The history behind the development and proliferation of the PAR can fixture is one of mystery and myth. Numerous theories exist regarding the fixture’s adaptation into the entertainment lighting industry and the path to its existence has multiple coinciding adaptations that all seem to meld together during the 1960’s. Like many early lighting fixtures, it was borrowed from another industry and used for something other than its intended purpose. The Parabolic Aluminized Reflector (PAR) lamp was developed as a sealed reflector, filament and lens assembly. This allowed for its use in multiple applications. The parabolic shaped reflector creates a high intensity, narrow beam of soft-edged light that is oval in shape. To use it how we wanted in the entertainment industry, a body or ‘can’ was eventually developed to enable the use of color filters and other fixture accessories. The PAR can primarily found its home in concert lighting rigs where they would number in the 100’s. They could also be found in film studios, but the theater typically preferred another type of wash fixture, the Fresnel.

PAR lamps come in multiple sizes, intensities and beam angles. The size of a PAR is designated by its diameter in eighths of an inch, i.e. a PAR64 lamp is 64 eighths inches in diameter (or 8”). They can also be found in multiple wattages, 500w and 1000w are most typical. Finally, it is available with various beam angles; Very Narrow Spot- VNSP (12°), Narrow Spot- NSP (14°), Medium Flood- MFL (24°) and Wide Flood- WFL (70°). To change the beam angle of a fixture a new lamp had to be installed, so a production company had to have multiple lamps on hand for each PAR fixture to allow for various uses.

  PAR 64 Example

The PAR fixture has been a mainstay in lighting design for generations as it is easily maintained and deployed. Because of the simplistic design, the fixtures are also relatively inexpensive. The possible uses for the fixture are almost endless and so the design of the fixture remained fairly constant throughout its existence. There were companies that designed their own versions, taking advantage of other lamp types, but the basic PAR remained the most popular. That is, until another technology revolution pushed its way into the lighting industry, LED.

The first LED fixtures developed were similar in design to a PAR fixture. They contained numerous independent through-hole mounted LED diodes attached near the front of the fixture and produced a soft edged, round beam of light. These fixtures usually contained Red, Green and Blue colored LEDs that when mixed could create numerous colors. While this was a good use of technology available at the time, the quality of light that the fixture provided was not great. These types of fixtures are still available but are typically relegated to entry-level applications, because the technology and materials to produce them are inexpensive.

 Chauvet SlimPar 64

Eventually, it was discovered that if you took the LED out of the independent lens assembly and placed it directly onto the circuit board, designers could then place a separate lens over the top of the emitter. These designs are referred to as single chip/ single lens fixtures. This change in design improves the quality and consistency of the light produced. It also allowed for an improved lens design that would provide different beam angles for the fixtures. Designers also began to incorporate more LED colors into the fixtures to allow for more possibilities when mixing colors. While these fixtures performed much better than the previous designs, they relied on the separate beams of light cast by each independent LED to be mixed in the air as they travel to the object the fixture is pointed at. If that distance is short, the color may not completely mix. This design can also cast multicolored shadows on objects as well. An additional issue is the aesthetic look of the lens when the fixture is on. Because of the multiple separate LED color lenses, the fixture can give a ‘Lite-Brite’ like appearance, which can be distracting to an audience when the fixture’s lenses are in view.

 ETC Desire D40

To alleviate the multiple shortcomings of the single chip/ single lens LED design, a new method of LED placement was engineered. This new development is referred to as multi-chip LED. Instead of placing only one colored LED under each lens, the different colored LED diodes in the fixture are all located on one chip and under one single lens.

With this design, all of the color is being premixed within the fixture before it exits. This allows for a better blended, or homogenized beam of light. It also removes the issues of multi-colored shadows that single chip/ single lens fixtures can create.

 

The multi-chip design was first developed and released by Elation Lighting in 2007 in a three color, RGB variation. In 2009, a white LED was added to the mix to create the first quad-color multi-chip design. Because of the improved color mixing capabilities of the design and the increased output of LED diodes now available, there has been continued to development of larger color array options. There are now even up to Seven color array chips available.

 

Elation Seven Par 19IP

           

These fixtures increase the color spectrum a designer is able to use and improve the CRI and TM-30 ratings of the light output by using a Red, Green, Blue, Amber, White, Lime and UV color array.

While multi-chip LED fixtures are the most popular style of fixtures available and in use today, they still have some downfalls. One is again purely aesthetic - when placed in view of an audience, multiple lenses can be seen. In some applications, that takes a person out of the environment that is being created. As for technical shortcomings, the use of multiple lenses and chips within a fixture can create multiple shadows when a subject that is being lit is located near a wall or other surface. Multi-chip fixtures also do not allow for easy beam manipulation or control through methods common in single-sourced incandescent devices. This can make them difficult to use in theatrical, architectural or other applications that may require very precise beam control.

LED designs are constantly improving and manufacturers eventually came up with the Chip-on-Board or ‘COB’ LED to improve on the multi-chip LED design. In a COB LED array, instead of mounting each LED directly to a circuit board, the bare LED chip is put in direct contact with a conductive substrate. This allows for the diodes to be packed in a higher density and creates a brighter array in a smaller area. A COB LED array allows for up to 8 ½ times more LEDs to be placed in a 10mm x 10mm square array than with existing SMD LEDs. This tighter spacing also allows for better light beam uniformity.

 

  A COB LED Chip

In our application, a COB LED creates a fully premixed, homogenized beam of light that exits the fixture through a single lens. This technology allows for the light to look reminiscent of the incandescent fixtures we are used to seeing. The aesthetics of the fixture are improved, but so is the way that the beam of light can be controlled. The single source of light allows for the use of a larger lens and reflector assembly and can create a wider beam angle than multi-chip LED designs. The beam can also be controlled very similarly to incandescent fixtures through the use of barn doors and other modifiers. Also, the issues of multiple shadows on surfaces is eliminated with these improvements.

  Elation KL PAR FC

So, with these options available, why should one technology be used over the other? Multi-chip LED fixtures are the most prevalent and they come in numerous color array options, from one color to seven color. Also, because the placement of the LED lenses is what dictates the fixture’s beam angle shape, these types of fixtures can be designed for different applications. They can be placed in a circular array to allow for a circular beam, like in a PAR, or they can also be arranged in a linear array to provide a linear asymmetrical beam, like in a batten fixture.

COB LED fixtures are becoming more popular in the house of worship and theatrical markets because of the single source element that they provide. They tend to be less of a visual distraction to the audience, so they have become very attractive to customers that value a more pleasant viewing experience if the lighting fixtures are in view of the audience. They are also great in venues that require the ability to manage the light bleed on displays or projection surfaces.  They also tend to provide a ‘softer’ light source, so they look better when lighting for camera applications as well. Because of the growing popularity for these types of LED fixtures, more development has been done with them recently, and full spectrum engines are now becoming available, making them a great choice when a high quality of light is needed.

            Whichever style of LED Par you prefer, we certainly have come a long way from the lamps in a coffee can that our predecessors used and perfected.