In a series of discussions on light-emitting diodes (LEDs), we discussed the short-term challenges of the LED industry – try to avoid discussions such as cost or focus on replacing such topics, focusing on the equally important LED industry development factors.
My latest blog post explores the consequences of driving LEDs with an existing DC component and AC (AC). This article wants to talk a little bit about one of the most notorious reasons for the LED industry: Flicker ). In recent days, flashing is a hot topic, and it is also a battlefield for LED manufacturers to "snap up."
First, first clarify the various phenomena covered by the flicker. Direct flicker can be judged by simply observing the light source. Direct flickering is highly dependent on the frequency of flickering. Direct flicker can be found by the 60 Hz peak sensitivity (Peak SensiTIvity) that humans have almost disappeared in a few Hz and sensitivity.
An image of a bouncing ball captured with a flash strobe at 25 frames per second. (Michael Maggs Photography, Richard Bartz)
However, Indirect Flicker can be found at higher frequencies, and its various manifestations. The most common, called Stroboscopic Flicker, is a jagged visual perception of a moving object or a rapid eye movement. Flashing flashing is some common user experience of LED users, and watching the context, the flashing flashing is almost inconspicuous, but it is unacceptable - lucky eyes can also follow the basketball in the wrong light .
Studies have shown that flashing flicker can be triggered at frequencies above 1,000 Hz, far beyond the threshold of human consciousness. In addition, indirect flashing can also cause physiological effects, similar to lower "employee performance", which can cause headaches or epilepsy when sensitive to light or flashing. Just as someone is in a daily run, crossing a sidewalk stripe, migraine because of flashing, I tend to be quite sympathetic...
The study of scintillation is ongoing. Obviously, the actual waveform of light (shape, amplitude variation, frequency, etc.) plays a central role. In addition, external factors including the visual environment (light source position, ambient illumination...) also have certain effects, such as personal sensitivity.
Unfortunately, this complexity has only a few indicators that can be used to indicate various problems with flicker. The two most common "flicker percentages" and "flicker indicators", while simple but have drawbacks: for example, these two indicators ignore the important perceived frequencies of direct flicker, so currently the various research units include the International Commission on Illumination (CIE). , Lighting Society (IES), Institute of Electrical and Electronics Engineers (IEEE) ... have put forward more advanced indicators. However, today, in the absence of a recognized metric, the best way is through experimentation: a simple visual test with a Flicker Wheel or a swinging finger often provides a clear answer. For example, the California Energy Commission's Voluntary Quality Spec mentions that the scintillation test should be performed by an auditor who is very sensitive to flicker.
LED flashing occurs in part because the LED follows a fast response time fed by the radio wave, and the LED driver attempts to correct the AC waveform to make it as smooth as possible, but this is a complex task—especially when the dimmer ( Dimmer) When entering the program, the drive must be compatible with waveforms input by different dimmers, which will cause the problem of LED flashing to be more pronounced in dim environments.
Therefore, how to reduce the phenomenon of LED flicker when actually designing LEDs? Of course, the simple way is to get rid of the AC current and use a constant-current device, but this is not the only option.
The most basic answer in retrofit applications is a driver that is better designed and can always be implemented with the correct capacitors. The difficulty is the balance between flicker and other key issues such as cost, size and heat. Capacitors with better energy storage capacity tend to be expensive, take up space, and have low heat tolerance—when the driver in a small retrofit lamp holder is filled with capacitors, it sounds a little bad!
Therefore, manufacturing is facing a difficult problem. A-bulb should be flash-free when it is sold in a home improvement store, or should it be reduced by another $1 to reach the consumer price threshold? Should Soraa's MR16 be given a very high Candela or a built-in low-flash drive that reduces power consumption and heat?
Fortunately, with the advancement of technology, the impact of the above trade-offs has become smaller and smaller. Taking the bulbs produced by Soraa as an example, the basic technology of LEDs continues to advance, enabling a new generation of lamps to emit brighter light as much as possible, while also having lower input power and less heat. Soraa said: "We are pursuing simple products, which is why we launched a true flicker-free solution this month - the Lightfair series, and the new MR16 bulb will be launched later this year, benefiting from its superior drive, Therefore, no matter what dimming conditions, the new bulb oscillates less than the halogen lamp."
Looking forward to the future, we can only hope that such a scheme will gradually become the mainstream, so that we will no longer have to worry about the problem of flickering, and it can be done once and for all.
What is Industrial DTU? Industrial DTU characteristics and application field analysis
What is DTU?
A Data Transfer unit (DTU) is a wireless terminal device that converts serial port data into IP data or IP data into serial port data over a wireless communication network.
Second, industrial DTU characteristics?
D220 is an industrial 4G DTU based on 4G wireless network, the product uses high-performance industrial embedded processor, real-time operating system as the software support platform, to ensure that the data link is smooth at any time, to provide users with high-speed, stable and reliable data transmission. It can be easily and quickly arranged in the industrial site, and can be used in harsh environments.
Hardware features:
Anti-interference design, suitable for harsh electromagnetic environment application requirements
Wide voltage power supply design, support DC5V-35V power input, built-in power reverse protection and overvoltage and overcurrent protection
The serial port can be a service serial port or a data serial port
Supports the many-to-many link configuration between the service serial port and the center
Select industrial-grade devices and optimize electromagnetic compatibility design to meet the requirements of harsh application environments
The D220 supports backward compatible 2G/3G network access based on 4G network.
Built-in hardware watchdog, regular detection mechanism, automatic resetting of abnormal equipment.
Complete industrial environment design requirements, all-metal structure, the whole machine has passed the strict electromagnetic compatibility test, CE certification
Software features:
Multi-center mode/Multi-backup mode (up to five multi-centers/backup centers)
Different serial ports can be used as maintenance or service serial ports, and different service serial ports can be connected to different multi-centers.
Multi-protocol upper development kit support (compatible with communication protocols of multiple DTU manufacturers, which can achieve seamless replacement of DTU)
Supports ICMP and LCP link detection technologies and keeps heartbeat alive, ensuring the stability and reliability of the network and communication
Supports local serial port upgrade and remote software upgrade
Supports TCP, UDP, DUTCP, DCUDP and other connection protocols
Supports multiple encryption modes to ensure secure data transmission
3. Application fields
D220 4G DTU conforms to industrial design, complete functions, stable transmission, widely used in environmental protection, water conservancy, meteorological industries; Industrial control field; Industry and special environment, oil and gas, heating industry, etc.
Industrial Dtu,Industrial 4G Dtu,Industrial 2G 3G Module 4G Dtu,4G Industrial Modem Dtu
Shenzhen MovingComm Technology Co., Ltd. , https://www.mcrouters.com