JP2002540476A - Method and apparatus for monitoring phase adjustment in flat panel displays - Google Patents

Abstract

The present invention relates to a method and apparatus for monitoring the phase adjustment between the pixel clock and the sampling clock of a graphic card of a flat panel display with an analog interface in a flat panel display-graphic card-computer system. . Here, a marker is set when the phase of the flat panel display is adjusted on the user side. This marker is queried when the flat panel display is switched on, the video mode is switched on the computer, and / or the graphics card is replaced, and / or the computer is replaced. If the query detects that the marker has not been set, a display is provided or a phase adjustment is introduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a method and apparatus for monitoring a phase adjustment between a pixel clock and a sampling clock of a graphic card of a flat panel display with an analog interface in a flat panel display-graphic card-computer system.

A flat panel display with an analog interface must be adapted to the graphics card of the connected computer. If the phase or sampling frequency is adjusted incorrectly, the image will not look sharp and will be disturbing.

In the standard mode, the value of the image position, that is, the vertical and horizontal adjustments and the sampling frequency can be determined as values to be adjusted in advance, but this is not possible for the phase. This is because the phase depends on the graphics card and the video line used.

[0004] Flat panel displays according to the prior art are usually provided with a microprocessor responsible for general control of the flat panel display. The microprocessor is configured to identify the computer adjusted video mode. If this mode has already been adjusted by the manufacturer or the user, the flat panel display is driven by the adjustment amounts stored for the image position, sampling frequency and phase. If, on the other hand, the mode remains the same as before the microprocessor was incorporated into the flat panel display, the standard mode is adopted for the image position, sampling frequency and phase. However, the standard mode is not satisfactory in all cases.

[0005] Adjustment of the sampling clock and phase directly affects image quality. The optimal sampling frequency is obtained, for example, if the sampling of all pixels of one scan line of the video signal takes place in a stable or characteristic region of the pixels (eg in the center of each pixel). In that case, the data conversion results in optimal results. The displayed image is stable without obstacles. In other words, the optimal sampling frequency is equal to the pixel frequency. If the wrong sampling frequency is set, for example, if the sampling clock is much faster than the pixel clock, the pixel will first be sampled in the allowed area, i.e. the center of the two edges, but subsequent pixels will always be in one It is sampled in the direction of the edges, and eventually the area between the two pixels is completely sampled. This clearly degrades the image quality. In areas where pixels are not sampled in the optimal feature area, incorrect sampling values are derived. The image shows strong vertical obstructions. As the frequency difference between the sampling clock and the pixel clock increases, more and more regions with vertical obstruction will be seen on the screen.

Further, even in the case where the sampling clock and the pixel clock match, if the phase cannot be adjusted properly, the image quality deteriorates. The reason for this is that the sampling is performed in an area of a pixel that is not ideally suited for sampling, for example in the vicinity of or in front or behind the pixel in question.
This problem is solved by shifting the phase or sampling instant as a whole until the sampling takes place in the characteristic or permissible region of the pixel. If the phase is not adjusted correctly, the image quality will be degraded by noise signals over the entire screen.

[0007] Many users do not know the relationship between sampling frequency and phase and image quality. If the image is not sharp, it is considered defective and customer service is required. This has unnecessary costs. Many users do not look at the hints on the instruction manual or display package. Furthermore, some users are unaware that the respective resolution adjusted for the graphics card requires unique compensation. If the image quality is insufficient for the reasons mentioned above, it is most convenient to contact customer service or a manufacturer hotline, which will prompt the user to compensate for the phase to be performed. However, in some cases, a perfect monitor may even be sent as a guarantee, although only the phase needs to be adjusted accurately.

[0008] From DE-A-39 14 249 a method is known for reconstructing an input signal formed by an unknown clock. Here, the input signal is digitized at various phase positions with the comparison clock. The difference between the clock frequency of the input signal and the comparison clock is determined from the characteristics of the phase position of the input signal with respect to the comparison clock, and the frequency of the comparison clock is corrected accordingly.

[0009] DE-A-197 51 719 describes a signal processing process for analog image signals. Here, the analog image signal is calculated by a calculation unit. This signal is digitally corresponding to a graphics standard, for example EGA or VGA, and subsequently converted to analog form. In this process, the analog image signal is subjected to analog-to-digital conversion at a selected first sampling frequency, and the sampled image is then inspected for image obstruction and a corrected sampling frequency is determined. Another approach involves determining the optimal sampling phase and determining the exact relative position between the active image and the horizontal or vertical sync pulses.

In this regard, it is an object of the present invention to provide a method and apparatus for monitoring a phase adjustment in a flat panel display so that the required phase adjustment can always be performed when such an adjustment is required. It is.

[0011] The object of the present invention is to provide a method for setting a marker when the phase of a flat panel display is adjusted by a user, switching on the flat panel display or switching a video mode on a computer, and / or graphics. Inquiry of this marker when replacing the card and / or computer, and display or introduce phase adjustment if the inquiry detects that the marker is not set Is solved by

In other words, a marker is inserted in a mode other than the adjustment already stored for each mode, and this marker is set when the user adjusts the phase. This not only informs the user of the necessity of the phase adjustment by means of an instruction manual or other attachments, but also makes it so-called forced whenever necessary.

When the flat panel display is switched on or the video mode of the computer is switched, the processor residing in the flat panel display queries the markers stored for the current mode. If the marker is set, i.e. if the flat panel display has already been adjusted to the user's system, further service of the system is performed as usual. On the other hand, when the marker is not set, the flat panel display takes a predetermined reaction and performs a corresponding display or automatically starts the phase adjustment.

In an advantageous embodiment of the method according to the invention, the markers are erased after a change in the video mode on the computer and / or after the replacement of the graphics card and / or after the replacement of the computer. In a new monitor, the marker must be erased for all pre-adjusted modes. Because the phase has not yet been adjusted for the user's system. Not only in these cases,
Each time a system change requires phase compensation, this is detected by an advantageous embodiment of the method of the invention. The same applies to a mode in which no pre-adjustment is performed in the flat panel display.

[0015] In another advantageous embodiment of the method of the invention, the markers are set or erased in a microprocessor of the flat panel display. The indication is preferably output via the OSD. This makes use of existing hardware and saves costs.

In a further advantageous embodiment of the method according to the invention, after the phase adjustment, at least the first row above and / or below the image area when the mode conversion is detected is “
It is checked whether it is "black" and / or if at least the first column of the column, ie the front porch area and / or the back porch area, is "black", and if the test is positive, the marker This checks the phase adjustments made by the user and gives the user an indication if the phase adjustments made are not optimal.

In another advantageous embodiment of the method according to the invention, an automatic adjustment of the phase is introduced. Compared to manual phasing, automatic phasing is advantageous for a large number of users without expertise.

In another advantageous embodiment of the method according to the invention, the rising edge of the video pulse of a sufficiently bright pixel is determined, the falling edge of the video pulse of a sufficiently bright pixel is determined, and the sampling instant is the video pulse. The phase is adjusted so as to be located approximately at the center between the rising edge and the falling edge of the.

In another advantageous embodiment of the method according to the invention, the rising edge of the video pulse of a sufficiently bright pixel is determined and the sampling instant is shifted by approximately １ ／ of the pixel width in the direction of the pixel center. Is adjusted in phase.

In another advantageous embodiment of the method according to the invention, the falling edge of the video pulse of a sufficiently bright pixel is determined, and the sampling instant is shifted by approximately の of the pixel width in the direction of the pixel center. The phase is adjusted as follows.

Although the image position and the sampling frequency are relatively easily determined by a predetermined algorithm and adjusted accordingly, it is difficult to determine the position of the phase. The above three embodiments of the method of the present invention are simple and reliable means of phase adjustment.

In another advantageous embodiment of the method according to the invention, an image area having pixels on a flat panel display is arranged between the back porch area and the front porch area in a matrix to determine a rising edge. The pixel of the first image column adjacent to the back porch region is selected as a sufficiently bright pixel, and the pixel of the first image column adjacent to the back porch region is selected as a sufficiently bright pixel for determining a falling edge. Is done. This method makes it possible, in particular, to evaluate the most prominent edges, as far as possible, in the case of successive regions or pixels having very different intensity intensities. The pixels of the first or the last image row are particularly well suited, since the necessary conditions in connection with the front porch area or the back porch area are completely satisfied and at a relatively low cost.

When automatically adjusting the phase position, a conventional flat panel display having an analog interface usually requires a unique test pattern for switching between white pixels and black pixels. This test pattern must be displayed by the graphic card. This has the disadvantage that the software has to be installed and started on the computer, and that the software has to be usable on all current operating systems. In contrast, in the above-described preferred embodiment of the method according to the invention, an automatic phase adjustment can be performed, advantageously without the need for such test patterns or corresponding software.

In another advantageous embodiment of the method of the invention, the brightness of a plurality of pixels of the first and the last image sequence is measured and the maximum brightness in the first and the last image sequence is determined. The pixels having are selected to determine the rising and falling edges of the video pulse. In this way, pixels with well-defined edges can be used for the measurement.

In another advantageous embodiment of the method according to the invention, first the pixels (n × k) n = 1, 2,. . . , N k = a constant, eg, 10, is measured, and if a sufficiently bright pixel is not found, pixels (n + m) × km = 1, 2,. . . , N 2 are measured. As a result, an appropriate pixel search is efficiently performed in a short time.

In another advantageous embodiment of the method of the invention, in order to determine the amplitude value of the pixel,
The phase is shifted until the measured amplitude value no longer fluctuates, and the determined amplitude value is subsequently processed.

Alternatively, in another advantageous embodiment of the method according to the invention, the phase used in determining the amplitude value is advanced to a predetermined limit value, for example less than 50% of the amplitude value,
The phase is further delayed by half the pixel width, and the measured amplitude value is further processed.

The above two embodiments of the method of the invention are simple means of determining the brightness of a pixel as a prerequisite for determining the location of the rising and falling edges of the pixel.

In another advantageous embodiment of the invention, the phase of the back porch region is reduced until the measured amplitude value falls to a predetermined percentage, for example 50% of the previously determined amplitude value, in order to determine the rising edge. And the phase value is temporarily stored as the position of the rising edge. In a further advantageous embodiment of the invention, the phase is shifted in the direction of the front porch area until the measured amplitude value drops to a predetermined percentage, for example 50% of the previously determined amplitude value, in order to determine the falling edge. And the phase value is temporarily stored as the position of the falling edge. In this way, the rising and falling edges of the two pixels are easily determined and the phase can be highly adjusted to be approximately centered between the rising and falling edges of the pixel.

In order to solve the above-mentioned problem, an apparatus for monitoring a phase adjustment between a pixel clock and a sampling clock of a graphic card of a flat panel display having an analog interface in a flat panel display-graphic card-computer system is provided. A microprocessor that sets a marker when the phase of the flat panel display is adjusted by the user, switches on the flat panel display, or switches the video mode on a computer, And / or replace graphics card and / or computer,
If it is detected that the marker is not set at the time of the inquiry, the display is performed or the phase adjustment is introduced. With this device, the invention can be easily implemented with simple means and very efficiently.

In another advantageous embodiment of the device according to the invention, a device for determining the rising edge of a video pulse of a sufficiently bright pixel in a first image sequence adjacent to a back porch region, and a video of a sufficiently bright pixel A device for determining the falling edge of the pulse in the last image sequence adjacent to the front porch area, and an adjustment to adjust the phase so that the sampling time is approximately centered between the rising and falling edges of the video pulse And an apparatus.

[0032] Further advantageous embodiments of the method and the device according to the invention are described in the further dependent claims.

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a block circuit diagram of a flat panel display connected to a graphic card of a computer system via an analog interface. FIGS. 2A and 2B show schematic diagrams of video signals. FIG. 3 shows a schematic diagram of a rising edge and a falling edge of a pixel of a video signal. FIGS. 4A and 4B show the effects of the two ideal video signals and the relative positions of the sampling pulses and the video signals.

FIG. 1 shows a control circuit for a flat panel display connected via an analog interface. The function of this control circuit will be described in detail below based on various input signals and their processing. On the input side of the control circuit, on the one hand, a video signal consisting of three color signals R, G, B is applied, and on the other hand, two synchronization signals H-sync, V-sync for horizontal and vertical image synchronization. Applied. H-sync and V-sync are transmitted digitally, and the signal voltage here is 0.
And> 3V. V-sync signals that the first row of the image is transmitted. This signal corresponds to the image repetition frequency, typically 60 Hz to 85 H
z. H-sync signals that a new image row will be transmitted. This signal corresponds to the line frequency and is typically 60 kHz.

The video signal composed of the color signals R, G, B is an analog signal. Signal voltage is 0V
０．７0.7V. The pixel clock, ie, the frequency at which the value of this voltage is changed, is 80 MHz. Since a predetermined number of pixels are transmitted per image row, the pixel clock is higher than the scan line frequency H-sync by that number of pixels.

The three color signals R, G, and B of the video signal are supplied to analog-digital converters ADCR, ADCG, and ADCB via a video amplifier VA. The two synchronization signals H-sync, V-sync are processed in separate circuits HSy, VSy, and the signal edges obscured by transmission and various EMV measures are refreshed. The synchronization signals H-sync and V-sync processed in this way are subsequently supplied to the microprocessor μP. The microprocessor μP measures the frequency and determines therefrom the adjusted resolution in the graphics card of the computer system. Subsequently, the data stored for this resolution is supplied to a phase control circuit PLL and a logic circuit realized in the form of an ASIC in parallel therewith for processing digital data.

The phase control circuit PLL controls the frequency of the synchronization signal H-sync and the microprocessor μ.
Multiply by the value sent from P. As a result, a sampling frequency (pixel clock) is obtained. Due to the delay time generated in the phase control circuit PLL, a phase difference occurs between the pixel clock and the sampling frequency. These two parameters are controlled via an on-screen OSD display. The sampling frequency obtained by the phase control circuit is further converted into three analog-digital converters ADCR and ADCG.
, ADCB. These converters convert an analog data stream into a digital data stream. The digitized data is further processed in a subsequent logic circuit ASIC using the data contained in the video memory VM. In the simplest case, the data is transmitted 1: 1 to a flat panel display connected to a logic circuit ASIC, and the video memory VM often has a time separation between the incoming data and the data transmitted to the flat panel display D. Used for Access to data stored in the video memory VM is similarly performed for low-resolution interpolation.

As mentioned above, in addition to adjusting the image position, sampling frequency and phase,
The user adjusts the phase and the marker is set in the flat panel display microprocessor after changes affecting the phase are made in the flat panel display-graphics card-computer system. The phase value stored at the time of adjustment by the manufacturer is a standard value or merely a set value overwritten by adjustment by the user.

In a new flat panel display, the markers should have been erased for all the modes adjusted in advance. In the event of a change in the graphics card or a change in the computer settings, the phase must be adjusted again and in order to instruct the user to make the necessary adjustments at the next start of use of the flat panel display Markers must be deleted accordingly. The same is, of course, true for modes that have not yet been pre-adjusted on flat panel displays.

If the marker is not set in any case and the flat panel display is switched on, the microprocessor displays a message, for example, via the OSD (on screen display) of the flat panel display and gives the user a phase adjustment. Prompt. Otherwise, if there is no marker, the phase adjustment starts automatically.

In a preferred embodiment of the invention, a check is made of the phase adjustments made by the user and a check is made at each mode change to see if the system has changed. In this way, it is detected whether or not the phase adjustment performed by the user is sufficient. During such inspection, one or more first rows above the image area, or one or more first rows below the image area, or one or more first rows adjacent to the front porch area Row of 1,
Alternatively, it is detected whether one or more first columns adjacent to the back porch area is "black". If the test finds that the corresponding row is not "black", the image is not centered correctly and needs to be aligned.
If the image is centered but the phase has not been adjusted correctly, at least one of the examined columns or rows is not "black". This is because part of the image information of the column / row adjacent to the image area is visible. In this case also, phase adjustment is required.

It is further pointed out that the invention detects all cases where the phase has to be adjusted later. Moreover, a case where the flat panel display is driven at the same resolution as another graphic card or another computer is also detected.

First, it can be seen from FIGS. 2A and 2B that the phase at which the video signal is sampled plays a large role in the quality of the image and that the phase is often different at different positions in different video signals. It is that it exists in. FIG. 2A shows a high speed video signal with overshoot, where the sampling area between the rising edge and the falling edge of the video signal is relatively narrow and is shifted in the direction of the falling edge. In contrast, FIG. 2B shows a slow video signal with no overshoot, with the sampling area between the rising and falling edges being relatively wide and centered approximately in the center. As can be seen by observing the two signals, for example, a slow video signal has a phase position on the right edge of the falling edge region, but no phase amplitude value is needed here. On the other hand, the required amplitude value is measured for the high-speed video signal at the same phase position. It can also be seen that the ideal phase position is located approximately at the center between the rising and falling edges of the video signal. The phase position must be adjusted to this value. Therefore, phase adjustment is important depending on the respective system.

As described above, automatic phase adjustment is more problematic than adjustment of other parameters. How this kind of automatic adjustment is performed will be further described with reference to the following figures.

When determining the phase position, one starts from the edge of the video signal. In order to determine the edge, this edge should be as strong as possible. This is the case where the signal at the front of the edge is made as small as possible to make the rear of the edge more prominent, or vice versa. The first requirement is ideally satisfied by the sampling gap or back porch and front porch regions, and the second requirement is satisfied by bright pixels. Bright pixels at the beginning of a scan line are very well suited for determining rising edges, and bright pixels at the end of a scan line are very well suited for determining falling edges.

In this case, it does not matter that this is the edge of two different pixels of different image scan lines. This is because the pixel clock and the sampling clock are known and are taken into account accordingly. The selected pixel has a sufficiently high intensity in at least one of the primary colors RGB so that edges of sufficiently large amplitude can be found.

Basically, all combinations of bright and dark pixels located in the video signal at any point are suitable for finding edges. In many cases,
The edge searched by the combination of the front porch area / back porch area and the bright pixels of the first image row / last image row can be determined. There is no need to search through the appropriate two pixel pairs throughout the image content.

As is apparent from the above, an ideal region for sampling a video signal is a region where the target value and the actual value of the signal match. However, it may be difficult to measure the amplitude in the edge region of the video signal. The reason is the jitter of the video signal and the sampling pulse. If the jitter is large compared to the rise and fall times of the video signal, the edge can be detected by averaging multiple measurements, but the description of the amplitude of the edge at the measurement point may not be applicable. There is.

FIGS. 4A and 4B show problems in detecting edges. A broken line representing a desired sampling point is inserted in the ideal video signal. The hatched area represents the area that is actually sampled through jitter during multiple measurements. When the measurements are averaged, in the first case the average is about 80%. If this average value is misinterpreted, it can be assumed that the rising edge is exactly where it reaches 80% of the amplitude. But that is not the case. 5 in the second case
A value of 0% is rather correct.

The result shows that it is almost impossible to find the position where the edge reaches a predetermined value due to jitter. The minimum error is often up to about 50% of the target value by averaging the measurements. Of course, other values can be searched. A small value has the advantage, for example, that the accuracy in determining the actual pixel amplitude can be somewhat reduced.

In the following, it is assumed that the image position and the sampling frequency have already been accurately adjusted. Further, it is possible to access data of the A / D converter. The rising and falling edges are determined (by performing the following steps) as follows.

Rising edge Search for a pixel in the first sequence of images having the largest possible value of R, G, or B.

[0053] 2. The actual value of the amplitude may be higher than the measured value since the phase would have been pre-adjusted in the first step and the measurement would be wrong. The actual value of the amplitude is determined by measurement at an appropriate sampling time. This is done by delaying the phase until the measured amplitude value no longer rises, or by advancing the phase until the measured amplitude value is very low. The phase value of interest marking the start of the edge is delayed by half the pixel width.

[0054] 3. The phase is shifted in the direction of the back porch area until the sampled value averaged over several measurements drops to about 50% of the value determined in the second step. The phase value concerned is temporarily stored because a rising edge exists here.

[0055] Falling edge Search for a pixel in the first sequence of images having the largest possible value of R, G, or B. In this case, it is sufficient to make only one measurement for each pixel to be examined. In order to obtain as accurate a measurement as possible, the phase before sampling must be adjusted to the value found in the second step.

[0056] 5. The averaged sampling value is about 50% of the value obtained in the fourth step
The phase is shifted toward the front porch area until the phase is reduced. The phase value concerned is temporarily stored since a falling edge exists here.

Alternatively, the rising edge of the video pulse for a sufficiently bright pixel is determined, and the sampling time is adjusted by adjusting the phase so that the sampling time is shifted by about の of the pixel width in the direction of the center of the pixel. Can be requested. Alternatively, the falling edge of the video pulse of a sufficiently bright pixel is determined, and the sampling time is determined by adjusting the phase so that the sampling time is shifted by about の of the pixel width in the direction of the center of the pixel. You may.
In this case, the above-mentioned first to fifth steps are correspondingly simplified.

The ideal sampling instant theoretically lies between two edges. However, it is more advantageous to consider that in practice it is not exactly at the center of the two edges, but rather sampled slightly later. As a result, an overshoot of the graphic card which may occur in some cases can be avoided, and a slight exponential characteristic of the edge can be taken into consideration.

In the hardware of the present invention, an apparatus for determining a rising edge of a video pulse of a sufficiently bright pixel, an apparatus for determining a falling edge of a video pulse of a sufficiently bright pixel, and a sampling point corresponding to a rising edge of a video pulse. An adjusting device for adjusting the phase so as to be located substantially at the center between the falling edge and
An apparatus is provided for shifting the phase until the measured amplitude value no longer fluctuates to determine the pixel sampling value and further processing the determined amplitude value.

Further, a device is provided for advancing the phase used in determining the sampling value until the measured amplitude value is smaller than a predetermined limit value, for example, 50% of the sampling value, and the phase is set to the pixel width. A device is provided for delaying by １ ／ and further processing the measured sampling values.

In order to further determine the rising edge, the measured amplitude value is determined by a predetermined percentage,
For example, a device is provided which shifts the phase in the direction of the back porch region until the amplitude value is reduced to 50% of the previously obtained amplitude value, and temporarily stores the phase value as the position of the rising edge. In order to determine the falling edge, the phase is shifted in the direction of the front porch area until the measured amplitude value decreases to a predetermined percentage, for example, 50% of the previously determined amplitude value, and this phase value is shifted to the falling edge. A device for temporarily storing the position is provided.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of a flat panel display.

FIG. 2 is a schematic diagram of a video signal.

FIG. 3 is a schematic diagram of a rising edge and a falling edge of a pixel of a video signal.

FIG. 4 illustrates the effect of two ideal video signals and the relative position of the sampling pulse and the video signal.

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Claims (30)

[Claims] 1. A method for monitoring the phase adjustment between a pixel clock and a sampling clock of a graphic card of a flat panel display with an analog interface in a flat panel display-graphic card-computer system, comprising the steps of: Sets the marker when adjusted by the user and queries the marker when switching on the flat panel display or switching the video mode on the computer and / or replacing the graphics card and / or replacing the computer. And performing a display or introducing a phase adjustment when it is detected at the inquiry that the marker is not set. A method of monitoring the phase adjustment. 2. The method according to claim 1, wherein the marker is erased after a change in the video mode on the computer and / or after the replacement of the graphics card and / or after the replacement of the computer. 3. The method according to claim 1, wherein the marker is set or erased in the microprocessor of the flat panel display. 4. The method according to claim 1, wherein the display is output via the OSD. 5. After the phase adjustment, when a mode conversion is detected, at least the first row above and / or below the image area is "black" and / or the column or front porch. 2. The method according to claim 1, further comprising checking whether at least the first column of the area and / or the back porch area is "black" and setting the marker only if the test was positive. 6. The method of claim 1, wherein automatic phase adjustment is introduced. 7. A method for determining a rising edge of a video pulse of a sufficiently bright pixel, determining a falling edge of a video pulse of a sufficiently bright pixel, and wherein a sampling point is substantially centered between a rising edge and a falling edge of the video pulse. 7. The method according to claim 6, wherein the phase is adjusted so that 8. The method of claim 6, wherein the rising edge of the video pulse of a sufficiently bright pixel is determined and the phase is adjusted so that the sampling instant is shifted by approximately one-half of the pixel width in the direction of the pixel center. . 9. The method of claim 6, wherein the falling edge of the video pulse of a sufficiently bright pixel is determined, and the phase is adjusted such that the sampling instant is shifted by approximately の of the pixel width in the direction of the pixel center. Method. 10. An image area having pixels on a flat panel display is arranged between the back porch area and the front porch area in a matrix and adjacent to the back porch area as a sufficiently bright pixel to determine a rising edge. 10. A pixel according to any one of claims 7 to 9, wherein a pixel of the first image column to be selected is selected and a pixel of the first image column adjacent to the front porch area is selected as a sufficiently bright pixel to determine a falling edge. The method of claim 1. 11. A method for measuring the brightness of a plurality of pixels in a first image sequence and a last image sequence, and determining a pixel having a maximum brightness in the first image sequence and the last image sequence in a rising edge and a falling edge of a video pulse. The method according to any one of claims 8 to 10, wherein the method is selected to determine an edge. 12. First, pixels (n × k) n = 1, 2,. . . , N k = constant, eg 10, and if no bright pixel is found, the pixels (n + m) × km = 1, 2,. . . , N 2 is measured. 13. The method according to claim 8, wherein the phase is shifted until the measured amplitude value does not fluctuate greatly in order to obtain the amplitude value of the pixel, and the obtained amplitude value is further processed. Method. 14. The phase used in determining the amplitude value is advanced until the measured amplitude value is smaller than a predetermined limit value, for example, 50% of the amplitude value, and the phase is further delayed by の of the pixel width. 11. The further processing of the measured amplitude values.
The method according to any one of the preceding claims. 15. The phase is shifted in the direction of the back porch area until the measured amplitude value drops to a predetermined percentage, for example 50% of the previously determined amplitude value, in order to determine the rising edge. 11. The method according to claim 8, wherein the position of the rising edge is temporarily stored. 16. The phase is shifted in the direction of the front porch area until the measured amplitude value is reduced to a predetermined percentage, for example 50% of the previously determined amplitude value, in order to determine the falling edge. Is temporarily stored as the position of the falling edge. 17. The method according to claim 8, wherein the phase and the sampling time are delayed by a predetermined value, for example, 10% of the pixel width, with respect to the center between the rising edge and the falling edge. the method of. 18. An apparatus for monitoring a phase adjustment between a pixel clock and a sampling clock of a graphic card of a flat panel display with an analog interface in a flat panel display-graphic card-computer system, wherein a microprocessor is provided. The microprocessor sets a marker when the phase of the flat panel display is adjusted by the user, switches on the flat panel display, and / or switches the video mode on the computer, and / or
Or configured to interrogate when exchanging a graphics card and / or computer, and to display or to introduce a phase adjustment if the interrogation detects that the marker is not set. An apparatus for monitoring phase adjustment. 19. The apparatus of claim 18, wherein the microprocessor is configured to erase the marker after changing the video mode on the computer and / or after replacing the graphics card and / or after replacing the computer. . 20. The apparatus of claim 18, wherein the microprocessor is configured to set or clear the marker within the microprocessor of the flat panel display. 21. The apparatus according to claim 18, further comprising a display device, wherein the display device outputs a display via the OSD. 22. An inspection device is provided, wherein at least the first line above and / or below the image area is “black” when the mode conversion after phase adjustment is detected by the inspection device. It is checked whether there is and / or whether at least the first row of the columns, ie the front porch area and / or the back porch area, is "black" and the marker is set only if the test was positive. 19. The device of claim 18, wherein the device is: 23. The device according to claim 18, wherein an adjusting device is provided, by which an automatic adjustment of the phase is introduced. 24. An apparatus for determining a rising edge of a video pulse of a sufficiently bright pixel in a first image sequence adjacent to a back porch region, and a falling edge of a video pulse of a sufficiently bright pixel adjacent to a front porch region. 24. An apparatus for determining within the last image sequence to be processed, and an adjusting apparatus for adjusting the phase such that the sampling time is located approximately at the center between the rising edge and the falling edge of the video pulse. The described device. 25. An apparatus for determining a rising edge of a video pulse of a sufficiently bright pixel in a first image sequence adjacent to a back porch region,
24. The apparatus of claim 23, wherein an adjusting device is provided for adjusting the phase such that the sampling time is shifted by about 1/2 of the pixel width in the direction of the pixel center. 26. An apparatus is provided for determining the falling edge of a video pulse of a sufficiently bright pixel in the last image sequence adjacent to the front porch region, wherein the sampling time is approximately one pixel width in the direction of the pixel center. 24. The device according to claim 23, wherein an adjusting device is provided for adjusting the phase so as to be shifted by / 2. 27. The apparatus according to claim 24, further comprising means for shifting the phase until the measured amplitude value does not fluctuate significantly to determine the sampling value of the pixel, and further processing the determined sampling value. An apparatus according to any one of the preceding claims. 28. A device is provided for advancing the phase used in determining the sampling value until the measured amplitude value is less than a predetermined limit value, for example, 50% of the sampling value, and furthermore, the phase is increased by one pixel width. 27. Apparatus according to any one of claims 24 to 26, wherein an apparatus is provided for delaying by / 2 and further processing the measured sampling values. 29. The phase is shifted in the direction of the back porch region until the measured amplitude value drops to a predetermined percentage, for example 50% of the previously determined amplitude value, to determine the rising edge, and the phase value is changed. 27. A device according to claim 24, further comprising a device for temporarily storing the position of the rising edge.
Item. 30. Shifting the phase in the direction of the front porch area until the measured amplitude value drops to a predetermined percentage, for example 50% of the previously determined amplitude value, to determine the falling edge, 27. Apparatus according to any of claims 24 to 26, characterized in that a device is provided for temporarily storing as the position of the falling edge.