Liquid crystal display and driving method thereof
A liquid crystal display device and a driving method thereof that are adaptive for detecting a presence and a frequency range of an input signal applied to the liquid crystal display. In the device, a timing controller is provided with a signal presence determiner for detecting an application of an input signal from an interface. The signal presence determiner is provided with an oscillator for generating a reference clock having the same frequency as a horizontal synchronizing signal and a pre-synchronizing signal having the same frequency as a vertical synchronizing signal, a period detector for comparing a data enable signal from the exterior thereof with the reference clock to output a period of the input signal with the aid of a detection reference signal and the pre-synchronizing signal, a period comparator for comparing a period range between a desired maximum value and a desired minimum value of the input signal, and signal presence/absence comparing means for determining a presence/absence of the input signal in response to a pulse number of the input signal detected within a period range between the maximum value and the minimum value during an application interval of the detection reference signal.
1. A liquid crystal display device including a timing controller provided with a signal presence determiner for detecting an application of an input signal from an interface, wherein said signal presence determiner comprises:
an oscillator for generating a reference clock having the same frequency as a horizontal synchronizing signal and a pre-synchronizing signal having the same frequency as a vertical synchronizing signal;
a period detector for comparing a data enable signal from the exterior thereof with the reference clock to output a period of the input signal with the aid of a detection reference signal and the pre-synchronizing signal; and
a period comparator for comparing a period range between a desired maximum value and a desired minimum value of the input signal, outputting a signal of a first state to a signal presence comparing means only if the period of the input signal is within the period range, and outputting the signal of the first state to a signal absence comparing means only if the period of the input signal is beyond the period range;
the signal presence comparing means for determining a presence of the input signal in response to a pulse number of the input signal detected within a period range between the maximum value and the minimum value if the number of pulses of the signal of the first state is larger than a predetermined plural number during an application input interval of the detection reference signal, being different from the signal of the first state, wherein each of the pulses is to be of the first state and continuously has same values; and
the signal absence comparing means for determining an absence of the input signal if the number of pulses of the signal of the first state is smaller than a predetermined plural number during an input interval of the detection reference signal, being different from the signal of the first state, wherein each of the pulses is to be of the first state and continuously has same values.
2. The liquid crystal display device as claimed in claim 1 , wherein said period range between the maximum value and the minimum value of the period comparator can be controlled by a user.
3. The liquid crystal display device as claimed in claim 1 , wherein said pulse number of the signal presence/absence comparing means can be controlled by a user.
4. A method of driving a liquid crystal display device including a timing controller provided with a signal presence determiner for detecting an application of an input signal from an interface, said method comprising the steps of:
generating a reference clock having the same frequency as a horizontal synchronizing signal and a pre-synchronizing signal having the same frequency as a vertical synchronizing signal;
comparing a data enable signal from the exterior with the reference clock to output a period of the input signal with the aid of a detection reference signal and the pre-synchronizing signal;
comparing a period range between a desired maximum value and a desired minimum value of the input signal;
outputting a signal of a first state to a signal presence comparing means only if the period of the input signal is within the period range,
outputting the signal of the first state to a signal absence comparing means only if the period of input signal is beyond the period range;
determining a presence of the input signal in response to a pulse number of the input signal detected within a period range between the maximum value and the minimum value if the number of pulses of the signal of the first state outputted to the signal presence comparing means is larger than a predetermined plural number during an application input interval of the detection reference signal, being different from the signal of the first state, wherein each of the pulses is to be of the first state and continuously has same values; and
determining an absence of the input signal if the number of pulses of the signal of the first state outputted to the signal absence comparing means is smaller than a predetermined plural number during an input interval of the detection reference signal, being different from the signal of the first state, wherein each of the pulses is to be of the first state and continuously has same values.
5. The method as claimed in claim 4 , wherein said period range between the maximum value and the minimum value can be controlled by a user.
6. The method as claimed in claim 4 , wherein said pulse number of the input signal can be controlled by a user.