Solid-state lighting technology with the performance and efficiency continue to go beyond the traditional lighting technology, the new technology has been widely used. However, if we just use static white LED to replace traditional techniques, then it is difficult to truly play the full potential of solid-state lighting technology, not the full realization of the characteristics of the product. The support of the smart drive, LED lighting can not only replace the white light illumination, but also achieve new functions, and these features with traditional lighting technology is difficult to achieve.
We all know that: "All colors are included white." Under the correlated color temperature (CCT), there are different white tone, from warm white (such as the incandescent light) until the cold white (as many early and power LED LED indicator light), these two color values in the range 2700 ~ 6000K or more. If we use traditional technology, it can only add white to "dimming" This intelligence. If the words used solid-state lighting technology, designers can derive a new function, for example, adjust the white color temperature, changing environment.
This new feature benefits include improved efficiency of the work unit, so that the retail environment more attractive to customers, thus increasing traffic and service industries in the hotel to produce a more friendly welcome lighting effects. In addition, we can according to different seasons, products, such as different times of the day to change the lighting effects in the retail environment, so as to promote sales, without the need for large-scale transformation of the shops. Adjustable brightness solid state lighting technology is one of the characteristics, of course, in addition, there are energy-saving solid-state lighting, reduce costs, extend equipment working hours and other advantages, these advantages are driving the LED lighting market in a wide range of applications.
Before the improvements, the primary job is to ensure proper lighting effects. To speed up the promotion of speed, we should follow the traditional lighting technical specifications, to ensure that new lighting technologies to meet the lighting designers, architects and end-user expectations. Only able to provide proper lighting effects, and add intelligent functions with scalability, lower business costs while ensuring that the technology can we revolutionize the lighting market. Performance (light intensity), quality (color temperature and color rendering) and light (the beam angle and luminous intensity) are important parameters we need to consider. Color rendering is usually used in specification IEC color-rendering index (CRI) standards, it reflects the ability of accurate color reproduction lighting.
For example, the red car in the low-pressure sodium light brown will show that there is a light amber tone, CRI is low. End users want to be able to extend through the LED lighting technology, the use of equipment time, reduce energy consumption and maintenance costs, but if you reach a new lighting technology lighting quality requirements, then would not even consider using this technology. Only the lighting effects achieved on the basis of performance requirements, we can turn to consider how to enhance functionality.
Effect on the light in order to achieve absolute control, it is necessary to resolve the issue of consistency. In a controlled solid-state lighting, we always have to consider the problem of color consistency, we should expect performance differences, including between different lamps produce over time the difference, temperature and set points. Despite the appropriate technology to solve these problems, but the overall system development remains a challenge to the lighting industry. This paper described the implementation of modular or system-level solutions can help solve the technical problems. The use of appropriate technology, LED power supply and control system should be a useful complement to current technology and cooperation, rather than conflict with existing technology, do not have to replace other techniques, the only way to help speed up new technology.
The problem is not limited to light
To replace small halogen lamps, NA me light flux should reach between 400 ~ 1000Lm. Although LED performance continues to be significantly improved, but to achieve the performance of high flux density of light is also rare. Existing single-chip LED above the flux can reach 100Lm, but few can achieve the equivalent of 20W, 35W or 50W halogen flux LED. We can combine some low-performance LED, but this will bring light control issues. Light generation is a problem, and control of light in order to achieve the best lighting effects is another issue. We should design a uniform to meet the required light flux, which helps simplify the optical design, and improve the efficiency of light bulbs.
Thermal management is any high-power solid-state lighting applications can not ignore another important issue. Heat generated LED light source must be properly controlled, so as to ensure that the equipment under certain conditions of work long enough life. Small package on the LED's, the heat problem may be difficult to resolve, but by minimizing the thermal resistance, help ease the system-level problems.
The basic design problem of adjustable white light is to support multiple control and can be mixed, respectively, the color channels. To ensure color consistency beam, does not appear the phenomenon of color edge or shadow, which is a very complex task. We can reduce the LED or LED light source the size of the system to improve the color mixing.
One solution is to design multi-chip LED, positioned in different colors as accurately as possible to shorten the mixing distance. Although the market selling a variety of multi-chip packaging solution, but also supports high flux density and color mixing does not have much packaging solutions. Most multi-chip package due to the low drive current limit, the lower flux density. In addition, designers also can use multiple discrete sources of high-throughput, but will increase the source size and color mixing problems.
Flux density, dimming of color mixing and thermal management, although not comprehensive requirements can not solve the problem, but does LED manufacturers poses a severe challenge. However, we should resolve these issues within the LED, which helps simplify the OEM and system integrators are facing problems.
We developed a multi-chip high power LED, adjustable in its capacity as "white spots" of light source, this reduces the color mixing problems, and to support the miniaturized light source lighting applications. Compared with the traditional power LED and the array assembly, this 10 ~ 15W program package can not only significantly improve the optical output power, but also greatly improve the flux density. This LED for cooling performance and reliability is optimized, can improve drive current, thereby further improving flux density. Materials, packaging and assembly processes connected with the die to achieve a more optimal combination of excellent thermal performance, thus improving application under different lighting effects available.
Adjustable LED lighting system usually red, green, blue color LED, through the mixed to generate white light, which is also known as RGB technology. RGB technology supports the rich colors and adjustable white light, but the CRI value is quite low. This system can support the color rendering CRI values generally between 40 and 60, depending on the target color temperature. CRI value of internal lighting usually require more than 80, if the retail and museums in the specific environment, require a higher CRI value. Thus, the light can be fully applied to the signal or the environment color (color-washing) applications, but do not fit with the white light source, adjustable interior lighting.
Improve the CRI value is a possible way to increase the color components. Achieved by adding the amber RGBA system, we can significantly improve the CRI value, while ensuring the adjustable color point. In addition, we can still achieve a high degree of flexibility of color, but the interior lighting is more important is that we can move the white point in the bold line, while allowing the value of close to 90 CRI, which achieve better color rendering, and generate high-quality white light.
Factors that we can combine these products to obtain better performance results. For example, has now launched the RGBA 10W transmitter, which can achieve high flux density, and mixed color control functions, and its packaging for heat dissipation and high reliability is optimized.
With this type of LED, we can develop a light intensity and quality to meet the appropriate light bulbs, but also support the white point adjustment, to improve color rendering. Product packaging is 7mm × 7mm, the ongoing work of a single chip currents up to 1000mA, luminous flux is 350Lm, the power consumption of only 10W.
Multi-channel drive: give color temperature setting, the quality of CRI (90 and above) will need many types of LED. CRI is the source spectral power distribution (SPD) of a function. SPD is given wavelength (frequency), the source of radiation. CRI value of the best (97 more) a shorter working life of an incandescent lamp (750 to 2500 hours), the efficiency is low (U.S. Department of Energy data for the 10 ~ 17Lm / W).
Obviously, RGB light source itself is not sufficient to support a higher CRI. Designers need to add more color to the band filling in the channel, so you can get close to the incandescent curve. Therefore, the device must drive at least 4 channels to drive red, green, blue and amber or red, green, amber and natural white light combination. The controller can be programmed in the factory manufacturing stage in order to obtain the correct u, v element values, communication links can also be dynamic programming.
EMI control: high-speed switching regulator as the reason, high-brightness (HB) LED lamps produce high electromagnetic interference (EMI), we shall adopt special design techniques for their control. Random we can be to rely on intensity modulation treatment techniques generated by pseudo-random counter cyclical component of output without leading function, to obtain one from the EMI / EMC point of view, low noise, easy to use modulation output.
Compensation: LED design requires a complex series of calculations to get a consistent color. High Brightness LED engineers face today is how the two biggest problems coded according to the production of LED performance specifications address different problems, and LED at different temperatures on the performance degradation issues (such as output flux and wavelength). LED lamps require smart drives, through a predictable manner to ensure that the color and CRI at different time and temperature consistency. For some applications, this drive should also be able to accept real-time feedback on color and temperature data to ensure that lighting performance.
Dimming: LED lamps should be easy dimming, the resolution should support deep color capabilities, and should avoid low brightness flicker problem. To help developers address multiple and complex color LED channel design and management issues, some companies introduced the ability to drive multiple LED LED designed to simplify the hardware and the software development and control, as shown in Figure 3.
Multiple channels through a single device driver (for Cypress Semiconductor has introduced the EZ-Color controller terms is 16), we can greatly reduce the large number of controllers needed to design, reducing design complexity and power consumption and saving board space.
In addition, we provide direct software drivers are available, which significantly reduces the HBLED design (including architectural lighting, general signage, rechargeable flashlights, entertainment lighting, emergency lights and vehicles, etc.) common low-frequency flicker and EMI radiation problems. Integrated development environment but also through the embedded visual design tool simplifies design, so even inexperienced engineers can easily select a selected special color LED.
