why were the bulbs called mazda ? i think of cars and trucks i knew they were called ge / edison then followed by mazda on the label ? i just like to know its history a little 

Ahura Mazda was the Persian Goddess of Light, and for this reason it came to be used as an appropriate name for electric lamps.  It was first used on tungsten filament lamps from the 21st December 1909, made by National Electric Lamp Association in USA (which later became GE).  Illustrations of Mazda featured for many years on company literature, and a large statue exists on the roof of what is now the Lighting Institute Building at GE's headquarters in Cleveland.

In USA Mazda was not the trade mark of the company, but rather the name of a service.  To promote development of the new tungsten lamp technology, a group of companies shared their inventions and pooled some resources in this field.  The Mazda name could be used by companies who were a part of this team, and it guaranteed to the customer that the lamp he was buying was made with the very best know-how in the fabrication of the most efficient and best performing tungsten lamps.  Westinghouse started using the name from 1912.

Overseas the name was also adopted by GE's partners, but here it was used purely as the brand name for all types of lamps.  It was used extensively by the British Thomson-Houston and French Thomson-Houston companies, which printed graphics of "The Mazda Fairy" for many years on their packaging.

Around 1945 the name was dropped in the USA.  But it continues to the present day as a very popular and well respected brand name in Europe.  In the UK the rights to the Mazda brand name are owned by GE Lighting Ltd.  In the rest of the world Philips now has the rights to the name, but the brand is only actively used by Philips in France, Belgium and the Netherlands.

Why was the name "Mazda" dropped in 1945 in the USA?

The name was dropped becase it inhibited competition between lamp makers.  Most people bought the Mazda lamps because they were known to be the best, therefore it was hard for anyone else who was not using that name to sell lamps.