New from Lumitex
Cut-to-Size Clad Flat Fiber™
Cut-To-Size Advantages
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Fast, low cost backlit prototypes with no tooling or NRE
Ideal for Low Volume Production
Easy to use
Good optical performance and appearance
Included PCB allows easy evaluation of your light guide
Flexible material
Lumitex Cut-to-Size Flat Fiber™ will enable you to produce fastturn backlit prototypes and marketing samples, evaluate our Clad
Flat Fiber technology, and provide lighting solutions for your
lower volume production projects.
About Lumitex
Lumitex is a US-based manufacturer of custom backlighting
products for membrane switches, keyboards, key pads, decals
and LCDs. Cut-To-Size takes advantage of Lumitex's highvolume Clad Flat Fiber product in a form that is easily applied to
moderate volume custom applications.
Cut-To-Size Technical Description
Cut-to-Size Clad Flat Fiber is a low profile light guide that
utilizes patented technology and a custom designed optical
pattern with an integrated rear reflector. The light guide can be
cut to a desired shape as long as there is a direct linear path for
the light from the LED. The light guide is designed to align the
optical edge (marked with a label) against LEDs that are
mounted on your switch circuit layer or PCB.
The goal is to have custom cut backlights using scissors, exactoknives, or a steel-rule die. The 0.5 inch transition area should
not be cut shorter as it will affect the optics of the part. The base
material should not be cut with lasers as this will discolor the
backlight.
Cut-To-Size Optical Study
A study was performed to determine the appropriate LED
spacing for a 0.50” Transition area. Illustration 1 describes the
parts used for the study.
Illustration 1: CFF Cut-To-Size Design Concept
The 0.50” optical transition is an untreated area which allows the
light to spread from the LEDs. In our study, we lit a 6 inch
cross-section of the sample, with from 4 (on a 1.2 inch pitch) to
7 LEDs (on a 0.75 inch pitch). Optimal LED spacing is achieved
at a pitch of 0.75 inches or less. This spacing results in a
uniform appearance at the nearest edge of the backlight. When
LEDs are spaced at a distance greater than 0.75”, triangular
shaped optical artifacts are apparent between LEDs, below the
intersection of the light rays.
Cut-To-Size Study Optical Results
With the 7 LED sample (Illustration 2), the average uniformity
was 72% with output of 172.8 nits.
Illustration 2: Typical properties for the .45 mm CFF with a 6 inch length.
Brightness and uniformity are predictable, and within uniformity
limits for most applications. The table in Illustration 4 shows
the data collected using a 7 LED set and 8 cut to size widths
using a Nichia, white, side firing LED PN: NSSW204CT.
Results may vary depending on LED used.
Illustration 4 shows the plots of the average output at various
part lengths. Results may vary.
Lumitex LED Board
Illustration 5 shows a photograph of the Lumitex PN: 010882, a
PCB which allows you to instantly look at the optics of your Cut
to Size part. The PCB has 8 white, side firing LEDs and can be
powered by applying 9 VDC to either set of wires.
Caution: you should not apply power to both sets of wires at the
same time.
Illustration 5:
Cutting the PCB
The PCB is thin enough that it will allow you to cut it into two
pieces using a pair of scissors.
Illustration 6: Though other cuts are possible, it is
recommended to cut between the empty pads. This will ensure
you do not damage any of the traces of the adjacent LED’s.
Illustration 6:
Each LED has its own regulator that will drive each LED at 20
mA nominal. So, once the board is cut, you can apply 9 VDC to
either set of leads, regardless of where the cut is made.
Illustration 7 : Board Schematic in Inches.
Illustration 7:
Electrical Information:
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Polarity: Black (-), Red (+)
Input: 9 VDC
WARNING: Never apply power to both sides.
Illustration 8: Adhesive strip to hold your light guide against the
LEDs
Illustration 8
LED Placement on Clad Flat Fiber
If placing LEDs on your own substrate, adhere to the following
guidelines as accurate placement of the LED’s is critical to the
successful application of Cut-to-Size Clad Flat Fiber technology.
Careful optical alignment of the LED determines performance
results as explained below. The testing was completed using a
Nichia PN: NSSW204CT.
Vertical LED Height- alignment with 0.45 mm Clad Flat
Fiber
For correct optimal coupling the CFF’s optical core should be
aligned with the center of the LED.
The illustration below shows what happens when a 0.010” thick,
full face adhesive is added to the stack-up with the same LED.
There is a misalignment between the LED and the Clad Flat
Fiber, which results in a loss of light intensity, or potentially a
color shift caused by a “prism” effect thru the fiber.
Other LED alignment issues include
Notes and exceptions: In some applications where overall part
length is greater than 6 inches, or if higher brightness is required,
it may be necessary to light the Lumitex CFF fiber from two
ends. Cut-To-Size Clad Flat Fiber is not designed for 6 inch or
greater designs, since the optical pattern is a maximum of 5.5
inches. Please contact your Lumitex sales representative for a
custom design if you need a longer part.
The Results
Lumitex’s new Cut-To-Size Clad Flat Fiber™ technology should
make it simpler and faster for you and your designers to light
your prototype membrane switches and other graphic images. It
is designed for fast turns, and modest volume production.
Consider collaborating with Lumitex to achieve the best results
on higher-volume or more complex applications. We are
motivated and prepared to work closely with you and your
engineering team to develop custom engineered solutions for
your lighting requirements.
Custom Designs
Lumitex Clad Flat Fiber technology allows us to produce a wide
spectrum of lighting products. Our Cleveland engineers can
provide solutions to all of your lighting requirements including
optical design, circuit layout, and the final light guide integration
into your assembly. We look forward to serving you in
developing new exciting lighting products together! Please
contact us with your requests and/or suggestions.
Lumitex, Inc.
8443 Dow Circle
Strongsville, OH 44136
T- (440) 243-8401
www.lumitex.com
email: info@lumitex.com
THIN PROFILES- CFF Thickness options include 0.2 mm (0.008”), 0.3 mm
(0.012”), and 0.45 mm (0.018”) exclusive of LEDs, traces, and any additional
layers such as diffusers or reflectors.
INTEGRATED SOLUTIONS- LEDs can be mounted to your printed circuit board
and mated to our light guide, or Lumitex can develop plug-and-play backlight
solutions integrating the light guide, reflectors, surface-mount LEDs, drive
circuitry, connectors, diffusers, and mounting adhesives. All are engineered into
one, thin backlight assembly.
COMPLEX GEOMETRIES- Unusual shapes, through-holes,
multiple LEDs, and multiple colors are all possible with
Lumitex CFF technology. Virtually any two-dimensional
shape or size is possible without the need for tooling.
Multiple through-holes in the backlight enable custom
fitting into complex assemblies without sacrificing lighting
uniformity.
POWER EFFICIENCY- Embedded LEDs improve optical coupling and efficiency,
and combined with the superior light transmission of Lumitex CFF, backlight
assemblies achieve maximum brightness and uniformity with fewer LEDs.
ROBUST AND FLEXIBLE- Our membrane switch backlights have been tested
millions of actuations without performance loss or degradation. Lumitex CFF
technology can be applied to singularly curved surfaces or installed in
hazardous and extreme- duty environments.
LOWER COSTS- CFF solutions can shrink costs by reducing part count and
simplifying assemblies, while offering reduced thickness and improved product
functionality.
SUPERIOR ENVIRONMENTAL AND ELECTRICAL PERFORMANCE- Used today
in the toughest environments including military applications, automotive
exterior lighting and under-hood applications, CFF technology withstands
temperature extremes from -50oC to over 100oC. Since the technology is LEDbased, our low voltage DC products are often designed to last the life of the
application.