Background:
COG LEDs (Chip On Glass), which are LEDs built on glass or sapphire strips, have been known for years and are increasingly efficient. Their advantage is that achieving circular illumination is much easier with them than with SMD packaged LEDs, which often rely on opal covers to enhance light distribution with varying degrees of success. However, COG LEDs have the disadvantage that less light reaches the direction of the filaments. To solve this problem, Filament LEDs are placed in multiple positions under the cover, or we must choose an appropriate light source with the knowledge that less light reaches the filament direction.
This problem of “less light in the filament direction” could be solved if the LED filament were flexible, thus allowing shadowed areas to be eliminated by appropriate bending.
…and yes, there is a flexible filament LED.
In the case of COG LEDs, a string of miniature light-emitting diodes is placed on a glass strip. However, since they are glued to the glass on one side, it is noticeable that one side of the filament emits less light. With this flexible LED filament, this is not noticeable. This LED filament is made from special polymer materials, appearing like a thin light tube with tiny LEDs inside, which are as hard to distinguish individually as with COG LEDs.
The fact that these flexible LED filaments can be bent almost at will allows for theoretically 360-degree uniform spatial illumination (excluding the socket). Additionally, they have a huge advantage, which is more emotional than professional.
These allow for the realization of previously unimaginable richly shaped LED light sources, moreover, in the currently fashionable retro and vintage styles.
Thus, we can evoke eras with energy-efficient lighting modes when only inefficient tungsten filament bulbs existed, even feeling like we are in the world of carbon filament Edison bulbs, which were once unique handmade forms and are now back.
Therefore, we can say that LED light sources that closely resemble traditional bulbs can be made from flexible filament LEDs. This creates shadow-free, circular illumination, and these types are also dimmable if the appropriate driver electronics are built in.
Two things that can be considered unfavorable:
- One is the efficiency. Based on the current lineup, it seems their efficiency is 50-70 lumens/watt, which is many times that of traditional bulbs but only half that of today’s COG filament LEDs. Although it is true that flexibility was the primary consideration here, while LEDs built on rigid glass or sapphire strips have settled and even excelled in the efficiency competition, since we can get COG LEDs in the 120-150lm/watt range, the flexible filament LED is still trailing.
- The other issue, typical of all newer technologies, is the higher price. Additionally, the higher price is maintained because they are quite unique in form, resulting in smaller series light sources being produced from them.