Backlight dimming method and control circuit for variable refresh rate display, and display apparatus using same

A control circuit having a controller and a driver circuit for performing a backlight dimming method for backlighting an LCD panel having a variable refresh rate with an LED module, the variable refresh rate having a maximum refresh rate and being determined by a first synchronizing signal having a variable frequency, the LED module having at least one LED sub-zone, the LED sub-zone including a plurality of LEDs, and the method including:

• using the controller to generate a secondary synchronizing signal having a frequency higher than the maximum refresh rate, wherein the secondary synchronizing signal is not synchronized with the first synchronizing signal;
• and
• using the controller to update dimming values for the at least one LED sub-zone at one or more pulses of the secondary synchronizing signal with current dimming data after the controller has received the current dimming data from a dimming data controller;
• wherein the at least one driver circuit is used to refresh the at least one LED sub-zone a plurality of times with a plurality of groups of sub-dimming values for each said LED subzone during a time period between two consecutive said pulses of the secondary synchronizing signal, wherein the plurality of groups of sub-dimming values add up to a value of the current dimming data for each said LED sub-zone.

A display apparatus comprising a control circuit, an LCD panel having a variable refresh rate and an LED module having at least one LED sub-zone, the LED sub-zone including a plurality of LEDs, the control circuit having a controller and at least one driver circuit for performing a backlight dimming method for backlighting the LCD panel with the LED module, the variable refresh rate having a maximum refresh rate and being determined by a first synchronizing signal having a variable frequency, and the method including:

• using the controller to generate a secondary synchronizing signal having a frequency higher than the maximum refresh rate, wherein the secondary synchronizing signal is not synchronized with the first synchronizing signal;
• and
• using the controller to update dimming values for the at least one LED sub-zone at one or more pulses of the secondary synchronizing signal with current dimming data after the controller has received the current dimming data from a dimming data controller;
• wherein the at least one driver circuit is used to refresh the at least one LED sub-zone a plurality of times with a plurality of groups of sub-dimming values for each said LED subzone during a time period between two consecutive said pulses of the secondary synchronizing signal, wherein the plurality of groups of sub-dimming values add up to a value of the current dimming data for each said LED sub-zone.