Light dispersal in LED bulbs (photos)
LED bulbs are energy-efficient but they are a directional light source versus the even distribution of incandescent bulbs and CFLs. Here is a comparison of how different LEDs disperse light from table lamps.
Desk lamp lighting incumbent
LED light sources give off directional light, which makes LED lighting well suited for retail stores or down lights above a kitchen counter. But what about for a desk lamp where you want an even dispersal of light so you can read?
Efficient and long-lasting LED bulbs now coming to market are designed to disperse light better than down lights, but there are still some limits to what they can do. This slideshow will compare how light is dispersed from a desk lamp using a few different bulbs.
Pictured here is a 75-watt incandescent bulb. Looking at the lamp shade and lamp itself, you can see light is given off in all directions.
"Snow cone design" LED
Pictured here is the same lamp with an LED bulb that uses the "snow cone" design" where most of the light comes out of the top end of the bulb. Note: this bulb gives off as much light as a 40-watt incandescent and has a cooler color temperature.
LED from Crane
Here is another LED bulb, this one the GeoBulb from Crane. The light dispersal seems to be concentrated on top as well. In my tests at home, I found that it distributed light more evenly than the previous Lighting Sciences Group bulb. Note: the color temperature is warmer, closer to an incandescent.
Still, because LED light sources tend to direct light, they are best for lamps that point light downward or spot lights of any kind.
Even light of CFL
For comparison, a 14-watt compact florescent light. To me, this has the most even distribution of light in the light shade compared to the previous photos.
In terms of efficiency, EnergyStar CFLs are much better than incandescents and only slightly behind LEDs in lumens per watt, although they are not rated to last last as long as LEDs.
GE's "omnidirectional" LED
GE is trying to differentiate its LED bulb with a design that distributes light more evenly than the snow cone design. This photo was taken from a GE-hosted conference on lighting technology.