6 ms·

The linked article omits one of the more interesting details, which is that the suit is being funded by a Longford Capital, a private investment company that sp

by nkurz 7y ago

The linked article omits one of the more interesting details, which is that the suit is being funded by a Longford Capital, a private investment company that specializes in funding commercial lawsuits. Usually, third parties are silent about their participation in such suits, but in this case Longford has publicly announced their backing: https://www.businesswire.com/news/home/20190730005899/en/Longford-Capital-Funds-Patent-Enforcement-Campaign-University https://www.businesswire.com/news/home/20190730005899/en/Lon... Separately, if you haven't tried filament LED bulbs, you should. They are a wonderfully simple design: stack lots of small LED's in string so that they can be run at full wall voltage. The lack of a voltage converter means that there are fewer parts to fail, and the long string of LED's makes heat dissipation a lot easier. I find them better than all the alternatives.

sevencolors 7y ago
Yeah, the bulbs are pretty awesome. My partner was complaining last year about how the LED bulbs are ugly to look at and really wanted an Edison like bulb but with LEDs. A quick google later and I was shocked to find that idea already existed.
staticautomatic 7y ago
Litigation finance is de rigueur these days. It's unusual that they've affirmatively stated they're funding it, but it's not unusual for there to be a funder and it's becoming more common for details to emerge in discovery about who the funder is and what the details of the funding arrangement are. It's possible that Longford issued a press release because they know or suspect it'll come out in discovery and want to get out ahead of the issue. https://abovethelaw.com/2019/07/3-thoughts-on-the-future-of-litigation-finance-part-i/ https://abovethelaw.com/2019/07/3-thoughts-on-the-future-of-...
sitharus 7y ago
The only downside to the filament LED bulbs is the flicker. Much like old fluorescent tubes they flicker at twice the supply frequency due to the very small driver circuitry. That said I just saw a Big Clive video with a much better driver embedded in the bulb, so tech is getting there.
- yeutterg 7y ago
  Not all filament designs have horrendous flicker—we are selling one that we designed with 8% worst case, usually more like 2-3% [0][1]. That's better than incandescent. Even the normal non-filament LED bulbs can have high levels of flicker. I found one product claiming to be "healthy" that had around 55% flicker. Most of the bulbs in The Home Depot are going to flicker a lot, especially the filament LEDs. [0] Bedtime Bulb: Low-blue, low-flicker light bulb https://bedtimebulb.com/ https://bedtimebulb.com/ [1] When I say percent flicker, I am referring to the modulation percentage. A good primer is this article: https://www.dial.de/en/blog/article/ieee-1789-a-new-standard-for-evaluating-flickering-leds/ https://www.dial.de/en/blog/article/ieee-1789-a-new-standard...
  - nkurz 7y ago
    Great article. What are the design decisions that affect the amount of flicker? Is it solely based on electronically smoothing out the input voltage, or are there other factors? For example, are there phosphors that are better at smoothing the white light even if the blue is modulated?
    - yeutterg 7y ago
      Adding capacitance to a "linear" driver design is one way to reduce modulation, with some tradeoffs. There are other power supply designs, such as switch-mode and several variations of "constant current" drivers, which could reduce modulation at a higher cost. Adjusting the frequency also plays a role in mitigating perceived flicker. In higher-end drivers, you'll often see a hybrid approach, such as constant current between 5 and 100% and PWM below 5%. Drivers with deep dimming down to 0.1% are just using 10-bit PWM. This would be difficult to do in a bulb form factor. I haven't seen any meaningful research into the persistence of various phosphors. It's an interesting thought. My guess is that there could be some effect, but usually we would just try to improve the power electronics.
      - jacobush 7y ago
        I heard IKEA uses the phosphor
bayindirh 7y ago
All the filament LED bulbs I have single die LEDs and have drivers embedded into the bottom of the bulb. I haven't seen multi-LED arrangements without drivers in a filament LED bulb yet.
zaarn 7y ago
The lack of a voltage regulator is quite bad; LEDs reduce their internal resistance as they get hotter, causing them to increase thermal output. That feedback loop, if not controlled for in some way, can easily destroy the lamp. You also still need a DC converter unless you prefer a 50Hz hum in your LEDs (which sucks).
- robomartin 7y ago
  Not sure what you mean. LED’s don’t have internal resistance. Can you ckarify?
  - zaarn 7y ago
    LEDs have an internal resistance, they're not superconductors. When you switch them on, they have a specific value on that resistance. Due to their internals, as they heat up, this resistance goes down, causing current and thermal output to go up.
    - robomartin 7y ago
      They have something that is sometimes referred to as "dynamic resistance", which is the inverse of the slope of the forward portion of the V-I curve, and yes, it's mostly constant (at constant temperature). For example, a typical lighting class LED will have a dynamic resistance in the order of 0.2 to 0.3 ohms. However, in as much as this varies a bit with temperature the change is mostly negligible. I am also not sure about your assertion that this dynamic resistance decreases with temperature. I took a few minutes to review the datasheets of a dozen OSRAM and Seoul Semiconductor 1W class LED's we use. In all cases the slope of the V-I curve increases slightly with temperature, which means the dynamic resistance decreases slightly with an increase in temperature. Can you explain the effect you are referring to in greater detail? Always interested in learning something new. Thanks.
      - zaarn 7y ago
        Dynamic and internal resistance probably mean different things, afaict, but essentially the internal resistance of an LED is a function of it's temperature. An exponential function in fact; the internal resistance of an LED is an exponential function with the temperature as the inverse in the exponent. Your dynamic slope would also be sufficient to get runaway meltdown. Essentially, imagine it like this; The LED has a starting temperature of 20°C and no power applied. When the appropriate voltage is applied, the LED heats up to 40°C. The dynamic resistance has a small slope, so as a result the dynamic and internal resistance both decrease. The current increases, the voltage is the same, the power output of the package goes up. The LED now heats to 45°C. The process repeats but because the internal resistance is exponentially inverse related to temperature, it speeds up. The LED is now 55°C. It repeats again and the LED reaches 75°C. Resistance drops again at the higher temperature, the current increases more. 115°C. At the next step the LED will reach 195°C, due to the exponential increase and likely the solder points will liquify. If the LED still works it'll hopefully melt itself from the PCB before it catches fire. This can happen incredibly fast, you can counteract it by running the LED well below maximum spec but then you're one power surge or heat surge away from meltdown. Similar to burning wood, the LED's meltdown requires a sufficient amount of extra heat to trigger, otherwise the exponential heat output is too small and is dissipated. This is why you need a current controller or atleast limiter so that the LED cannot pull more current than it's designed for. 0: https://www.researchgate.net/publication/49586062_Internal_Resistance_of_an_LED_as_a_function_of_Temperature https://www.researchgate.net/publication/49586062_Internal_R...
bobongo 7y ago
What brands would you recommend?

by nkurz 7y ago

sevencolors 7y ago

Yeah, the bulbs are pretty awesome. My partner was complaining last year about how the LED bulbs are ugly to look at and really wanted an Edison like bulb but with LEDs. A quick google later and I was shocked to find that idea already existed.

staticautomatic 7y ago

Litigation finance is de rigueur these days. It's unusual that they've affirmatively stated they're funding it, but it's not unusual for there to be a funder and it's becoming more common for details to emerge in discovery about who the funder is and what the details of the funding arrangement are. It's possible that Longford issued a press release because they know or suspect it'll come out in discovery and want to get out ahead of the issue. https://abovethelaw.com/2019/07/3-thoughts-on-the-future-of-litigation-finance-part-i/ https://abovethelaw.com/2019/07/3-thoughts-on-the-future-of-...

sitharus 7y ago

The only downside to the filament LED bulbs is the flicker. Much like old fluorescent tubes they flicker at twice the supply frequency due to the very small driver circuitry. That said I just saw a Big Clive video with a much better driver embedded in the bulb, so tech is getting there.

yeutterg 7y ago
Not all filament designs have horrendous flicker—we are selling one that we designed with 8% worst case, usually more like 2-3% [0][1]. That's better than incandescent. Even the normal non-filament LED bulbs can have high levels of flicker. I found one product claiming to be "healthy" that had around 55% flicker. Most of the bulbs in The Home Depot are going to flicker a lot, especially the filament LEDs. [0] Bedtime Bulb: Low-blue, low-flicker light bulb https://bedtimebulb.com/ https://bedtimebulb.com/ [1] When I say percent flicker, I am referring to the modulation percentage. A good primer is this article: https://www.dial.de/en/blog/article/ieee-1789-a-new-standard-for-evaluating-flickering-leds/ https://www.dial.de/en/blog/article/ieee-1789-a-new-standard...
- nkurz 7y ago
  Great article. What are the design decisions that affect the amount of flicker? Is it solely based on electronically smoothing out the input voltage, or are there other factors? For example, are there phosphors that are better at smoothing the white light even if the blue is modulated?
  - yeutterg 7y ago
    Adding capacitance to a "linear" driver design is one way to reduce modulation, with some tradeoffs. There are other power supply designs, such as switch-mode and several variations of "constant current" drivers, which could reduce modulation at a higher cost. Adjusting the frequency also plays a role in mitigating perceived flicker. In higher-end drivers, you'll often see a hybrid approach, such as constant current between 5 and 100% and PWM below 5%. Drivers with deep dimming down to 0.1% are just using 10-bit PWM. This would be difficult to do in a bulb form factor. I haven't seen any meaningful research into the persistence of various phosphors. It's an interesting thought. My guess is that there could be some effect, but usually we would just try to improve the power electronics.
    - jacobush 7y ago
      I heard IKEA uses the phosphor

bayindirh 7y ago

All the filament LED bulbs I have single die LEDs and have drivers embedded into the bottom of the bulb. I haven't seen multi-LED arrangements without drivers in a filament LED bulb yet.

zaarn 7y ago

The lack of a voltage regulator is quite bad; LEDs reduce their internal resistance as they get hotter, causing them to increase thermal output. That feedback loop, if not controlled for in some way, can easily destroy the lamp. You also still need a DC converter unless you prefer a 50Hz hum in your LEDs (which sucks).

robomartin 7y ago
Not sure what you mean. LED’s don’t have internal resistance. Can you ckarify?
- zaarn 7y ago
  LEDs have an internal resistance, they're not superconductors. When you switch them on, they have a specific value on that resistance. Due to their internals, as they heat up, this resistance goes down, causing current and thermal output to go up.
  - robomartin 7y ago
    They have something that is sometimes referred to as "dynamic resistance", which is the inverse of the slope of the forward portion of the V-I curve, and yes, it's mostly constant (at constant temperature). For example, a typical lighting class LED will have a dynamic resistance in the order of 0.2 to 0.3 ohms. However, in as much as this varies a bit with temperature the change is mostly negligible. I am also not sure about your assertion that this dynamic resistance decreases with temperature. I took a few minutes to review the datasheets of a dozen OSRAM and Seoul Semiconductor 1W class LED's we use. In all cases the slope of the V-I curve increases slightly with temperature, which means the dynamic resistance decreases slightly with an increase in temperature. Can you explain the effect you are referring to in greater detail? Always interested in learning something new. Thanks.
    - zaarn 7y ago
      Dynamic and internal resistance probably mean different things, afaict, but essentially the internal resistance of an LED is a function of it's temperature. An exponential function in fact; the internal resistance of an LED is an exponential function with the temperature as the inverse in the exponent. Your dynamic slope would also be sufficient to get runaway meltdown. Essentially, imagine it like this; The LED has a starting temperature of 20°C and no power applied. When the appropriate voltage is applied, the LED heats up to 40°C. The dynamic resistance has a small slope, so as a result the dynamic and internal resistance both decrease. The current increases, the voltage is the same, the power output of the package goes up. The LED now heats to 45°C. The process repeats but because the internal resistance is exponentially inverse related to temperature, it speeds up. The LED is now 55°C. It repeats again and the LED reaches 75°C. Resistance drops again at the higher temperature, the current increases more. 115°C. At the next step the LED will reach 195°C, due to the exponential increase and likely the solder points will liquify. If the LED still works it'll hopefully melt itself from the PCB before it catches fire. This can happen incredibly fast, you can counteract it by running the LED well below maximum spec but then you're one power surge or heat surge away from meltdown. Similar to burning wood, the LED's meltdown requires a sufficient amount of extra heat to trigger, otherwise the exponential heat output is too small and is dissipated. This is why you need a current controller or atleast limiter so that the LED cannot pull more current than it's designed for. 0: https://www.researchgate.net/publication/49586062_Internal_Resistance_of_an_LED_as_a_function_of_Temperature https://www.researchgate.net/publication/49586062_Internal_R...

bobongo 7y ago

What brands would you recommend?