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| Authored by: Anonymous on Saturday, October 13 2012 @ 10:11 PM EDT |
I might have buried away somewhere one of my old college lab books
from 1969 or so with a PWM LED project. Apart from the '661 patent
being all about flashlights, this company's place of business is
stated to be in the lovely litigous Tyler TX, but the suit has been
filed in Delaware. Go figure, while I glance at the other patents...
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| Authored by: Anonymous on Saturday, October 13 2012 @ 10:36 PM EDT |
Well the patents might be rubbish due to prior art, but that needs proof.
Three of the complaints are rubbish because they patents describe
in some detail a flashlight intended for single handed portable
operation. They don't say what it's s'posed to do, but it doesn't
take much nous to guess what a flashlight does.
The '390 patent might take some more investigation because I'm
not clear what the iPad3 or MacBookPro does that might infringe.
Now you've possibly heard of people strapping a flashlight to a
video camera for illumination of the scene. Well, the '390 patent
is for strapping a video camera to a flashlight to control the
illumination. The camera and PWM LEDs are synchronised, and
the camera output is used to control both illumination and
color of the flashlight output. The camera is not claimed to be
used for any other purpose.
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- Rubbish, indeed! - Authored by: albert on Sunday, October 14 2012 @ 12:07 PM EDT
- Rubbish - Authored by: dio gratia on Sunday, October 14 2012 @ 04:59 PM EDT
- Rubbish - Authored by: Anonymous on Sunday, October 14 2012 @ 06:47 PM EDT
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| Authored by: Tufty on Sunday, October 14 2012 @ 01:43 AM EDT |
Class D amplifiers.
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Linux powered squirrel.[ Reply to This | Parent | # ]
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| Authored by: JamesK on Sunday, October 14 2012 @ 07:39 AM EDT |
Ever hear of light dimmers? Those use a form of PWM by controlling when power
is turned on during the AC cycle. It has also been used for motor control and
heating for decades.
Oh, I forgot, this is being done on a computer.
</sarcasm>
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The following program contains immature subject matter. Viewer discretion is
advised.[ Reply to This | Parent | # ]
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| Authored by: albert on Sunday, October 14 2012 @ 12:04 PM EDT |
I like to see Apple get a dose of its own medicine, but those are bogo-patents.
Using feedback to control _anything_ is as old as the hills.
The patents cited were issued in 2000, 2002, 2004, 2008. Feedback control of
photo strobes goes back to the 1960s, IIRC. There is nothing novel or unique
about ANY of the circuits shown. Pulse width modulation predates 2000. These
patents are merely collections of existing technology and should never have been
granted. I strongly suspect the 2000 was a trial balloon, and the remainder
filed after the first was granted.[ Reply to This | Parent | # ]
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| Authored by: Anonymous on Sunday, October 14 2012 @ 04:56 PM EDT |
PWM has been *the* standard way of controlling or regulating voltage or
current for decades (since power transistors became available). The exceptions
are applications where you need low noise (like stereo amplifiers) or where the
amount of power involved is very tiny. The alternative is a linear regulator
which while simple wastes power and needs a lot of heat dissipation ability for
anything other than very small power levels. Electroluminescent back lights used
PWM, and that is what the LEDs are replacing here.
However, before everyone goes off the handle here, there
are lots of individual circuit designs, and many of them are patented (generally
by a driver chip manufacturer). There are lots of alternative ways of doing the
same thing, so no one patent covers the whole field. I doubt that Apple designed
their own LED dimmer circuit when they could use an off the shelf driver chip. I
haven't researched the case behind this, but it's quite possible that the
patents in question here are valid (at least for flashlights), and that Apple
just picked a driver chip out of the catalogue that happened to in inadvertently
step on this particular patent in some manner.
In this case the patent
holder would go after Apple as the one with the money, rather than some Korean
or Taiwanese chip manufacturer. If the circuit is in an off the shelf chip, then
the patent holder could go after lots of other companies as well.
On
the other hand it's also quite possible that this is a "rectangle with rounded
corners" class of patent which deserves to get tossed out once someone is
sufficiently motivated to challenge it.
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| Authored by: myNym on Monday, October 15 2012 @ 04:50 AM EDT |
LEDs are designed to operate at a specific voltage and
current.
More correctly, a specific current. Once the LED (the D
stands for diode) has sufficient forward voltage to allow
current to flow, the current will rise non-linearly to the
voltage, and will burn out the LED if the current is not
limited.
So the only way to "dim" an LED is to pulse it at a high
enough frequency that the flicker is not noticeable to the
human eye.
-myNym- (It's not my name, it's just a nym.)[ Reply to This | Parent | # ]
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