extremely Hi DC Voltage LCD's

Archived from groups: comp.sys.laptops (More info?)

I read recently that LCD's (laptops or TV's) have internal very
High Dc voltages involved. Higher than even the old cathode ray
type tv tubes had. Does anyone know about this??
kokomo Joe


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Archived from groups: comp.sys.laptops (More info?)

Joe,

No, you read wrong, and also we need a bit of clarification here.

TV sets with CRTs have voltages from about 3,000 volts (5" monochrome
screen) to over 30,000 volts (large color screen). The current levels,
however, are quite low (micro-amps). It normally won't kill you (unless
you have a heart attack), but it can kick like hell (and the ones at the
higher end of the range might kill).

LCD panels themselves are all low-voltage, typically nothing over 12
volts if that.

However, the BACKLIGHT for an LCD display does have high voltages to
drive the flourescent lamp. This can be anywhere from about 500 volts
to 3,000 volts. Also, while they are still not considered "high"
currents, they are MUCH higher than a CRT 2nd annode voltage. 5 to 8
milliamps (ma) would be a typical value, but some could be much higher.
There is a potential for serious injury with that combination of
voltage and current. Note that the backlight is really not "part of"
the LCD panel, although the lamp may be physically mounted inside the
panel. The dispaly and the backlight are at least logically separate.

Were you perhaps thinking of Plasma screens? They have higher voltages,
but a plasma screen is not an LCD screen.


Joseph Fenn wrote:

> I read recently that LCD's (laptops or TV's) have internal very
> High Dc voltages involved. Higher than even the old cathode ray
> type tv tubes had. Does anyone know about this??
> kokomo Joe
>
>
> ****************************************************
> * Ham KH6JF AARS/MARS ABM6JF QCWA WW2 VET WD RADIO *
> ****************************************************
>