Noise elimination circuit of matrix display device and matrix display device using the same
View Patent ↗A noise elimination circuit that eliminates a noise of a display control signal of a matrix display device, includes a rising edge detection circuit unit that detects a rising edge of a signal for eliminating a noise, a counter that performs a count operation during a predefined period of time, an initialization circuit unit that generates an initialization signal of the counter, a count enable circuit unit that generates a count allowance signal of the counter, and an initial state detection circuit unit that detects whether or not the counter is in an initial state. The counter starts the count operation from an initial value in response to a rising edge detection by the rising edge detection circuit unit. The counter is initialized again after the count operation during the predefined period of time is completed. An initial state detection signal by the initial state detection circuit unit becomes a signal from which a noise is eliminated.
1. A noise elimination circuit that eliminates a noise of a display control signal of a matrix display device, comprising:
a rising edge detection circuit unit that detects a rising edge of a signal for eliminating a noise;
a counter that performs a count operation during a predefined period of time;
an initialization circuit unit that generates an initialization signal of the counter;
a count enable circuit unit that generates a count allowance signal of the counter; and
an initial state detection circuit unit that detects whether or not the counter is in an initial state,
wherein the counter starts the count operation from an initial value in response to a rising edge detection by the rising edge detection circuit unit,
the counter is reinitialized after the count operation during the predefined period of time is completed, and
an initial state detection signal by the initial state detection circuit unit becomes a signal from which a noise is eliminated.
2. The noise elimination circuit according to claim 1 ,
wherein a count value of the counter is maintained while a data enable signal is in an active state, and
the counter is initialized when the data enable signal becomes in an inactive state.
3. A noise elimination circuit that eliminates a noise of a display control signal of a matrix display device, comprising:
a rising edge detection circuit unit that detects a rising edge of a data enable input signal included in the display control signal;
a counter that counts a clock signal included in the display control signal, is initialized by an initialization signal, and performs a count operation in response to a count allowance signal;
a horizontal pixel number detection unit that outputs a count stop signal when an output value of the counter becomes a predefined value;
an initial state detection circuit unit that detects whether or not the counter is in an initial state and outputs an initial state detection signal;
an initialization circuit unit that is input with an output signal of the rising edge detection circuit unit and the count stop signal, and outputs the initialization signal; and
a count enable circuit unit that is input with the output signal of the rising edge detection circuit unit, the count stop signal, and the initial state detection signal, and outputs the count allowance signal,
wherein the counter starts the count operation in response to the count allowance signal output from the count enable circuit unit by a rising edge detection output of the rising edge detection circuit unit, the count stop signal is output from the horizontal pixel number detection unit after the predefined value is counted, the count allowance signal becomes in an unallowed state and the initialization signal is output from the initialization circuit unit in response to the count stop signal, the counter is initiallized, and the initial state detection signal becomes as a data enable output signal.
4. The noise elimination circuit according to claim 3 ,
wherein the rising edge of the signal for eliminating a noise is detected by the rising edge detection circuit unit that detects the rising edge of the signal for eliminating a noise on a basis of a logical product operation output of a plurality of stages of delay circuits having different delay time.
5. The noise elimination circuit according to claim 4 ,
wherein the delay circuits are two to thirty D flip-flop circuits.
6. The noise elimination circuit according to claim 1 , further comprising:
a control circuit unit that is input with a count stop signal of a horizontal pixel number detection unit and a rising edge detection output,
wherein an arbitrary horizontal pixel number can be set in the horizontal pixel number detection unit as a specified value by using an output signal of the control circuit, and
when the count stop signal is input to the control circuit unit, the control circuit unit increments the horizontal pixel number if the rising edge detection output is in an inactive state.
7. The noise elimination circuit according to claim 3 , further comprising:
a control circuit unit that is input with a count stop signal of the horizontal pixel number detection unit and the rising edge detection output,
wherein an arbitrary horizontal pixel number can be set in the horizontal pixel number detection unit as a specified value by using an output signal of the control circuit, and
when the count stop signal is input to the control circuit unit, the control circuit unit increments the horizontal pixel number if the rising edge detection output is in an inactive state.
8. The noise elimination circuit according to claim 4 ,
wherein a display data signal passes through delay circuits as many as a number corresponding to a delay amount of a signal for eliminating a noise in the rising edge detection circuit unit.
9. A resolution judgment circuit comprising:
a first counter that counts between an edge of a data enable input signal waveform and next edge thereof; and
a count value holding circuit unit that holds a first count value of the first counter; and
a second counter that determines whether the first count value held in the count value holing circuit is larger or smaller than a predetermined threshold value in synchronization with an output of a noise elimination circuit, and increments a second count value if the first count value is larger than the predetermined threshold value and decrements the second count value if the first count value is smaller than the predetermined threshold value,
wherein the noise elimination circuit includes:
a rising edge detection circuit unit that detects a rising edge of a signal for eliminating a noise;
a counter that performs a count operation during a predefined period of time;
an initialization circuit unit that generates an initialization signal of the counter;
a count enable circuit unit that generates a count allowance signal of the counter; and
an initial state detection circuit unit that detects whether or not the counter is in an initial state,
the counter starts the count operation from an initial value in response to a rising edge detection by the rising edge detection circuit unit,
the counter is reinitialized after the count operation during the predefined period of time is completed, and
an initial state detection signal by the initial state detection circuit unit becomes a signal from which a noise is eliminated.
10. A matrix display device using a noise elimination circuit, which includes:
a rising edge detection circuit unit that detects a rising edge of a signal for eliminating a noise;
a counter that performs a count operation during a predefined period of time;
an initialization circuit unit that generates an initialization signal of the counter;
a count enable circuit unit that generates a count allowance signal of the counter; and
an initial state detection circuit unit that detects whether or not the counter is in an initial state,
the counter starts the count operation from an initial value in response to a rising edge detection by the rising edge detection circuit unit,
the counter is reinitialized after the count operation during the predefined period of time is completed, and
an initial state detection signal by the initial state detection circuit unit becomes a signal from which a noise is eliminated.