guess is a uproc based digital lockin impedance analyzer that "polls" the s tate of the switch. The bulb will not light on power failure if the switch is in OFF position for example. Patent is assigned to TLV who sued Sengled (Everbright) for infringement but lost.
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Why wouldn't it be worth a patent? It's a novel idea to use these devices to measure the line impedance to distinguish the state of the power source whether the switch is on or off. I think that is very much worthy of a pat ent rather than the many patents granted that are truly the same idea as ma ny others just embodied in newer technology such as many computer architect ure patents because they were on a chip rather than a board.
Only that in this case there is a well known history of prior art.
Electrical safety testers (like the "Duspol" series) have been doing this for quite some time, and they can detect and differentiate even more different states of line conditions via a 2-pole connection.
For example, a "Duspol Expert" has different indications for:
- Hazardous voltage, AC, with voltage range indication
- Hazardous voltage, AC, high impedance (capacitive pickup)
- Hazardous voltage, DC, with range and polarity indication
- DC continuity / low impedance connection
- Phase rotation (line-line in 3-phase systems only)
Not sure how long it's been on the market - looks it's been a while. Fluke also makes instruments (T110, T130, T150) with these functions.
All 3 states (HV, open circuit, low impedance) that the lamp needs to differentiate, have already been well supported by electrical safety testers, so the only "novel idea" seems to be, to put it into a lamp.
How is any of that relevant? They are test gear designed to test something (I don't know exactly what, but similar details to the lamp I suppose), bu t none of them are remotely the same application. As I mentioned in the po st you replied to, it is very common to be able to obtain a patent for the same type of technology as other patents when applied to a new application. Clearly the testers and a battery backed up light bulb are dissimilar app lications.
This topic drift to the issue of questionable patents reminds me of my own research into a topic I raised in this group a few months back concerning adding electric start capability to a cheap 1KW inverter petrol (gasoline) powered generator cursed by the classic recoil starter and an engine vacuum powered fuel lift pump (a horrible combination when said generator is sans fuel priming bulb).
In this case, I was seeking advice on how best to drive the PMG as a BLDC starter motor using either a R/C ESC BLDC motor module (cheap commodity item but voltage isolation issues) or a wide voltage range mains voltage (240vac) rated VFD module (voltage safe but a damned expensive and OTT solution) or something built using a high voltage three phase half bridge driver module and controller (voltage safe mid priced option).
In my searching of internet hosted sources (BLDC technology tutorials, suppliers and data sheets) I came across a patent application in regard of exactly this goal of mine, namely US7180200B2 which included amongst a long list of patent references, a rather questionable patent regarding a method of BLDC control to break the Back EMF rpm speed limit, namely US6137251A.
This last one appears to be making a totally bogus claim whilst the former seems to be trying to patent a basic no-brainer use of existing technology to recruit the formerly ignored BLDC starter motor function of the PMG already in place on the ICE shaft of the inverter generator.
Furthermore, US7180200B2 is proposing a needless level of complexity in the form of a low voltage tapping of the PMG windings which not only increases manufacturing costs of a commodity PMG, it also compromises efficiency with (slightly) increased copper losses[1] when the electronics of the starter module can address such voltage mismatch much more effectively much of which already exists in the inverter/control module, merely requiring a 40 to 48 volt dc-dc converter[2], the driver logic (which can be recruited from the existing microprocessor), a 3 cell LiPo battery pack (or connection for a small 12v SLA) and a charging circuit.
Quite frankly, I find it hard to believe that such additional functionality hasn't already been incorporated as standard in such inverter/controller modules for at least the past decade, requiring only the addition of the optional starter battery and starter switch terminals.
When you see who the Assignee is of US7180200B2, it's quite obvious that it's all about expanding the market for B&D battery packs. As for the basic idea of recruiting the unused starter motor functionality inherent to the PMG, I can't see how this patent could be enforced.
As for the other 'bogus' patent, US6137251A, I can't believe what it claims is even remotely possible since it clings onto the idea that advancing the commutation timings can overcome the basic physics of BEMF in a PM BLDC motor... Just had a thought this might have been referencing a three phase induction or separately excited motor but another quick look reveals they're discussing a PM BLDC motor so, yep! It's a nonsense patent.
Apropos of my ongoing "Electric start of a cheap inverter genset", I'm still working on it (FVSVO 'working on it"). I got my hands on a R/C ESC module, gifted to me by my SiL a few weeks ago. It would have been very useful if he'd also lent me a 4 cell LiPo battery pack and a receiver with transmitter to speed up my testing of the concept (too low a voltage for actual starting duty, even assuming I could add an effective means of isolating it from the 400vac once it had fired up). Unfortunately, I've not been able to prevail upon his generosity any further in this regard on account of his recovery from a recent laser eye surgery, hence the
At this stage, I just want to see whether it will crank the engine at
*any* speed, even if it means testing with the spark plug removed. I just need some test data by which which to extrapolate to actual voltage requirements. Thus far, the only monetary expense has been the
pack of five NE555P timer chips to generate a servo signal to drive the ESC module (1 to 2 ms wide pulses at a 35 to 50 Hz repetition rate).
The timer chips arrived nearly a week ago and I just need to gird my loins to descend back into my basement 'workshop' (one time radio shack, now dumping ground for a varied collection of electronics/computer parts and domestic detritus) to grab hold of the remaining components required to lash up a servo tester (I'm pretty certain I saw my plug in breadboard module recently, handily, afaicr, amongst my small collection of vero boards and other handy bits gathered for never completed projects). I might have some actual data by the end of the week. :-)
[1] The only useful and worthwhile modification to the PMG would be the incorporation of three Hall Effect sensors to simplify the circuitry and logic of the BLDC starter module. The expensive copper can remain optimised for best efficiency/cost ratio.
Since may aim is to create a "Universal Inverter Genset Electric Starter" drop-in module, this is not a modification I care to get involved in since it goes against the very concept of the "Electrical Modification Only" nature of this project.
[2] I estimate a cranking speed of just 400rpm, about a tenth of the generator's operating speed for the nominal 400vdc used by the pair of bridged class D amps fed by a 50Hz sine reference in the inverter module will suffice, hence the 40 to 48vdc requirement. However, judging by how readily the genset will 'kick back' on the pull starter, I suspect a cranking speed even as low as 150rpm might suffice, say a 24v starter battery (allowing for the resistive volt drop in the PMG windings), which could save the need for a dc-dc converter module. In this case, a 6 cell LiPo or Li-ion battery pack would be a better and longer lived option over a pair of 4AH 12v SLAs when considering the infrequent use of such an emergency generator.
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