light output is highly directional. That means LEDs require sophisticated
reflectors, placement angles, and lenses to satisfactorily disperse the light. While
the LEDs are supplied by various manufactures, the housings, reflectors, light
diffusers, collimators, and lenses are carefully designed, engineered, and
assembled by the lightbar manufacturers. In many cases, these components are
proprietary to that particular manufacturer.
poses some special problems considering the somewhat limited viewing angles at
the ends of linear lightbars, and the fact that even clear end-caps tend to
distort light-rays. Some manufacturers installed more powerful LED modules at
45-degree angles to improve visibility when the vehicle enters intersections.
Others have gone to “U” or “V”-shaped lightbars to ensure 360 degrees of
reflector design is a critical component of LED lighting. Reflectors are shiny,
chrome-plated plastic or sometimes polished aluminum or stainless steel. Some
manufacturers utilize multiple rows of LEDs offset at slightly different angles
to obtain a broader range of visibility.
light-dispersing method is a collimator, a light-modification device that has
been around for centuries. The collimator is a clear plastic or glass tube
mounted between the LED and outer lens, which can absorb light and then
redirect it, ultimately spreading the beam into a wider pattern. Its function
is similar to that of a neon light, which bends the light into the form of the
optical device that successfully adapted the LED to be viable for emergency
lighting is the Fresnel lens. Far from being a new invention, the Fresnel lens
has been used in lighthouses and other optical devices since 1823. Essentially,
the Fresnel lens consists of a series of prisms meticulously ground into a
clear surface—glass or plastic—which modifies the light beams, allowing them to
be visible over farther distances.
directional lighting characteristics of LEDs mean that spreading the light out
is the major design challenge. Of the dozen or so lightbar manufacturers, here
is a sampling of how some of them are solving the LED reflector or lens challenge
with their latest LED modules and an example of lightbar with that module.
Heads-up! Each manufacturer still makes older generation lightbars with
previous LED module designs.
Code 3® PSE
3 uses the most different ways of spreading out the LED light. The TriCore® TC2
module is used in their Defender lightbar. The PriZm™ II module is used in their
RX 2700™ CC MultiColor (MC) lightbar. Other Code 3 lights and lightbars use
SIRIS™ (structured internal reflector illumination system) LED modules, Torus™
LED modules XT-series LED modules and LED X™ LED modules.
TriCore is the latest Code 3 technology, and is one of the brightest LED
lightheads on the market. TriCore is unique and significant because it does not
use mirrored reflectors. Instead TriCore uses long, thick and optically clear
lenses (collimator) to funnel and selectively diffuse the light. The light
passes through a convex lens surface, which mates up to a larger diameter, opposing
convex lens. The entire module is mounted in a clear housing, which may or may
not have areas of grooved or roughened surface to further reflect the light.
PriZm II is a polished reflector LED module. The large outer reflector has a
parabolic shape, but the inner part of the reflector has at least four other
reflecting surfaces. The long and narrow inner reflector stands off a bit from
the LED emitters, is mirrored on both sides, and reflects light from the outer
parabolic surface. However, some of the LED output from each emitter goes
straight into the inner reflector where it is reflected by angle boxed mirrored
surfaces on all four sides.
Torus is a NextGen replacement for the Optix lightheads. These use Total
Internal Reflection technology. This is essentially a long lens mounted in
front of the LED emitters, which are mounted directly to the circuit board.
That lens has the exact cross-section of the Fresnel lens. A Fresnel lens was
first used in lighthouses to magnify the light output from a mere lantern as a
distant warning signal. This is a very small, thin LED module but makes maximum
use of the light.
TriCore LED (dual-color) LED module is used in Code 3 lightbars like the
Defender TC2 (MultiColor). The MultiColor (dual-color) PriZm II LED module is
used in Code 3 lightbars like the RX 2700CC MC. Torus MultiColor (dual-color)
LED module is used in Code 3 lightbars like the 21TR Plus MuliColor. The
dual-level Triumph™ lightbar uses SIRIS LED modules.
Electronics recently introduced the WDR12, their newest LED module. It sets the
standard for the most reflected LED light from the simplest reflector. All LED
modules from every lightbar manufacturer involve the LED emitter soldered directly
to a printed circuit board. All these printed circuit boards have some kind of aluminum
heat-sink attached to the board.
WDR12 module is simply a chrome-plated reflector mounted directly on top of that
circuit board. No multiple reflectors, no lenses, just the reflector, proving
that a great reflector design will definitely do the job.
WDR12 one-piece reflector is quite a clever, complex design based around a very
deep parabolic shape. It fits tightly around each LED emitter and opens up more
like a long megaphone than a pure parabolic shape. The reflecting surfaces
above and below the LED emitter are molded in a scalloped profile, each forming
a separate reflection, then each reflecting off the overall reflector. As the
light exits the reflector, it passes through a diffused clear cover.
Prowler is the new generation linear lightbar from D&R. The Prowler uses
the WDR12 LED module and meets applicable SAE Class 1 and California Title 13 requirements.
The Prowler has selectable flash patterns, has an optional auto dim mode, and
is available with six or 12 LED modules.
uses the Solaris® LED module in their Valor® lightbar. The LED light is emitted
up from the printed circuit board onto a mirror-finish plastic reflector. Manufactured
with ROC (Reliable Onboard Circuitry™), the Valor has fewer failure points than
a typical lightbar.
chrome-appearing, ripple-textured reflector has a parabolic shape for the
forward light signal. The inner sides of the LED module are also reflective.
Some reflectors use sides with a 90-degree angle for the most forward signal.
In other locations on the lightbar, the sides are at a 45-degree angle for the
best off-axis signal.
Solaris reflector is simple and very straightforward. It is the perfect
reflector design for the non-linear shape of the Valor. The Solaris produces a
very strong forward signal, so the Solaris module is simply mounted in the
direction the light is needed, i.e., pointing forward or pointing off-axis.
is built with FedSig’s Solaris LED reflector technology. The non-linear shape
of the Valor™ lightbar provides 360 degrees of light output and off-axis
lighting at critical intersection points. In combination with its specific shape,
the Valor also uses SpectraLux™ multicolor LED technology. SpectraLux
technology provides the ability to change LED colors for combinations of Amber,
Blue, Red or White. Other lightbars that use the Solaris LED reflector technology
include the Integrity, Legend and Vision SLR.
Signal uses the Nexus LED module in their nFORCE® lightbar. The use of Nexus
Technology in the reflector is a reinventing of the LED light module for
SoundOff. The LED emitter was upgraded and so was the exact shape and form of
the plastic reflector. Nexus Technology, or nFORCE, is what defined the final
shape of each reflector. The goal for any lightbar manufacturer is the optimum
balance between the forward light output (reflection) and the off-axis or
intersection light output.
LED modules in SoundOff Signal’s lightbars have previously used Total Internal
Reflection (TIR) technology. The LED light output was collected internally and dispersed
via collimator lenses, i.e., the light output did not involve reflected surfaces.
With Nexus LED modules, the texture, profile, internal reflecting surfaces, and
curvature of the mirror design do all the reflecting. This gives SoundOff
Signal the capability of precisely controlling and tailoring the amount of
forward and off-axis light.
Signal uses many different designs of reflector in their new nFORCE line. The
center of the Nexus Technology nFORCE modules has a wavy texture on an
elliptical profile to diffuse the light forward. The sides of the nFORCE module
are specifically designed to reflect light off-axis. That said, SoundOff Signal
diffuses the off-axis light two different ways—one for external lightbar, one
for internal lightbar. Of course, the take-downs and alley lights use a long-range
Nexus Technology LED modules are used in the nFORCE exterior and interior lightbars,
directional warning, and surface-mounted perimeter lighting. These are all available
in Bronze (single color), Silver (dual color) and Gold (tri-color).
newest lightbars from Star Signal Vehicle Products use a combination of, or the
options of, three different LED modules. One is the brand-new Lineum™ LED lighthead,
which uses six Gen IV LEDs. The Star Lineum LED technology produces a wide-angle
light distribution and is used primarily on the front and rear heads.
Importantly, the Lineum module is also capable of dual color to the front for
takedown/pursuit and to the rear for traffic director.
Star SVP High Density™ LED lighthead also uses Gen IV LEDs with 12 or 18 LED
head versions available. This is the module designed to meet high LED count bid
specs. The wide-angle light distribution achieves SAE Class I rating without
the use of flashing alley lights.
Star SVP Starburst™ LED lighthead uses eight Gen IV LED in a narrow light distribution.
A general-purpose LED module, Starburst is compatible with end or front facing
heads, traffic directors and stop/tail/turns, and can be programmed for
LASER® is Start SVP’s newest generation of low-profile lightbars. It uses Laser
Cage Technology™ componentry design, i.e., the ability for each modular head to
be interchangeable with other modular heads for multiple custom configurations.
The Versa Max™ Razor lightbar also uses the dual-color Lineum LED module.
Tomar LED module uses a short but very complex collimator design, i.e., a clear
lens mounted on top of the circuit board-mounted LED emitter. The plastic
enclosure has a very aggressive, fine-ribbed texture to further diffuse the LED
light output. The magnifying effect of the collimator is quite dramatic.
typical single-color LED module for the front or rear location may have six
LEDs in a staggered row while the dual-color LED modules will have 12 LEDs. The
typical single-color LED module for the corner locations may have 12 LEDs,
while the dual-color versions have 24 LEDs.
970L Scorpion™ lightbar is the latest from Tomar. It continues in the same
basic design of extruded aluminum housing and cast-aluminum end caps; however,
the Scorpion is a very low-profile lightbar. It is available in 10 different
lengths from 21 inches to 80 inches.
Engineering uses the Linear LED® Super-LED® (linear technology) LED module in their
Liberty™ II lightbar. LED light is not just reflected or diffused using
mirror-surface plastic and aluminum. LED light is also diffused, spread out,
and in some cases amplified by passing through a clear plastic optic or lens.
Collimator™ patented design captures, collects and focuses LED light with an
extremely simple design involving a Fresnel-like lens running the entire width
of the reflector and a large, parabolic-shaped, highly polished reflector.
Whelen Liberty II SOLO™ lightbar uses single-color inboard and corner LED
modules. The Whelen Liberty II DUO+™ lightbar uses dual-color LED modules for
the inboard and corners. The DUO modules have the LED emitters placed on the
circuit board with interleaved colors, for example, red and blue alternating,
red and amber alternating, or blue and white alternating.
NextGen Liberty II lightbar has 30 percent more illuminated surface area than
the original Liberty lightbar. A photocell that automatically dims the light at
night while still meeting SAE Class 1 is optional on the Liberty II SOLO and
standard on the Liberty II DUO.
The Same But Different
every modern lightbar uses virtually identical LED emitters. There is some
variation of color as some of these LEDs heat up, so evaluate the LED lightbar
after it has been activated for 30 minutes or so. However, LED emitters used by
nearly all lightbar manufacturers today are all basically the same design and
the same quality.
difference between lightbars today is not the LED emitter, but how each
manufacturer collects, magnifies, focuses, deflects and then diffuses that
light output. Some companies use very complex reflectors or collimators, while other
companies use very simple lenses, reflectors and diffusers.
companies achieve a balance of forward and off-axis (intersection) warning
signal. Some do it with a combination of narrow-focus and wide-focus lenses and
reflectors. Some do it by simply pointing a narrow-focus LED module forward for
a forward signal and at an angle for an off-axis signal. Every single one of
these LED modules and lightbars is different, i.e., they all achieve the same
goals by different means. Check them all out.