Make LED design unique

This article will explore several simple LED designs . Although these examples are worth discussing in depth, we will focus on the beginning of extending creative applications. At this stage, the key to success is to use microcontrollers to add basic intelligence to the circuit, so that white light LED designs can be used as flexibly as colored LEDs .

As the LED market continues to grow, lighting equipment manufacturers are facing increasing pressure. In addition to maintaining their existing market share, they also have to compete with hundreds of new manufacturers who want to seize this $2 billion business opportunity. However, most manufacturers have no experience in designing other electronic devices except for being familiar with standard fluorescent bulbs and incandescent bulbs. For these manufacturers, the most urgent issue is how to make their lighting products have a unique design.

At present, when many lighting manufacturers think about the uniqueness of their products, they may think of using colored LEDs to mix various colors of light, which is the so-called RGB, RGBA and other applications. This type of design also happens to meet the needs of architectural or stage lighting design. However, most products are still designed according to similar application principles, resulting in the market being flooded with unimaginative designs. This phenomenon is also invading the vast white light market.

Most engineers adopt a conventional approach in white light design, which is to increase the lumen of several factory-made LEDs (such as Lumileds) to the same level as fluorescent lamps or even higher, and then install a ballast lamp holder to claim superior performance. However, this is not a good way to achieve the expectations of success in the growth period. So far, there is almost no new technology on the market that can replace the current applications. If there is no wider use, it will be an unfortunate loss for LEDs customers who still have many expectations.

This article will explore several simple LED designs. Although these examples are worth further discussion, we will only focus on the beginning of extending creative applications. At this stage, the key to success is to use a microcontroller to add basic intelligent features to the circuit, so that white light LED designs can be as flexible as colored LEDs.

Adjust color temperature

The first example of a key differentiating design is the ability to adjust color temperature along the black body locus. It is obvious why manufacturers would want to use a mixed color approach, but it is difficult to apply the same approach to white light. As lighting equipment customers become more discerning about light, there is a growing demand for color temperatures between 3000K and 6500K, which means that designers can continue to maintain the design of a single white light fixture without having to constantly make adjustments based on the Correlated Color Temperature (CCT) specification.

It is worth noting that the adjustment of the color temperature of white light is usually done by mixing color LEDs. This was originally done using a simple RGB interface , but designers soon noticed that the Color Rendering Index (CRI) performance was quite poor. CRI is an important indicator of whether the color of an object under natural light can be reproduced, especially in display lighting applications. Because a jeweler would not want his gemstone to look dull. To address this concern, designers will try RGBA, RGGB and RGBW configurations, and each configuration has its advantages. Intelligent design can effectively calculate the dimming ratio required in the area of ​​​​the driven LED, which can ensure that the designer can get the best CRI index no matter which LED configuration method is selected. Many companies, such as Future Electronics , have successfully helped designers complete this previously difficult workflow in this way.

However, even having a high CRI is not the first priority in design. A simple adjustment can effectively improve the overall design. This time, only two rows of white LEDs are needed, one row with a cool color temperature and one row with a warm color temperature. This method allows designers to easily design a unique product that is different from ordinary fluorescent bulbs under the same lumen.

Intelligent Design in Communication Technology

The second form of design that is both intelligent and unique is in the communication aspect. Even in the application of stable white light, updating the lighting operation in the existing infrastructure allows designers to introduce the network function at the same time, and there is no need to configure additional network cables. This is a very important advantage because few designers are willing to add expensive additional wiring. However, the potential for communication is quite large, for example, the brightness and color temperature can be controlled through a central controller .

Power Line Communication ( PLC ) technology uses existing power lines to transmit communication signals, thus saving the cost of network wiring. Existing cases have shown that PLC can stably transmit 2.4kbps FSK modulation signals over a distance of more than 100m. This technology can be used in home or office applications. Since PLC communication transmission is independent of the voltage value of the power line, there is no need to redesign the circuit even in the face of different usage conditions. It is worth mentioning that PLC can also achieve higher bandwidth through power line or Ethernet transmission. Some manufacturers have even designed transmission rates up to 200 Mbps.

《Figure 1 Application of power line transmission in home appliance control》

Using different wireless communication technologies can also reduce the hassle of wiring chaos in the home or office. The reliability of wireless transmission solutions is constantly improving, including the ability to eliminate interference from other household appliances, such as microwave ovens. Integrating wireless technology is much easier than before, as manufacturers have introduced modular solutions that can be connected to the main microcontroller using a simple serial transmission interface, thus eliminating the design challenges such as FCC certification. In the entertainment lighting market, the addition of wireless technology will become particularly interesting because the location of the light display will no longer be controlled by the wires.

Figure 2: Wireless USB (WUSB) controller for remote control of lighting

Peripheral functions

In addition to light adjustment and communication technology, creative designers can still find ways to develop unique products from the peripheral functions to be discussed next.

As energy costs continue to rise, many companies are looking for more ways to increase their added value, and Energy Star compliance has become one of the important selling points of many products, which has forced designers to find more unique ways to manage power . Obviously, this feature is usually advertised when selling LED products, because their energy efficiency is about four times higher than that of ordinary bulbs. Manufacturers can highlight their uniqueness as long as they can improve energy efficiency with additional peripheral controls; and these goals can be achieved by simply using inexpensive ambient light sensors or infrared PIR sensors.

《Figure 3 Infrared PIR object sensor》

Everyone knows the basic functions of ambient light sensors or PIR sensors, so I won’t go into detail here. The key is whether tracking light intensity and object presence can significantly reduce the overall power consumption of the lamp. Here are a few examples for reference.

Ambient light sensors track light changes at different times of the day and adjust the office lighting network. PIR sensors can be used in cars, rooms, homes and other environments to detect the entry and exit of people or objects to turn lights on or off. Even the simplest display lights of household appliances can use simple sensors to make them light up only when necessary.

The last peripheral function that makes the product unique is the added capacitive control technology, which is to replace mechanical buttons or switches with capacitive sensing track interfaces . In addition to making the appearance more beautiful, it can also achieve the sealing of the device. This control interface is very popular in the MP3 and mobile phone markets, and it has also aroused everyone's interest in this technology in lighting applications. In addition, as the number of manufacturers investing in the development of capacitive solutions is rapidly increasing, the ability of designers to find suitable applications for their own solutions is gradually improving.

Figure 4 Philips capacitive lighting remote control

The following two examples are both very simple ways to apply this technology to the lighting market. The first example is a simple switch control or brightness adjustment lever. This basic additional function allows manufacturers to easily use it in their LED wall projection lighting or table lamps. In addition, the control lever can also be used in conjunction with the white light control mentioned earlier to achieve the purpose of setting the color temperature of the light.

By increasing the sensitivity of the capacitor circuit, a simple switch can be turned into a proximity switch, which can turn on the light by waving your hand near the light. Such a unique product does not require any additional processing or design on the LEDs themselves.

Conclusion

For creative designers, the LED market is a great opportunity to give full play to their strengths and stand out from the growing number of competitors. The characteristics of LEDs also represent infinite possibilities for lighting applications. Designers can win the competition if they can master these characteristics. The above-mentioned concept of differentiated design is just the tip of the iceberg. We look forward to seeing more creative ideas that will drive the market forward in the future.

---The author works for Cypress Semiconductor ; all the examples discussed in this article, from lighting adjustment, communication applications, to peripheral functions, can be integrated into existing designs using Cypress's existing application guides and firmware.