Philips is introducing a new 60W-replacement dimmable LED bulb called the SlimStyle
that looks radically different. Its design showcases a low-cost innovative approach is exactly what’s needed in the world of LED replacement bulbs. I got hold of a preliminary version and put it through its paces — before tearing it down.
Here’s a look at the bulb and its performance before we tear it down.
I like the way the SlimStyle looks. It’s a double-take kind of clever. If your first look is front-on, it has a classic light bulb shape. If you move a bit you see it’s actually almost two-dimensional. It’s very light: only a bit over 2 oz. (63g). It’s hard to over-emphasize the importance of lightness in replacement light bulbs: When you’re twiddling these things around at an odd angles, possibly standing on a ladder, extra ounces make it very easy to screw up and drop them. It’s also sturdy: dead cold or warmed up, you can grab any part of the bulb to unscrew it.
Philips says the bulb puts out 800lm of light at a CRI of 80 at 2700K. It draws 10.3W on a KiloWatt watt meter.
The bulb had problems dimming with the Lutron Maestro programmable dimmer switch. It can’t dim all the way down to off with the Maestro; It just stays on a very low light output. The Maestro is just one dimmer product out of hundreds, but it is probably the most popular of the modern programmable dimmer switches, and has a large installed base. In addition, when it’s on any dimming circuit, even at the non-dimmed setting, it has an audible hum. It dims nicely with the traditional phase-cut triac wall-switch (the ones with the round control knob.) I didn’t see any flashing or flicker nor could I measure any significant ac flicker with a light sensor.
I was curious to see if the side illumination of the SlimStyle would show a shadow at the top of the bulb. Not the case, as you can see from the light pattern here.
Philips has said that they have submitted the bulb for Energy Star certification, which requires an even, omnidirectional light and are confident they will get it. I think it’s likely.
The bulb owes its flat shape to a simple pc board that has 13 white single-emitter (that is, non-array) LEDs on one side and 13 on the other. No tricky secondary phosphor design here: The white plastic cover acts only as a cover and light diffuser. Here’s what it looks like with one side of its plastic cover off. (It’s off due to a Dremel tool — no way this cover can just pop off.)
The inexpensive pc board is a clever design, designed to act as a light, inexpensive heat sink. You’ll notice that unlike other current LED bulbs, the SlimStyle lacks a heavy heat sink at its base. Here’s how the LEDs disperse their heat:
The pc board, which is not a metal core board, has lines on it which you can faintly see in the photo below.
These are not pc board traces, but rather a gap between the copper pads that serve as inexpensive heat sinks, radiating heat out through the plastic flat cover, and each LED sits on its own separate flat copper heat sink. Pretty clever, and the reason the bulb is so light: 2.2 oz.
This is the first new bulb I’ve seen recently that is an isolated driver design: In the photo below you can see the ac line transformer, as well as two 6-pin ICs, one of which is probably the power management IC. UPDATE: I was too hasty in assuming that was an isolation transformer: The bulb uses a non-isolated driver. For more information, read A closer look at the Philips SlimStyle LED light bulb driver.
Here’s a close up of the markings on the two 6-pin ICs:
THe smaller one is clearly marked “3Ft”; the “t” could be a logo. The markings on the larger one:
Anybody have any idea what the power management chip might be or whose logo that is? Again, this is an isolated design, as you can see from the prominent yellow-colored transformer, so the power control will be a PWM dc-dc converter.
Even though it has the obligatory transformer, electrolytic capacitors, and inductors that go along with an isolated design, you can see that the driver electronics fit into a tiny space. Getting the heat sink out of the base and up into the bulb area was a very clever move.
The bulb will come with a 3-year warranty, and be sold by Home Depot — I don’t know how exclusive that retail arrangement will be.
No price is firmly set at this point, although to be competitive it will need to be in the <$11 range. UPDATE: You can also buy the SlimStyle from Amazon for the same price — $9.95. If you have a Prime account, it’s free shipping.
If/once it gets the Energy Star certification it will be eligible for utility rebates — although not in California, where its CRI of 80 will not meet the California Quality stipulation of 90+ CRI. Either way, it will be here in time to take advantage of the 2014 EISA phase-out of the 60W incandescent light bulb.