Zackees receives a lot of comments about the surprising brightness of our Turn Signal Gloves.
This brightness is quite intentional and was the result of our team researching the science of how light-emitting-diodes generate light and how as engineers we can push brightness to the extreme.
Our gloves are bright for two primary reasons
1) We overdrive our LED brightness
2) We choose energy-efficient LEDs.
To know how we do this it’s useful to know what LEDs are and how they work.
What are LEDs?
LEDs, or Light-Emitting-Diodes are a technology that converts electrical movement into light. Frankly put, they are awesome.
How do LEDs work?
LEDs work by forcing electrons to change energy states, releasing photons in the process. They do this by sandwiching two semiconductor materials together, forming a diode. One side has a surplus of electrons, making in negatively charged. The other side has a deficit of electrons, making it positively charged.
When electrons are forced into the diode, they are attracted to the negatively charged material. Specifically, they are attracted to positively ionized atoms on the other side of the diode. It is possible to flood an LED with electrons, resulting in a permanent chemical change to the LED materials.
These materials are sensitive and can only hold a certain amount of electrons at one time. Too many result in a permanent damage to the diode materials. However, at a resting state electrical charges force electrons into a corner of the diode, resulting in a sort of electron depletion.
This means something important to us:
LEDs can be overloaded with electrons after a resting state.
This is how a typical diode works. What makes an LED special is that when the electrons move from one side to the other, they must change energy states to fit into the empty space of the electron shell of the ionized atoms. And in order to change energy states, they must release a photon – a quantum unit of light.
The wavelength of the photon released depends on the magnitude of energy the electron changes, which depends on the chemical composition of the LED.
This means something else important to us:
Different colored LEDs have different quantum energy efficiencies.
Here’s how we take advantage of these two properties:
LED brightness is very hard to control. They are generally only on or off.
Many people who work with LEDs create the illusion of brightness control by intermittently turning the LED on and off faster than the human eye can see, using a process known as Pulse-Width-Modulation (PWM). In this way, an LED that is turned on and off 1000 times in one second will appear to be a fraction as bright as one that is on for the entire second.
We employ a similar technique as PWM to overload the LED with electrons for brief periods of time, but not so long as to damage the LED. This makes the LED appear nearly twice as bright as a regular LED.
Optimizing Quantum-Energy Efficiency
Knowing that each color LED has its own quantum efficiency allows us to pick a color that is both highly visible at a distance and energy efficient.
Blue light is most visible and red light is least visible. Yet blue light is least energy efficient and red light is most energy efficient.
In order to maximize both energy efficiency and visibility, we went with an amber LED. This allows Zackees Turn Signal Gloves to squeeze out 4-8 weeks out of a coin cell battery yet still be as bright as a halogen bulb, making cyclists visible to cars any time of day or night.