Info on COB (chip-on-board, led) bulbs please?

I'd be interested in any info available on COB led lamps, especially suitable applications.
How do they compare with the 3 (or more) x LED type bulbs?
How long have they been on the market?
Who are the main manufacturers?
Any web pointers to further info?
TIA
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    uncle_jim_in snipped-for-privacy@hotmail.co.uk writes:

Try newsgroup sci.engr.lighting
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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