Display backlight driving device and its backlight dimming device

Abstract

A display backlight driving device includes a backlight module, a current backlight driving circuit for controlling the backlight module, and a backlight dimming device including a first to a fourth arithmetic unit. The first arithmetic unit generates a flicker adjustment signal corresponding to the brightness indicated by a corresponding DC dimming signal. The second arithmetic unit generates a DC factor signal based on the DC dimming signal adjusted by a flicker depth signal. The third arithmetic unit generates a flicker factor signal based on the flicker factor signal and the DC factor signal. The fourth arithmetic unit generates a flicker dimming signal based on the DC dimming signal and the flicker factor signal. By generating the flicker dimming signal through the arithmetic unit, the backlight module flickers at a specific frequency during display, thereby further improving the user experience during extended viewing of the display.

Claims

1. A backlight dimming device, applicable to a backlight driving circuit and a backlight module having a plurality of LEDs, the backlight driving circuit being used to control the current flowing through the LEDs, the backlight dimming device comprising: an arithmetic module including first to fourth arithmetic units, the first arithmetic unit receiving a DC dimming signal indicating the brightness of the LEDs and a flicker waveform signal, and processing the flicker waveform signal according to the DC dimming signal to generate a flicker adjustment signal, the flicker adjustment signal being related to the flicker waveform signal corresponding to the brightness of the LEDs indicated by the DC dimming signal; the second arithmetic unit receiving the DC dimming signal and a flicker depth signal, and generating a DC factor signal according to the flicker depth signal and the DC dimming signal, the flicker depth signal being related to a ratio, the DC factor signal being related to the DC dimming signal adjusted according to the ratio related to the flicker depth signal. The third arithmetic unit is electrically connected to the first and second arithmetic units to receive the flicker adjustment signal and the DC factor signal, and generates a flicker factor signal based on the flicker adjustment signal and the DC factor signal. The fourth arithmetic unit receives the DC dimming signal and is electrically connected to the third arithmetic unit to receive the flicker factor signal, and generates a flicker dimming signal based on the DC dimming signal and the flicker factor signal. A conversion module is electrically connected to the arithmetic module to receive the flicker dimming signal and generates a conversion signal related to the current flowing through the LEDs based on the flicker dimming signal.

2. The backlight dimming device as claimed in claim 1, wherein, The flicker waveform signal contains a sine wave. For the first arithmetic unit, the flicker adjustment signal is generated based on the product of the DC dimming signal and the flicker waveform signal. The flicker adjustment signal contains a peak portion of the sine wave corresponding to the brightness of the LEDs indicated by the DC dimming signal.

3. The backlight dimming device as described in claim 2, wherein, For the second arithmetic unit, the DC factor signal is generated based on the product of the ratio associated with the flash depth signal and the DC dimming signal, the ratio of which is not greater than 1, and the DC factor signal contains a brightness of the LEDs not greater than that indicated by the DC dimming signal.

4. The backlight dimming device as described in claim 3, wherein, For the third arithmetic unit, the flicker factor signal is generated based on the difference between the flicker adjustment signal and the DC factor signal, and the flicker factor signal includes the peak portion of the flicker adjustment signal that is not lower than the DC factor signal.

5. The backlight dimming device as described in claim 4, wherein, For the fourth arithmetic unit, the flicker dimming signal is generated based on the difference between the DC dimming signal and the flicker factor signal, and the flicker dimming signal includes the DC dimming signal with the peak portion indicated by the flicker factor signal removed.

6. The backlight dimming device as claimed in claim 1, wherein, The conversion module includes a comparator and a sawtooth wave generator for generating a sawtooth wave. The comparator is electrically connected to the arithmetic module to receive the flicker dimming signal generated by the fourth arithmetic unit, and is electrically connected to the sawtooth wave generator to receive the sawtooth wave, and generates the conversion signal based on the sawtooth wave and the flicker dimming signal.

7. The backlight dimming device as claimed in claim 1 further includes an input module having a buffer for receiving a dimming signal and a first operational amplifier electrically connected to the operational module. The buffer is used to adjust the voltage level of the dimming signal, and the first operational amplifier is electrically connected to the buffer to receive the dimming signal with the adjusted voltage level, generate the DC dimming signal based on the dimming signal with the adjusted voltage level, and input the DC dimming signal to the operational module.

8. The backlight dimming device as claimed in claim 7 further includes an output module having a buffer circuit and a second operational amplifier. The buffer circuit is electrically connected to the conversion module to receive the conversion signal and to adjust the voltage level of the conversion signal. The second operational amplifier is electrically connected to the buffer circuit to receive the conversion signal with the adjusted voltage level, and to generate a drive signal based on the conversion signal with the adjusted voltage level. The drive signal is input to the backlight driving circuit, such that the backlight driving circuit controls the current flowing through the LEDs according to the drive signal.

9. The backlight dimming device as claimed in claim 7, wherein the backlight driving circuit further includes a driving device for generating a driving signal related to the current flowing through the LEDs; wherein, The conversion module is electrically connected to the drive device and is used to input the conversion signal to the drive device, so that the drive device generates the drive signal according to the conversion signal.

10. A display backlight driving device, comprising: a backlight module having a plurality of LEDs; a backlight driving circuit for controlling the current flowing through the LEDs; and a backlight dimming device including an arithmetic module and a conversion module, the arithmetic module having first to fourth arithmetic units, the first arithmetic unit receiving a DC dimming signal indicating the brightness of the LEDs and a flicker waveform signal, and processing the flicker waveform signal according to the DC dimming signal to generate a flicker adjustment signal, the flicker adjustment signal being related to the flicker waveform signal corresponding to the brightness of the LEDs indicated by the DC dimming signal; the second arithmetic unit receiving the DC dimming signal and a flicker depth signal, and generating a DC factor signal according to the flicker depth signal and the DC dimming signal, the flicker depth signal being related to a ratio, the DC factor signal being related to the DC dimming signal adjusted according to the ratio related to the flicker depth signal. The third arithmetic unit is electrically connected to the first and second arithmetic units to receive the flicker adjustment signal and the DC factor signal, and generates a flicker factor signal based on the flicker adjustment signal and the DC factor signal. The fourth arithmetic unit receives the DC dimming signal and is electrically connected to the third arithmetic unit to receive the flicker factor signal, and generates a flicker dimming signal based on the DC dimming signal and the flicker factor signal. The conversion module is electrically connected to the arithmetic module to receive the flicker dimming signal, and generates a conversion signal related to the amount of current flowing through the LEDs based on the flicker dimming signal.

Images