Moving Light With Bivar’s Press-Fit Rigid Light Pipes

Moving Light With Bivar’s Press-Fit Rigid Light Pipes



Light pipes are the most efficient and cost-effective solution for moving LED light in a variety of applications. These products offer design flexibility, easy installation, and uniform illumination at user interfaces, and minimizes light loss and glare. This technical article by Bivar explores what light pipes are, types, applications, and how to choose the right light pipe for a particular design. 

What Are LED Light Pipes?

LED light pipes are solid transparent plastic rods or optical fibers used for transmitting light from a Light-emitting diode (LED) source mounted on a printed circuit board to a user interface. They are utilized in a wide range of electronic applications that require some form of LED indication to communicate the operational status of a device or equipment, for decoration, or to enhance the display quality. The working principle is capturing light from a LED source and transporting it to a separate location with minimal loss of light, also known as “light bleed”. 

Two main types of light pipes are rigid and flexible. They are made of acrylic or polycarbonate; low-weight materials with superior optical properties. Rigid light pipes come in fixed right-angle, vertical, and multi-level styles and only move light over short distances. On the other hand, flexible light pipes are ideal for moving light over longer distances where the user interface is far from the light source. Using optical-grade fibers, they move light around board components while minimizing light leakage. 

Applications of Light Pipe Technology

Light pipes are used in a wide range of applications that require LED indication. In automobiles, they can illuminate buttons on a dashboard as well as switches and body electronic modules. In security and surveillance hardware, light pipes can transmit light to LED indicators for real-time tracking and remote monitoring. In industrial facilities, light pipes help to increase visual communications for monitoring industrial processes and operational status of devices and equipment. Consumer electronics, such as washing machines, household appliances, notebook computers, and more also utilize light pipes for LED indication. 

Considerations For Light Pipe Matching

The ideal light pipe for any particular application depends primarily on the characteristics of the LED light source. Typically, the light intensity from a light pipe depends on the type of LED used. Dual in-line package (DIP) LEDs are some of the most common types, featuring a chip enclosed in a plastic bulb and parallel pins that extend from the bottom of the package. DIP LEDs perform well in outdoor environments with high ambient lighting, emitting up to 4 lumens per LED pixel. However, their high luminescence decay results in lower efficiency compared to newer solutions. 

Another main drawback is that DIP lighting requires separate LEDs for Red, Yellow, Blue (RGB) indication. On the other hand, Surface-mount (SMT) LEDs offer an optimal solution with smaller sizes, low-power consumption (up to 80% lower than DIP LEDs), and multiple-color indication. A newer LED technology is the Chip-on-Board (COB) LED which comprises an array of LED chips on a single substrate functioning as one compact LED unit. Other key considerations include distance from the source (location), size/mounting styles, viewing angle, and color binning. 

Location

To minimize light bleed, a light pipe must be placed extremely close to the source. Optical-grade light pipe materials transmit up to 92% of light captured from an LED source, depending on the design. Light is propagated through a light pipe using the principle of total internal reflection. However, due to Snell’s Law of refraction, a small amount of light is always lost when crossing a boundary from one medium to another (e.g., from air to plastic). Therefore, the closer the pipe is to the source, the greater the efficiency. To capture as much light as possible, the LED should be enclosed or built-in to a board mount adapter which maximizes light transmission. 

Size

Key dimensions for light pipe sizing include length, height, and width. Selecting the appropriate dimensions ensures as much light as possible moves through the pipe without escaping into the surrounding. To minimize light loss, the entrance of a light pipe should match the shape and size of the LED to focus the light flux. Mounting styles are critical for achieving the best illumination in any application. The most common styles include panel press-fit (hover style placed close to LED without touching), and board mount using a surface mount or through hole mounting styles. Surface mount light pipes are matched with SMT LEDs and are mounted directly onto a PCB. Press-fit light pipes are not directly mounted onto a PCB. Instead, they offer a low-profile flush design that hovers over an SMT LED. Meanwhile, through-hole light pipes feature leads at the bottom that extends through holes on the PCB. 

Viewing Angle

The viewing angle of a LED plays a key role in determining its intensity of light pipe illumination. Whereas wide-angle LEDs are able to disperse light over 120 degrees resulting in a short view distance, narrow-angle LEDs beam high-intensity light further, over a 30-degree angle. Engineers looking to incorporate light pipes into their products should note the viewing angles of each LED and choose the ones with the smallest possible viewing angle to avoid color diffusion from adjacent pipes in close proximity. 

Color Binning

In industrial LED usage, binning is the process of grouping LEDs based on characteristics such as color, forward-biased voltages, and lumens. For best practices in applications that require LED arrays in similar colors, they should be sorted based on the American National Standards Institute (ANSI) color binning guidelines to ensure consistent colors and uniformity of output. 

Bivar RHD Series Light Pipes Assure Zero Light Leakage 

Bivar’s RHD Series press-fit rigid light pipes offer hover-style proximity to SMT LEDs for optimal light transfer to panel-mounted lenses in a host of applications. These small-footprint light pipes are interchangeable with flexible light pipe systems using the same lens. RHD Series light pipes allow single or multiple-color indication and are suitable for use with narrow-angle LEDs in top or side-mount configurations. Their IP ratings ensure dust and water protection. Bivar also offers custom solutions to meet application-specific requirements. 

Industry Articles are a form of content that allows industry partners to share useful news, messages, and technology with All About Circuits readers in a way editorial content is not well suited to. All Industry Articles are subject to strict editorial guidelines with the intention of offering readers useful news, technical expertise, or stories. The viewpoints and opinions expressed in Industry Articles are those of the partner and not necessarily those of All About Circuits or its writers.



For lighting, electrical, signage, and technology solutions that allow you to do more call Sverige Energy today at +4(670) 4122522.

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