Brightness control for dynamic scanning backlight

A backlight luminaire controller comprising:

• a means for receiving a luminance setting signal defining a luminance of a backlight luminaire on an individual frame basis;
• a means for receiving a reference value defining a target color temperature;
• a feedback controller requiring a plurality of frames to converge;
• a modulated signal generator immediately responsive to said received luminance setting signal and said feedback controller;
• an optical sampler arranged to output a signal, on at least said individual frame basis, representative of the optical output of a backlight luminaire driven responsive to said modulated signal generator;
• a scaler arranged to scale, by a scaling factor responsive to said received luminance setting signal, a first one of said received reference value and said output signal of said optical sampler to be consonant with a second one of said received reference value and said output signal of said optical sampler;
• and
• a difference circuit, arranged to output a signal representative of the difference between the output of said scaler and the output of said second one of said received reference value and said output signal of said optical sampler,
• said feedback controller responsive to said output signal of said difference circuit to output a signal operative to reduce said difference.

A method of controlling the luminance of a luminaire on an individual frame basis, without affecting a slow acting color loop controlling the color temperature of the luminaire, the method comprising:

• receiving a reference value representative of a target color;
• receiving a luminance signal defining the luminance of the luminaire per frame;
• adjusting a modulated signal driving the luminaire directly responsive to said received luminance signal, thereby controlling the luminance of the luminaire per frame;
• sampling the optical output of the luminaire per frame;
• comparing a value responsive to said sampled optical output with a value responsive to said received reference value to output a difference signal;
• and
• further adjusting said modulated signal driving the luminaire responsive to said compared value so as to reduce said difference signal.

A backlight luminaire controller comprising:

• a feedback controller requiring a plurality of frames to converge;
• a modulated signal generator immediately responsive to a received luminance setting signal and said feedback controller;
• an optical sampler arranged to output a signal, on at least said individual frame basis, representative of the optical output of a backlight luminaire driven responsive to said modulated signal generator;
• a scaler arranged to scale a first one of a received reference value and said output signal of said optical sampler to be consonant with a second one of said received reference value and said output signal of said optical sampler, said received reference value defining a target color temperature;
• and
• a difference circuit, arranged to output a signal representative of the difference between the output of said scaler and the output of said second one of said received reference value and said output signal of said optical sampler,
• said feedback controller responsive to said output signal of said difference circuit to output a signal operative to reduce said difference.