Page 60 - Sensors and Control Systems in Manufacturing

22
Cha p te r
O n e

1.11.13 Nanometers (nm)
Nanometers (nm) are used to measure the wavelengths of light. The
lower the wavelength (e.g., 400 nm), the bluer and stronger the light
source. Longer wavelengths above 600 nm are red. Above 680 nm,
they fall into the infrared range, which is colorless to our eyes. White
LEDs have no specific wavelength. They are measured by the color of
white against the chromaticity scale.

1.11.14 Operating Life
Operating life is usually referred to as the number of hours a specific
type of LED is expected to be operational. With high-powered LEDs,
that usually means life after it loses 10–15 percent or more rated out-
put after 1000 or more hours of runtime. The Luxeon LEDs are rated
for 50,000 at 75 percent maintenance for 50,000 hours.

1.11.15 Printed Circuit Boards
Printed circuit boards (PCBs) are made from various materials,
including fiberglass and aluminum. The PCB has an electrical circuit
imprinted in silver etching. The PCB is the platform by which LEDs
are employed in various applications. It can be a rigid board, flexible,
or twistable.

1.11.16 Power Supply
The power supply transforms voltage and current, causing electrical
conversion of 110/120/240 V AC line power into 12 V DC or any
other values that will then be applied directly to the LED light prod-
uct. Power supplies are rated according to the current/amperage
load capacity each can handle. It is an electrical or electromechanical
device sometimes referred to as a LED driver.

1.11.17 PWM
The Pulse Width Modulation (PWM) with respect to LEDs is the LED
pulsed or strobed at a fast rate that the eye will see the light as being
constant. This pulsing or turning on and off of the LED lowers the
potential heat-stress on the chemical that makes the light, thus allow-
ing the LED to often have a longer life than anticipated. This is one of
the reasons why a dimmer/PWM is recommended with the use of a
12 V DC LED product.

1.11.18 RGB
RGB stands for red, green, and blue, the three primary colors that
make up white light and all other colors. It can be preprogrammed to