13.12.2014
Compact fluorescent lamps (CFLs) are replacing incandescent light bulbs at a rapid rate due to their tremendous energy savings and longer lifetime.
This two-stage conversion process is much more efficient than incandescent lamp process, resulting in 25% of the total energy consumed used to generate light, lower lamp temperatures (40° C) and longer lifetime (10,000 hours). The lamp requires a current to preheat the filaments, a high-voltage for ignition, and a high-frequency AC current during running. The AC mains voltage is full-wave rectified and then peak-charges a capacitor to produce a smooth DC bus voltage.
When the CFL is first turned on, the control IC sweeps the half-bridge frequency from the maximum frequency down towards the resonance frequency of the high-Q ballast output stage. The frequency keeps decreasing until the lamp voltage exceeds the lamp ignition voltage threshold and the lamp ignites.
To dim the fluorescent lamp, the frequency of the half-bridge is increased, causing the gain of the resonant tank circuit to decrease and therefore lamp current to decrease. The IRS2530D Dimming Control IC from International Rectifier includes such a feedback control circuit, as well as all of the necessary functions to preheat and ignite the lamp,and to protect against fault conditions such as open filament failures, lamp non-strike and mains brown-out.
The feedback circuit regulates the valley of the AC+DC signal to COM as the DC dimming level is increased or decreased by continuously adjusting the half-bridge frequency. This will increase the lamp current, as well as the amplitude of the AC+DC signal at the DIM pin, until the valley reaches COM again.
The first socket switch position is the off setting, where no filaments are connected, the second position connects the first filament across the AC line for the lowest-brightness setting, the third position connects the second filament for the medium-brightness setting, and the fourth position connects both filaments in parallel for the highest-brightness setting.
The circuit includes a rectifier and voltage doubler circuit at each input (D1, D2, D3, D4, C3 and C4), the half-bridge control circuit and MOSFETs (IRS2530D, Q1 and Q2), the resonant tank (LRES and CRES), the lamp-current sensing and feedback circuit (RCS, RFB and CFB), and the 3-way interface circuit (R3, R4, R5, R6, R7, RPU, Q3, Q4, DZ1 and C5). Resistors R5 and R6 pull up the DC dimming reference across resistor R7 and capacitor C5 to the appropriate level to set the minimum and medium brightness levels. The IRS2530D controls the preheat and ignition timing with capacitor CPH, and controls the dimming loop speed with capacitor CVCO.
The challenge is to design each different interface circuit that converts the user dimming method to the necessary DC dimming reference. Tom Ribarich is the Director, Lighting IC Design Center, at International Rectifier Corporation, El Segundo, CA, where he is responsible for developing control ICs for the global lighting market, including fluorescent, halogen, HID, LED and LCD backlighting applications. For this reason I still prefer incandescents and it really bothers me that some nanny-staters can limit my choices. Ultra-violet LED (UV LED) is a device which emits ultraviolet light or waves having wavelength of less than 400nm and is known for its compactness, superior performance, and low cost. Previously, UV lamps were widely used application of UV LED, but the applications of UV LED have enhanced over the time with the growth of UV curing application which utilizes UV-A technology. The UV LED market is expected to grow with new applications such as disinfection, that is, air and water purification system which works on UV-C technology. With the development of better chips and components, UV LED technology is continuously advancing further. The illustrative segmentation, analysis, and forecast of the major geographical markets give an overall view of the market. The future of UV LED is studied and estimated from technical as well as market-oriented perspectives. The UV LED technology is used in various applications such as industrial, medical & scientific, sterilization, and security. This report describes market trends, drivers, and challenges for the market and forecasts the UV LED market size for the period between 2015 and 2020, on the basis of technology, application, and geography.
The growth of the UV LED market is driven by the availability of advanced UV LED devices such as evolution of mercury lamp to UV LED lamp and the increasing demand for UV LED in the disinfection and curing applications.


Additional energy savings can be achieved by dimming, but the electronic ballast required to control the lamp has a higher cost and is difficult to design.
This conversion is very simple but the disadvantages are that only 5% of the total energy consumed by the lamp is used to generate light (95% is wasted as heat!) and the lifetime is limited to about 2,000 hours. Electrons flow through the fluorescent lamp and collide with mercury atoms, causing photons of UV light to be released.
The lamp load itself is resistive, but the electronic ballast that is connected between the AC line voltage and the lamp for controlling the lamp current is a capacitive load.
The additional circuit block required for dimming is also shown; it includes a feedback circuit for controlling the lamp current. To fulfill these requirements, the electronic ballast circuit first performs a low-frequency AC-to-DC conversion at the input, followed by a high-frequency DC-to-AC conversion at the output.
The DC bus voltage is then converted into a high-frequency, 50% duty-cycle, AC square-wave voltage using a standard half-bridge switching circuit.
After ignition and during running, the tank is a series-L, parallel-RC circuit, with a Q-factor somewhere between a high and low value, depending on the lamp dimming level. The lamp filaments are preheated as the frequency decreases and the lamp voltage and load current increase (Figure 3). Once the lamp ignites, the lamp current is controlled such that the lamp runs at the desired power and brightness level. A closed-loop feedback circuit is then used to measure the lamp current and regulate the current to the dimming reference level by continuously adjusting the half-bridge operating frequency.
The dimming function is realized by combining the AC lamp current measurement (Figure 4) with the DC reference voltage at a single node. The 3-way dimming incandescent lamps include two filaments and two connections on the lamp screw base. To achieve the equivalent functionality for a CFL, a dimming electronic ballast circuit is used to control the lamp current for each brightness level. As the switch position is changed for each dim setting, the circuit detects the change in voltage at the two screwbase input connections (PL1 and PL2) with the voltage divider formed by resistors R5, R6 and R7. To set the maximum brightness level, transistors Q1 and Q2 are both turned on and the DC dimming reference is then pulled up high enough to ensure the circuit will reach the maximum brightness level. If the lamp does not ignite, or one or both of the filaments open up, then the IRS2530D will disable the complete circuit safely to prevent excessive voltages or currents from damaging components.
Each dimming application presents a different set of challenges, especially with the interface circuit required. The new IRS2530D greatly simplifies dimming designs and helps close the gap between dimming and non-dimming designs. He has a BSEE degree from California State University, Northridge, and a master's degree in ASIC design from University of Rapperswil, Switzerland. Few main applications of UV LED market include air & water purification, medical, and security purposes.
New technological advancements such as replacement of mercury lamp, flux density, and high performance with the high wavelength are also fostering the growth of the UV LED market. Today, technologically-advanced UV LED devices such as counterfeit detection systems, equipment sterilizers, and curing and coating methods offer best UV LED experiences to users.
The UVA LED wavelength range between 320-400nm and has high adoption rate because of the presence of variety of UVA applications such as counterfeit detection, UV curing, forensics, and many others. Several companies are investing heavily in the research and development of innovative UV LED devices because of its lucrative growth potential. The UVA comprises wavelength range between 320-400nm and has high adoption rate because of the presence of variety of UVA applications such as counterfeit detection, UV curing, forensics, and so on.


The company profiles include the company overview, products & services, and the recent developments. This article explains how a CFL works, how to dim them, and describes a solution for 3-way dimming applications.
The UV light is then converted into visible light as it passes through the phosphor coating on the inside of the glass tube. The complete CFL (Figure 1) includes the Edison screwbase and plastic housing, the electronic ballast, and the fluorescent lamp formed into a compact spiral shape. The high-frequency AC square-wave voltage then drives the resonant tank circuit and becomes filtered to produce a sinusoidal current and voltage at the lamp. The AC lamp current measurement across the sensing resistor RCS is coupled onto the DC dimming reference through a feedback capacitor CFB and resistor RFB. If the DC reference is increased, the valley of the AC+DC signal will increase above COM and the feedback circuit will decrease the frequency to increase the gain of the resonant tank. The feedback circuit will then increase the frequency to decrease the gain of the resonant tank until the valley reaches COM again.
A 4-position switch in gthe socket (off, low, medium, high) is then used to switch between different filament connections, to step through three dimming levels (Figure 5). The dimming control loop required to regulate the lamp current is basically the same for each application.
This will enable CFL products to compete with incandescent ones, while maintaining a small form factor and a low cost.
I should think that 99% of all light fixtures are not connected to dimmers, so this is a niche market.
One of the emerging trends with respect to the industrial application of UV LED is the growing demand for UV curing solutions that integrates coating, printing, and adhesives and the evolution of UV lamps to UV LED.
Initially used in curing and printing applications, the UV LED market is now being used in medical, automotive, security, electronics, and many other applications.
Various applications of the UV LED market such as curing, printing, forensic, coating, R&D, disinfection, counterfeit detection, deodorization, and others mainly use wavelengths from 100 to 400nm. This report covers regions such as North America, Europe, APAC, and RoW (Rest of the World). Additional dimming circuits to consider to further enhance the performance of CFLs include triac dimming, powerline communication and wireless applications. The UVC technology is expected to grow at the highest growth rate in the coming years as it is mainly used for germicidal & sterilization purposes, protein analysis, and other applications of the medical and sterilization segments. The UV LED market is also segmented on the basis of application into industrial, medical and scientific, sterilization, and security application. In this report UV LED applications such as industrial, medical & scientific, security and sterilization are considered. The industrial segment has a major share in the market owing to its capability to provide better performance, in terms of printing, curing, coating and so on. The sterilization market is expected to grow rapidly in the coming years given the increasing growth of UV LED applications such as disinfection and deodorization.



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