbonate or an acrylic. The cover
119 may be of a non-
scratch resistant material that is sacrificed and replaced over time. The
cover 119 may also be of
suitable non-plastic material that is preferably shatter resistant.
Preferably a tubular transparent plastic cover 119 would be extruded in order
to avoid an
5 unsightly seem or mold lines. Alternatively, a tubular transparent
plastic cover 119 can be made
by rolling plastic sheet into a tube and then fastening the sheet into a tube
such as by gluing or
welding it. Further alternatively, a tubular transparent plastic cover 119 can
be cut from a bottle-
like structure made by blowing plastic into a mold. Other alternative ways of
producing a
transparent plastic tube such as casting are possible.
Ti The transparent plastic cover 119 may be intended to be disposable when
it has become
excessively scratched and scraped, and afterwards replaced by the user of the
LED work light
100.
Although the transparent structural tubes 103 for LED work lights have been
made of acrylic or
polycarbonate in past practice, it may be found practical to make the
transparent structural tube
103 of polyethylene terephthalate to improve resistance to scratching,
scraping, and some
solvents, other materials may be used.
The cover 119 may be in the form of two longitudinally split cover halves, no
shown, that
combine about the cap 110 and cover 112 over the otherwise exposed portion of
the tube 103.
The halves may be formed in such a manner as to snap together, while
permitting removal for
30 cleaning or replacements. The halves may form a hinge on one side where
the halves meet and a
closure on the other side where the halves meet. Other techniques for
attaching the halves are
possible, such as for example by screws, glue, heat welding or the like.
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Referring to FIG. 7, the LED work light 700 is a modification of the LED work
light 100 shown
in FIG. 6 in that the top cap 110 and the handle cover 112 have narrrowed
regions 120a, 120b to
fit tightly into the tubular plastic cover 119. The top cap 110 and the handle
cover 112 are both
preferably made of rubber to enable the tubular plastic cover 119 to fit
tightly around the
narrowed regions 120a, 120b of these parts. Achieving a tight fit among these
parts can protect
the transparent structural tube 103 from solvents, greases and oils and
automotive fluids, and fine
gritty materials such as abrasive dusts and soil runoff. It is preferable in
such a case that the top
cap 110 and the handle cover 112 be made of a type of rubber that is resistant
to solvents and
fluids that the transparent tubular structure 103 is to be protected from.
0 Alternatively, the plastic cover 119 may be sealed from the region of the
transparent structural
tube 103 to be protected by means of gaskets or 0-rings in lieu of narrowed
regions 120a, 120b
of the top cap 110 and handle cover 112.
Referring to FIG. 8, the LED work light 100 of FIG. 6 has added to it 0-rings
121 to seal from
the environment the region of the transparent structural tube 103 that is
covered by the plastic
5 cover 119.
The 0-rings 121 are shown as being fitted under the ends of the plastic cover
119 about the tube
103. Alternative arrangements are foreseeable, such as having the 0-rings 121
compressed
between the ends of the plastic cover 119 and the nearby edges of the top cap
110 and handle
cover 112. Further alternatively, sealing means other than 0-rings 121 may be
used, such as
l0 gaskets or glue or a sealant such as caulk. Such a sealant may be
removeable during replacement
of the plastic cover 119, and may be for example a type of caulk that is easy
to peel off. It is
further foreseeable that gaskets or 0-rings 119 may be combined with a
sealant.
During assembly or reassembly after removing a worn tubular plastic cover 119,
typically the
tubular plastic cover 119 is placed over the narrowed region 120b of the
handle 112, and
afterwards the top cap 110 is installed, with the narrow region 120a being
pushed into the tubular
plastic cover 119.
Preferably, the top cap 110 and the handle cover 112 have overall width
(diameter) greater than
that of the tubular plastic cover 119 in order to minimize scratching and
scraping of the tubular
plastic cover 119 by any surfaces that the LED work light 700 is placed upon.
The greater
30 diameter holds the cover 119 off surfaces the LED work light 700 is
placed upon.
Referring to FIG. 9, the plastic cover 119 mentioned above may be in the form
of a roll of plastic
tape 119a. The tape roll 119a is preferably made transparent by use of a
suitable plastic film and
a suitable adhesive with few or no bubbles and voids. When the exposed outer
surface of the
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tape roll 119a is scratched, scraped or worn, a small portion of the tape roll
119a may be peeled
off and discarded. The tape roll 110a is shown as having a perforation 901
through all turns of
the tape roll 119a to facilitate removal of one turn of the tape roll 119a.
Referring to FIG. 10, a further alternative protective cover 119b for tubular
work lights can be
made with a transparent window 1001 and a window holder 1002. The window
holder 1002 is
shown as being part of a non-circular tube so that it combines with the window
1001 to form the
protective cover 119b in the form of a non-circular tube. The generally
tubular form of the
protective cover 119b permits it to be used over tubular work lights, whether
or not such tubular
work lights have a circular cross section. Such a tubular protective cover
119b can even be used
0 over some non-tubular work lights, such as one having heatsinkable LEDs
mounted onto a piece
of channel stock or semicircular tube that is used both as a main structural
member and as a
heatsink.
The window 1001 is shown as fitting into grooves 1003 within the window holder
1002.
Alternatively, the window holder 1002 may have latches or other means of
holding the window
5 1001. Further alternatively, the window holder 1002 may be of a form
other than a portion of a
non-circular tube, such as latches that are attached to straps or to the work
light being protected
by the window 1001.
The window 1001 is shown as being a flat piece of transparent material such as
plastic. The
window 1001 may alternatively be curved or bent in shape to make the
protective cover 119b
more circular in shape. The window 1001 and the protective cover 119b may be
made of
polyethylene terephthalate or polycarbonate or another suitable material.
Referring to FIG. 11, an LED work light 1100 can be made with a metal channel
1101 as a main
structural member, where the metal channel 1101 has grooves 1104 to accomodate
a transparent
protective shield 1108.
The metal channel 1101 is preferably made of aluminum or an aluminum alloy
such as 6061 and
can be used as a heatsink for the LEDs (not shown). Other heat conductive
materials may be
used. The LEDs would typically be placed under lenses 1105 and may be
connected to wires
1106. Electrical power for the LEDs may be supplied from circuitry or through
one or more
resistors (not shown) within handle 1103. The handle 1103 is preferably made
of or covered in
;0 rubber or plastic. The metal channel 1101 is shown as having its sides
1102 cut away from the
portion surrounded by the handle 1103, although alternative arrangements are
possible.
The LED work light 1100 is shown as having a cord 1107 for receiving
electrical power from an
external power source. The LED work light 1100 may have batteries that may be
rechargeable.
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Any batteries would typically be located within the handle 1103. The handle
1103 would
typically be hollow and comprise a removable or hinged cover (not shown) in
order to
accomodate any batteries.
The transparent shield 1108 is shown as having a base layer 1109 and a face
layer 1110. The
base layer 1109 is typically made of a high strength transparent plastic such
as
polymethylmethacrylate or polycarbonate, but may be made of an alternative
material such as
glass. The face layer 1110 may be a stack of separately removable thin
transparent laminations
that are preferably made of a suitable plastic film such as polyethylene
terephthalate and which
are attached to each other with a suitable adhesive. The outermost lamination
1110a may be
0 peeled away and discarded after it is no longer suitably transparent due
to being scratched,
abraded, or marred by solvents during use of the LED work light 1100.
Other techniques may be used to protect transparent, light-transmitting parts
of work lights with
covers that are removable and replaceable. Some work lights protected in such
a manner may
have transparent covers or shields comprising multiple layers of a protective
material that can be
5 removed one layer at a time as the exposed surface becomes excessively
scratched, abraded or
otherwise worn. Some work lights protected in such a manner may have 0-rings,
gaskets or
other sealing means associated with such transparent covers or shields.
Sealing means may be
rubber or otherwise suitable parts that also have other purposes, such as caps
at either end of a
tubular structure or any handle cover.
0 The LED work light 1100 is shown as including magnets 1111 to allow the
LED work light 1100
to be attached to magnetic surfaces such as automobile hoods and other
automobile frame and
body surfaces. The magnets 1111 are shown as disposed inside the work light
1100, attached to
the inner surface of the metal channel 1101. Some rare earth magnets can be
powerful enough to
allow an LED work light 1100 to be attached to automotive body surfaces
despite being disposed
5 on the inside surface of the rear side of the metal channel 1101 as
shown.
Other mounting locations can be found for magnets 1111. For example, magnets
1111 may be
placed in several locations within an LED work light such as the LED work
light 1100 or 100 to
allow the LED work light to be attached to a surface in more than one
position. This allows
adjustment of the direction that light from the LED work light 1100 is
directed into.
Alternatively, mounting means for magnets 1111 may allow movement of the
magnets 1111.
The magnets 1111 may be mounted in grooves that the magnets 1111 can slide
within. The
magnets 1111 may be mounted on the exterior surface of the LED work light 1111
to permit use
of less expensive magnets 1111.
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Referring to FIG. 12, an LED work light 1100a has a metal channel 1101a that
has the shape of a
partial octagon. With this shape and magnets 1111 disposed on at least one of
the diagonal rear
surfaces 1112 as shown, the LED work light 1100 can be attached to a magnetic
surface with
light being directed into a direction 45 degrees from perpendicular to the
metal surface. This can
be useful when attaching the LED work light 1100a to the underside of an
automotive hood.
Other shapes of LED work lights such as the LED work light 1100a may be found
useful. Such
shapes may include irregular octagons with the two diagonal rear surfaces 1112
having different
angles from the direction that light is directed into, polygons other than
octagons, circular tubular
and oval tubular.
0 Referring to FIG. 13, the assembly of FIG. 3 with only minor changes can
accept the Cree
Xlamp LED in lieu of the CL-652-8WN type LED.
Shown are the LED PCB 106, lenses 200, and screws 300. The LEDs 1301 are Cree
Xlamp type
LEDs or other LEDs that can be mounted onto a metal core printed circuit
board, such as
Lumileds "Luxeon Emitters". The LEDs 1301 are mounted onto a metal core
printed circuit
5 board 1302 that is used as a heatsink. The LED PCB 106 of Fig. 3 may be
replaced with a heat
conducting sheet or plate 106a other than a PCB, such as a metal such as
aluminum, copper or
brass, since it does not have any electrical function in this arrangement. The
LED PCB 106 or
sheet or plate 106a has holes to accommodate the protruding domes of the LEDs
1301 or to
allow light from the LEDs 1301 to pass through. Any sheet or plate 106a would
be used as a
0 spacer between the lenses 200 and the metal core printed circuit board
1302.
Alternatively, the heatsink 108 of FIG. 3 may be used, especially if the LEDs
1301 are Lumileds
"Luxeon Stars" or of another type that is mounted onto a heats ink and
typically receives power
from wires in lieu of being mounted to a printed circuit board. Further
alternatively, the metal
core printed circuit board 1302 can be mounted to an additional heatsinking
means.
5 Referring to FIG. 14, a tubular LED work light 1400 is like that of the
tubular work light 100 of
FIG. 1; however, its LEDs 104 are mounted to direct their light output at an
angle that is not
perpendicular to the axis of the LED work light 1400.
This is shown as being accomplished by mounting the LEDs 104 to a zigzag-
shaped heatsink
1400. Alternatively, LEDs 104 can be mounted to individually associated
heatsinks that are
0 mounted at an angle to the axis of the LED work light 1400 as opposed to
in a manner in parallel
with the axis of the LED work light 1400. Other methods for having an
arrangement for light
from LEDs to be directed at an angle from the axis of the LED work light 100
are possible. For
example, the LEDs may be of a type that is typically mounted to a printed
circuit board rather
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CA 02652218 2013-03-28
than to a heatsink, and such a printed circuit board may be mounted in an
orientation at an angle
to the axis of the LED work light 1400. Further alternatively, the LEDs 104
may be mounted
with their axes perpendicular to the axis of the LED work light 1400 but one
or more prisms or
other optical means may be added to redirect the light at an angle from
perpendicular to the axis
of the LED work light 1400.
For simplicity, lenses are not shown; however, lenses are preferably included.
Circuitry 1402 is shown as provided since an LED work light 1400 typically
requires circuitry
1402 such as a boost converter or a current regulator or one or more resistors
in order for the
LEDs 104 to receive a suitable magnitude of current. The circuitry 1402 is
shown as mounted to
the heatsink 1401, however, it may be located anywhere within the LED work
light 1400.
An LED work light 1400 having light output directed from it at an angle from
perpendicular to
its axis can have an advantage over an LED work light whose light output is
directed from it
perpendicularly from its axis for some applications. For example, if the LED
work light 1400 is
hanging by its hook 111, then light will be directed from the LED work light
1400 at a
downward angle. This may be especially useful if the LED work light 1400 is
hanging from the
tip of the hood of a car to illuminate the engine compartment of the car.
The optimum angle for light to be directed from the LED work light 1400 could
be as little as 30
degrees or even less from parallel to the axis of the LED work light 1400 to
optimally illuminate
the engine compartment of a car if the LED work light 1400 is hanging
vertically from the hood
of the car whose engine compartment is being illuminated. However, an angle
less parallel to the
axis of the LED work light 1400 eases construction and makes the LED work
light 1400 more
suitable for handheld use. Meanwhile, having a wider beam of light from the
LED work light
1400 enables adequate downward illumination from a vertically hanging LED work
light 1400
even if the axis of the beam of light output is at an angle closer to
perpendicular to the axis of the
LED work light 1400. As a result, having the light output directed at a larger
angle from the axis
of the LED work light 1400, for example 60 degrees, may be found preferable.
The LEDs 104 may be not only mounted at an angle from being perpendicular to
the axis of the
LED work light 1400, but also that angle may be adjustable. However, it is
currently preferred
to have that angle being not adjustable to simplify construction of the LED
work light 1400 and
to minimize the chance of entry of spilled liquids into the LED work light
1400. Any angle
adjustment means may have a provision such as magnets to allow adjustment
through a
liquidproof housing.
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Other means may be found for achieving the beam of the LED work light 1400
being directed at
a downward angle when the LED work light 1400 is hanging by its hook 111. For
example, a
weight can be added to the LED work light 1400 to cause it to hang at an
angle. Alternatively,
the LED work light 1400 may have a cord that has means of attachment to the
hood of a car to
cause the LED work light 1400 to hang less vertically. Further alternatively,
an LED work light
can have a head section with LEDs that has an axis that is at an angle with
the axis of a handle
section, and the handle section can have a hook.
Referring to FIG 15, LED work light 1500 is shown with certain removable parts
separated from
it for clarity. The LED work light is shown as comprising a structural
transparent tube 1501, a
0 plastic or rubber handle cover 1502, and a top end cap 1503 with a hook
1504. Removable parts
of the LED work light 1500 shown separated from it are a threaded bottom end
cap 1508, an
overlapping transparent cover piece 1505, and an overlapped transparent cover
piece 1506. Not
shown are internal parts such as LEDs, batteries, and circuitry.
The threaded bottom end cap 1508 has threads 1509 so that the bottom end cap
1508 can be
5 screwed onto threads 1510. As shown, the threads 1510 are on the handle
cover 1502. The
threads 1510 may be molded into the handle cover 1502, cut or machined from
the handle cover
1502, or in a part added onto the handle cover 1502. Alternatively, the
threads 1510 may be
molded into, cut or machined from or added to the transparent structural tube
1501. The
threaded bottom end cap 1508 is typically removed for battery replacement. A
set screw hole
0 1512 is shown as being provided in the threaded bottom end cap 1508 to
accommodate a set
screw 1511. The set screw 1511 is typically provided to prevent accidental or
unnecessary
removal of the threaded bottom end cap 1508.
The bottom end cap 1508 can be sufficiently wide to permit the LED work light
1500 to stand
vertically.
5 The handle cover 1502 is shown as having a flange 1502a, and the top end
cap 1503 is shown as
having an opposing flange 1503b, that the plastic cover pieces 1505, 1506 fit
between. The
handle cover 1502 is shown as having notches 1502b, and the top end cap 1503
is shown as
having notches 1503b, that tabs 1505a, 1506a on the plastic cover pieces 1505,
1506 fit into.
Preferably the overlapped plastic cover piece 1506 has tabs 1506b that snap
into holes 1505b in
0 the overlapping plastic cover piece 1505 when the overlapping plastic
cover piece 1505 is
properly fitted over the overlapped plastic cover piece 1506. Alternatively,
the overlapping
plastic piece 1505 may have tabs fitting into corresponding holes on the
overlapped plastic piece
1506. The overlapping plastic piece 1505 is transparent in order to allow
light from the LEDs
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(not shown) to emerge from the LED work light 1500, and the overlapped plastic
piece 1506
may also be transparent. The overlapping plastic piece 1505 and the overlapped
plastic piece
1506 may be injection molded.
If the handle cover 1502 is made of rubber, then it can have a raised (or
other indication of
location) area 1507 that fits over a pushbutton switch (not shown). The
pushbutton switch (not
shown) may be fitted into or through a hole (not shown) in the transparent
structural tube 1501.
Preferably as shown, the raised area 1507 of the handle cover 1502 and the
accompanying
pushbutton switch (not shown) are on the same side of the transparent
structural tube 1501 that
the overlapping plastic cover piece 1505 fits over. Alternatively, the
pushbutton switch (not
0 shown) and accompanying raised area 1507 of any rubber handle cover 1502
may be located
elsewhere, such as on the same side of the transparent structural tube 1501
that the overlapped
plastic cover piece 1506 fits over. Preferably the light from the LEDs (not
shown) passes
through overlapped plastic cover piece 1506 rather than the overlapping
plastic cover piece 1505
because the overlapped plastic cover piece 1506 is typically smaller and
farther from any surface
5 that the LED work light 1500 is set horizontally upon and less likely to
be scratched by such a
surface.
Referring to FIG. 16, a circuit diagram is shown as an example of a circuit of
electrical
components and connections in an LED work light having resistors 1602 to limit
the magnitude
of current flowing through LEDs 1601. The LEDs 1601 may be the LEDs 104
described above.
0 Such an electrical arrangement may be suitable for work light embodiments
described herein.
Two 8-chip LEDs 1601 are shown, and they may be a Citizen CL-652-8WN type
suitable for
parallel connection of their respective chips. Any number of LEDs 1601 may be
used as an
alternative to the two LEDs 1601 shown, typically with each having a
respective dropping
resistor 1602. LEDs 1601 may be of a type other than the 8-chip ones shown.
5 The shown 8-chip LEDs 1602 are shown as having their respective chips
connected in parallel
with each other. Alternatively, the chips of each of any multichip LED 1601
may be connected
in series or in a series-parallel arrangement. Only one dropping resistor 1602
is shown as being
associated with an associated LED 1602, and such an arrangement with any
parallel or series-
parallel connection of the chips of a multichip LED 1601 requires a multichip
LED 1601 to have
0 its chips having characteristics that permit such an arrangement.
Otherwise, LED chips in a
parallel or series-parallel arrangement may have excessively unequal current
flow and this can
cause unequal heating that can change conductivity of the LED chips in a way
that exacerbates
inequality of current magnitude among the LED chips. Alternatively, multichip
LEDs 1601 may
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each have more than one associated dropping resistor 1602, for example a
dropping resistor 1602
to individually limit current through each paralleled current path through a
multichip LED 1601.
The LEDs 1601 are shown as receiving electrical power supplied by a battery
1603 through a
switch 1604. Dropping resistors 1602 are shown as provided to limit the
magnitude of current
that flows through the LEDs 1601 to a value that permits sufficient life
expectancy of the LEDs
1601 and that permits sufficient operation time of the battery 1603.
Alternatively, LEDs 1601
and a battery 1603 may be of a type that permits satisfactory performance
without the dropping
resistors 1602, for example if the battery 1603 or the LEDs 1602 have
substantial internal
resistance or any built-in resistors or if the LEDs 1601 contain LED driver
circuitry.
[0 The battery 1603 is preferably rechargeable, in which case it would
benefit from the shown
charging circuit 1605 and the shown charging jack 1606 for the charging
circuit 1605 to receive
electrical power from an external power source (not shown). The external power
source (not
shown) is preferably only connected to the charging jack 1606 when the battery
1603 requires
charging or recharging. The battery 1603 is preferably replaceable, but may
alternatively be
5 permanently installed. Alternatively to a rechargeable battery 1603, the
battery 1603 may be
non-rechargeable.
The charging circuit 1605 is shown as having two input terminals 1608 and two
output terminals
1607. Alternative arrangements, for example, may have only three terminals
with one of the
output terminals 1607 and one of the input terminals 1608 consolidated into a
common terminal
,0 (not shown) if the specific type of charging circuit 1605 permits such
an arrangement.
The charging circuit 1605 may include charge status indication such as
indicator LEDs (not
shown).
The switch 1604 is preferably a pushbutton switch that is usable as a push-on-
push-off type, also
known as an alternate action type. Any such pushbutton switch 1604 may have
ability to be used
5 as a momentary pushbutton switch by pushing its button only partially
inward.
Referring to FIG. 17, an electrical arrangement is shown for an LED work light
having LEDs
1602 receiving electrical power from an LED driver circuit 1701 that provides
current through
the LEDs 1602 that is limited in magnitude. This arrangement is shown as
having a battery
1603, charging circuit 1605 with input terminals 1608 and output terminals
1607, and a charging
0 jack in the same manner as the electrical arrangement shown in FIG. 16.
Two 8-chip LEDs 1602 are shown, although with their chips connected in a
series-parallel
arrangement and the two LEDs 1602 are shown as being connected in series with
each other.
Numerous alternative arrangements of series connection, parallel connection
and series-parallel
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CA 02652218 2011-07-22
connection are possible, and the number of LEDs 1602 may be other than two,
and the LEDs
1602 may be of a type other than a type having 8 chips. One alternative
example is that the
LEDs 1602 may be single chip LEDs. Further alternatively, the LEDs 1602 may be
of a
multichip type having only two external terminals and connections of their
respective chips of
each multichip LED 1602 being internal, such as Lumileds Luxeon V LEDs.
The LED driver circuit 1701 may be a boost converter whose output current is
limited in
magnitude, such as any of the boost converter circuits shown as being used for
LED inspection
lamps in US Patent Application 20050007777 previously mentioned. The LED
driver circuit
1701 may alternatively be a switching current regulator such as one shown in
US Patent
Application 20050265035 previously mentioned. Further alternatively, other
types of an LED
driver circuit 1701 may be used, such as, for example, a "linear" (non-
switching) current
regulator.
As shown, one LED driver circuit is provided to supply electrical power to the
LEDs 1602 with
current sufficiently limited in magnitude. Alternatively, more than one LED
driver circuit 1701
may be used, for example each LED 1701 being associated with a respective
separate LED
driver circuit 1701.
Referring to FIG. 18, a cross sectional end view of the head section of the
tubular LED work
light 100 of FIG. 1 is shown. Shown is the structural transparent tube 103,
one of the LEDs 104,
one of the lenses 105, the LED board 106, the heatsink 108 and the circuitry
109.
Further shown in the structural tube 103 is a holding means 1801 comprising
two ridges 1802
extending from the tube 103 into an interior of the tube 103 and comprising a
groove 1803. As
shown, the LED board 106 slides into the board holding means 1801. The groove
1803 extends
into the tube 103 itself The groove 1803 may be used alone or in conjunction
with the ridges
1802. The board holding means 1801 may alternatively hold the heatsink 108 in
lieu of the LED
board 106. Further alternatively, holding means such as the board holding
means 1801 may be
provided for both the LED board 106 and the heatsink 108. For example, both
the LED board
108 and the heatsink 106 may be placed into the same groove 1803 or separate
grooves 1803.
Referring to FIG. 19, a cross section of a tubular LED work light 100A that is
similar to the
tubular LED work light 100 of FIGs. 1 and 18 is shown. As in FIG. 18, the
section is through
the head section and perpendicular to the axis of the structural transparent
tube 103A. The
structural transparent tube 103A differs from the above described structural
transparent tube 103
by having board holding means 1801A shown as comprising only two ridges 1802.
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CA 02652218 2013-03-28
The LED work light 100A differs from the LED work light 100 by having the
assembly of FIG.
3 that is currently preferred when the LEDs 104 are to be Citizen CL-652-8WN.
Shown is the
heatsink 108, one of the LEDs 104, the LED board 306, and one of the lenses
200 shown in FIG.
3 and accordingly described above. Circuitry 109 and connector 1901 are also
shown, and in the
LED work light 100A is preferably a battery charging circuit. The current
limiting means
typically required by each LED 104 is shown in the LED work light 100A as
being a resistor
1902 mounted to the LED board 306 rather than the circuitry 109.
The ridges 1802 may extend longitudinally for the length of the tube 103.
Alternatively, a
plurality of pairs of ridges 1802 may be spaced apart along the length of the
tube 103 to hold the
light source assembly in place at certain locations. The holding means 1801
holds the light
assembly from rotational and lateral movement with the tube 103. The light
assembly may be
held in place longitudinally by sandwiching the light assembly and other
internal components of
the work light between the top cap and end cap. Alternatively or in addition,
the light assembly
may be held longitudinally by other techniques such as for example glue or
another adhesive.
The holding means 1801 are examples only. Many other forms of holding means my
be utilized
to hold the light source assembly in place, such as for example glue or
another adhesive, or
circular holders above and below the light source assembly, for example
respectively forming
part of the top cap and sandwiched between the assembly and the battery.
Referring to FIG. 20, a position sensing switching means 2000 can be useful in
LED work lights
generally, including for example those described herein. The position sensing
switching means
2000 is mounted within a structural tube 103 such as that of the tubular LED
work light 100
shown in FIGS. 1 and 18 and described above. The position sensing switching
means 2000 may
be arranged so that an LED work light would be switched off by placing it in a
particular
position, such as horizontally and facing upwards.
The position sensing switching means 2000 is shown as comprising a magnetic
reed switch 2001
with leads 2002, a leaf spring 2003 with a mounting block 2004, a first magnet
2005, a second
magnet 2009, a small spherical weight 2006, and a hollow sphere 2007 having a
hole 2008. The
leaf spring 2003 is shown as being mounted to the mounting block 2004 which is
shown as being
mounted to the housing of the LED work light, in this instance being the above-
described
structural tube 103.
If an LED work light having the position sensing switching means is placed in
the position
intended to cause actuation of the reed switch 2001, the small spherical
weight rests on the
magnet 2005 and pushes the magnet 2005 towards the magnetic reed switch 2001.
This results
in the magnetic reed switch 2001 actuating. If the LED work light is in any
other position, then
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CA 02652218 2008-11-04
WO 2007/128126
PCT/CA2007/000802
the small spherical weight 2006 rolls into a location that does not push the
magnet 2005 towards
the magnetic reed switch 2001. This can be found useful to make an LED work
light that can be
switched off by placing it into a particular position and switching it on by
holding it in any other
position.
Optionally, a second magnet 2009 can be provided and the small spherical
weight 2006 can be
magnetic. In such an optional arrangement, an LED work light having this
arrangement can be
tilted into a position that causes the small spherical weight 2006 to stick to
a position in the
hollow sphere 2007 near the second magnet 2009. This can permit an LED work
light having
such an arrangement to be placed in any position without actuating the
magnetic reed switch
2001. This may be found useful should a user of such an LED work light want to
use it in a
position normally intended to turn off such an LED work light. After such use,
such an LED
work light can be tapped or shaken to cause the small spherical weight 2006 to
be released from
the position near the second magnet 2009. This provides a releasably
overridable position
sensing switch which may be overridden for use in a position that would
otherwise turn the
position switch off and such override is releasable to return the switch to
its normal position
sensing operation.
A magnetic reed switch 2001 may be particularly useful in work lights to be
used in
environments having flammable gases, vapors, or dusts since any sparks
resulting from
switching would be contained within the magnetic reed switch 2001 and thereby
isolated from
!O such gases, vapors or dusts. The switch contacts may be further
contained and isolated from the
environment in which the work light is used by sealing the work light to
prevent entry of
flammable material into the structural tube 103.
Referring to FIG. 21, a magnetic reed switch 2001 is normally open and is used
in an electrical
circuit 2100 which may be utilized in a work light, such as for example, the
embodiments of
15 work light described herein where its actuation results in LEDs 2103 in
such an arrangement to
be turned off. Numerous alternative arrangements are known to able to achieve
such a result.
A battery 2101 is shown as being provided as a source of electrical power for
an LED driver
circuit 2102, which provides electrical power to the LEDs 2103. The LED driver
circuit 2104 is
shown as being switched by an N-channel enhancement mode MOSFET type
transistor 2104. A
0 resistor 2105 normally causes the gate terminal 2106 of the MOSFET 2104
to be at essentially
the same potential as the positive terminal of the battery 2101, while the
source terminal of the
MOSFET 2104 is connected to the negative terminal of the battery 2101, and
this causes the
MOSFET 2104 to be conductive and allow the LED driver circuit 2102 to receive
power from
the battery 2101.
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CA 02652218 2013-03-28
If the magnetic reed switch 2101 is closed, then the gate terminal 2106 is
shorted to the source
terminal 2107, causing the MOSFET 2104 to become nonconductive, resulting in
the LED driver
circuit 2102 not receiving power from the battery 2101.
Referring to FIG. 22, a tilt switch 2200 can be mounted within an LED work
light housing such
as the above-described structural tube 103. The tilt switch 2200 is an example
of a position
sensing switch that is open when it is in a particular position and closed
when it is in most other
positions. It is possible for such a position sensing switch to be used to
have a work light
operating when it is in most positions and off when it is in a particular
position. As a result, it is
possible for such a position sensing switch such as the tilt switch 2200 to be
used as the main
switch of an LED work light such as the LED work light 100 shown in FIGS. 1
and 18 and
described above.
The tilt switch 2200 is shown as comprising a pendulum formed by a conductive
rod 2201, a
conductive weight 2203, and a suitable joint 2207 between the conductive rod
2201 and a first
wire 2206, and mounting means 2204 such as glue. The tilt switch 2200 is
further comprising a
conductive washer 2205 which is contacted by the conductive weight 2203 when
the tilt switch
2200 is not in or nearly in a specific position. A second wire 2208 is also
shown. The first wire
2206 and the second wire 2208 are leads of the tilt switch 2200.
Optionally provided with a position sensing switch such as the magnetic reed
switch 2101 is a
bypass switch 2108. The bypass switch 2108 is shown as being a 3-position
slide switch with
contacts 2108a, 2108b, 2108c, 2108d and a movable contact 2108e. The movable
contact can be
moved to a position that connects the contact 2108a to the contact 2108b,
resulting in the slide
switch 2108 shorting the magnetic reed switch 2001 and causing the LEDs 2103
to not receive
power regardless of the status of the magnetic reed switch 2101. The movable
contact 2108e can
be moved to a position that connects the contact 2108c to the contact 2108d,
to bypass the
MOSFET 2104 so that the LEDs 2103 receive power regardless of the status of
the magnetic
reed switch 2001. Such an arrangement or alternative arrangements with similar
results can be
useful in an LED work light such as any of the LED work lights described
herein to bypass a
position sensing switch so that such an LED work light can be turned on or off
regardless of its
position. Such an arrangement provides an alternative releasably overridable
position sensing
switch. Other forms of such switches are possible.
The above specification is to provide examples of the present invention.
Features and functions
of one embodiment may be utilized in other embodiments. Not all combinations
of features and
functions have been described herein.
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CA 02652218 2013-03-28
It will be understood by those skilled in the art that this description is
made with reference to the
preferred embodiment and that it is possible to make other embodiments
employing the
principles of the invention.
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