Nuwai,
I can easily trace multi-LED white flashlights to 1997. That was when I built my first 25-LED array of white LEDs. A production light (the Action Light I) was designed and went into production in 1998. The same year also saw a 48-LED Action Light of which only a few were made and sold. And a 19-LED drop-in module for the Princeton Tek Solo. And a 7-LED drop-in module for the Mini-mag flashlight. The latter two were never sold commercially, although working prototypes were built.
Several European Cavers also built some large white LED arrays around the same timeframe - the largest one being 50 LEDs on a circular circuit board.
Further, there were several articles published in publications of wide circulation in 1997 and 1998 which discussed the use of arrays of LEDs.
Now if we take a look at the use of non-white LEDs, we can go much further back. I talked to an guy in Australia that had build a 96 LED array using red, amber, green and blue LEDs for his bicycle. His early arrays originated from at least 1995.
I also built a 4 LED combo light - modifying a Kohler Mine Spot to include 4 HP amber LEDs and a smaller incandescent main light. The main light is for running around and the 4 LEDs are for in camp, eating or just waiting around so I would not have to sit in the dark when the main beam was turned off. For long duration cave trips if you were wondering. That would be the early 1990s, although I don't remember exactly which year. If I had to, I could track it down from public records.
Prior to HP introducing the high brightness amber LEDs, LEDs were not real practical as a navigation light source and were mostly used as survey markers and such by the caving community. If you were desperate, you could use one of these to find your way out. Again, I forget exactly which year HP started marketing the high brightness amber LEDs, but they were handing out free flashlights made from these LEDs to show how bright they were. I still have one. Arrays of these LEDs followed quickly.
All the patents that I am aware of for LED flashlights were filed after the Action Light went to market - at least one year after. Therefore, the Action Light represents pre-existing artwork that invalidates all such patents I am aware of.
Henry.