Photos courtesy Cirrus LED
By Guadalupe Tofalo-Davtchev
Over the past few years, the light-emitting diode (LED) digital signage sector has seen vast change. Fundamental shifts
in LEDs, software and hardware have forced manufacturers to adapt quickly, particularly in the face of innovations in competitive technologies.
Hardware, in particular, is becoming lighter, smaller and faster, with microprocessors and microcontrollers becoming more powerful every day. As per ‘Moore’s law,’ the number of transistors that can be squeezed into an integrated circuit has doubled approximately every two years. Advances in software have kept pace, enabling rich applications in devices as small as smartphones.
Technology has also become more energy-efficient, not merely because customers are environmentally conscious, but also because they are protecting their wallets. No one wants to spend extra money on increased consumption of electricity.
Digital displays have become brighter, sturdier and less expensive. This trend involves deconstructing and rethinking every part of an LED advertising board to keep up to date with competitive technologies, lest they take over the market.
Hence, the following are some factors that need to be kept in mind when developing the next generation of LED panels.
Many cabinet-style LED signs feature only one transformer, long, exposed cables and blowing fans, all of which reduce energy efficiency.
Energy efficiency
Rethinking the way electricity is used by an LED display sign has involved the reduction of wasted energy and, thus, the reduction of costs, but also an increase in reliability.
As the law of conservation of energy states in physics, energy cannot be created or destroyed, merely transformed. Any electricity that is ‘wasted’ in a device like an LED display is actually transformed into heat, through a process referred to as resistive heating. This poses a problem, as small, delicate electrical components risk overheating and failing.
Resistive heating is also the result of friction caused when an electric current flows through a given material. Some materials (like wood) offer a lot of resistance, while others (like copper) put up very little, but there is always some level of resistance, which produces heat. The friction is created by microscopic collisions between electrons.
Joule’s first law (Q= I2*R*T) states the amount of heat released (Q) is equal to the square of the electric current flowing through a conductor (I) multiplied by the resistance of the conductor (R) multiplied by the time during which this happens (T). So, to reduce the amount of heat lost or released—i.e. increase energy efficiency—it is necessary to diminish I, R and/or T:
- I: Electrical power can be transmitted at different voltages. As counterintuitive as it may sound, the higher the voltage, the lower the current, since the amount of electric power is equal to the product of voltage and current (P= E*I). So, at a higher voltage, a lower current is needed to obtain the same amount of power. That is why electricity is transmitted at higher voltages and then converted to lower voltages through transformers in most electrical devices. LED sign systems, for their part, include one or more transformers to lower the voltage of the electricity coming out of the outlet.
- R: To reduce the resistance of a conductor, most electronic devices—including all LED displays in the market—use copper, which is known for its properties of low resistance and high conductivity. Pretty much the only way to reduce resistance further would be to use gold cabling instead of copper, so it is more practical to work on reducing I and T instead.
- T: The longer it takes for electricity to travel, the more it is wasted as heat. For LED signs, this translates into longer cables causing panels to heat up more than shorter cables.
