Display device with gradually changing driving frequency and method for driving the same
A display device includes: a display panel; and a frequency controller which receives an image data signal and an input frequency information and outputs the image data signal and a timing control signal. The frequency controller includes: an image processor which receives the image data signal; a frame memory which stores the image data signal; an output frequency determining unit which receives the input frequency information and determines an output frequency based on a variation amount of the input frequency; and an image output unit which receives the image data signal from the image processor, receives an output frequency information from the output frequency determining unit, and outputs the image data signal and the timing control signal. When an input frequency varies, the output frequency determining unit determines the output frequency based on the following equations: K = FREQ - P_FREQ M_FREQ × SLOPE + OFFSET , and FREQ ′ = FREQ × K + P_FREQ × ( 1 - K ) .
1. A display device comprising:
a display panel; and
a frequency controller which receives an image data signal and an input frequency information and outputs the image data signal and a timing control signal,
wherein the frequency controller comprises:
an image processor which receives the image data signal;
a frame memory which stores the image data signal;
an output frequency determining unit which receives the input frequency information and determines an output frequency based on the input frequency information; and
an image output unit which receives the image data signal from the image processor, receives an output frequency information on the output frequency from the output frequency determining unit, and outputs the image data signal and the timing control signal based on the output frequency information,
wherein
when an input frequency varies, the output frequency determining unit determines the output frequency based on a variation amount of the input frequency acording to Equation 1 and Equation 2,
Equation 1 is defined by equation:
K
=
FREQ
-
P_FREQ
M_FREQ
×
SLOPE
+
OFFSET
,
Equation 2 is defined by equation:
FREQ′=FREQ× K+P _FREQ×(1− K ),
wherein
K denotes a weight,
FREQ denotes the input frequency,
FREQ′ denotes the output frequency,
P_FREQ denotes a previous output frequency, which is previously stored in the output frequency determining unit,
M_FREQ denotes a maximum frequency of driving frequencies of the display panel,
SLOPE denotes a first variation rate constant, and
OFFSET denotes a second variation rate constant.
2. The display device as claimed in claim 1 , wherein each of SLOPE and OFFSET in Equation 1 is greater than zero and less than 1.
3. The display device as claimed in claim 2 , wherein
SLOPE in Equation 1 is 0.4 or greater and 0.6 or less, and
OFFSET in Equation 1 is 0.1 or greater and 0.3 or less.
4. The display device as claimed in claim 2 , wherein the output frequency determining unit further comprises a frequency storing unit.
5. The display device as claimed in claim 1 , wherein M_FREQ in Equation 1 is 144 hertz.
6. The display device as claimed in claim 1 , further comprising:
a timing controller comprising the frequency controller.
7. The display device as claimed in claim 1 , further comprising:
a scaler comprising the frequency controller.
8. The display device as claimed in claim 1 , wherein
when the input frequency varies, the output frequency information gradually approaches the input frequency information.
9. The display device as claimed in claim 1 , wherein
the image output unit calculates a period of the image data signal according to Equation 3,
wherein Equation 3 is defined by equation:
T
=
1
FREQ
′
,
wherein T denotes the period.
10. A method of driving a display device, the method comprising:
obtaining an input frequency information;
determining whether an image data signal is input;
storing the image data signal;
identifying a previous frequency information;
calculating and determining an output frequency;
calculating a period based on the output frequency and delaying an output of the image data signal by the period; and
outputting the image data signal,
wherein the calculating and determining the output frequency comprises:
calculating the output frequency according to Equation 1 and Equation 2,
wherein
Equation 1 is defined by equation:
K
=
FREQ
-
P_FREQ
M_FREQ
×
SLOPE
+
OFFSET
,
Equation 2 is defined by equation:
FREQ′=FREQ× K+P _FREQ×(1− K ),
wherein
K denotes a weight,
FREQ denotes an input frequency,
FREQ′ denotes the output frequency,
P_FREQ denotes a previous output frequency, which is previously stored,
M_FREQ denotes maximum frequency of driving frequencies of a display panel of the display device,
SLOPE denotes a first variation rate constant, and
OFFSET denotes a second variation rate constant.
11. The method as claimed in claim 10 , wherein the calculating the period and the delaying the output of the image data signal by the period comprises:
calculating the period according to Equation 3;
outputting a timing control signal for delaying the output of the image data signal by the period; and
delaying the output of the image data signal based on the timing control signal,
wherein Equation 3 is defined by equation:
T
=
1
FREQ
′
,
wherein T denotes the period.
12. The method as claimed in claim 10 , wherein the storing the image data signal comprises:
storing the image data signal when it is determined that the image data signal is input, and
not storing the image data signal when it is determined that the image data signal is not input.
13. The method as claimed in claim 12 , wherein the outputting the image data signal comprises:
outputting an stored image data signal when it is determined that the image data signal is not input.