The transformer is originally developed for back-light of color liquid crystal displays and is optimized for that purpose.
The impedance of the back-light ranges from lOOK to 200KOhm.
In order to light up the back-light with high luminance, supply voltage to the back-light is required to be more than 500V.
The impedance of the transformer is designed to match that of the back-light so that the back-light could be lighted up efficiently.