KR100751127B1 - The image display apparatus having removing noise means and method for removing noise - Google Patents

Abstract

The present invention relates to an image display device capable of actively adjusting the filtering amount of high frequency noise according to a frequency state of an image signal. The image display device according to the present invention comprises: signal receiving means for receiving an image signal; Image processing means for displaying on the display unit an image signal received through the signal receiving means; A signal component detector for detecting a vertical frequency and a horizontal frequency of the image signal input to the image processing means, respectively; A controller for comparing the vertical frequency and the horizontal frequency detected by the signal component detector with a predetermined reference vertical frequency and the reference horizontal frequency, respectively, and outputting a control signal for adjusting the filtering amount of the high frequency noise according to the comparison result; And a filtering unit adjusting the amount of filtering the high frequency noise according to the control signal. According to this, since an image signal having an optimal frequency can be displayed, tearing noise of the screen can be effectively removed.

Video display device, noise, frequency, rejection

Description

The image display apparatus having removing noise means and method for removing noise}

1 is a block diagram of a video display device according to the prior art.

2 is a block diagram of a video display device having a noise removing device according to an embodiment of the present invention.

3 is a block diagram of an apparatus for removing noise according to an embodiment of the present invention.

4 is a flowchart illustrating a method of removing noise of a video signal according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100, 200: video display device 110, 210: input port

120, 220: signal receiving unit 130, 230: display unit

140 and 240: image processing unit 150: control unit

250: noise canceller 251: signal component detector

252: control unit 253: filtering unit

260: filter

The present invention relates to a video display device, and more particularly, to a video display device having a noise removing means capable of actively adjusting the filtering amount of high-frequency noise in accordance with the frequency state of the video signal.

Thanks to the development of digital technology, digital TVs have been able to provide a large amount of information faster and more reliably by compressing and transmitting video data and audio data with MPEG technology. A configuration of a conventional video display device capable of providing a composite image as described above will be briefly described with reference to FIG. 1.

1 is a block diagram of a video display device according to the prior art.

Referring to FIG. 1, the conventional video display device 100 includes an input port 110 for receiving a composite video signal and a signal receiver 120 for receiving a composite video signal input through the input port 110. ), A display 130 for displaying an image signal, an image processor 140 for displaying the image signal received through the signal receiver 120, and an image processor 140. A control unit 150 for controlling the image signal processing and a filter 160 for removing noise by filtering the image signal transmitted from the signal receiving unit 120 to the image processing unit 140.

The input port 110 receives a digital composite video signal or an analog composite video signal processed by a high definition multimedia interface (HDMI) signal system. Here, the composite video signal consists of a video signal and an audio signal.

The signal receiving unit 120 performs a function of receiving a digital composite video signal or an analog composite video signal input through the input port 110 and connecting the image processing unit 140 to the composite image processed by the HDMI signal system. It may be implemented as a Transition Minimized Differential Signaling (TMDS) receiver for receiving a signal.

The display unit 130 is implemented as a display device such as a liquid crystal display (LCD) or a plasma display panel (PDP), and displays an image signal subjected to resolution processing by the image processor 140. do.

The image processor 140 displays the image signal input from the signal receiver 120 on the display 130 according to a predetermined resolution, and at this time, the brightness and contrast of the screen according to a predetermined brightness value and contrast value are displayed. Adjust

The controller 150 sets the brightness value, the contrast value, and the like to the image processor 140 according to a user's command, and controls the image processor 140 to display the input image signal on the display 130. .

The filter 160 includes a capacitor C1 having a constant time constant, and removes noise of an image signal transmitted from the signal receiver 120 to the image processor 140 in proportion to the time constant of the capacitor C1. give. This is to prevent noise from occurring in the process of receiving the composite image signal from the outside to the image display device 100 so that the frequency of the composite image signal is distorted.

If the frequency of the composite video signal is distorted by the harmonic noise, the resolution of the composite video signal input to the image processor 140 may be different from the predetermined reference resolution. In this case, the horizontal / The amount of high frequency noise induced by the vertical synchronization signal (H / V Sync) is changed, and the signal-to-noise ratio (S / N) is lowered, thereby generating tearing noise in the display unit 130. That is, the filter 160 removes high frequency noise that is the cause of the tearing noise to prevent frequency distortion of the composite video signal. Here, since the filtering amount of the filter 160 is determined in proportion to the time constant of the capacitor C1, as the time constant increases, the filtering amount increases, so that the amount of high frequency noise is removed. This reduces the amount of high frequency noise removed.

However, in the conventional video display device, since the time constant of the capacitor C1 constituting the filter 160 is fixed, the filtering amount is not actively adjusted even if the resolution distortion of the composite video signal increases and the harmonic frequency is severely distorted. Because of this, there is a problem in that tearing noise cannot be completely removed by preventing distortion of the harmonic frequency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is a video display device and a noise removing method having a noise removing means capable of actively adjusting the filtering amount of high frequency noise according to the frequency state of an image signal. To provide.

The present invention for achieving the above object, the signal receiving means for receiving a video signal; Image processing means for displaying on the display unit an image signal received through the signal receiving means; A signal component detector for detecting a vertical frequency and a horizontal frequency of the image signal input to the image processing means, respectively; A controller for comparing the vertical frequency and the horizontal frequency detected by the signal component detector with a predetermined reference vertical frequency and the reference horizontal frequency, respectively, and outputting a control signal for adjusting the filtering amount of the high frequency noise according to the comparison result; And a filtering unit adjusting the amount of filtering the high frequency noise according to the control signal.

According to the present invention, when the image signal is input to the image processing unit, detecting the vertical frequency and the horizontal frequency of the video signal, respectively; Comparing the detected magnitudes of the vertical frequency and the horizontal frequency with a predetermined reference vertical frequency and the horizontal frequency, respectively; And adjusting the filtering amount of the high frequency noise of the video signal according to the comparison result.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

2 is a block diagram of an image display device for removing noise according to an exemplary embodiment of the present invention.

Referring to FIG. 2, the image display device 200 of the present invention includes an input port 210 for receiving a composite video signal and a signal receiving unit for receiving a composite video signal input through the input port 210. 220, a display unit 230 for displaying an image signal, an image processor 240 for displaying the image signal received through the signal receiver 220, and an image processor 240. And a noise removing device 250 for adjusting the frequency of the video signal according to the magnitude of the frequency of the video signal input thereto.

In addition, the image display device 200 of the present invention further includes a filter 260 for filtering out image signals transmitted from the signal receiver 120 to the image processor 140 to remove noise.

The input port 110 receives a digital composite video signal or an analog composite video signal processed by a high definition multimedia interface (HDMI) signal system, but the present invention differs from the HDMI signal system. When applied to remove the high frequency noise of the video signal processed by the input port that can receive the video signal can be applied to the present invention. Here, the composite video signal is composed of a video signal and an audio signal.

The signal receiving unit 220 receives a digital composite video signal or an analog composite video signal input through the input port 210 and connects the image processing unit 140 to the image processing unit 140. Only the signal is transmitted to the image processor 240. The signal receiver 220 may be implemented as a Transition Minimized Differential Signaling (TMDS) receiver for receiving a composite video signal processed by an HDMI signal system, but is not limited thereto.

The display 230 is implemented as a display device such as a liquid crystal display (LCD) or a plasma display panel (PDP), and displays an image signal subjected to resolution processing by the image processor 240. do.

The image processor 240 displays the image signal input from the signal receiver 220 on the display 230 according to a predetermined resolution, and at this time, displays the brightness and contrast of the screen according to a predetermined brightness value and contrast value. Adjust

When the vertical frequency and the horizontal frequency of the image signal input to the image processor 240 are detected by the signal component detector 251, the noise removing apparatus 250 detects the predetermined reference vertical and horizontal frequencies and the detected vertical and horizontal frequencies. Compare the magnitude of each frequency. As a result of the comparison, if both the predetermined reference vertical frequency and reference horizontal frequency and the detected vertical frequency and horizontal frequency are the same, the noise removing device 250 generates a pulse width modulated signal having a pulse width of an initial state, thereby changing the variable capacitance and time constant. Keep it constant. If, as a result of the comparison, the predetermined reference vertical frequency and the reference horizontal frequency are larger than the detected vertical frequency and the horizontal frequency, respectively, the noise canceller 250 generates a pulse width modulated signal having a relatively narrow width, and then proportionally to the narrowed width. In addition to reducing the variable dose, it also reduces the time constant. Finally, if the predetermined reference vertical frequency and reference horizontal frequency are smaller than the detected vertical frequency and horizontal frequency as a result of the comparison, the noise canceller 250 generates a pulse width modulated signal having a relatively wide width and is proportional to the widened width. This increases the variable dose and the time constant.

The filter 260 is formed of a capacitor C2 having a constant time constant, and removes high frequency noise of an image signal transmitted from the signal receiver 220 to the image processor 240 in proportion to the time constant of the capacitor C2. By doing so, high frequency noise is generated in the process of receiving the composite video signal from the outside to the image display device 200 to prevent the frequency of the composite video signal from being distorted.

3 is a block diagram of an apparatus for removing noise of an image display device according to an exemplary embodiment of the present invention. Hereinafter, the configuration and operation of the noise removing device according to the present invention will be described in detail.

As shown in FIG. 3, the noise removing apparatus 250 is detected by a signal component detector 251 and a signal component detector 251 for detecting signal components of an image signal input to the image processor 240. The control unit 252 outputs a control signal for controlling the filtering of the high frequency noise according to the received signal component, and the image signal input to the image processor 240 by filtering the high frequency noise according to the control signal output from the control unit 252. It is provided with a filtering unit 253 for adjusting the frequency of.

The signal component detector 251 detects a signal component of the image signal input to the image processor 240, that is, a vertical frequency and / or a horizontal frequency, and outputs the signal component to the controller 252.

The controller 252 controls the image processor 240 to set the brightness value and the contrast value to the image processor 240 according to a user's command and display the input image signal on the display 230. As described below, the high frequency filtering amount of the filtering unit 253 is adjusted according to the vertical frequency and / or the horizontal frequency detected by the signal component detecting unit 251. The control unit 252 may preset a reference vertical frequency and a reference horizontal frequency of an image signal suitable for the display unit 230, and in particular, the predetermined reference vertical frequency and reference horizontal frequency may be constructed and stored in the lookup table.

First, when the signal receiver 220 transmits the received image signal to the image processor 240, the signal component detector 251 detects the vertical frequency and the horizontal frequency of the image signal input to the image processor 240 to control the controller ( 252).

When the signal component of the image signal is detected as described above, the controller 252 compares the predetermined reference vertical frequency and the reference horizontal frequency with the magnitude of the detected vertical frequency and horizontal frequency, respectively, and controls the filtering amount of the high frequency noise according to the comparison result. A pulse width modulation (PWM) signal is output to the filtering unit 253 as a control signal.

As a result of the comparison, if the predetermined reference vertical frequency and the reference horizontal frequency are larger than the detected vertical frequency and the horizontal frequency, the controller 252 outputs a pulse width modulated signal having a relatively narrow width to the filtering unit 253. When the pulse width modulated signal having the narrow width is input to the filtering unit 253, the filtering unit 253 reduces the filtering amount of the high frequency noise in proportion to the narrow width of the pulse width modulated signal. In addition, when the predetermined reference vertical frequency and the reference horizontal frequency are smaller than the detected vertical frequency and the horizontal frequency as a result of the comparison, the controller 252 outputs a pulse width modulated signal having a relatively wide width to the filtering unit 253. When the pulse width modulated signal having the wide width is input to the filtering unit 253, the filtering unit 253 increases the filtering amount of the high frequency noise in proportion to the wide width of the pulse width modulated signal.

The filtering unit 253 includes a transistor TR1 in which a turn-on and turn-off period is adjusted in proportion to the width of the pulse width modulation signal input from the control unit 252, and the transistor TR1. Integrator 253-1 for blocking the passage of AC component voltage and passing only DC voltage by filtering the voltage output through the output terminal N1 of the < RTI ID = 0.0 >), < / RTI > A diode D1 for passing a DC voltage above a threshold passing therethrough and a varactor VR1 whose capacitance changes in proportion to the magnitude of the DC voltage passing through the diode D1 are provided.

The transistor TR1 is an NPN type bipolar transistor whose base is connected to the output terminal of the control unit 252 which outputs the pulse width modulation signal, the emitter is connected to ground, and the collector is connected to the power supply VCC. The output node N1, which is an output terminal of the transistor TR1, is positioned on the collector side to which VCC is applied.

Since the transistor TR1 is turned on in the high section of the pulse width modulated signal applied to the base and turned off in the low section of the pulse width modulated signal, if a pulse width modulated signal having a narrow pulse width is applied to the base, the transistor ( Since the turn-on and turn-off periods of the TR1 become very fast, the frequency oscillated by the transistor TR1 becomes high, and a high voltage is output through the output terminal N1. On the contrary, when a pulse width modulated signal having a wide pulse width is applied to the base, the turn-on and turn-off period of the transistor TR1 becomes very slow, so that the frequency oscillated by the transistor TR1 is lowered and lowered through the output terminal N1. The voltage is output. Here, the high and low of the voltage output through the transistor TR1 is not determined critically, but relatively determined by the width of the pulse width modulated signal.

Due to the operation characteristics of the transistor TR1, the controller 252 outputs a pulse width modulated signal having a narrow width when the predetermined reference vertical frequency and the reference horizontal frequency are larger than the detected vertical frequency and the horizontal frequency, respectively. On the contrary, if a predetermined reference vertical frequency and reference horizontal frequency are smaller than the detected vertical frequency and horizontal frequency, a pulse width modulated signal having a wide width is output to the base of the transistor TR1.

The integrator 253-1 includes a resistor R1 connected between the output terminal N1 of the transistor TR1 and the node N2, and a capacitor connected between the node N2 and the ground and in parallel with the resistor R1. (C3). The integrator 253-1 filters the voltage output through the output terminal N1 of the transistor TR1 to remove the AC component and outputs only the DC voltage toward the diode D1.

The diode D1 has an anode connected to the node N2 of the integrator 253-1 and a cathode connected to the node N3. The diode D1 is short when the anode is subjected to a voltage equal to or greater than the threshold.

The varactor VR1 is connected in series with the capacitor C2 of the filter 260 between the output terminal of the signal receiver 220 and the ground, and is common to the node N3 located between the capacitor C2 and the varactor VR1. It is in parallel with the connected diode (D1).

The voltage of the DC component is reversely applied among the voltages output from the transistor TR1 to the varactor VR1. When a relatively high reverse voltage is applied, the capacity is smaller and the time constant is smaller due to the variable characteristics of the varactor VR1. You lose. When the time constant of the varactor VR1 decreases, the amount of high frequency noise filtering decreases in proportion to the reduced time constant, thereby reducing the amount of high frequency noise removal of the image signal input to the image processor 240.

If a relatively low reverse voltage is applied to the varactor VR1, the capacity of the varactor VR1 is increased and the time constant is also increased. As the time constant of the varactor VR1 increases, the amount of high frequency noise filtering increases in proportion to the increased time constant, thereby increasing the amount of high frequency noise removed from the image signal input to the image processor 240.

As described above, when the amount of removal of high frequency noise decreases due to the change in the time constant of the variable capacity VR1 having a variable capacitance characteristic, the vertical frequency and the horizontal frequency of the video signal decrease in proportion to each other. As the number of high frequency noises is increased by the number, the vertical frequency and horizontal frequency of the video signal increase in proportion to this.

That is, the present invention actively adjusts the filtering amount of high frequency noise by changing the time constant of the varactor VR1 in proportion to the magnitude of the frequency of the image signal input to the image processor 240, Regardless of the amount of high frequency noise generated, an image signal having an optimal frequency may be output to the display 230.

Referring to a flowchart, a process of actively removing high frequency noise of an image signal by a noise removing device of the present invention having the above-described configuration and function is as follows.

4 is a flowchart illustrating a method of removing noise of a video signal according to an exemplary embodiment of the present invention.

Referring to FIG. 4, first, when an image signal received from the signal receiver 220 is input to the image processor 240 (S401), the signal component detector 251 performs a vertical frequency of the image signal input to the image processor 240. And detects the horizontal frequency and outputs it to the control unit 252 (S402).

When the signal component of the video signal is detected, the controller 252 compares the predetermined reference vertical frequency and the reference horizontal frequency with the magnitudes of the detected vertical frequency and the horizontal frequency, respectively (S403).

As a result of the comparison, if the predetermined reference vertical frequency and reference horizontal frequency and the detected vertical frequency and horizontal frequency are all the same, the controller 252 outputs a pulse width modulated signal having a pulse width of an initial state to the filtering unit 253 ( In operation S404, the filtering unit 253 maintains the time constant constant without changing the capacity of the varactor VR1 (S405).

As a result of the comparison, if the predetermined reference vertical frequency and the reference horizontal frequency are larger than the detected vertical frequency and the horizontal frequency, that is, the detected signal component is smaller than the magnitude of the reference signal component, the control unit 252 has a relatively narrow pulse. The width modulated signal is output to the filtering unit 253 (S406), and then the filtering unit 253 reduces the capacity of the varactor VR1 in proportion to the width of the narrowed pulse width modulation signal and reduces the time constant. (S407).

As a result of the comparison, if the predetermined reference vertical frequency and the reference horizontal frequency are smaller than the detected vertical frequency and the horizontal frequency, that is, the detected signal component is larger than the magnitude of the reference signal component, the control unit 252 has a relatively wide pulse. The width modulated signal is output to the filtering unit 253 (S408), and then the filtering unit 253 increases the capacity of the varactor VR1 in proportion to the width of the widened pulse width modulation signal and increases the time constant. (S409).

By repeatedly performing the high frequency noise removing process as described above, the present invention displays an image signal having an optimal frequency.

As described above, according to the present invention, by actively adjusting the filtering amount of the high frequency noise according to the frequency state of the video signal, the video signal having the optimal frequency can be displayed, thereby effectively removing the tearing noise of the screen. All.

Claims (6)

Signal receiving means for receiving an image signal; Image processing means for displaying on the display unit an image signal received through the signal receiving means; A signal component detector for detecting a vertical frequency and a horizontal frequency of the image signal input to the image processing means, respectively; A controller for comparing the vertical frequency and the horizontal frequency detected by the signal component detector with a predetermined reference vertical frequency and the reference horizontal frequency, respectively, and outputting a control signal for adjusting the filtering amount of the high frequency noise according to the comparison result; And, And a filtering unit which controls the amount of filtering the high frequency noise according to the control signal. delete The method of claim 1, The controller compares the detected vertical frequency and horizontal frequency with a predetermined reference vertical frequency and reference horizontal frequency, respectively, and controls filtering of the high frequency noise according to a comparison result. If the detected vertical frequency and horizontal frequency and the predetermined reference vertical frequency and reference horizontal frequency are all the same, the control unit outputs the control signal to maintain the filtering amount of the high frequency noise to the filtering unit, If the detected vertical frequency is smaller than the predetermined reference vertical frequency and the detected horizontal frequency is smaller than the predetermined reference horizontal frequency, the control unit filters the control signal to reduce the filtering amount of the high frequency noise. Output as negative, If the detected vertical frequency is greater than the predetermined reference vertical frequency and the detected horizontal frequency is greater than the predetermined reference horizontal frequency, the control unit sends the control signal to the filtering unit to increase the filtering amount of the high frequency noise. And a video display device. The method according to claim 1 or 3, The filtering unit, A transistor whose turn-on and turn-off period is adjusted according to a control signal of the controller; An integrator for filtering a voltage output through an output terminal of the transistor to block passage of an AC component voltage and to pass only a DC voltage; A diode for passing a DC voltage above the threshold passing through the integrator; And And a varactor in which a variable capacitance and a time constant change in proportion to the magnitude of the DC voltage passing through the diode. Detecting a vertical frequency and a horizontal frequency of the video signal when the video signal is input to the video processor; Comparing the detected magnitudes of the vertical frequency and the horizontal frequency with a predetermined reference vertical frequency and the horizontal frequency, respectively; And And adjusting the filtering amount of the high frequency noise of the video signal according to the comparison result. The method of claim 5, Adjusting the high frequency noise filtering amount of the video signal according to the comparison result, Maintaining a filtering amount of the high frequency noise if the detected vertical frequency and horizontal frequency and the predetermined reference vertical frequency and reference horizontal frequency are the same; When the detected vertical frequency is smaller than the predetermined reference vertical frequency and the detected horizontal frequency is smaller than the predetermined reference horizontal frequency, reducing the filtering amount of the high frequency noise; And if the detected vertical frequency is greater than the predetermined reference vertical frequency and the detected horizontal frequency is greater than the predetermined reference horizontal frequency, increasing the filtering amount of the high frequency noise. How to remove noise.

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