Yesterday, I had a chance to get an advance briefing from BrightView Technologies (Morrisville, NC; www.brightviewtechnologies.com). We have been tracking their progress since 2002 and it now seems that the company has finally developed its design, development and mass production of light management structures to the point that its first customers are in sight. "It is now time to be a little more visible," explained BrightView’s VP Business Development & Marketing, Doug Adams. What BrightView does is develop light management films that can control and direct light for general lighting, LCDs, PDPs, and even projection screens. They can design a wide array of 2D and 3D structures that can be fabricated with a laser light source to create soft-tooled structures on flexible substrates. This means the process is compatible with roll-to-roll manufacturing and can create films that are up to 150 inches in diagonal from their nearly fully automated web processing line.
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What differentiates the company is the ability to create complex film structures by laminating together a series of films, each created on their web machine and assembled on-site. Other companies working to develop similar capabilities, like Fusion Optix, Luminit and Rochester Photonics, are pursuing different approaches or offer limited sizes and/or designs. Adams says BrightView can offer very flexible design services, large-size films and multiple layer films, all with very small feature sizes and at a very cost competitive price.
So what does this mean? In an LCD backlight for example, there are lots of ways to stack films to homogenize the light and direct it through the LCD panel. One simple way to do this is by using three separate diffuser sheets. What BrightView has developed is a solution (LCD-ACE-1F) that offers better performance in a single sheet.
Another popular film configuration is to use a diffuser-prism sheet-diffuser stack with the prism sheet allowing some recycling of light for greater efficiency and higher brightness. The BrightView solution (LCD-ACE-1F+) combines prism sheet structures and diffusion into one film. This is added to a low-cost diffuser to offer a two-sheet solution that is brighter with higher uniformity.
But the approach I like the best is one they call RAC (Recirculation Angle Collimation). This approach adds a reflective layer with clear apertures to the light-guide-facing side of a substrate with a microlens on the other side. The reflective layer recycles light between the lightguide and the back reflector of the BLU until it can exit through one of the clear apertures. The microlenses above each aperture then collimate this light to pass it through the LCD panel.
Adams says they have built RAC films and compared them to film stack that employs two prism sheets in between two diffusers. When the half angle of collection of the microlens is 14.5 degrees, they can match this 4-sheet performance with a single RAC sheet. If they decrease the half angle to 9.5 degrees, they can create even higher gain screens that will have brighter on-axis performance - again, all in a single sheet.
Will this approach create moiré, you ask? Yes, but this can be greatly reduced by making the microlenses 65-100 microns in size and by adjusting the aperture pattern to reduce higher order moiré effects.
Adams says they have been diligently working with backlight, panel and finished product makers from handheld devices to TVs to prove the power of their approach. And it is starting to bear fruit. Adams says they expect a big LCD design win this fall, with more to follow.
In addition, the company is applying the same approach to solve illumination problems in solid-state light illumination such as down-lights, architectural lights, retail lighting and signage. Conventional diffusers can even out light in these applications, but it is inefficient and not very uniform. Using a BrightView ACEL film, the post-film brightness of a 4×4 LED array was measured at very uniform 3240 cd/m2, compared to 812 cd/m2 with dim corners for the diffuser solution. BrightView says it has its first high volume customer in this segment now and expects two more shortly.
The company currently does design and manufacturing in its North Carolina facility, which has plenty of room to add additional web production lines as needed. Judging by our conversation, the company does indeed look ready to RAC and roll-to-roll.