CN101276558B - Method and device for preventing interference images - Google Patents

Abstract

A method for preventing interference image for preventing the control signal of lamp tube of LCD from interfering the image signal includes regulating the frequency of said control signal to make the frequency spectrum of said control signal and the frequency spectrum of said image signal be interlaced.

Description

Method and device for preventing interference images

technical field

The invention relates to a display and its driving method, and especially designs a display and its driving method capable of overcoming image signal interference.

Background technique

An Inverter is a high-voltage converter that converts current from DC to AC, and is used to light up the light source of the display, such as the cold cathode lamp (CCFL) that lights up the panel.

Traditionally, there are two ways to light the CCFLs, one is the continuous mode of driving the lamp (Continue mode), and the other is the mode of intermittently driving the lamp (Burst mode). Among them, the way of continuously driving the lighter to light up consumes a large amount of power. Therefore, in the current environment where environmental protection awareness is rising, the mode of intermittently driving the lighter to light up has gradually become the mainstream.

However, since the lighting device uses high voltage to light the cold-cathode lamp, it will interfere with the image signal at the moment of its startup and shutdown, resulting in partial or overall unevenness of the picture and the formation of water ripples.

Therefore, there is a need for a lighting device driving method that can reduce power consumption without generating image signal interference or water ripples.

Contents of the invention

Therefore, an object of the present invention is to provide a driving method of a lamp, so as to avoid disturbing image signals.

According to the above purpose of the present invention, a method for preventing interference with images is proposed, which is used to prevent the working signal of the lamp tube of the liquid crystal display from interfering with the video signal, including adjusting the frequency of the working signal of the liquid crystal lamp so that the frequency spectrum of the working signal is consistent with the frequency of the working signal. The image signal spectrum is interleaved.

According to the above purpose of the present invention, a device for preventing interference with images is further proposed to prevent the working signal of the lamp tube of the liquid crystal display from interfering with the image signal. The working signal of the tube, and the lamp (inverter), which is coupled to the zoom controller, is used to light a backlight according to the working signal of the lamp, wherein the working signal of the lamp has a frequency such that the working signal The frequency spectrum and the frequency spectrum of the video signal are interleaved with each other.

The present invention completely staggers the frequency spectrum of the working signal of the lighting device and the frequency spectrum of the image signal, so that the water ripple phenomenon formed by the mutual interference between the two can be avoided.

Description of drawings

In order to make the above and other objects, features, advantages and embodiments of the present invention more comprehensible, the accompanying drawings are described below:

FIG. 1 shows a spectrum diagram presented in the frequency domain after performing Fourier transform on an image signal according to an embodiment of the present invention;

Fig. 2 shows a control circuit diagram of a lamp according to an embodiment of the present invention; and

Fig. 3 shows the operation flowchart of the present invention.

[Description of main component symbols]

201 Zoom controller

202 Lighter

203 filter circuit

301～303 steps

Detailed ways

The image signal includes various video signals, such as voltage and current amplitude, gain, frequency, power, etc. When analyzing the image signal, the image signal with many frequencies can be mathematically transformed, such as Fourier transform, to present it in the frequency domain, thereby displaying the characteristics of the image signal in the frequency domain.

FIG. 1 is a spectrum diagram presented in the frequency domain after performing Fourier transform on an image signal according to an embodiment of the present invention. The horizontal axis is frequency, and the vertical axis is amplitude. According to the spectrogram, there is no signal transmission between any two adjacent multiplied frequencies, such as between the 1-octaved frequency 101 and the 2-octaved frequency 102 or between the 2-octaved frequency 102 and the 3-octaved frequency 103 . In other words, if the spectrum of the working signal of the lamp lighter of the light source and the spectrum of the video signal can be staggered from each other, that is, each multiplier in the spectrum of the working signal is sequentially located between adjacent multipliers in the spectrum of the video signal, then The working signal will not affect the image signal, so that the interference between the working signal and the image signal can be avoided to cause water ripples.

Fig. 2 is a circuit diagram of a lamp lighter control circuit according to an embodiment of the present invention. The lighter 202 is coupled to a scalar controller 201 . The zoom controller 201 is used to automatically adjust the zoom in and zoom out of the display image according to the size of the liquid crystal display panel. The control software of the zoom controller 201 generates a pulse width modulation (PWM) signal according to the vertical synchronous signal (V _sync ) of the liquid crystal display, and transmits it to the lighter 202 after passing through the filter circuit 203 for intermittently driving the cooling Cathode tubes.

According to the present invention, the frequency spectrum formed by the working signal of the lamp can be sequentially positioned between the frequency spectrum of the image signal to avoid the water ripple phenomenon. In one embodiment, according to the image signal spectrum diagram shown in FIG. 1 , since there is no signal transmission between the one-octave frequency and the two-octave frequency spectrum, the 1-octave frequency of the working signal spectrum can be located at the 1.5-octave frequency of the image signal spectrum. Avoid water ripple phenomenon. In other embodiments, the 1-fold frequency of the working signal spectrum may also be located in other parts of the image signal spectrum diagram that do not have signal transmission, such as 2.5-fold frequency or 3.5-fold frequency. In another embodiment, if the images are scanned from the middle of the screen to the upper and lower directions or from the upper and lower sides of the screen to the middle, the time required for the scanning signal to scan to the middle of the screen is half of the time shown in Fig. The frame time, that is, the frequency of the scanning signal will be twice its original frequency. At this time, if the frequency of the image signal of the system is set to be synchronized with the scanning signal, the frequency of the image signal must also be doubled; therefore, in making In an embodiment in which the 1-fold frequency of the working signal spectrum is located at the 1.5-fold frequency of the image signal spectrum to avoid signal interference, the vertical synchronization signal (V _sync ) input to the scaling controller 201 needs to be tripled (1.5 ×2=3 frequency multiplication), so that the pulse width modulation signal used to control the lighter 202 also becomes 3 times the original, that is, the 1 multiplication frequency of the working signal spectrum can be located at the 3 multiplication frequency of the original image signal spectrum .

Fig. 3 shows the operation flowchart of the present invention, referring to Fig. 2 at the same time. In step 301 , the scaling controller 201 detects the magnitude of the vertical synchronization signal used at that time, and in step 302 reads out the vertical synchronization signal. Since in this embodiment, the 1-fold frequency of the working signal spectrum is located at the 1.5-fold frequency of the image signal spectrum to avoid the water ripple phenomenon, so in step 303, the vertical synchronization signal (V _sync ) double frequency is changed to the original 3 times, so that the pulse width modulation signal used to control the igniter 202 is also tripled.

To sum up the above, the present invention completely staggers the spectrum of the working signal of the lighting device and the spectrum of the image signal, so as to avoid mutual interference between the two, and further avoid the formation of water ripples. In addition, the double frequency of the frequency spectrum of the working signal can also be located in each part of the spectrum of the image signal that does not have signal transmission, so it is quite convenient in design. Moreover, the frequency spectrum of the working signal can be corrected in real time according to the input vertical synchronous signal (V _sync ), so the water ripple phenomenon can be effectively improved.

Although the present invention has been disclosed with preferred embodiments, it is not intended to limit the present invention. Those skilled in the art can make various changes and additions without departing from the spirit and scope of the present invention. Therefore, protection of the present invention The scope is determined by the appended claims.

Claims (11)

1. A method for preventing interference images, used to prevent the working signal of the light source of the display from interfering with image signals, the method comprising: The frequency of the working signal of the light source is adjusted so that the spectrum of the working signal of the light source is completely interleaved with the spectrum of the image signal. 2. The method according to claim 1, wherein each octave in the spectrum of the operating signal of the light source is located between adjacent octaves in the spectrum of the image signal. 3. The method according to claim 1, wherein the image signal spectrum includes a first multiplied frequency and a second multiplied frequency, and the operating signal spectrum of the light source includes a third multiplied frequency, which is located in the first multiplied frequency and the second octave. 4. The method of claim 3, wherein the frequency of the third multiplier is 1.5 times the frequency of the first multiplier. 5. The method of claim 3, wherein the frequency of the third multiplier is 3 times the frequency of the first multiplier. 6. A device for preventing interference with images, used to prevent the working signal of the light source of the display from interfering with the image signal, said device comprising: a scaling controller, configured to output an operating signal of the light source according to the first signal; and a lighting device, coupled to the scaling controller, for lighting the light source according to the working signal of the light source, wherein the working signal of the light source has a frequency such that the frequency spectrum of the working signal and the frequency spectrum of the image signal are mutually completely staggered, Wherein, the first signal is a vertical synchronization signal. 7. The device according to claim 6, wherein the working signal of the light source is a pulse width modulation signal. 8. The apparatus of claim 6, wherein each multiplier in the spectrum of the operating signal of the light source is located between adjacent multipliers of the spectrum of the image signal. 9. The device according to claim 6, wherein the image signal spectrum includes a first multiplied frequency and a second multiplied frequency, and the operating signal spectrum of the light source includes a third multiplied frequency, which is located at the first multiplied frequency frequency and the second octave. 10. The apparatus of claim 9, wherein the frequency of the third multiplier is 1.5 times the frequency of the first multiplier. 11. The apparatus of claim 9, wherein the frequency of the third multiplier is 3 times the frequency of the first multiplier.

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