Television and back lighting source module capable of preventing harmonic interference

A back lighting source module capable of preventing harmonic interference in a television, the television receiving a television image signal having a display scanning frequency, and presenting an image corresponding to the television image signal, said back lighting source module comprising:

• a light source;
• a pulse-width-modulation controller coupled electrically to said light source, and operable so as to generate a source control signal for controlling turning on and turning off of said light source;
• and
• a control component coupled to said pulse-width-modulation controller for controlling frequency of the source control signal outputted by said pulse-width-modulation controller;
• wherein said control component has a plurality of control states that correspond to distinct display scanning frequencies of television standards, respectively;
• wherein setting of said control component in a selected one of said control states results in control of the frequency of the source control signal outputted by said pulse-width-modulation controller such that the frequency of the source control signal is not an integer multiple of the distinct display scanning frequency that corresponds to the selected one of said control states.

A light source control unit adapted for controlling turning on and turning off of a light source in a television, the television receiving a television image signal having a display scanning frequency, and presenting an image corresponding to the television image signal, said light source control unit comprising:

• a pulse-width-modulation controller adapted to be coupled electrically to the light source, and operable so as to generate a source control signal for controlling turning on and turning off of the light source, said pulse-width-modulation controller being configured with two preset frequency ranges that correspond to two distinct display scanning frequencies, respectively, each of the preset frequency ranges excluding integer multiples of the corresponding distinct display scanning frequency;
• and
• a switch coupled electrically to said pulse-width-modulation controller and having first and second control states that correspond to the two preset frequency ranges, respectively;
• wherein setting of said switch in a selected one of said first and second control states results in control of said pulse-width-modulation controller such that frequency of the source control signal outputted by said pulse-width-modulation controller falls within the preset frequency range that corresponds to the selected one of said first and second control states.