A backlight device for LCD displays can include a light-emitting source of the type that includes a cold-cathode or hot-cathode fluorescent tube that is lit with a high-frequency power supply. The high-frequency power supply can be PWM-controlled to adjust the brightness. The high-frequency power supply can also be randomly phase-modulated with an irregular modulation code to light the fluorescent tube. This enables the infrared radiation from the fluorescent tube to be spread over a wider band such that the level thereof is lowered to a level that does not interfere with typical remote controls.