Custom LED displays for instrumentation and message panels

LEDs are used in a wide variety of display applications ranging from large outdoor display screens with dimensions measured in metres to high-resolution arrays with emitters as small as 10 microns. Within this broad field, PRP Optoelectronics Ltd has specialised in the design, development and manufacture of smaller-scale custom LED arrays for instrumentation and message panels, mainly for avionic applications, as well as multi-element fine-geometry monolithic arrays for display and imaging equipment.

The arrays are based on two different technologies, hybrid and monolithic, depending on the application, although there is some cross-over where displays using a monolithic LED chip are packaged with controlling or matching hybrid electronic components.

Hybrid displays

Figure 1a
These are made using hybrid electronic assembly methods in which individual LED die are assembled onto the front face of a multi-layer ceramic package or PCB in the required display pattern. The electronic drive circuitry, typically consisting of custom ASICs, memory devices and FETs etc. is mounted onto the rear face of the package or PCB. The device is then completed by fitting a suitable window and/or filter to the front of the package and a cover to the rear protecting the electronics.

Figure 1b
The display layout is very flexible and can range from a set of 7 x 5 characters to a full XY matrix, or even a circular pattern mimicking a moving pointer instrument. The LED die are generally 0.28mm square spaced on a 0.5mm pitch, but other sizes and custom rectangular bar shaped LED die are used on some displays, in particular for circular instrument panels.

As single LED die are used, it is possible to mix and match any of the wide range of LEDs that are now available, and so multi-colour displays with blue, green, amber or red emitters can be made. Figure 1 shows an example of an amber circular display showing the patterns on the front (LEDs) and rear (drive electronics) of the package together with the fully-illuminated display. This particular device, in addition to acting as an analog display, can also show the measured value as a rolling-digit digital display.

Figure 2
The LED dice are viewed directly and there is no epoxy encapsulation over them acting as a lens. This means that the displays, if fitted with an appropriate contrast enhancement filter, can be easily be seen in direct sunlight allowing them to be used on aircraft flight decks. It is also possible with suitable pulse-width modulation (PWM) driving techniques to dim the display down to very low levels so that they are also compatible with night vision systems. For some applications, fixed legends are needed and in this case back-lit screen-printed windows are used with the LED dice embedded in a diffusing medium. Again, with suitable optical design, these can be sunlight visible.

Figure 3
The window/filter can be either glass, plastic or a combination of both to provide the correct transmission characteristics, and is usually fixed to the package with an epoxy or silicone glue. As the LED chips are themselves relatively robust, this type of structure usually provides sufficient protection in most normal environments. However for use in extreme conditions, particularly high humidity ones, a conformal coating such as Parylene can be deposited over the chips before the window is fitted to protect the LED dice, the chip bonds and the package metallization.

Figure 4
LED displays operate over a very wide temperature range and it is usually the mechanical components such as the (plastic) filters or adhesives that limit the operating temperature range of the units. The assemblies are mechanically very robust and the LEDs have lifetimes of at least 105 hours. These characteristics make this type of display ideally suited to high reliability applications. Further examples of this type of displays are in Figures 2 to 4.

Monolithic arrays

These are multi-element emitters on a single chip with each of the emitters having a separately addressable connection (usually the anode) to allow it to be driven independently, and a common (cathode) return connection. The emission areas can vary in size from a few microns across, while the formats and spacings that can be produced depend on the need for contact metallizations to make contact to the emitting regions.

Obviously a separate connection and hence wire bond for each element is required and therefore the wire bond pad layout is usually the factor that limits the size of a chip. To overcome this limitation, XY matrix addressable arrays are currently under development.

Figure 5a
These kinds of arrays can be made by a variety of techniques such as diffusion, mesa etching or implantation. As they are produced in the same way as an IC on a complete epitaxial wafer, and the area of material used for each chip is relatively small, the uniformity of emission and colour across a chip is well controlled.

Figure 5b
Individual emitting areas vary from 10 microns across and linear arrays with up to 512 emitting areas on a chip are being used in commercial applications, while the development of the XY arrays with thousands of emitters is underway. Arrays can be made with the full wavelength range from blue through to red for visual applications and into the infra-red for machine applications. These types of array are used in thermal imaging displays, head-up displays and helmet-mounted sights. They are also used in reprographics, high speed printing, PCB patterning and can potentially be used for lab-on-a-chip applications.

The LED chips can be mounted into a variety of packages depending on the intended use, and this can include optical components (such as lenses etc) and/or electronic components to provide local LED drivers or output matching. The emission levels across an array are usually matched to within a few percent as processed, but this can be improved by the inclusion of either active matching using previously stored coefficients, or passively by the use of pre-determined resistor networks. Examples of various types of device and packages are shown in Figure 5.

Figure 6
A close up view of an array with a double row of emitters that has some of the elements illuminated is seen in Figure 6. This has elements measuring 30 microns across and spaced on a 42 micron pitch. The typical forward intensity obtained from this type of array, emitting at a wavelength of 650 nm, is 80 micro-W/steradian (~ 1 x 107candela/m2) when driven at an element current of 10 mA.

Most applications of monolithic arrays use one or two chips per unit, but for some printing applications, wide print bars are required. In Figure 7 we can see such a unit. This particular example is 20 inches wide with emitters spaced at 600 dpi. Individual linear arrays are assembled end to end to maintain the 600 dpi spacing along the full length of the bar.

Figure 7
These examples show some of the typical formats of monolithic arrays that are used, but it is possible to produce other types of layouts, ranging from small seven-segment numerics to compound displays with characters and symbols, such as reticules and geometric overlays for optical instruments.


Zierick Manufacturing Corp

Offers innovative solutions for interconnect applications. Specializes in wire-to-board and board-to-board applications. Provides surface mount and thru-hole products while further reduci...

Cree Inc

Leads the LED industry in performance, brightness and reliability with its XLamp LED family, enabling the lighting industry with efficient, environmentally-friendly LEDs that produce beau...

InnoLight sp zoo

EU located lighting manufacturer for LED GU10 5W 600lm CRI>80 reflector, great performance, and LED E27 5W 380lm classic traditional appearance.

CSA Group

A global solutions provider of product testing and certification services for electrical, mechanical, plumbing, gas, medical and a variety of other products.

Energy Efficient Lighting

Energy Efficient Lighting offers total solutions to both conventional and more advanced LED lighting fixtures and LED retrofit kits for commercial and industrial applications.


48 companies worldwide, passionate about light and innovation, experts in developing LED lighting solutions for safe and comfortable environments with significant energy and cost savings,...

Guardian Industries

Guardian Industries Corp. is a leader in float glass, fabricated glass and high performance coated glass products. Guardian lighting solutions deliver optimal performance, flexibility and...

ELMA Electronic Inc

Provides standard and customized LED solutions. Elma's LED family offers consistent, reliable, and durable illuminating and indicating solutions.

LEDSAmerica Inc

LedsAmerica is a full line LED line company and has manufacturing in Iowa where T8 LED-O tubes and street lights are made together with PL, PARs, High Bay lights. MAx

Lumentra Inc

Provides NVLAP accredited optical (photometry, colorimetry, Lumen maintenance), thermal (mapping and transient analysis), electrical characterization services, product development, supply...


The LED, DC-DC and AC-DC power supplies from 1W - 1600W. Cincon’s lighting controllers, interfaces and devices incorporating DALI protocol. LED drivers from 25W - 150W with international ...


LTF, LLC is a U.S based solid-state lighting product development and manufacturing company with facilities located in both USA and China.

Marian Inc

Marian is a global company who supplies die cut and converted parts to the LED market. Materials include thermal pads, reflective, venting, gaskets, insulators, diffusers and more.

Colorimetry Research

Specializes in the field of optics, manufacturing, electronics and software enables us engineer products with the right balance of hardware and software.

eldoLED America Inc

Designs and manufactures drive solutions for LED based lighting systems. Our technologies empower our customers to deliver the promise of LED lighting.

Cirrus Logic Inc

Cirrus Logic develops high-precision, analog and mixed-signal integrated circuits for a broad range of innovative customers across a variety of energy-related applications, including the ...


Established in 2002 as an ecommerce store for all your LED product needs.


Designer and manufacturer of custom and industry standard LED, DC-DC and AC-DC power supplies from 1W to 1600W. Cincon also designs and manufacturers lighting controllers, interfaces...

Illumination Machines

Illumination Machines designs custom optics, heat sinks, and remote phosphor systems for LED luminaires and lamps.

eldoLED BV

eldoLED is a world leader in the design and manufacture of intelligent drive solutions for LED based lighting systems. Our technologies empower our customers to deliver the promise of LED...

Cree CXA LED Array Family

Cree’s CXA LED Arrays are optimized to simplify design and lower system cost, delivering high lumen output and efficacy with a family of single, easy-to-use arrays.

Cree LED Modules

Cree LED modules deliver beautiful, consistent light, backed by a 5-year warranty. They offer a choice of dimming options, while reducing the lighting power load by 80%.

Cree XLamp® XP-L LEDs-the industry’s highest efficacy single-die LED.

Cree® XP-L LED is the first commercially available single-die LED to achieve up to 200LPW at 350mA. The XP-L enables 50% or more performance increase as a drop-in upgrade.

Surface Mount Wire Gripper - Part Number 1301

The Zierick 1301 is designed to allow customers to easier terminate a stripped wire to a PCB. Wire sizes to 24 AWG. Terminal is UL Recognized.

Surface Mount Wire Gripper - Part Number 1262

The Zierick 1262 is designed to allow customers to easier terminate a stripped wire to a PCB. Wire sizes from 0.025" to 0.095". Terminal is UL Recognized.

Unlock new LED lighting solutions with Cree High Density LEDs

Cree® High Density LEDs deliver the industry’s highest optical control factor enabling lighting manufacturers to improve performance, cost and size of LED lighting—enabling never before p...

Cree XLamp® XM-L2 EasyWhite® LED

The first 5mmx5mm LED to enable color-consistent 50W halogen performance; the XM-L2 EasyWhite delivers 1,100 lumens and is optimized to replace halogen technology.

Surface Mount Insulation Piercing Terminals

Surface Mount Wire-to-Board terminals available for wire gauges ranging from 24 to 14 AWG. Parts can be terminated to allow daisy-chain applications. Eliminates difficulty with direct...

LED flexible strip and aluminum LED bar

Full range of LED strip and bar including the unique high lumen strip. Protection degree up to IP68.Epistar 3528/5050 SMD LED.Compliant with CE & RoHS.2-year warranty.3528: 60LED/m,120LED...

P3 Indoor Full Color LED Display Video screen

High-density pixel pitch,high resolution,high refresh rate,magnificent and high-definition image and video effect.P3,P5,P6,P7.62 to P10 available.Epistar SMD LED,wide viewing angle.High r...

LED Panel Light

Designed to replace T8 fluorescent tube or Phillip Grille light.Epistar 3528/3014 SMD LED.Aluminum alloy body.Even and Soft light beam.Various mounting means.50,000 hours lifetime.Environ...

Rotatable LED Down Light, beam angle adjustable 10-60°

Beam angle adjustable 10-60 degree.Shell can rotate 360°,vertical 0-40°.High power CREE LED,even and uniform light output,Die casting aluminum alloy housing,good heat sinking.Widely used ...

Solar LED Paver Light

100% solor powered.No wires, no electricians.Super capacitors instead of battery,maintenance-free.Absorb sunlight in daytime and illuminate 8-12 hours during night. Epistar LED.Activation...

T8 LED tube light

Epistar Super bright 3528/2835 SMD LED.Aluminum alloy body with plastic cover.Consist with traditional fluorescent tubes.Easy mounting.PF>0.90,CRI>72,Over 60% energy-saving,Low degradatio...

LED light Bulb – LED spotlight

The AR111,GU10,MR16,PAR30,PAR38 LED bulbs are ideal replacement of 10-75W halogen or CFL bulbs.Cree/Everlight LEDs.PMMA lens.Aluminum housing.Good heat dissipation.Surface temperature les...

Super bright Injection LED modules

Housed by ABS material,covered by epoxy resin on surface with good insulation.Beautiful appearance.Waterproof.Anti-fire.Super bright 5050/3528 LED.12V voltage.Ideal light source for backl...

Flexible LED screen - Rental and Stage LED billboard

Special design,flexible use,light weight,super slim,transparent,SMD technology,easy to install.Can realize any curved and creative installation horizontally and vertically.IP65 protection...

iVAR COB LED Downlight

iVAR COB LED Downlight use die-casting magnesium alloy to make the main body,has Excellent heat dissipation performance,and Unique and delicate looking design.

LIMS - Liquid Injection Molding System

Silicone LIMS can be used to injection mold silicone components such as lenses or gaskets in an automated process. The two-component, thermoset material ranges in Shore A hardness from 5-80.

360 degree 10W led bulb

360 degree 10W led bulb has high efficiency, high power factor,environmental friendly, unique heat-dissipating design and perfect thermal management.







Have a press release or other announcement you'd like to share?

Submit Announcement

Miss a webcast? Watch it in the archives


LEDs Magazine Newsletter

Our weekly flagship news source

Product Focus

Monthly newsletter

Illumination in Focus

Bi-monthly newsletter

Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved.