Description of the required characteristics
LED modules with the following properties are required to operate side- or endlight fibers with LED light sources:
- fibers and fiber bundles of different diameters, including a ferrule, should be inserted into the LED module in a stable and loss-free manner,
- fiber bundles must be uniformly illuminated by the LED module in a way that each individual fiber is illuminated equally bright; a difference in brightness between different fibers in a fiber bundle should not occur or be practically invisible,
- the optical coupling efficiency should be as high as possible in order to reduce the electrical power supplied to the module as far as possible and to reduce the heat loss or temperature increase resulting from the power consumption as low as possible,
- sufficiently large cooling surface on the LED module to dissipate the heat loss,
- the housing geometry must be adapted to the most common application “textile integration”, i.e. flat geometries are desirable,
- a safe power supply from a generally available power source such as USB 5V from USB power supplies or USB PowerBanks,
- for applications in portable textiles a waterproof, washing machine suitable design,
- each LED module can be controlled via a passive or active central unit. An active central unit may comprise a microcontroller that controls the brightness of each LED via pulse width modulation (PWM). PWM can be controlled externally via radio (WLAN, Bluetooth).
The DieMount Solutions
All the above-mentioned attributes need great effort to be implemented in only one single design. Therefore, DieMount has developed the following designs for the different requirements and applications.
Description of the different LED modules
The LED module has a cylindrical insert inside which receives the optical fiber. Inside the insert there is a mixing unit for the uniform illumination of the optical fibers. A lateral plastic screw is used to fix the optical fiber.
LED module with direct LED connection
LED module with round heat sink (Ø = 16mm, height 20mm or 32mm) and direct LED connection via 2-pin header
The connection for the PowerLED (current consumption typically 350mA) is led out with a 2-pole pin header at the bottom of the PCB. The forward voltage of the LED is between 2.2V and 3.5V, depending on the LED colour (red, green, blue, UV, etc. are possible).
The module is available with 20mm and 32mm high heat sinks. If the module is to be operated with high LED currents of up to 700mA, the 32mm heat sink is recommended.
LED module with connected driver
An interesting version is the LED module with round heat sink and connected LED driver:
A 5V power source like an USB charger or an USB PowerBank can be connected directly to the module. The LED module is mobile and independent of the power supply of the mains.
The dimming of the LED is also possible, if the driver electronics is connected to a central unit via an at least 3-wire cable. (Description of the central unit see below “Textile LED”)
The data sheet “LED for thick SL – POF” describes the different application possibilities of LED – illuminants for light bands and the resulting designs of LED – modules.
LED module for integration in textiles
rectangular heat sink with electric cable and receiving ferrules for two optical fibers or optical fiber bundles
Fiber optic bundle at the end of a light band, assembled for illumination with two colours. The electrical cables are used to feed the light also at the other end of the light band
Active luminous textiles are a preferred application of side light fibers. They can be used in the field of road safety, as warning clothing for people involved in activities that pose a risk to safety. But as eye-catching jewellery in clothing for evening events these textiles are attractive.
The DieMount “Textile LED Module” was developed as an LED module for these applications: