Display EHT Voltage Set-Up
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
The method disclosed allows measurement of EHT voltage indirectly to allow adjustment during CRT display production without the need to probe high voltages. With the horizontal yoke replaced by a dummy inductance in the drive circuitry, a test signal is passed through the horizontal yoke winding to produce two vertical lines whose separation is a measure of EHT voltage, allowing adjustment to the correct value. Modern displays for very high quality graphics applications use an independent EHT stage that can be accurately and precisely regulated. However, this has a disadvantage that this voltage must be accurately set up in mass production, requiring special very high voltage equipment. During the set-up stage the horizontal yoke is disconnected and a dummy inductance plugged in its place in the drive circuitry.