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Old 25th January 2004, 06:39 PM   #1
Pabo is offline Pabo  Sweden
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Default Patents on classd??

I have studied a lot of patent applications on classd circuits and techniques and have found some conflicts that are really interesting.

There are some important patent applications that have been made and those are on self oscillating circuits. Karsten Nielsen with ICEpower made a patent application on a self oscillating current loop with a global voltage loop in 2001 (I think it was 2001). This technique has been used in power supplies for decades and by the way, a company named Bose Corporation patented the exact same thing 1978. The application back then was in a power supply but that is not important, the important thing is that the technique existed. Later on I discovered that ICEpower uses a technique in their modules which is based on a self oscillating voltage loop. The amplifier oscillates at the frequency where the phase lag is 180 degrees and this frequency is controllable by adding some extra phase lag at wish. The thing is that Simon J Broadley with Mitek Corporation made a patent application 6 months before ICEpower on the exact same thing So this means that ICEpower is using a technique that may be patented by Mitek

A couple of months ago I read about Bruno Putzeys Ultimate Class D (UCD). When reading more about this it is based on the same technique as Broadley's and ICEpower's voltage loop.

So my question is, does anyone have an idea about what is going on???
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Old 25th January 2004, 08:19 PM   #2
Steven is offline Steven  Netherlands
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Differences between patents can be in small details, so all claims should be checked carefully. Also improvements on existing patents are patentable.
Also it is possible to patent the same thing in a different application field, like the case with the power supply and the amplifier. If the power supply patent does not claim that this technique can also be used in power amplifiers, then the application of the same principle in power amplifiers can be new and patentable.
But it could very well be that the examiner(s) did not search thoroughly enough to find prior patents disclosing the same. I think this could easily happen if the prior patents have a different main application.

I also was surprised when I saw a patent in the eighties describing a normal two-transistor current mirror (well-known for decades). However, not the current mirror action was claimed, but its operation as a current divider: when pulling a current from the emitters of the NPN current mirror, the collector outputs of the transistors each sink half that current; just like a differential pair but with the bases connected to one of the collectors. My reaction was, if you can patent that, you can patent anything.

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Old 25th January 2004, 08:19 PM   #3
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Assuming that they are both US patents and that the later
one references the first, then it is probably the language of
the claim that is different in some way. Often what amounts
to the same idea can be described differently, and it appears
to be at the discretion of the examiner.

In my opinion, though, the patent office has gone to hell anyway.

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Old 25th January 2004, 08:32 PM   #4
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Hi Pabo,

with patents, you usually do not try to patent the principle, but some specific aspect of the design, trying to describe is as broad as possible and even trying to encompass principle in this description. For instance, you do not patent the principle but circuit topology that makes the principle operational. When you look at the patents, the things that counts are the claims (first one beeing the most important), not the description.

About the patents you listed, I think there are some differences regarding if the feedback is taken from the switching stage or the output filter, I think that Bose invented hysteretic current control etc.

Where did you read about UCD, I would really like to read an article about it, so far all I have is patent application from this post .

Best regards,

Jaka Racman
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Old 25th January 2004, 09:29 PM   #5
Steven is offline Steven  Netherlands
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Default Re: Patents on classd??

Quote:
Originally posted by Pabo
...A couple of months ago I read about Bruno Putzeys Ultimate Class D (UCD)...
Although UCD originally stood for Ultimate Class D, nowadays it is used as abbreviation for Universal Class D. Philips Research Lab in Leuven (Louvain) wanted to sound a little less arrogant. Well, the difference is not that big.

Steven
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Old 26th January 2004, 02:56 AM   #6
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Quote:
Originally posted by Nelson Pass
Assuming that they are both US patents and that the later
one references the first, then it is probably the language of
the claim that is different in some way. Often what amounts
to the same idea can be described differently, and it appears
to be at the discretion of the examiner.

In my opinion, though, the patent office has gone to hell anyway.


If only we could also get the patent attorneys to go to hell also!

I just helped a guy get a patent and won't be buying a new car this year as a result.
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Old 26th January 2004, 03:55 AM   #7
David M is offline David M  Canada
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This is something I type into Google occasionally and today it gave a new answer:

http://www.hypex.nl/classd/classd.PDF

Hypex Electronics calls their module "Universal Class D" and "UCD".
The module is very small and gives a claimed 150W.

I'm totally new to switching amps and am not sure if this is the Philips product or someone being sneaky with their names. They do seem to be located in the right end of the planet. Anyone?
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Old 26th January 2004, 05:06 AM   #8
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Looks like the proper one, thanks for the link.

Best regards,

Jaka Racman
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Old 26th January 2004, 05:45 PM   #9
km is offline km
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hi.

the hypex amps are philips ucd.

you can find lots of patens that are either meaningless or trying to patent things that were patented before and/or published and known before.

about the icepower patents you could easily be right.

i understand that us patent office doesnt perform a patent search to see if a new patent is valid (mr. pass please correct me here if im wrong) and this could be the main reason for this.

the rest is up to the lawyers i guess

best rgds - karsten madsen - cadaudio.dk
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Old 26th January 2004, 10:12 PM   #10
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Default Patents

What is a patent really worth. See www.tinaja.com.

My patent was only good for getting a better job. It looks great on my resume and that's about it. But then, that's all I ever expected from it and someone else was paying for the lawyer anyway.

And, the ICEPower amplifiers, while they do indeed self oscillate, they have two feedback loops. as well, they actually did the mathematics to figure out exactly how it works while a lot of the earlier work was empirical. I've met the designers of the ICEPower product several times, in fact, earlier this month at CES in Las Vegas and in October at AES in New York and have never ceased to be impressed by their knowledge of how these things work.

I use their ICE1000A, 500A and 250A products now and they have some exciting new stuff coming out including a 2 x 150W module that is under 4" square and needs no heatsinking. This is also a half bridge design so it can be used in stand alone amplifiers. They will also be offering a switching power supply for it.
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