US RE50,213 E1
Synchronous backlight device and operation method thereof
Chung-Wen Wu, Yilan County (TW); Wen-Chi Lin, Yilan County (TW); and Sih-Ting Wang, Kaohsiung (TW)
Assigned to Novatek Microelectronics Corp., Hsinchu (TW)
Filed by Novatek Microelectronics Corp., Hsinchu (TW)
Filed on Jun. 7, 2022, as Appl. No. 17/833,906.
Application 17/833,906 is a reissue of application No. 15/828,396, filed on Nov. 30, 2017, granted, now 10,692,443, issued on Jun. 23, 2020.
Int. Cl. H03K 7/08 (2006.01); G02F 1/13357 (2006.01); G09G 3/34 (2006.01)
CPC G09G 3/3406 (2013.01) [G02F 1/133602 (2013.01); H03K 7/08 (2013.01); G09G 2310/0264 (2013.01); G09G 2310/08 (2013.01)] 28 Claims
OG exemplary drawing
 
[ 14. A synchronous backlight device for a display panel, comprising:
a pulse width modulation (PWM) control circuit, configured to receive a video sync information and generate a PWM control signal, wherein the PWM control signal is adapted to control a backlight source of the display panel, wherein
the video sync information defines a plurality of video frame periods comprising a first video frame period and a second video frame period of different period lengths,
the PWM control circuit divides each of the first video frame period and the second video frame period into different sub-frame periods including a first period and a second period corresponding to the first period, wherein length of the first period of the first video frame period is substantially equal to length of the first period of the second video frame period, and length of the second period of the first video frame period is different from length of the second period of the second video frame period,
in each of the first periods, the PWM control signal comprises a first active pulse, and
in each of the second periods, the PWM control signal comprises a plurality of second active pulses having substantially identical pulse width,
wherein a flicker effect of the backlight source is reduced by setting a pulse width of the first active pulse of the PWM control signal wider than the pulse width of each of the second active pulses of the PWM control signal, and a first duty ratio of the PWM control signal in each of the first periods is equal to a second duty ratio of the PWM control signal in each of the second periods.]