Apr. 29, 2024
Midnight Moment is the world's largest and longest-running digital public art program. Presented nightly to millions of viewers each year, Midnight Moment showcases the work of contemporary artists on one of the most iconic public canvases — the electronic billboards of Times Square.
For more information, please visit billboard light.
Synchronized nightly from 11:57pm to 12am on over 92 digital displays spanning 41st to 49th Streets, this program brings public art on a monumental scale to New Yorkers and visitors from all across the globe, 364 nights a year.
Presenting a new Midnight Moment each month, the program has featured the work of over 100 artists since 2012, thanks to the Times Square Advertising Coalition and our participating billboard operators.
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Light-emitting diode (LED) is a widely used standard source of light in electrical equipment. It has a wide range of applications ranging from your mobile phone to large advertising billboards. They mostly find applications in devices that show the time and display different types of data.
A light-emitting diode (LED) is a semiconductor device that emits light when an electric current flows through it. When current passes through an LED, the electrons recombine with holes emitting light in the process. LEDs allow the current to flow in the forward direction and blocks the current in the reverse direction.
Light-emitting diodes are heavily doped p-n junctions. Based on the semiconductor material used and the amount of doping, an LED will emit coloured light at a particular spectral wavelength when forward biased. As shown in the figure, an LED is encapsulated with a transparent cover so that emitted light can come out.
Read More: Diodes
The LED symbol is the standard symbol for a diode, with the addition of two small arrows denoting the emission of light.
The figure below shows a simple LED circuit.
The circuit consists of an LED, a voltage supply and a resistor to regulate the current and voltage.
When the diode is forward biased, the minority electrons are sent from p → n while the minority holes are sent from n → p. At the junction boundary, the concentration of minority carriers increases. The excess minority carriers at the junction recombine with the majority charges carriers.
The energy is released in the form of photons on recombination. In standard diodes, the energy is released in the form of heat. But in light-emitting diodes, the energy is released in the form of photons. We call this phenomenon electroluminescence. Electroluminescence is an optical phenomenon, and electrical phenomenon where a material emits light in response to an electric current passed through it. As the forward voltage increases, the intensity of the light increases and reaches a maximum.
The colour of an LED is determined by the material used in the semiconducting element. The two primary materials used in LEDs are aluminium gallium indium phosphide alloys and indium gallium nitride alloys. Aluminium alloys are used to obtain red, orange and yellow light, and indium alloys are used to get green, blue and white light. Slight changes in the composition of these alloys change the colour of the emitted light.
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Laser light is monochromatic, directional and coherent.
Unlike white light, which is made of seven colours, laser light is made of a single colour.
Laser light is highly directional.
Laser light is coherent because the wavelengths of the laser light are in phase in space and time.
LEDs find applications in various fields, including optical communication, alarm and security systems, remote-controlled operations, robotics, etc. It finds usage in many areas because of its long-lasting capability, low power requirements, swift response time, and fast switching capabilities. Below are a few standards LED uses:
Below is the list of different types of LED that are designed using semiconductors:
Some advantages of LEDs over Incandescent Power Lamps are:
Read More: Types of LED
Frequently Asked Questions – FAQs
Q1
A light-emitting diode (LED) is a semiconductor device that emits light when an electric current flows through it.
Q2
LEDs have a wide range of applications ranging from your mobile phone to large advertising billboards. They mostly find applications in devices that show the time and display different types of data.
Q3
LEDs work on the principle of Electroluminescence. On passing a current through the diode, minority charge carriers and majority charge carriers recombine at the junction. On recombination, energy is released in the form of photons. As the forward voltage increases, the intensity of the light increases and reaches a maximum.
Q4
Electroluminescence is an optical phenomenon, and electrical phenomenon where a material emits light in response to an electric current passed through it.
Q5
LEDs consume less power, and they require low operational voltage. No warm-up time is needed for LEDs.
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