Thomas Edison did not invent the light bulb. What he did do is make the first bulb that did not burn out in less than one minute, making the idea usable.
Alexander Graham Bell did not invent the telephone, the idea for such a device had been around for a while. He invented the electric telephone, making the idea usable.
Philo T. Farnsworth did not invent the television. He invented electronic television, making the idea usable. Somehow his name got lost (ignored, omitted) from the history books and our common knowledge. If you would like to find out more, check out these links.