Q1: Is turning an LED on and off bad for it? What's "PWM"?
No. LEDs are semiconductors, which are quite happy with transitioning between an "on" and an "off" state. In fact, most LED flashlights provide extra output levels by flickering the LED at a faster rate than the human eye can usually detect. When the output is not filtered and smoothed out, the flicker can be seen when the light source, subject, or viewer moves. This flicker is commonly known as "PWM," or "Pulse Width Modulation." Unfiltered PWM must be driven to frequencies of at least 50Hz, or else the flickering will be too pronounced and will irritate users.
Q2: What is an LED?
A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Appearing as practical electronic components in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness.
When a light-emitting diode is forward-biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electro luminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor.
Q3: How can an LED be more efficiently driven?
LEDs are more efficient at lower drive levels. This means that slow, unfiltered PWM is less efficient than filtered and smoothed output, known as "current regulation." This is because an ordinary PWM light is active part of the time and completely off at other times, but during the active portion, the LED is being driven at full blast, which is comparatively inefficient. Therefore, a multi-emitter, current-regulated light is more efficient than a single-emitter, PWM light, as the LEDs in a multi-emitter light will operate more efficiently (and use less power) than the LED in a single-emitter light when pushed to the same amount of output.
Q4: What is "Binning "?
Bin codes are used to sort LEDs by luminous flux (lumen output at a specified drive level), colour, tint, and Vf.