Logo Evolution of Famous Brands. (CBS logo)

 The CBS eye logo was introduced in the early 1950s. Since its introduction, the eye itself has remained unchanged, but the type style for the network name has changed frequently. Sometimes the type style has changed on a yearly basis, and it is not unusual for CBS to use several variants at once.

CBS has used different idea for its logo along with time.

More at: http://logos.wikia.com/wiki/CBS